Dissertations / Theses: 'Cardiac Functional Assessment'

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Puyol, Anton Esther. "A multimodal spatiotemporal atlas for cardiac functional assessment." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/a-multimodal-spatiotemporal-atlas-for-cardiac-functional-assessment(7c37e366-728b-4cb0-bffc-33f467c67354).html.

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The estimation of cardiac motion is an important aid in the quantification of the contractility and function of the left ventricular myocardium, as well in detect-ing cardiovascular disease. A statistical cardiac motion atlas provides a space in which the motions of a cohort of subjects can be directly compared. Statistical atlases have been proposed for characterising abnormal cardiac motion, as well as for detecting suspected disease as early as possible. Typically, such atlases are formed and applied using data from the same modality, e.g. cardiac magnetic resonance (MR) or 3D ultrasound (US). This thesis proposes a new pipeline to build a multi-modal cardiac atlas from both MR and US data. The hypothesis is that such an atlas will benefit from the synergies between the motion features derived from the two modalities. The processing pipeline of the multimodal motion atlas formation initially involves normalisation of subjects’ cardiac geometry and motion both spatially and over time, and extraction of motion descriptors, i.e. displacements. This step was accomplished following a similar pipeline proposed by other authors for single modality atlas formation. The main novelty of this project lies in the use of a dimensionality reduction algorithm to simultaneously reduce the dimension-ality of both the MR and US derived motion data. Three di ̇erent dimensional-ity reduction algorithms were investigated: Principal component analysis (PCA), Canonical correlation analysis (CCA), and Partial least squares regression (PLS). A leave-one-out cross validation was employed to quantify the accuracy of the three algorithms. Results show that Partial least squares regression resulted in lower errors, with a reconstruction error less than 2.5 mm for MR-derived motion data, and less than 3 mm for US-derived motion data. The second part of the project aims to describe a diagnostic pipeline which uses as input only US data, but is at the same time informed by a training database of multimodal MR and US data. To this end, the previous multi-modal cardiac motion atlas is used together with multi-view machine learning algorithms to combine and extract the most meaningful cardiac descriptors for classification using only US data. More specifically, two algorithms are proposed: multi-view linear discriminant analysis (MLDA) and multi-view Laplacian sup-port vector machines (MvLapSVM). Furthermore, a novel regional multi-view approach is proposed to exploit the regional relationships between the two modal-ities. The proposed pipeline is evaluated on the classification task of discrimi-nating between normals and patients with dilated cardiomyopathy. Results show that the use of multi-view classifiers together with a cardiac motion atlas results in a statistically significant improvement in accuracy compared to classification without the multimodal atlas. The highest accuracy for the global approach was achieved with the MvLapSVM algorithm and was 93.78%. In the regional case the highest accuracy was 95.78% using MvLapSVM. Finally, the framework is extended to integrate automatically estimated strain values, and the strain values are used to validate the proposed pipeline for at-las formation and identification of DCM patients. Results show similar patterns using displacement and strain values. However, strain values consistently have slightly higher errors than displacement values. Overall, I expect that the work presented in this thesis will have a significant impact on the assessment of cardiac function by enabling the exploitation of complementary information from multiple imaging modalities.

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Finnemore, Anna. "Quantitative assessment and functional correlates of cardiac mechanics and energetics in newborn infants." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25281.

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Introduction: As preterm birth and survival rates continue to rise, circulatory failure remains a leading cause of mortality and morbidity. Structural and functional variations in circulatory physiology within the preterm population have been described, secondary to pre and post natal factors. This study applied magnetic resonance imaging techniques to assess cardiac function; analysed suitable techniques for indexing functional parameters by body size and applied a novel method of body composition quantification to investigate the impact of varying growth patterns on cardiac measures. Methods: Steady state free precession MRI imaging was used to analyse cardiac function in 78 preterm neonates. Analysis techniques were validated by comparison to phase contrast measures in 40 infants. Current methods of indexing for body size were compared. A modified DIXON whole body MRI scan utilising chemical shift was validated in phantoms and in vivo and successfully applied to 20 infants to assess adipose tissue content. Results: Validation of acquisition and analysis techniques demonstrated an acceptable level of accuracy. Functional measures indexed by body weight generally decreased with increasing corrected gestational age but patterns were altered when indexed by body surface area. Allometric transformation did not significantly improve correlation between size and function. Full body MDIXON scans demonstrated variations in body fat percentage of between 15 and 25%. Indexing cardiac function by lean body mass gave differing trends to total weight. Conclusions: Analysis of cardiac function in preterm neonates using MRI can be used to describe normative ranges and causes of variation for functional parameters. However, until an appropriate indexing technique for body size can be determined, the impact of pre and post natal factors cannot be fully understood. Analysis of body composition using MRI imaging may present a new indexing technique and allow us to investigate the effects of different growth patterns on cardiac function.

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Dreyer, Liezel Ann. "Current practices in cardiac rehabilitation : implications for scope of rehabilitation and assessment of functional capacity." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/2750.

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Pepera, Garyfallia K. "Assessments of functional capacity in cardiac rehabilitation." Thesis, University of Essex, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536959.

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Chan-Dewar, Fang. "Cardiac mechanics and activation delay in the assessment of exercise-induced changes in cardiac function." Thesis, Liverpool John Moores University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549431.

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Brookes, Carl I. O. "The evaluation and assessment of right ventricular function using conductance catheters." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326042.

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Scott-Park, Freda Marion. "Quantitative assessment of the cardiac function in dogs using the apexcardiogram." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/29988.

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Grigorescu, Fredriksson Alexandru. "Blood flow specific assessment of ventricular function : Visualization and quantification using 4D flow CMR." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143417.

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The spectrum of cardiovascular diseases is the leading cause of morbidity and mortality globally. Early assessment and treatment of these conditions, acquired as well as congenital, is therefore of paramount importance. The human heart has a great ability to adapt to various hemodynamic conditions by cardiac remodeling. Pathologic cardiac remodeling can occur as a result of cardiovascular disease in an effort to maintain satisfactory cardiac function. With time, cardiac function diminishes leading to disease progression and subsequent heart failure, the end-point of many heart diseases, associated with very poor prognosis. Within the normal cardiac ventricles blood flows in highly organized patterns, and changes in cardiac configuration or function will affect these flow patterns. Conversely, altered flows and pressures can bring about cardiac remodeling. In congenital heart disease, even after corrective surgery, cardiac anatomy and thereby intracardiac blood flow patterns are inherently altered. The clinically most available imaging technique, ultrasound with Doppler, allows only for one-directional flow assessment and is limited by the need of clear examination windows, thus failing to fully assess the complex three-dimensional blood flow within the beating heart. Cardiovascular magnetic resonance imaging (CMR) with phase-contrast has the ability to acquire three-dimensional (3D), three-directional time resolved velocity data (3D + time = 4D flow data) from which visualization and quantification of blood flow patterns over the complete cardiac cycle can be performed. Four functional blood flow components have previously been defined based on the blood route and distribution through the ventricle, where the inflowing blood that passes directly to the outflow is called Direct flow. From these components, various quantitative measures can be derived, such as component volumes and kinetic energy (KE) throughout the cardiac cycle. In addition, the 4D flow technique has the ability to quantify and visualize turbulent flow with increased velocity fluctuations in the heart and vessels, turbulent kinetic energy (TKE). The technique has been developed and evaluated for assessment of left ventricular (LV) blood flow in healthy subjects and in patients with dilated dysfunctional left ventricles, showing significant changes in blood flow patterns and energetics with disease. There is however still no study addressing the gap in the spectrum from the healthy cohorts to patients with moderate to severe left ventricular remodeling. In Paper III, 4D flow CMR was utilized to assess LV blood flow in patients with subtle LV dysfunction, and a shift in blood flow component volumes and KE was seen from the Direct flow to the non-ejecting blood flow components. In patients with both left- and right-sided acquired and congenital heart disease, right ventricular (RV) function is of great prognostic significance, however this ventricle has historically been somewhat overseen. With its complex geometry, advanced physiology and retrosternal location, assessment of the RV is still challenging and the right ventricular blood flow is still incompletely described. In Paper I, the RV blood flow in healthy subjects was assessed, and the proportionally larger Direct flow component was located in the most basal region of the ventricle and possessed higher levels of KE at end-diastole than the other flow components suggesting that this portion of blood was prepared for efficient systolic ejection. In Paper II, the blood flow was assessed in the RV of patients with subtle primary LV disease, and even if conventional echocardiographic or CMR RV parameters did not show any RV dysfunction, alterations of flow patterns suggestive of RV impairment were found in the patients with the more remodeled LVs. With improvements of the cardiovascular health care, including the surgical techniques, the number of adult patients with surgically corrected complex congenital heart diseases increases, one of which is tetralogy of Fallot (ToF). Surgical repair of ToF involves widening of the pulmonary stenosis, which postoperatively may cause pulmonary insufficiency and regurgitation (PR). Disturbed or turbulent flow patterns are rare in the healthy cardiovascular system. With pathological changes, such as valvular insufficiency, increased amounts of TKE have been demonstrated. Turbulence is known to be harmful to organic tissues and could be significant in the development of ventricular remodeling, such as dilation and other complications seen in Fallot patients. In Paper IV, the RV intraventricular TKE levels were assessed in relation to conventional measures of PR. Results showed that RV TKE was increased in ToF patients with PR compared to healthy controls, and that these 4D flow-specific measures related slightly stronger to indices of RV remodeling than the conventional measures of PR. 4D flow CMR analysis of the intracardiac blood flow has the potential of adding to pathophysiological understanding, and thereby provide useful diagnostic information and contribute to optimization of treatment of heart disease at earlier stages before irreversible and clinically noticeable changes occur. The flow specific measures used in this thesis could be utilized to detect these alterations of intracardiac blood flow and could thus act as potential markers of progressing ventricular dysfunction, pathological remodeling or used for risk stratification in adults with early repair tetralogy of Fallot. Visualizations of intracardiac flow patterns could provide useful information to cardiac/thoracic surgeons pre- and post-operatively.

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McIntosh, Robert A. "Novel contractility assessments in the evaluation of cardiac function : applications to common clinical practice and cardiac device therapy." Thesis, St George's, University of London, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.754069.

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Background Commonly employed assessments of systolic cardiac function are limited by their emphasis on two-dimensional assessment of chamber volume or dimension at end-systole and end- diastole. Such measures are poorly reproducible and are sensitive to limitations in image quality and changes in haemodynamic loading. In performing examinations only at rest, we also fail to assess the ability of the myocardium to augment in its contraction. These limitations may explain why such assessments often correlate poorly with patient symptoms and exercise capacity. By developing enhanced assessment techniques we may improve the relevance of our investigations and allow for detection of cardiac disease at an earlier stage than is currently possible. Methods Standard echocardiographic measures of systolic function (left ventricular ejection fraction (LVEF), left ventricular outflow tract velocity time integral (LVOT VTI) and cardiac output (CO)); measures of left ventricular contractility obtained by pulsed-wave tissue Doppler examination (LV Vmax) and measures of contractility derived from sensor-derived peak-endocardial acceleration (PEA1) or closed loop (CLS) assessments were obtained during rest, exercise and/or dobutamine stress. Groups studied included healthy subjects, patients with heart failure and reduced left ventricular ejection fraction (HFREF), subjects undergoing mitral valve repair, patients with implanted cardiac devices and subjects with persistent atrial fibrillation. During exercise assessments, cardiopulmonary gas exchange analysis was performed allowing for calculation of peak oxygen uptake (pVCh). PEA1 and femoral artery dP/dTmax measures were also obtained in subjects undergoing invasive electrophysiology studies in both sinus rhythm and during arrhythmia. Results In a resting comparison between heart failure (N=20) and healthy control subjects (N=10), both LVEF (P=<0.01) and LV Vmax (P=<0.01) were significantly lower in the heart failure population. There was no difference in resting PEA measures between the groups. During exercise significant differences in LVEF (P=<0.01), LV Vmax (P=<0.01), LVOT VTI (P=<0.01), CO (P=<0.01) and PEA1 (P=<0.01) were identified. LV Vmax during both rest (R=0.535, P=0.006) and exercise (R=0.774, P=<0.001) was the parameter most strongly related to pVO2. There was no significant relationship between pVO2 and any other resting contractility parameter. Of other parameters on exercise, only LVEF (R=0.412 P=0.04) and change in PEA1 (R=0.409, P=0.04) showed a significant association with pVO2. In 10 subjects undergoing mitral valve repair, no PEA1 or echocardiographic contractility parameter during either rest or stress was significantly related to postoperative functional outcome as judged by change in pVO2 post-operatively. Change in LV Vmax (R=0.61, P=0.08) and change in PEA1 amplitude (R=0.6, P=0.09) during dobutamine stress displayed nonsignificant associations with post-operative change in pVO2. During invasive electrophysiology assessment in 57 subjects, change in PEA amplitude was found to be significantly related to change in femoral artery dP/dtmax during rhythm transition from sinus rhythm to both supraventricular tachycardia (R=0.52, P=0.069) and atrial fibrillation (R=0.68, P=0.005). PEA data extraction was not possible during rapid ventricular tachycardia (heart rate 255 ± 89bpm) due to described methodological constraints. Echocardiographic assessment of aortic VTI was conducted in 19 patients during cardiac resynchronisation therapy in states of rest, low-level exercise and atrial overdrive pacing. The effect of adjustment in atrio-ventricular (AV) and ventriculo-ventricular (VV) delay on mean aortic VTI was examined. There was substantial inter-subject variability in the haemodynamic response to adjustment of AV and VV delay within each state. Assessed across all states of testing, adjustment in VV delay was found to have no consistent independent impact on aortic VTI. Across all states adjustment in AV delay was found to have a significant independent impact on aortic VTI (P=0.02) with long (166±39ms) and medium (120±21ms) AV delays being associated with a higher AoVTI compared to short (78±8 ms) AV delays. In 22 atrio-ventricular (AV) node-ablated and paced subjects, tissue Doppler-derived electromechanical delay following a right ventricular pacing stimulus was assessed in relation to the CLS contractility waveform. At both three (R=0.518, P=0.019) and twelve months of follow-up (R=0.457, P=0.049), there was a significant association between electromechanical delay and the time between pacing stimulus delivery to trough CLS impedance. An analysis of 101 subjects undergoing cardiopulmonary exercise echocardiography included subjects from a range of cardiac patient groups. Of the echocardiographic parameters assessed, pVO2 was strongly related to LV Vmax on exertion (R=0.84, P < 0.001). The strength of this relationship was greater than that observed with any other echocardiographic measure of cardiac function either during rest or during exercise. Conclusion Of the echocardiographic measures of cardiac function that were assessed, LV Vmax was more strongly related to exercise capacity than any other assessment of systolic function. Examination on exertion increased the strength of the relationship and LV Vmax on exertion was the best echocardiographic indicator of functional capacity. Contractility data derived from the PEA and CLS sensors provides a means to incorporate haemodynamic measures of cardiac function into implantable device diagnostic monitoring or treatment algorithms. Such sensor-derived assessments may assist in improving technology in areas such as contractility monitoring, arrhythmia discrimination or pacing-interval optimisation.

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Fonseca, Carissa Grace. "Assessment of left ventricular diastolic function with three dimensional cardiac magnetic resonance imaging." Thesis, University of Auckland, 2004. http://hdl.handle.net/2292/5715.

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Measurement of diastolic left ventricular (LV) function is vitally important in the assessment of cardiac disease. However, only limited information on tissue function can be obtained with current clinical techniques. This Thesis developed and investigated novel parameters of both global and regional myocardial function, using cardiac magnetic resonance imaging (MRI) with three-dimensional tissue tagging. Multidirectional peak myocardial shortening strains and strain rates, as well as the peak systolic displacement and velocity of the mitral valve annulus plane (MVP), were considered as parameters of LV systolic function. The corresponding peak diastolic strain relaxation rates and peak diastolic MVP velocity were used to assess diastolic function. The effects of normal ageing were studied in people with no evidence of cardiac disease, and compared with the effects of disease in patients with type 2 diabetes mellitus (DM). In normal healthy subjects, systolic strain parameters were preserved, while diastolic parameters were impaired, with age. DM patients showed impaired diastolic function on correction for age, and systolic functional parameters were also impaired, even though LV ejection fraction was normal. MVP systolic and diastolic motion were reduced both with age and in DM patients. Systolic LV torsion was increased with age and in DM, with no corresponding increase in torsional relaxation. Both systolic and diastolic function parameters were regionally heterogeneous. With normal ageing, diastolic function was impaired in a regionally non-uniform manner. Thus, a complete assessment of LV function requires measurement of LV tissue mechanics as well as chamber haemodynamics. MRI provides valuable information regarding myocardial tissue behaviour, contributing to systolic and/or diastolic dysfunction, which cannot be obtained otherwise. Systolic tissue dysfunction may develop concomitantly in patients with diastolic dysfunction, even when global ejection fraction is preserved. Regional analyses provide important information on how local changes contribute to global function. The influence of age must be taken into account in studies of disease.

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Coats, Andrew J. S. "Doppler aortic velocimetry and the assessment of cardiac function in chronic heart failure." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305499.

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Lawless, Michael. "An integrative assessment of phosphodiesterase 5 inhibition on cardiac function in heart failure." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/an-integrative-assessment-of-phosphodiesterase-5-inhibition-on-cardiac-function-in-heart-failure(5d4e804f-591d-4131-8443-9f8c1b722f5d).html.

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Heart failure is the leading cause of morbidity and mortality in the world. It is an incurable disease and most treatment strategies aim to treat the symptoms or slow the progression of the condition. Cardiac contractility is governed by calcium homeostasis within cardiac myocytes and is modulated by the sympathetic nervous system. Both mechanisms are detrimentally altered in heart failure. An important group of enzymes, phosphodiesterases, are fundamental to the sympathetic (beta-adrenergic) modulation of calcium cycling in cardiac myocytes. The selective inhibition of phosphodiesterase 5 (PDE5) has recently been considered as a potential therapy for heart failure; having beneficial effects in human and animal models of the disease. The present study employs a large animal model of tachypacing induced heart failure to test the effect of PDE5 inhibition on myocyte and whole heart contractility and beta-adrenergic function, to assess the molecular mechanisms by which PDE5 inhibition is beneficial to the failing myocardium. In initial experiments the PDE5 inhibitor sildenafil was applied acutely to voltage clamped ventricular myocytes from uninstrumented sheep. PDE5 inhibition reduced baseline L-type calcium current and systolic calcium transient amplitude, suggesting it is negatively inotropic. Furthermore, the positive inotropic effects of beta-adrenergic stimulation were somewhat reversed by acute PDE5 inhibition. Interestingly, such negative inotropic effects of acute PDE5 inhibition were not observed in failing ventricular myocytes, which have dysfunctional calcium homeostasis and beta-adrenergic reserve. When delivered chronically over 3 weeks to tachypaced animals, PDE5 inhibition restored and augmented the systolic calcium transient and beta-adrenergic responsiveness at both the whole heart and myocyte level. These effects were associated with changes to the expression and phosphorylation status of the proteins that control calcium homeostasis in left ventricular tissue. In vivo, PDE5 inhibition prolonged longevity and reduced the onset of clinical signs of heart failure in sheep, as well as arresting cardiac dilatation and wall thinning. Chronic PDE5 inhibition however had no effect on cardiac contractility or heart failure induced changes in cardiac electrophysiology. This study presents a novel mechanism by which PDE5 inhibition may be beneficial in a large animal model of heart failure by restoring calcium homeostasis and beta-adrenergic responsiveness. This study may have important implications for the management of heart failure in clinical practice.

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Swoboda, Peter Paranthaman Louis. "Assessment of subclinical cardiac changes in structure and function by cardiovascular magnetic resonance." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/12592/.

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Background: The early identification of disease can benefit patients clinically and provide a powerful research tool. This thesis aims to identify subclinical cardiac change using cardiovascular magnetic resonance (CMR) in both disease and health and evaluate its diagnostic and prognostic uses. Methods: We have prospectively recruited and conducted multi-parametric CMR in 50 patients with hypertrophic cardiomyopathy (HCM), 40 endurance athletes and 100 asymptomatic patients with type 2 diabetes mellitus. Results: Study 1 and 2 evaluated CMR in the early diagnosis of HCM. Study 1 demonstrated the diagnostic accuracy of extracellular volume (ECV) mapping is superior to volumetric methods of differentiating HCM from athletic left ventricular (LV) hypertrophy. Study 2 demonstrated that ECV expansion could be detected prior to overt hypertrophy or impairment of contractile function in patients with HCM. Study 3 demonstrated that LV torsion is lower in endurance athletes than controls and is predominantly influenced by lactate threshold and intensity of training. Study 4 and 5 investigated the role of CMR in identifying patients with type 2 diabetes at risk of heart failure and silent myocardial infarction. Study 4 found that the increased risk of heart failure in patients with type 2 diabetes was mediated by ECV expansion and diffuse fibrosis. There was a high rate of silent myocardial infarction (17 %) which was unrelated to heart failure risk. In study 5 we developed a simple screening tool, using measures that can be carried out in a cardiology clinic, for the detection of silent myocardial infarction in type 2 diabetes. Conclusions: CMR is able to detect subclinical change in both tissue characteristics and function of the heart. This can aid the early and appropriate diagnosis of disease and identify those at the highest risk of adverse outcomes.

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Jorstig, Stina. "On the assessment of right ventricular function using cardiac magnetic resonance imaging and echocardiography." Doctoral thesis, Örebro universitet, Institutionen för medicinska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-51662.

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Transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) imaging are two commonly used imaging modalities for evaluating the size and function of the heart. There are advantages and disadvantages associated with both modalities when examining the right ventricle (RV). The RV is positioned partly behind the sternum and lung, sometimes causing shadows in the TTE images. This along with the complex shape of the RV makes volume calculations challenging by 2D TTE. CMR is considered to be the reference method for volume calculations of the ventricles. The valve separating the RV from the right atrium is however often oblique compared to the valve separating the left ventricle from the left atrium. This complicates RV volume calculations using conventional CMR short-axis stack images. The aim of this thesis was to find ways to improve the RV stroke volume and ejection fraction calculations using TTE and CMR. A method, transferring the position of the tricuspid plane from RV long-axis images to short-axis images, was developed to improve the separation of the right atrium from the RV when calculating RV stroke volumes by CMR. The method provided calculations of RV stroke volumes with good agreement to reference volumes. Further, the movements contributing to the RV stroke volume was studied aiming to find new ways of calculating RV stroke volumes and ejection fraction by TTE. A model for RV stroke volume and ejection fraction calculations was evaluated showing underestimation of stroke volumes by TTE compared to CMR, which probably depend on differences in distance measurements using the two modalities. The model provided, however, promising results for ejection fraction calculations which was validated in a study of 37 participants that covered a wide range of EF.

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Chambers, John Boyd. "Studies on the use of Doppler ultrasound in the assessment of prosthetic cardiac valve function." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390391.

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LaFountain, Richard A. "Validation of VO2max Assessment and Magnetic Resonance Cardiac Function Measurements Utilizing an MRI Compatible Treadmill." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405431417.

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Otsuka, Naoki. "Assessment of cardiac sympathetic function with iodine-123-MIBG imaging in obstructive sleep apnea syndrome." Kyoto University, 1997. http://hdl.handle.net/2433/202173.

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Cabrita, Ines Zimbarra. "The heart in Sickle Cell Disease : role of non invasive cardiac imaging by advanced echocardiography and cardiac magnetic resonance assessment of myocardial function." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24569.

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Sickle cell disease (SCD) is one of the most prevalent genetic disorders worldwide that affects approximately 12,000 people in the United Kingdom. Raised tricuspid regurgitant velocity (TRV), which may be related to left ventricular diastolic dysfunction (LV DD), occurs in approximately 30% of adults with SCD, and has been shown to be an independent risk factor for death. This thesis examines aspects of the role of LV DD in the development of increased tricuspid regurgitant velocity and investigates the hypothesis that myocardial dysfunction, affecting the right and left ventricle, is an important cardiovascular risk factor in patients with SCD. In the retrospective study, we determine the 5 year- survival of a cohort of patients with SCD based on their TRV. The association between raised TRV and mortality in a UK SCD population has been confirmed. Higher values of TRV were associated with a greater than 4 fold increased risk of death (HR: 4.48, 99%CI 1.01-19.8). In the prospective study, sixty-one patients with SCD were included in the study (mean duration of follow-up 17.13±3 months). In the serial echocardiographic study, left ventricular average E/E' ratio which is a predictor of increased left ventricular filling pressures, was independently associated with an increased tricuspid regurgitation velocity (p=0.007). In addition, blood urea nitrogen and global function index lateral showed independent association with an increased LV lateral E/E' ratio. Biventricular myocardial deformation by 2D and 3D speckle tracking revealed significant changes in the serial measurements of systolic function. These findings provide novel insight into the pathophysiology of the cardiovascular complications of SCD and support the implementation of echocardiographic screening of adult patients with SCD to identify high-risk individuals for further evaluation.

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Backlund, Emma. "Assessment of ventricular morphology using echocardiography in Ornate tinamous (Nothoprocta ornata) and domestic chickens (Gallus domesticus)." Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-103754.

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The Ornate Tinamou (Nothoprocta ornata), an ancient bird, has adapted to life at high altitude (>2.400 m.a.s.l) for a longer period than the domestic chicken (Gallus domesticus), which came to South America with the Spanish conquerors. Ornate tinamous have a smaller heart in relation to body size than domestic chickens. This study was made to evaluate heart morphometric measurements comparing Ornate Tinamou and domestic chicken using echocardiography measurements to determine wall thickness and chamber size and to evaluate whether it can retrieve measurements consistent with previous results on dissected hearts. I was also interested in evaluating potential adaptations of the Ornate Tinamou to life in hypoxic environments by exposing the heart to positive inotropic stimulation. The results were compared with those previously obtained on dissected hearts. The results showed that the chamber size of the domestic chicken was significantly larger than in Ornate Tinamou, both in conscious and anesthetized birds. Injection of 1µg/kg isoproterenol caused domestic chickens’ systolic chamber size to decrease significantly and fractional shortening to increase significantly. The same changes were seen in the Ornate Tinamou but they were not significant. In conclusion, this study confirms that echocardiography is a valid method for retrieving cardiac measurements without euthanizing animals, opening for the possibility of taking several measurements at different ages.

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Wright, D. J. "Towards a more comprehensive, non-invasive evaluation of cardiac function in the assessment of therapeutic interventions." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399663.

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Mahmod, Masliza. "Multiparametric cardiovascular magnetic resonance for the assessment of cardiac function and metabolism in hypertrophy and heart failure." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:ff24c167-e00d-4c6d-9809-82203979ba7a.

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Both hypertrophied and failing hearts are characterised by pathological left ventricular (LV) remodelling, impaired myocardial energy status and alteration in substrate metabolism. Cardiac magnetic resonance imaging (CMR) and magnetic resonance spectroscopy (MRS) are powerful tools in the characterisation of these disease conditions. More recent techniques have allowed assessment of myocardial steatosis using ¹H-MRS and tissue oxygenation using blood oxygen level dependent (BOLD) CMR. In hypertrophy and heart failure, studies on steatosis and the relationship with other parameters such as myocardial function and fibrosis, especially in humans are limited. I therefore investigated the presence of steatosis in severe aortic stenosis (AS) and dilated cardiomyopathy (DCM), and further assessed its relation to contractile function. This study found that myocardial triglyceride (TG) content is increased in both symptomatic and asymptomatic AS patients (lipid/water ratio 0.89±0.42% in symptomatic AS; 0.75±0.36% in asymptomatic AS vs. controls 0.45±0.17%, both p<0.05) and DCM patients (lipid/ratio 0.64±0.44% vs. controls 0.40±0.13%, p=0.03). Circumferential strain was lower in both AS (-16.4±2.5% in symptomatic AS; -18.9±2.9% in asymptomatic AS vs. controls 20.7±2.0%, both p<0.05) and DCM patients (-12.3±3.4% vs. controls -20.9±1.7%, p<0.001). In AS, myocardial contractility is related to the degree of steatosis, and were both reversible following aortic valve replacement (AVR), lipid/water ratio 0.92±0.41% vs. pre AVR 0.45±0.17%, p=0.04 and circumferential strain -17.2±2.0% vs. pre AVR -19.5±3.2%, p=0.04. A novel finding of this study was significant correlation of MRS-measured TG content with histological staining of TG of the myocardium, taken from endomyocardial biopsy during AVR. In DCM, myocardial TG was independently associated with LV dilatation and correlated significantly with hepatic TG, which suggests that both cardiac and hepatic steatosis might be a common feature in the failing heart. Additionally, although the hypertrophied heart is characterised by impaired perfusion, it is unknown if this is severe enough to translate into tissue deoxygenation and ischaemia. I assessed this by using adenosine vasodilator stress test and BOLD-CMR in patients with severe AS. It was found that AS patients had reduced perfusion (myocardial perfusion reserve index-MPRI 1.0±0.3 vs. controls 1.7±0.3, p<0.001), and blunted tissue oxygenation (blood-oxygen level dependent-BOLD signal intensity-SI change 4.8±9.6% vs. controls 18.2±11.6%, p=0.001) during stress. Importantly, there was a substantial improvement in perfusion and oxygenation towards normal after AVR, MPRI 1.5±0.4, p=0.005 vs. pre AVR and BOLD SI change 16.4±7.0%, p=0.014 vs. pre AVR. Overall, the work in this thesis supports the powerful role of CMR in assessing LV function and elucidating metabolic mechanisms in the hypertrophied and failing heart.

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22

McLure, Lindsey Elizabeth Robertson. "The role of cardiac magnetic resonance imaging in the assessment of right ventricular function in pulmonary hypertension." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6884/.

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Pulmonary hypertension (PH) is a rare disease of the pulmonary arteries. It is characterised by vascular proliferation and remodelling resulting in a progressive increase in pulmonary vascular resistance and right ventricular failure. The functional capacity of the right ventricle is the major prognostic determinant in PH, and death usually results from right ventricular failure. Although recent therapeutic advances have improved the short-to-medium term outlook of PH patients, early death due to right ventricular failure remains inevitable in many patients. The imperative role of RV performance in the clinical status and long- term outcome in PH patients is evident. Evaluation of right ventricular function is essential in the management of patients with pulmonary hypertension. Current methods of assessment of PH patients are suboptimal. The right ventricle is difficult to assess due to its position and geometry. Recent developments in imaging techniques, such as cardiac magnetic resonance (CMR) imaging and echocardiography, have improved our understanding of the structure and function of the right ventricle. Assessment of RV function is complex and no single measurement is generally accepted in clinical practice. The experimental work performed in this thesis aimed to improve our understanding of RV function in PH patients and to provide clarity in the role of CMR in the non-invasive assessment and monitoring of pulmonary hypertension patients. A non-invasive measurement of stroke volume would be beneficial to monitor disease progression in pulmonary hypertension patients. Chapter 3 demonstrated that cardiac magnetic resonance imaging provided non-invasive measurements of stroke volume that were as accurate as those obtained by thermodilution measured during right heart catheterisation. Inert gas rebreathing using photoacoustic analysis also provided accurate non-invasive measurements of stroke volume. Chapter 4 compared two patient groups: idiopathic pulmonary arterial hypertension (IPAH) and pulmonary hypertension associated with connective tissue disease (CTDPAH). We clarified that there was no significant differences in RV structure and performance between these two distinct patient groups to account for the poorer prognosis in the CTDPAH group. Treatments for PH are always expensive, sometimes invasive and carry significant side effects. It is imperative that we are able to assess the patient’s response to therapy in a clinically meaningful, accurate and non-invasive manner. The importance of escalating therapy if a patient does not respond to initial treatment has been emphasised in recently published guidelines. Current monitoring techniques have acknowledged limitations and are suboptimal. Chapter 5 presents the results obtained from my contribution to the prospective, longitudinal multinational EURO-MR study. Longitudinal CMR examination identified significant improvements in cardiac function with the introduction of disease-targeted therapy. Baseline and 4 months post therapy CMR scans were compared. It is anticipated that CMR could be a useful monitoring technique for patients with pulmonary hypertension.

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Paramasivam, Gowrishankar. "Ultrasound assessment of fetal cardiac function and risk of adverse obstetric and neonatal outcomes in term fetuses." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/48187.

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Aim: To measure fetal cardiac output prior to labour and assess the risk of adverse obstetric and neonatal outcome in singleton pregnancies with appropriately grown for gestational age (AGA) fetuses at term. Methods: This was a prospective observational study conducted at Queen Charlotte’s and Chelsea Hospital, London UK. Fetal cardiac output and fetal cerebroplacental ratio (CPR) was measured within 72 hours before birth in 200 nulliparous women having singleton pregnancies with AGA fetuses. Scan details were not available to the clinicians and delivery was managed per the local protocol and guidelines. Obstetric and neonatal outcomes were obtained from case notes and correlated with the ultrasound findings. Results: Delivery was vaginal in 129 (64.5%) cases and by caesarean section in 71 (35.5%), including 34 (17.0%) for fetal distress and 37 (18.5%) for failure to progress. Fetuses delivered by caesarean section for fetal distress, compared to the remaining fetuses, had a lower median left cardiac output(LCO) (152.3 vs. 191.7 mL/min/kg; p=0.003), higher difference in the median ratio between the right to left cardiac output (RCO to LCO ratio) 1.925 vs. 1.340; p=0.002) and lower CPR (1.222 vs. 1.607; p < 0.0001). In screening for emergency caesarean section for fetal distress, for a 10% false positive rate, the detection rate with the RCO to LCO ratio was higher that with the LCO (41% vs. 29%) and with the CPR (41% vs. 27%). Similarly, the positive predictive value for the RCO to LCO ratio (45%) was higher than LCO (37%) and the CPR (35%). Conclusion: In AGA fetuses at term that develop intrapartum distress, there is evidence of prelabour redistribution of the cardiac output. The RCO to LCO ratio is superior to the LCO and CPR in predicting intrapartum fetal distress. Such assessments may be useful in stratifying patients for the intensity of monitoring during labour.

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Unsworth, Bethan. "The assessment of right ventricular function during and following routine cardiac surgery and the evaluation of preserving pericardial integrity." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9048.

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The assessment of right ventricular tricuspid annular velocities and excursion is a robust and common technique of evaluating right ventricular function. The measurement of peak systolic myocardial velocities using pulsed wave tissue Doppler imaging correlates well with estimates of systolic function. It is well known that right ventricular velocities are significantly reduced in patients following cardiac surgery; however the precise cause of this post-operative phenomenon remains unknown despite a number of proposed mechanisms. In this thesis I have carried out observational studies before, during and after surgery in number of patients undergoing different cardiac and thoracic operations. I found using intra-operative transoesophageal and pre and post-operative transthoracic echocardiography that the onset of right ventricular myocardial velocity reduction is immediately marked by the full opening of the pericardium following traditional-midline thoracotomy. I also identified that this reduction is present in all operations where the pericardium is opened fully regardless of the underlying pathology i.e. cardiac or noncardiac. By measuring simultaneous pericardial support pressures and intra-operative transoesophageal velocities during a staged pericardiotomy I also showed, in patient where there pericardium was to be opened fully, that this loss occurs consistently and specifically during the second-stage of a three-staged pericardiotomy which demonstrated in a novel way the substantial and localised mechanical support provided by the intact pericardium. Furthermore, I found that right ventricular longitudinal velocities do not reduce in those patients undergoing minimally invasive cardiac surgery where pericardial integrity is preserved. I believe this thesis has helped to prune the range of possible mechanism for this post operative phenomenon which is frequently seen and commented upon.

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25

Augustine, Daniel. "Cardiovascular magnetic resonance deformation imaging by feature tracking for assessment of left and right ventricular structure and function." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/7872.

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Cardiac magnetic resonance (CMR) imaging is the gold standard imaging technique for assessment of ventricular dimensions and function. CMR also allows assessment of ventricular deformation but this requires additional imaging sequences and time consuming post processing which has limited its widespread use. A novel CMR analysis software package, ‘feature tracking’ (Tom Tec, Germany) can measure ventricular deformation directly from cine CMR images. This thesis seeks to further our understanding of the feasibility of feature tracking to assess myocardial deformation and volumetric measures. Chapter 3 validates normal ranges for deformation parameters and compares values against traditional tagging measures. The work identifies global circumferential strain measures as being the most reproducible. In chapters 4 and 5, feature tracking values for left and right ventricular strain are compared with echocardiography derived speckle tracking indices of deformation. For left ventricular (LV) parameters, circumferential and longitudinal strain are most consistent and for the right ventricular (RV) measures, assessment of free wall strain using feature tracking shows promise and with modifications in algorithms is likely to further improve in the future. Chapter 6 assesses the ability of feature tracking to measure diastolic function. The results show that radial diastolic velocities and longitudinal diastolic strain rates can predict diastolic dysfunction (as diagnosed by echocardiography) with acceptable levels of sensitivity and specificity, particularly when used in combination. 11 The use of feature tracking to provide automated measures of ventricular volumes, mass and ejection fraction is assessed in chapter 7. Feature tracking in this context shows acceptable correlation but poor absolute agreement with manual contouring and further adjustments to algorithms is necessary to improve its accuracy. This work offers insights into the use of feature tracking for the assessment of ventricular deformation parameters. It is a technique with advantages over CMR tagging methods and given the speed of post processing has the potential to become the CMR preferred assessment for strain quantification in the future.

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Afiune, Fernanda Guedes. "Alterações cognitivas em pacientes idosos com insuficiência cardíaca." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7524.

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Among the various diseases that affect the elderly stand out from them cardiovascular disease among them heart failure (HF). Recently seeks to check for cognitive impairment associated with physical and psychological damage commonly known in the IC. We analyzed a population of patients with heart failure in order to compare their cognitive performance with that of individuals with normal aging in paired age. It was also verified whether there was any more specific impairment of some cognitive function in these HF patients. Through neuropsychological tests it was compared to 78 elderly and 37 in the control group (mean age 68.3 ± 6.3), 41 clinical group with mean age of 68.6 ± 6.9). The subjects were matched to the level of education with a predominance of elderly people with 0-4 years of education (65.9% in the Clinical Group and 59.5% in the control group). We used 11 neuropsychological tests covering the cognitive functions: attention, language, memory, mood and executive function. The results showed significant differences mainly in executive functions which include planning capacity, organization, alternation and evocation of Previously stored information. Cognitive performance in other functions was similar between the groups. The data collected when indicating cognitive impairment in individuals with HF, suggest that new studies be performed with this population since the impairments in cognitive abilities have implications in the daily life of the individual, in their independence and quality of life, as well as in adherence to treatment.
Dentre as diversas patologias que acometem os idosos destacam-se as doenças cardiovasculares, entre elas a Insuficiência Cardíaca (IC). Recentemente, busca-se verificar a existência de prejuízos cognitivos associados a prejuízos físicos e psicológicos, comumente conhecidos na IC. Analisamos uma população de pacientes com insuficiência cardíaca com o objetivo de comparar seu desempenho cognitivo com o de indivíduos com envelhecimento normal em idade pareada. Verificou-se, ainda, se havia nesses pacientes com IC algum comprometimento mais específico de alguma função cognitiva. Foram utilizados onze testes neuropsicológicos abrangendo as funções cognitivas: atenção, linguagem, memória, humor e função executiva. A amostra foi composta de 78 idosos ao total. O grupo controle foi composto de 37 indivíduos (com idade média de 68,3 ± 6,3) e o grupo clínico de 41 indivíduos (com idade média de 68,6 ± 6,9). Os sujeitos foram pareados em relação ao nível de escolaridade, com predomínio de idosos com 0 a 4 anos de estudo (65,9% no Grupo Clínico e 59,5 % no Grupo Controle). Os resultados apontaram diferenças significativas entre os grupos, principalmente nas funções executivas, que englobam capacidade de planejamento, organização, alternância e evocação da informação anteriormente armazenada. O desempenho atentivo mostrou-se alterado no que se refere à atenção alternada, bem como no que diz respeito à velocidade de processamento, tendo o grupo clínico mostrado pior desempenho nessas habilidades. A memória de curto prazo também possui pior desempenho no grupo clínico, grupo que, ademais, apresentou dificuldades na memória de longo prazo, sofrendo interferência de prejuízos executivos nessa habilidade. Os dados colhidos ao apontarem prejuízos cognitivos nos indivíduos com IC sugerem que novos estudos sejam realizados com essa população, visto que os prejuízos nas habilidades cognitivas implicam em danos no cotidiano do indivíduo, na sua independência e na qualidade de vida, bem como na adesão ao tratamento.

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27

Sharma, Sumeet. "Thrombotic risk assessment in end stage renal disease patients on renal replacement therapy." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/17114.

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End stage renal disease (ESRD) patients have an excess cardiovascular risk, above that predicted by traditional risk factor models. Despite the advances in both Cardiovascular disease (CVD) management and renal replacement therapy (RRT), there still is a major burden of cardiovascular mortality and morbidity in the chronic kidney disease (CKD) population. Declining renal function itself represents a continuum of cardiovascular risk and in those individuals who survive to reach ESRD, the risk of suffering a cardiac event is uncomfortably and unacceptably high. Pro-thrombotic status may contribute to this increased risk. Global thrombotic status assessment, including measurement of occlusion time (OT) the time taken to form an occlusive platelet rich thrombus and thrombolytic status (time taken to lyse such thrombus) as assessed by measuring Lysis Time (LT), may identify vulnerable patients. The aim of this study was to assess overall thrombotic status in ESRD and relate this to cardiovascular and peripheral thrombotic risk. Small sub studies were also planned to establish the effect of RRT modality on the thrombotic status.

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28

Zajac, Jakub. "Assessment of Ventricular Function in Normal and Failing Hearts Using 4D Flow CMR." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141006.

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Heart failure is a common disorder and a major cause of illness and death in the population, creating an enormous health-care burden. It is a complex condition, representing the end-point of many cardiovascular diseases. In general heart failure progresses slowly over time and once it is diagnosed it has a poor prognosis which is comparable with that of many types of cancer. The heart has an ability to adapt in response to long lasting increases in hemodynamic demand; the heart conforms its shape and size in order to maintain adequate cardiac output. This process is called remodeling and can be triggered by pathologies such as hypertension or valvular disease. When the myocardial remodeling is maintained chronically it becomes maladaptive and is associated with an increased risk of heart failure. In many cases, heart failure is associated with left bundle branch block (LBBB). This electrical disturbance leads to dyssynchronous left ventricular (LV) contraction and relaxation which may contribute to cardiac dysfunction and ultimately heart failure. Mechanical dyssynchrony can be treated with cardiac resynchronization therapy (CRT). However, many heart failure patients do not demonstrate clinical improvement despite CRT. Blood flow plays an important role in the normal development of the fetal heart. However, flow-induced forces may also induce changes in the heart cells that could lead to pathological remodeling in the adult heart. Until recently, measurement tools have been inadequate in describing the complex three-dimensional and time-varying characteristics of blood flow within the beating heart. 4D (3D + time) flow cardiovascular magnetic resonance (CMR) enables acquisition of three-dimensional, three-directional, time-resolved velocity data from which visualization and quantification of the blood flow patterns over a complete cardiac cycle can be performed. In this thesis, novel 4D Flow CMR based methods are used to study the intraventricular blood flow in healthy subjects and heart failure patients with and without ventricular dyssynchrony in order to gain new knowledge of the ventricular function. Different flow components were assessed in normal heart ventricles. It was found that inflowing blood that passes directly to outflow during the same heartbeat (the Direct Flow component) was larger and possessed more kinetic energy (KE) than other flow components. Diastolic flow through the normal heart appears to create favorable conditions for effective systolic ejection. This organized blood flow pattern within the normal LV is altered in heart failure patients and is associated with decreased preservation of KE which might be unfavorable for efficient LV ejection. Inefficient flow of blood through the heart may influence diastolic wall stress, and thus contribute to pathological myocardial remodeling. In dyssynchronous LVs of heart failure patients with LBBB, Direct Flow showed even more reduced preservation of KE compared to similarly remodeled LVs without LBBB. Furthermore, in LBBB patients, LV filling hemodynamic forces, acting on the myocardium, were more orthogonal to the main flow direction compared to patients without LBBB. Deviation of LV flow forces and reduction of KE preservation and may reflect impairment of LV diastolic function and less efficient ensuing ejection related to dyssynchrony in these failing ventricles. Blood flow patterns were also studied with respect to fluctuations of the velocity of the flow (turbulent flow) in normal and failing LVs. In failing hearts, turbulent kinetic energy (TKE) was higher during diastole than in healthy subjects. TKE is a cause of energy loss and can thus be seen as a measure of flow inefficiency. Elucidating the transit of multidimensional blood flow through the heart chambers is fundamental in understanding the physiology of the heart and to detect abnormalities in cardiac function. The 4D Flow CMR parameters presented in this thesis can be utilized to detect altered intracardiac blood flow and may be used as markers of deteriorating cardiac function, pathological remodeling and mechanical dyssynchrony in heart failure.

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29

Barbosa, Daniel. "Automated assessment of cardiac morphology and function : An integrated B-spline framework for real-time segmentation and tracking of the left ventricle." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0111.

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L’objectif principal de cette thèse est le développement de techniques de segmentation et de suivi totalement automatisées du ventricule gauche (VG) en RT3DE. Du fait de la nature difficile et complexe des données RT3DE, l’application directe des algorithmes classiques de vision par ordinateur est le plus souvent impossible. Les solutions proposées ont donc été formalisées et implémentées de sorte à satisfaire les contraintes suivantes : elles doivent permettre une analyse complètement automatique (ou presque) et le temps de calcul nécessaire doit être faible afin de pouvoir fonctionner en temps réel pour une utilisation clinique optimale. Dans ce contexte, nous avons donc proposé un nouveau cadre ou les derniers développements en segmentation d’images par ensembles de niveaux peuvent être aisément intégrés, tout en évitant les temps de calcul importants associés à ce type d’algorithmes. La validation clinique de cette approche a été effectuée en deux temps. Tout d’abord, les performances des outils développés ont été évaluées dans un contexte global se focalisant sur l’utilisation en routine clinique. Dans un second temps, la précision de la position estimée du contour du ventricule gauche a été mesurée. Enfin, les méthodes proposées ont été intégrées dans une suite logicielle utilisée à des fins de recherche. Afin de permettre une utilisation quotidienne efficace, des solutions conviviales ont été proposées incluant notamment un outil interactif pour corriger la segmentation du VG
The fundamental goal of the present thesis was the development of automatic strategies for left ventricular (LV) segmentation and tracking in RT3DE data. Given the challenging nature of RT3DE data, classical computer vision algorithms often face complications when applied to ultrasound. Furthermore, the proposed solutions were formalized and built to respect the following requirements: they should allow (nearly) fully automatic analysis and their computational burden should be low, thus enabling real-time processing for optimal online clinical use. With this in mind, we have proposed a novel segmentation framework where the latest developments in level-set-based image segmentation algorithms could be straightforwardly integrated, while avoiding the heavy computational burden often associated with level-set algorithms. Furthermore, a strong validation component was included in order to assess the performance of the proposed algorithms in realistic scenarios comprising clinical data. First, the performance of the developed tools was evaluated from a global perspective, focusing on its use in clinical daily practice. Secondly, also the spatial accuracy of the estimated left ventricular boundaries was assessed. As a final step, we aimed at the integration of the developed methods in an in-house developed software suite used for research purposes. This included user-friendly solutions for efficient daily use, namely user interactive tools to adjust the segmented left ventricular boundaries

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30

Eißler, Christoph Marcel [Verfasser], Andreas [Gutachter] Buck, Stefan [Gutachter] Störk, Takahiro [Gutachter] Higuchi, and Constantin [Gutachter] Lapa. "Assessment of the left ventricular systolic and diastolic function in rats using electrocardiogram-gated cardiac positron emission tomography / Christoph Marcel Eißler ; Gutachter: Andreas Buck, Stefan Störk, Takahiro Higuchi, Constantin Lapa." Würzburg : Universität Würzburg, 2021. http://d-nb.info/1225684900/34.

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31

Sofronescu, Alina G. "Identification and functional assessment of the fibroblast growth factor-16 (FGF-16) promoter in cardiac myocytes." 2006. http://hdl.handle.net/1993/20872.

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32

Lin, Chien-Chung, and 林建仲. "Motion Analysis and Assessment of Cardiac Function for Cardiac Images." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2uhv85.

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博士
元智大學
資訊管理學系
104
This thesis proposes a series of methods in analyzing cardiac motion sequences. It is helpful to assist the cardiologist to analyze the medical images for further diagnosis. Coronary angiogram is one of the most valid methods for diagnosing the presence of coronary artery disease. Therefore, we propose a method to select the optimum phase from the image sequence. The optimum phases were selected by evaluating the correlation coefficients with minimum inconsistency of motion in the selected data. The result of the optimum image phase selection shows that the automatically determined phases yield the optimum image quality. To achieve the purpose of providing accurate information in coronary artery images, an algorithm to extract the skeletons and borders of coronary arteries in digitalized angiograms automatically is also proposed. Based on the optimum image, we develop a combination of fragment strategy and tubular enhancement to figure out the vessel structure clearly. Cardiac wall motion plays an important role in the analysis and interpretation of various kinds of cardiac diseases. However, it is difficult to find the initial contour of cardiac boundary and produce an accurate motion flow field at motion boundaries. In this study, we propose a novel and non-iterative approach to segment the boundaries in motion images based on voting processes for catheterization angiocardiography. A voting process is first used to enforce the smoothness of motion and determine an estimation of pixel velocities, motion regions and boundaries. For the purpose of locally defining a boundary tensor field, boundary estimation is combined with intensity information from the original images. Correct velocities are computed for the pixels near boundaries, as they are reassigned to different regions. Furthermore, we propose a computer aided diagnosis/detection system for cardiac motion analysis of catheterization ventriculography. The purpose of this method is to develop a computerized system which helps physicians and radiologists to automatically predict the presence of heart disease as early as possible. The adaptive ellipse active contour model is used to refine the contours. Motion analysis of cardiac are performed according to the extracted contours to form the motion vector field by Empirical Mode Decomposition (EMD) method. The results of motion detection are displayed in the formats of motion vector fields and Doppler color display. The combination of quantitative cardiac motion analysis obtained from cardiac images enable the clinician to determine whether there exists a heart disease and therefore may need treatment. The purpose of this thesis is to make use of image information to assistant the diagnosis. Experiment results show that physicians can use the proposed solid model for process of evaluation and planning before the surgeries to promote the efficiency of diagnosis, medical treatment qualities and reduce the waste of medical resource.

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33

Yang, Shih-Yu, and 楊詩郁. "Motion Analysis and Assessment of Cardiac Function in Catheterization Ventriculography." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04623345291203615943.

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碩士
元智大學
資訊管理學系
98
This study propose a computer-aided system to provide the motion analysis and assessment of cardiac function in catheterization ventriculography. First, we use the block matching method to segment the coarse contour of left ventricular region. Then, morphological operations were used to refine the contour. Secondly, a two step fuzzy logic system was used to identify the direction of heart motion. The Doppler ultrasonography representation was used to present a more intuitive and objective interpretation of cardiac information. Finally, some of the parameters such as Ejection Fraction and slope variation of ventricular are used to evaluate the cardiac function. Experimental results show that the proposed method can provide an effective motion analysis and assessment of cardiac function in catheterization ventriculography. Meanwhile, it can be further as the computer aided diagnosis system (CAD) for differential diagnosis in the future.

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34

Krishnamurthy, Ramkumar. "Cardiac MRI: Improved Assessment of Left Ventricular Function, Wall Motion, and Viability." Thesis, 2013. http://hdl.handle.net/1911/71979.

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Heart failure is the clinical syndrome accompanying the inability of the heart to maintain a cardiac output required to meet the metabolic requirements and accommodate venous return, and is one of the leading causes of mortality in United States. Accurate imaging of the heart and its failure is important for successful patient management and treatment. Multiple cardiac imaging modalities provide complementary information about the heart – LV function and wall motion, anatomy, myocardial viability and ischemia. In many instances, it is necessary for a patient to undergo multiple imaging sessions to obtain diagnostic clinical information with confidence. It would be beneficial to the individual and the health care system if a single imaging modality could yield reliable clinical information about the heart, leading to a reduced cost, anxiety and an increased diagnostic confidence. This thesis proposes methods that would make cardiac MRI perform an improved assessment of LV function, wall motion, and viability, such that cardiac MRI is taken one step closer to being a single stop solution for imaging of heart. Conventional cardiac MR imaging is performed at a temporal resolution of around 40 ms per cardiac phase. While the global left ventricular (LV) function can be reliably established at this temporal resolution, functional metrics characterizing transient function like peak filling and ejection rates are not accurately assessed. A high temporal resolution is necessary to characterize such transient LV function and wall motion mechanics. This thesis proposes methods to acquire cine-images of the heart at a higher temporal resolution (~ 6 ms) and algorithms to acquire the LV volume across all cardiac phases that would yield functional metrics characterizing LV function and wall motion mechanics. The validation of these algorithms was performed on human subjects. Cardiac MR imaging is the current gold standard of myocardial viability imaging, in which scarred regions of the heart following myocardial infarction are visualized. However viability imaging faces image quality challenges in patients with severe arrhythmias and in cases where a higher spatial resolution, and hence a longer acquisition time, is desired. This thesis also proposes an arrhythmia insensitive inversion recovery (AIIR) algorithm that would significantly reduce artifacts that degrade image quality, thereby extending viability imaging to higher spatial resolution and in patients with severe arrhythmia. Simulations, experimental validation on phantoms and clinical verification on patients are performed. Results from high temporal resolution imaging reveal that obtaining cine cardiac MR images at a temporal resolution of 6 ms per cardiac phase is feasible. Appropriate validated algorithms yield LV time-volume curve from which LV functional metrics are reliably extracted. A dependence on temporal resolution is revealed, and a temporal resolution cut-off of 12 ms is proposed to reliably capture the temporal dynamics of the LV. Also, results from cardiac viability imaging show that the AIIR algorithm performs significantly better than conventional imaging methods in both phantoms and human subjects, as shown by the blinded expert scores, leading to a better image quality. In conclusion, this thesis proposes and implements methods that help cardiac MRI yield 1) a better function and wall motion assessment of the heart through high temporal resolution imaging and 2) a better assessment of myocardial viability through the AIIR algorithm.

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Lin, Kuen-You, and 林琨祐. "Assessment of the cardiac function of zebrafish and the cardiac activities of drugs with pseudo-dynamic three-dimensional imaging." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/w2jb34.

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碩士
國立交通大學
應用化學系碩博士班
102
The zebrafish (Danio rerio) possesses various attractive features including rapid development, ease of genetic manipulation and low cost of maintenance, and has become a popular animal model for the study of cardiovascular diseases and for the screening of drugs with therapeutic or adverse effects. Herein, we demonstrate a novel application of pseudo-dynamic three-dimensional (3D) cardiac imaging for precise determination of the cardiac function of zebrafish. With this technique, we particularly determined individual important parameters of the cardiac function of zebrafish larvae (including ventricular stroke volume, ejection fraction, cardiac output, heart rate, diastolic filling function and ventricular mass). We compared critically the cardiac parameters obtained with our approach with those derived with conventional 2D approximation termed “fit-to-ellipse”, and show that our 3D approach is superior in several respects. To demonstrate potential applications of our approach to pharmaceutical development, we evaluated specifically the inotropic and chronotropic response of the heart of zebrafish subject to pharmacological interventions of epinephrine, esmolol and doxazosin. Our results show that zebrafish exhibited pharmacological responses to these cardioactive drugs in a way similar to human beings do. We revealed also an impaired cardiac function of a zebrafish model of cardiomyopathy induced by a treatment of doxorubicin. Given the growing interest in the application of zebrafish in both basic and applied biomedical research, we anticipate that our approach should have widespread applications in not only pharmaceutical development but also studies of cardiac development, pathophysiology or therapies targeting human heart diseases.

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Couceiro, Ricardo Jorge dos Santos. "Cardiovascular Performance Assessment for p-Health Applications." Doctoral thesis, 2015. http://hdl.handle.net/10316/26987.

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Tese de doutoramento em Ciências e Tecnologias da Informação, apresentada ao Departamento de Engenharia Informática da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
As doenças cardiovasculares (CVDs) são atualmente a principal causa de morte no mundo e são responsáveis por mais de 7 milhões de mortes todos os anos. A mortalidade decorrente das CVDs tem vindo aumentar, principalmente devido ao crescimento da população nos países de baixo e médio rendimento, que alojam cerca de 85% da população mundial. Nos países de elevado rendimento, o acesso a melhores tecnologias de diagnostico e melhores terapêuticas, bem como estilos de vida mais saudáveis, inverteram esta tendência e a mortalidade resultante das CVDs está a decrescer. Este facto, aliado ao aumento da esperança média de vida das populações, leva a que as pessoas sejam afectadas ou morram devido a CVDs em idades mais avançadas, contribuindo para o aumento dos gastos com a saúde em todo o mundo. Uma condição que contribui largamente para este problema é a síncope, que têm um impacto económico equivalente a doenças como a asma, HIV e doença pulmonar obstrutiva crónica. Mais conhecida como “desmaio”, a síncope está associada a uma frequência elevada de quedas e de hospitalizações, e é responsável por uma menor a qualidade de vida, especialmente em populações mais idosas. Para enfrentar os encargos socioeconómicos derivados das CVDs, o paradigma da saúde tem vindo a mudar de reativo e centralizado nos hospitais para preventivo e centrado em cada individuo, com um foco especial no diagnostico precoce e em melhores estratégias de prevenção e gestão das CVDs. Assim, o desenvolvimento de novas metodologias para monitorização da função cardiovascular, capazes de serem aplicadas em sistemas de baixo custo, não invasivos e portáteis, são essenciais para a prevenção e controlo desta crescente epidemia que são as CVDs. Apesar dos recentes avanços tecnológicos, as técnicas padrão atuais para a avaliação da função cardiovascular, como a ressonância magnética cardíaca e ecocardiografia, ainda apresentam várias limitações no que diz respeito à sua aplicação em ambientes de saúde personalizada. Assim, a utilização de modalidades amplamente disponíveis e de baixo custo, como o eletrocardiograma e o fotopletismograma, para a avaliação não-invasiva, contínua e de longo prazo da função cardiovascular pode ser a chave para melhores estratégias de prevenção e gestão de doenças cardiovasculares. Mais concretamente, a extração de parâmetros cardiovasculares a partir destas modalidades pode ser crucial na predição de síncopes e prevenção de quedas. A principal contribuição da presente tese consiste no desenvolvimento de novos algoritmos para a avaliação continua, não invasiva e robusta da função cardiovascular, com base na análise do eletrocardiograma e do fotopletismograma. Visto que o fotopletismograma é facilmente afectado por ruído e artefactos de movimento, o que representa um obstáculo para a extração de parâmetros cardiovasculares, é fundamental detectar quais as secções do fotopletismograma passiveis de serem posteriormente analisadas. Assim, propomos um novo método para detecção de artefactos de movimento baseado na extração e análise de características do domínio temporal e de período. Consequentemente, propomos um novo algoritmo para a estimação do tempo de ejecção do ventrículo esquerdo, o qual está associado com a função cardíaca, bem como outros parâmetros relacionados com alterações de pressão sanguínea e de tónus vascular. Finalmente, propomos um novo algoritmo para a predição de síncopes (mais especificamente, síncope neuromediada) baseada na avaliação dos parâmetros previamente extraídos. Os métodos propostos foram validados em três bases de dados, coligidas no Departamento de Engenharia Informática da Universidade de Coimbra, no Centro Hospitalar da Universidade de Coimbra e no departamento de Eletrofisiologia do Centro Universitário do Coração, Hospital Universitário de Eppendorf, Hamburgo, Alemanha.
Cardiovascular diseases (CVDs) are currently the leading cause of death in the world and are responsible for over 17 million deaths per year. The mortality of CVDs is increasing, mainly driven by the increase of the population in low and middle income countries, which house about 85% of the world’s population. In high-income countries, the access to better diagnostic and therapeutic technologies, as well as healthier life stiles, reverses this tendency and CVD mortality is decreasing. In combination with the increase in the populations’ life expectancy, people are affected or die as a result of CVD at older ages, contributing to the rise in the health care expenditures all over the world. A condition largely contributing to this matter is syncope, which has an economic impact equivalent to conditions such as asthma, HIV, and chronic obstructive pulmonary disease. More commonly known as fainting, syncope is associated with high rate of falls and hospitalization and is responsible for reducing lifestyle quality, especially in the elderly. To face this socioeconomic burden caused by CVDs, the health care paradigm is shifting from a reactive hospital-centered to a preventive individual-centered care, with special emphasis in earlier diagnosis and better prevention and management strategies. Therefore, the development of new methodologies for monitoring the cardiovascular function, capable of being applied in low-cost, non-invasive and portable systems, are essential to prevent and control the evolving epidemic of CVDs. Despite the recent technological advances, the current standard techniques for the assessment of cardiovascular function, such as the cardiac magnetic resonance and echocardiography, still exhibit several limitations in what concerns to their application in personal health environments. Therefore, the use of widely available and cost-effective modalities such as the electrocardiogram and photoplethysmogram, for the non-invasive, continuous and long-term assessment of the cardiovascular function may be the key to provide a better prevention and management strategies of CVDs. More specifically, the extraction of cardiovascular parameters from these modalities may be crucial in the prediction of syncope events and prevention of falls. The key contribution of the present thesis is the development of new algorithms for the continuous, non-invasive and robust assessment of cardiovascular function, based on the analysis of the electrocardiogram and photoplethysmogram. Since the photoplethysmogram is easily influenced by noise and motion artifacts, which can be a serious obstacle in the extraction of cardiovascular parameters, it is essential to detect which sections of the photoplethysmogram are liable for further analysis. Therefore, we propose a new method for the detection of motion artifacts, based on the extraction and analysis of time and period domain features. Consequently, we propose a new algorithm for the assessment of the left ventricular ejection time, which is associated with the cardiac function, among other parameters related with blood pressure and vascular tones changes. Finally, we propose a new algorithm for the prediction of syncope events (more specifically, neurally mediated syncope), based on the evaluation of changes in the previously extracted cardiovascular parameters. The proposed methods were validated in three databases collected in the Department of Informatics Engineering of the University of Coimbra, in the Hospital Center of University of Coimbra and in the Department of Electrophysiology of the University Heart Center, University Hospital Eppendorf, Hamburg, Germany.

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Molaee, Payman. "Assessment of left atrial structure and function in the setting of atrial fibrillation using cardiac magnetic resonance imaging." Thesis, 2012. http://hdl.handle.net/2440/76646.

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Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with significant morbidity and mortality. As a result of AF, patients develop palpitations, syncope, cardiac failure and thromboembolic complications. The management of AF has revolved around the issues of rate versus rhythm control, and stroke prevention. Although rhythm control was thought to be the most desirable approach, several large randomised trials failed to show a significant difference between the two treatment strategies. In fact, rhythm control strategy may be associated with increased adverse outcomes. This has largely been attributed to the poor efficacy and significant toxicity of antiarrhythmic agents. Since the seminal observation that the pulmonary veins play an important role in triggering AF, radiofrequency catheter ablation of AF has evolved rapidly. Although this is a potentially curative treatment for selected patients with AF, there are several issues that need to be addressed, including predictors of success of the procedure, effects of ablation on cardiac structure and function, and implications of AF ablation for long-term stroke risk. Cardiac magnetic resonance imaging (CMR) is now regarded as the “gold standard” non-invasive imaging modality for the assessment of cardiac structure and function. It is thus an ideal tool for initial assessment and follow-up of patients with AF undergoing ablation. The chapters in this thesis are based on CMR studies in patients with AF. Left atrial (LA) volume is an established prognostic marker. Currently, LA volume is commonly measured using the biplane area-length method and applying the method of discs. This involves geometric assumptions, which may introduce inaccuracies. In Chapter 3, the accuracy and reproducibility of biplane area-length method was compared with the “gold standard” volumetric measurement using CMR, in healthy controls and subjects with AF. The biplane area-length method correlated well with the volumetric method in healthy controls, but in subjects with AF, the correlation was less robust and the area-length method was less reproducible. Traditionally, “lone” AF has been defined as the occurrence of AF in the absence of any cardiopulmonary disease. However, the CMR study presented in Chapter 4 demonstrates that despite having no evidence of cardiac abnormalities on echocardiography, subjects with “lone” AF have atrial functional abnormalities and ventricular structural changes compared with controls. The success of AF ablation can be variable depending on the expertise of the centre, clinical and imaging characteristics. Predictors of success following AF ablation have not been well established. The clinical and CMR factors associated with medium-term outcomes following AF ablation are presented in Chapter 5. Following multivariate analysis, increased LA volume and female gender were the only predictors of AF recurrence at one year post-ablation. In the study presented in Chapter 6, CMR was performed at baseline and 12-month follow-up to assess the impact of AF ablation on cardiac structure and function. In subjects with successful ablation, there was evidence of reverse remodelling within the atria and ventricles, with reduction in chamber volumes post-ablation. Importantly, these changes associated with cardiac reverse remodelling after ablation may indeed contribute to the success of ablation.
Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2012

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Lin, Shih-Hsuan, and 林士軒. "Assessment of Left Ventricular Function after Parachute Device Implantation in Patients with Ischemia Heart Failure using Cardiac CT." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/53634533161629252676.

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碩士
國立陽明大學
生物醫學影像暨放射科學系
103
Background Left ventricular (LV) remodeling after (MI) is characterized by progressive LV dilatation, which if left untreated, may ultimately result in progressive systolic dysfunction, LV aneurysm formation, heart failure and death. Recently, an implantable novel percutaneous device had been developed, aiming for proper isolation of the dysfunctional region of the LV in order to reduce both LV volume and attenuate myocardial wall stress. This study aimed to evaluate whether Parachute LV partitioning system implantation improved LV diastolic function assessed by MDCT. Material and methods Twenty eight patients who had cardiac CT images before and 6 months after Parachute device implantation, and twenty eight subjects with normal cardiac CT images were included in this retrospective study. The cardiac functional indexes including left ventricle length, end-diastolic and end-systolic volume as well as systolic function and diastolic function were analyzed by off-line analysis (TeraRecon Aquarius workstation, San Mateo, Calif). The normal group is for the validation of the value of cardiac functional indexes. Result The comparison of LV structure variables between baseline, 6 months follow up groups showed a significantly decrease in LV length, LV end-systolic volume, and LV end-diastolic volume; LV systolic function indexes shows a significantly improved in LV ejection fraction (LVEF) (0.31 ± 0.10 vs. 0.35 ± 0.10, respectively, p < 0.01), but there were no significant difference in stroke volume (78.71 ± 24.82 ml vs. 78.07 ± 20.60 ml, respectively, p = NS); LV diastolic function parameters showed a significantly improved in E/Ea (21.96 ± 15.58 ml vs. 13.55 ± 9.86, respectively, p < 0.01), but no significant difference in E/A (2.23 ± 2.09 vs. 2.16 ± 1.56, respectively, p = NS). The result of normal group showed the minimum LV length, LV end-systolic volume, LV end-diastolic volume among the three groups, and LVEF, LV diastolic function parameters which were E/Ea, E/A were all in the normal range (0.73±0.08, 3.70±2.22, 1.36±0.51, respectively). Discussion and conclusion This study successfully used cardiac CT images to evaluate these cardiac functional indexes, and the results which in the normal range of normal group were ensured the accuracy of CT measurement. A significant decrease in LV structure and improvement in both systolic and diastolic function occurred after device implantation showed a potential beneficial effect of this novel device in treatment of LV aneurysm.

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Eißler, Christoph Marcel. "Assessment of the left ventricular systolic and diastolic function in rats using electrocardiogram-gated cardiac positron emission tomography." Doctoral thesis, 2021. https://doi.org/10.25972/OPUS-21976.

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DD is a cardiac disturbance, which has gained increasing importance in recent years due to its important role in different cardiac disease and cardiomyopathies including ischemic cardiomyopathy, arterial hypertension and diabetic cardiomyopathy. ECG-gated 18F-FDG PET is an imaging technique, that can distinguish between districts of myocardial viability and myocardial scars and further provides information of great interest on the efficacy of experimental approaches designed to improve the cardiac function and/or myocardial metabolism in experimental small animal models. However, ECG-gated 18F-FDG PET is a technique whose feasibility in the assessment of the LV diastolic function in small animals has not been a subject of study. In this thesis, the ability of the ECG-gated 18F-FDG PET for the assessment of both the systolic and diastolic function in eight control rats and in seven ZDF rats, which are an experimental animal model mimicking T2DM conditions and diabetic related complications in humans including DCM, has been investigated The ECG-gated 18F-FDG PET imaging was performed under hyperinsulinemic-euglycemic clamping and the data were stored in list mode files and retrospectively reconstructed. The systolic and diastolic parameters were achieved from the time/volume and the time/filling curve calculated from the software HFV. Additionally, the influence of the number of gates per cardiac cycle on the LV volumes and function parameters has been studied. Hyperinsulinemic-euglycemic clamp procedure and blood glucose measurement did confirm the development of a manifest diabetes in the ZDF rats at the timepoint of the experiments. Regarding the systolic parameters, no significant difference could be detected between the ZDF and ZL rats. The values for the CO were similar in both groups, which demonstrates a similar LV systolic function in the ZDF and the ZL rats at the age of 13 weeks. Values for the systolic parameters are in good line with previous PET, MRI and cardiac catheterization-based studies in diabetic rats. The main finding of this study was that by using in vivo ECG-gated 18F-FDG PET and the software HFV, reliable diastolic parameters could be calculated. Moreover, it was possible to detect the presence of a mild impaired diastolic filling in the ZDF rats in absence of any systolic alteration. This impaired diastolic function in an early stage of diabetes could also be detected by other investigators, who used echocardiography or cardiac catheterization. Therefore, this is the first study showing, that the assessment of the diastolic function in rats can be carried out by ECG-gated 18F-FDG PET imaging. In conclusion, additionally to calculating LV volumes and LV EF, ECG-gated 18F-FDG PET can evaluate the diastolic function of healthy and diabetic rats and is able to detect a DD in ZDF rats
Die DD ist eine Störung der Herzdynamik, welche, aufgrund ihrer Beteiligung in verschiedenen Herzerkrankungen und Kardiomyopathien wie der ischämischen Kardiomyopathie, der arteriellen Hypertonie und der diabetischen Kardiomyopathie, in den letzten Jahren zunehmend in das Interessenzentrum der Herzforschung gerückt ist. Die EKG-getriggerte 18F-FDG PET ist eine Bildgebungsmethode, welche die Unterscheidung von vitalem Myokard und Narben ermöglicht und zusätzlich noch in der Lage ist, wichtige Informationen zu erheben, welche von Bedeutung für die Beurteilung von experimentelle Behandlungen zur Verbesserung der Herzfunktion und/oder des kardialen Stoffwechsels in präklinischen Tiermodellen sind. Trotz dieser Möglichkeiten wurde bisher noch nicht die Fähigkeit der EKG-getriggerten 18F-FDG PET zur Bestimmung der LV diastoischen Funktion in Kleintiermodellen untersucht. Deshalb wurde in dieser Arbeit das Potential der EKG-getriggerten 18F-FDG PET in Bezug auf die Bestimmung der LV systolischen und diastolischen Funktion in acht Kontrollratten (ZL) und sieben ZDF-Ratten, welche eine experimentelles Tiermodell für T2DM und die damit verbundenen Komplikationen einschließlich der diabetischen Kardiomyopathie sind, untersucht. Die EKG-getriggerte 18F-FDG PET wurde unter der hyperinsulinämischen euglykämischen Klemm Methode durchgeführt, die Daten in „list-mode“ Dateien gespeichert und retrospektiv rekonstruiert. Die Berechnung der LV systolischen und diastolischen Parameter erfolge aus der Zeit-Volumen-Kurve und der Zeit-Füllungs-Kurve durch das Programm HFV. Zudem wurde der Einfluss der pro Rekonstruktion verwendeten „frames“ pro kardialen Zyklus auf die LV Volumina und die linksventrikulären Funktionsparameter untersucht. Durch die hyperinsulinämische euglykämische Klemm Methode und durch Blutglukose Messungen konnte die Entwicklung eines manifesten Diabetes zum Zeitpunkt der Experimente in den ZDF Ratten nachgewiesen werden. Es konnte kein signifikanter Unterschied zwischen den systolischen Parametern der ZDF und der ZL Ratten gefunden werden. Der kardiale Auswurf war nahezu identisch in den beiden Gruppen zum Zeitpunkt der Experimente, was eine vergleichbare systolische Funktion in beiden Gruppen demonstriert. Die erhobenen Werte für die systolischen Parameter befinden sich in guter Übereinstimmung mit den Werten der Literatur von vorherigen PET, MRT und Katheter-gestützten Experimenten in diabetischen Rattenmodellen. Ein wichtiges Ergebnis dieser Arbeit ist die Erhebung von verlässlichen diastolischen Parametern durch den kombinierten Einsatz von EKG-getriggerter 18F-FDG PET und HFV. Zudem war es möglich, eine gestörte diastolische Füllung des LV in den ZDF Ratten nachzuweisen, in Abwesenheit von systolischen Funktionseinschränkungen. Eine Beeinträchtigung der diastolischen Funktion in der frühen Phase des Diabetes wurde bereits in anderen Rattenstudien mittels Echokardiografie und Katheter basierten Untersuchungen gezeigt. Dennoch ist dies hier die erste Studie, welche demonstriert, dass die Bestimmung der diastolischen Funktion auch mit Hilfe der EKG-getriggerten 18F-FDG PET durchgeführt werden kann. In Zusammenfassung lässt sich festhalten, das zusätzlich zu der Bestimmung der LV-Volumina und der LVEF durch EKG-getriggerten 18F-FDG PET auch die Bestimmung der diastolischen Funktion in gesunden und diabetischen Ratten möglich ist und dass durch EKG-getriggerten 18F-FDG PET die Identifikation einer DD in ZDF Ratten möglich ist

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Azevedo, Ana Catarina Soares Feio de. "Pressure-wire based functional assessment of coronary stenoses in surgical heart valve disease patients: impact in the coronary revascularization technique." Master's thesis, 2019. http://hdl.handle.net/10316/89728.

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Trabalho Final do Mestrado Integrado em Medicina apresentado à Faculdade de Medicina
Objetivos: Descrever de que forma a informação obtida pela realização de avaliação funcional por guia de pressão afetou a estratégia de revascularização cirúrgica das artérias estudadas e realizar o seguimento clínico, a um ano, em termos de eventos cardio e cerebrovasculares: morte cardiovascular, enfarte agudo do miocárdio e revascularização não planeada.Métodos: Foi conduzida uma análise retrospetiva de um coorte prospetivo de 32 doentes com doença valvular cardíaca, de um grupo de 298 doentes submetidos a uma avaliação funcional de estenoses coronárias intermédias por guia de pressão no nosso centro entre outubro de 2013 e fevereiro de 2018. As características dos doentes foram retiradas de duas bases de dados. O tempo médio de seguimento clínico foi de 421 dias. Na análise dos dados usaram- se como valores de referência de FFR e IFR um cut-off de ≤0,80 e de ≤0,89, respetivamente.Resultados: Neste estudo foram incluídos 32 doentes com doença valvular cardíaca com indicação cirúrgica, tendo sido avaliadas através do FFR e/ou iFR 42 lesões coronárias. Foram integrados 23 doentes do sexo masculino e a idade média foi de 73 anos. Relativamente aos fatores de risco para doença cardiovascular, 81,3% dos doentes tinham hipertensão, 81,3% eram dislipidémicos, 31,3% tinham diabetes mellitus e 18,8% eram fumadores. A descendente anterior foi a artéria coronária mais vezes envolvida, afetando 23 (54,8%) doentes. Apenas 9 lesões foram classificadas como sendo hemodinamicamente significativas e 6 dessas foram revascularizadas. As 33 lesões restantes não tinham indicação para serem tratadas, no entanto 1 lesão foi revascularizada cirurgicamente.Conclusão: No nosso centro os cirurgiões cardíacos acreditam e atuam consoante os resultados da avaliação funcional. Após um ano de seguimento clínico não se registaram eventos cardiovasculares major nos doentes cuja avaliação funcional tinha sido negativa, confirmando a segurança da utilização do FFR e iFR nesta população com doença valvular grave.
Aims: Describe how the pressure-wire based functional assessment of intermediate coronary stenoses affected the strategy of myocardial revascularization and to perform a one-year analysis in terms of cardiovascular events: cardiovascular death, myocardial infarction and unplanned revascularization.Methods: We conducted a retrospective analysis on a prospective cohort of 32 patients with valvular heart disease out of 298 patients who underwent a pressure-wire based functional assessment of coronary stenosis between October 2013 and February 2018. The baseline data were extracted from two main databases. The median follow-up was 421 days. The cut- off values of 0.80 and 0.89 were used for FFR and iFR, respectively.Results: We included 32 patients with valvular heart disease, which of 42 coronary lesions were functionally assessed by FFR and/or IFR. There were 23 male and 9 female patients and the median age was 73 (66.0-78.0) years. Regarding risk factors for cardiovascular diseases, 81.3% of the patients had hypertension, 81.3% were dyslipidemic, 18.8% were smokers and 31.3% were diabetic. The most frequent lesion was on the left anterior descending coronary artery, affecting 23 (54.8%) patients. Only 9 lesions were classified as hemodynamically significant and 6 of them were treated, either by PCI or CABG. The 33 remaining lesions didn’t have an indication for revascularization, however, one lesion was treated with CABG. There were no major cardiovascular events within 12 months of follow-up.Conclusion: In our centre, the cardiothoracic surgeons believe and act accordingly to the functional assessment evaluation of the coronary lesions. During the follow-up time, no cardiovascular events were registered among the patients which coronary physiological measurements were negative, confirming the safe use of FFR or iFR in this population with valvular heart disease.

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Dissertations / Theses on the topic 'Cardiac Functional Assessment'

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