Journal articles: 'Stroke volume variability'

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Liu, Hongjian, Tomoyuki Yambe, Hiroshi Sasada, Shunsuke Nanka, Akira Tanaka, Ryoichi Nagatomi, and Shin-ichi Nitta. "Comparison of heart rate variability and stroke volume variability." Autonomic Neuroscience 116, no. 1-2 (November 2004): 69–75. http://dx.doi.org/10.1016/j.autneu.2004.09.003.

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Mailloux, Patrick, and William McGee. "STROKE VOLUME VARIABILITY, SVO2 AND INTRAVASCULAR VOLUME DURING CVVHD." Critical Care Medicine 34 (December 2006): A174. http://dx.doi.org/10.1097/00003246-200612002-00602.

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Cote, Anita T., Shannon SD Bredin, Aaron A. Phillips, and Darren ER Warburton. "Predictors of orthostatic intolerance in healthy young women." Clinical & Investigative Medicine 35, no. 2 (April 1, 2012): 65. http://dx.doi.org/10.25011/cim.v35i2.16290.

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Purpose: Orthostatic intolerance is more prevalent in women. The purpose of this investigation was to evaluate the physiological responses of orthostatic tolerant and intolerant females to progressive lower body negative pressure (LBNP) and to identify predictors of orthostatic tolerance. Methods: Following baseline measurements, eleven healthy, moderately active women (mean age 24 ± 3 yr) underwent an orthostatic challenge involving four 12-minute stages of progressive LBNP at -15, -30, -45 and -60 mmHg. Traditional haemodynamic characteristics, as well as baroreceptor sensitivity, were analyzed across all stages. Results: Five women became presyncopal during the test and were classified as low tolerant (LT) while the remaining six were classified as high tolerant (HT). LBNP by group (tolerance) interactions were significantly different for stroke volume (P=0.008) and the rate of decline (slope) of stroke volume (P=0.03). During the early stages of LBNP, the LT group displayed a higher stroke volume than the HT group (76.4 ± 8.6 vs. 60.0 ± 13.3 mL/beat; P=0.02) yet by the final stage, stroke volumes were similar (22.5 ± 11.9 vs. 22.7 ± 4.5 mL/beat, P = 0.99). Baroreceptor sensitivity, heart rate variability and blood pressure variability were not significantly different between the groups. Conclusions: The results of this investigation suggest that orthostatic intolerance in women can be identified during the initial stages of an LBNP challenge, as evidenced by a more rapid decline in stroke volume.

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Robertson, Donald U., Lynda Federoff, and Keith E. Eisensmith. "Cardiac Response During Trumpet Playing." Medical Problems of Performing Artists 25, no. 1 (March 1, 2010): 16–21. http://dx.doi.org/10.21091/mppa.2010.1004.

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Heart rate, heart rate variability, stroke volume, and cardiac output were measured while six college students and six professionals played trumpet. One-minute rest periods were followed by 1 minute of playing exercises designed to assess the effects of pitch and articulation. Heart rate and heart rate variability increased during playing, but stroke volume decreased. Changes in heart rate between resting and playing were greater for students, although beat-to-beat variability was larger for professionals in the upper register. These results suggest that expertise is characterized by greater physiological efficiency.

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Steendijk, P., E. T. Van der Velde, and J. Baan. "Left ventricular stroke volume by single and dual excitation of conductance catheter in dogs." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 6 (June 1, 1993): H2198—H2207. http://dx.doi.org/10.1152/ajpheart.1993.264.6.h2198.

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The conductance method employs a multielectrode catheter to measure intracavitary electric conductance from which left ventricular volume is estimated. A dual-excitation method introduced by us uses a more homogeneous electric field and thereby should enable more accurate volume estimation. In six anesthetized open-chest dogs we compared stroke volume obtained from electromagnetic flow probes with the conventional single-excitation method and with the new dual-excitation conductance method. Caval occlusion and left atrial hemorrhage were used to obtain a wide range of stroke volumes. The slope of the relation between stroke volume calculated from the flow probes and from the conductance catheter increased significantly (P < 0.001) from 0.635 with single excitation to 0.835 with dual excitation, but the interanimal variability was not reduced. The linearity of the relation was substantially improved.

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Dunn, Lauren E., Adam B. Schweber, Daniel K. Manson, Andrea Lendaris, Charlotte Herber, Randolph S. Marshall, and Ronald M. Lazar. "Variability in Motor and Language Recovery during the Acute Stroke Period." Cerebrovascular Diseases Extra 6, no. 1 (March 22, 2016): 12–21. http://dx.doi.org/10.1159/000444149.

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Background: Most stroke recovery occurs by 90 days after onset, with proportional recovery models showing an achievement of about 70% of the maximal remaining recovery. Little is known about recovery during the acute stroke period. Moreover, data are described for groups, not for individuals. In this observational cohort study, we describe for the first time the daily changes of acute stroke patients with motor and/or language deficits over the first week after stroke onset. Methods: Patients were enrolled within 24-72 h after stroke onset with upper extremity hemiparesis, aphasia, or both, and were tested daily until day 7 or discharge with the upper-extremity Fugl-Meyer Assessment of Motor Recovery after Stroke, the Boston Naming Test, and the comprehension domain from the Western Aphasia Battery. Discharge scores, and absolute and proportional changes were examined using t-tests for pairwise comparisons and linear regression to determine relative contributions of initial impairment, lesion volume, and age to recovery over this period. Results: Thirty-four patients were enrolled: 19 had motor deficits alone, 8 had aphasia alone, and 7 had motor and language deficits. In a group analysis, statistically significant changes in absolute scores were found in the motor (p < 0.001) and comprehension (p < 0.001) domains but not in naming. Day-by-day recovery curves for individual patients displayed wide variation with comparable initial impairment. Proportional recovery calculations revealed that, on average, patients achieved less than 1/3 of their potential recovery by the time of discharge. Multivariate regression showed that the amount of variance accounted for by initial severity, age, and lesion volume in this early time period was not significant for motor or language domains. Conclusions: Over the first week after stroke onset, recovery of upper extremity hemiparesis and aphasia were not predictable on the basis of initial impairment, lesion volume, or age. In addition, patients only achieved about 1/3 of their remaining possible recovery based on the anticipated 70% proportion found at 90 days. These findings suggest that the complex interaction between poststroke structural repair, regeneration, and functional reorganization during the first week after stroke has yet to be elucidated.

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Smeshnoi, I. A., I. N. Pasechnik, E. I. Skobelev, D. A. Timashkov, М. A. Onegin, Yu V. Nikiforov, and S. I. Kontarev. "Infusion Therapy Optimization in Selective Abdominal Surgery." General Reanimatology 14, no. 5 (October 28, 2018): 4–15. http://dx.doi.org/10.15360/1813-9779-2018-5-4-15.

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Purpose. Evaluation of the influence of intra-operative targeted infusion therapy managed by the monitoring of stroke volume variability on post-operative results of major surgeries of gastrointestinal organs.Materials and Methods. The prospective study included 80 patients subjected to selective operative interventions of abdominal organs involving entero-enteroanastomosis. In the experimental group (n=39), the infusion therapy was conducted according to the developed targeted therapy protocol, of which the key parameter was stroke volume variability. In the control group (n=41), infusion therapy was conducted based on routine hemodynamic monitoring (average arterial pressure, heart rate, blood loss level with regard to intra-operative situation). In both groups, operative intervention was carried out in identical conditions (combined anesthesia, identical drugs to induce and maintain anesthesia); the only differences included infusion therapy.Results. In the experimental group versus the control group the intra-operative infusion volume was smaller, the number of patients with complications and the total number of complications were reliably lower, and the gastrointestinal tract functional recovery occurred earlier. Conclusion. A targeted infusion therapy based on a stroke volume variability monitoring as the key parameter allows optimizing the infusion load and facilitates reduction of the number of patients with complications and earlier recovery of gastrointestinal tract functions after major operative abdominal interventions.

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Trotman-Lucas, Melissa, and Claire L. Gibson. "A review of experimental models of focal cerebral ischemia focusing on the middle cerebral artery occlusion model." F1000Research 10 (March 26, 2021): 242. http://dx.doi.org/10.12688/f1000research.51752.1.

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Cerebral ischemic stroke is a leading cause of death and disability, but current pharmacological therapies are limited in their utility and effectiveness. In vitro and in vivo models of ischemic stroke have been developed which allow us to further elucidate the pathophysiological mechanisms of injury and investigate potential drug targets. In vitro models permit mechanistic investigation of the biochemical and molecular mechanisms of injury but are reductionist and do not mimic the complexity of clinical stroke. In vivo models of ischemic stroke directly replicate the reduction in blood flow and the resulting impact on nervous tissue. The most frequently used in vivo model of ischemic stroke is the intraluminal suture middle cerebral artery occlusion (iMCAO) model, which has been fundamental in revealing various aspects of stroke pathology. However, the iMCAO model produces lesion volumes with large standard deviations even though rigid surgical and data collection protocols are followed. There is a need to refine the MCAO model to reduce variability in the standard outcome measure of lesion volume. The typical approach to produce vessel occlusion is to induce an obstruction at the origin of the middle cerebral artery and reperfusion is reliant on the Circle of Willis (CoW). However, in rodents the CoW is anatomically highly variable which could account for variations in lesion volume. Thus, we developed a refined approach whereby reliance on the CoW for reperfusion was removed. This approach improved reperfusion to the ischemic hemisphere, reduced variability in lesion volume by 30%, and reduced group sizes required to determine an effective treatment response by almost 40%. This refinement involves a methodological adaptation of the original surgical approach which we have shared with the scientific community via publication of a visualised methods article and providing hands-on training to other experimental stroke researchers.

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Trotman-Lucas, Melissa, and Claire L. Gibson. "A review of experimental models of focal cerebral ischemia focusing on the middle cerebral artery occlusion model." F1000Research 10 (June 11, 2021): 242. http://dx.doi.org/10.12688/f1000research.51752.2.

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Cerebral ischemic stroke is a leading cause of death and disability, but current pharmacological therapies are limited in their utility and effectiveness. In vitro and in vivo models of ischemic stroke have been developed which allow us to further elucidate the pathophysiological mechanisms of injury and investigate potential drug targets. In vitro models permit mechanistic investigation of the biochemical and molecular mechanisms of injury but are reductionist and do not mimic the complexity of clinical stroke. In vivo models of ischemic stroke directly replicate the reduction in blood flow and the resulting impact on nervous tissue. The most frequently used in vivo model of ischemic stroke is the intraluminal suture middle cerebral artery occlusion (iMCAO) model, which has been fundamental in revealing various aspects of stroke pathology. However, the iMCAO model produces lesion volumes with large standard deviations even though rigid surgical and data collection protocols are followed. There is a need to refine the MCAO model to reduce variability in the standard outcome measure of lesion volume. The typical approach to produce vessel occlusion is to induce an obstruction at the origin of the middle cerebral artery and reperfusion is reliant on the Circle of Willis (CoW). However, in rodents the CoW is anatomically highly variable which could account for variations in lesion volume. Thus, we developed a refined approach whereby reliance on the CoW for reperfusion was removed. This approach improved reperfusion to the ischemic hemisphere, reduced variability in lesion volume by 30%, and reduced group sizes required to determine an effective treatment response by almost 40%. This refinement involves a methodological adaptation of the original surgical approach which we have shared with the scientific community via publication of a visualised methods article and providing hands-on training to other experimental stroke researchers.

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Roeth, Nathan A., Timothy R. Ball, William C. Culp, W. Todd Bohannon, Marvin D. Atkins, and William E. Johnston. "Effect of Increasing Heart Rate and Tidal Volume on Stroke Volume Variability in Vascular Surgery Patients." Journal of Cardiothoracic and Vascular Anesthesia 28, no. 6 (December 2014): 1516–20. http://dx.doi.org/10.1053/j.jvca.2014.05.014.

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Szwarc, R. S., D. Laurent, P. R. Allegrini, and H. A. Ball. "Conductance catheter measurement of left ventricular volume: evidence for nonlinearity within cardiac cycle." American Journal of Physiology-Heart and Circulatory Physiology 268, no. 4 (April 1, 1995): H1490—H1498. http://dx.doi.org/10.1152/ajpheart.1995.268.4.h1490.

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The conductance catheter gain factor, alpha, is usually determined by an independent measure of stroke volume and, as such, is assumed to be constant. However, nonlinearity of the conductance-volume relation has been proposed on theoretical grounds. The present study was designed to establish the extent of nonlinearity, or variability of alpha, within the cardiac cycle using magnetic resonance imaging (MRI) as the reference method. Pentobarbital-anesthetized minipigs (n = 10, 10–13 kg) were instrumented with left ventricular (LV) conductance and Millar catheters. Conductance catheter signals were recorded, and volumes were corrected for parallel conductance using a saline-dilution technique. Animals were then placed in a 4.7-T magnet, and first time derivative of LV pressure-gated transverse MRI images (5-mm slices) acquired during isovolumic contraction (end diastole) and relaxation (end systole). LV cavity volumes were then determined using a third-order polynomial model. The gain alpha was computed three ways: by dividing conductance stroke volume by MRI stroke volume (alpha SV), by dividing conductance end-diastolic volume by MRI end-diastolic volume (alpha ED), and by dividing conductance end-systolic volume by MRI end-systolic volume (alpha ES). alpha SV was 0.62 +/- 0.15, with alpha ED (0.71 +/- 0.17) significantly lower than alpha ES (0.81 +/- 0.21; P < 0.001). Using alpha SV to adjust conductance gain (i.e., assuming constant gain) resulted in a significantly larger end-diastolic volume (25.8 +/- 4.6 ml) and smaller ejection fraction (46.8 +/- 7.2%) than those obtained with MRI (23.0 +/- 4.1 ml and 53.1 +/- 7.3%, respectively; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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Loeber, Cleo P., Stanley J. Goldberg, Richard L. Donnerstein, and Margaret A. Butler. "Time variability of cardiac output and stroke volume in persons without cardiac disease." American Journal of Cardiology 59, no. 6 (March 1987): 714–16. http://dx.doi.org/10.1016/0002-9149(87)91204-5.

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Rewell, Sarah SJ, Amy L. Jeffreys, Steven A. Sastra, Susan F. Cox, John A. Fernandez, Elena Aleksoska, H. Bart van der Worp, Leonid Churilov, Malcolm R. Macleod, and David W. Howells. "Hypothermia revisited: Impact of ischaemic duration and between experiment variability." Journal of Cerebral Blood Flow & Metabolism 37, no. 10 (January 13, 2017): 3380–90. http://dx.doi.org/10.1177/0271678x16688704.

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To assess the true effect of novel therapies for ischaemic stroke, a positive control that can validate the experimental model and design is vital. Hypothermia may be a good candidate for such a positive control, given the convincing body of evidence from animal models of ischaemic stroke. Taking conditions under which substantial efficacy had been seen in a meta-analysis of hypothermia for focal ischaemia in animal models, we undertook three randomised and blinded studies examining the effect of hypothermia induced immediately following the onset of middle cerebral artery occlusion on infarct volume in rats (n = 15, 23, 264). Hypothermia to a depth of 33℃ and maintained for 130 min significantly reduced infarct volume compared to normothermia treatment (by 27–63%) and depended on ischaemic duration (F(3,244) = 21.242, p < 0.05). However, the protective effect varied across experiments with differences in both the size of the infarct observed in normothermic controls and the time to reach target temperature. Our results highlight the need for sample size and power calculations to take into account variations between individual experiments requiring induction of focal ischaemia.

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Doshchannikov, D. A., and T. V. Mokina. "Influence of ishemic stroke on changes of parameters of heart rate variability and clinical-echocardiografical parameters in patient with chronic heart failure in the early recovery period." Bulletin of Siberian Medicine 7, no. 5-1 (December 30, 2008): 122–27. http://dx.doi.org/10.20538/1682-0363-2008-5-1-122-127.

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The purpose of present research is to estimate the influence of ischemic stroke on changes of clinical and instrumental parameters in patients with chronic heart failure (CHF) depending on expressiveness of neurologic deficiency. We supervised 103 patients with CHF, among them 71 patients with stroke. In all the patients twice heart rate variability and echocardiography were carried out. To determine CHF FC we used an estimation scale of a clinical condition (SHOCKS by Mareev, 2000). After 6 months all the patients were divided into 2 groups depending on expressiveness of neurological deficieny. Significant deterioration of heart rate variability (HRV) parameters in the group of patients with expressed neurological deficiency was revealed. Also in this group increase of end diastolic volume, end systolic volume and deterioration of diastolic function was revealed. 6 months after stroke in patients with CHF with expressed neurological deficiency reduction of parameters of HRV, progressiveness of hyperactivity of sympathetic adrenal system, deterioration of morphological-functional parameters of left ventrical was revealed.

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Richardson, Ashley K., Andrew CS Mitchell, and Gerwyn Hughes. "The effect of movement variability on putting proficiency during the golf putting stroke." International Journal of Sports Science & Coaching 13, no. 4 (April 4, 2018): 590–97. http://dx.doi.org/10.1177/1747954118768234.

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Movement variability has been considered important to execute an effective golf swing yet is comparatively unexplored regarding the golf putt. Movement variability could potentially be important considering the small margins of error between a successful and a missed putt. The aim of this study was to assess whether variability of body segment rotations influence putting performance (ball kinematic measures). Eight golfers (handicap range 0–10) performed a 3.2 m level putt wearing retro-reflective markers which were tracked using a three-dimensional motion analysis system sampling at 120 Hz. Ball roll kinematics were recorded using Quintic Ball Roll launch monitor. Movement (segment) variability was calculated based on a scalene ellipsoid volume concept and correlated with the coefficient of variation of ball kinematics. Statistical analysis showed no significant relationships between segment variability and putting proficiency. One significant relationship was identified between left forearm variability and horizontal launch angle, but this did not result in deficits in putting success. Results show that performance variability in the backswing and downswing is not related to putting proficiency or the majority of ball roll measures. Differing strategies may exist where certain golfers may have more fluid movement patterns thereby effectively utilising variability of movement. Therefore, golf instructors should consider movement variability when coaching the golf putt.

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SIEBERT, JANUSZ, JERZY WTOREK, and JAN ROGOWSKI. "Stroke Volume Variability Cardiovascular Response to Orthostatic Maneuver in Patients with Coronary Artery Diseases." Annals of the New York Academy of Sciences 873, no. 1 ELECTRICAL BI (April 1999): 182–90. http://dx.doi.org/10.1111/j.1749-6632.1999.tb09466.x.

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Elstad, Maja, Erin L. O’Callaghan, Alex J. Smith, Alona Ben-Tal, and Rohit Ramchandra. "Cardiorespiratory interactions in humans and animals: rhythms for life." American Journal of Physiology-Heart and Circulatory Physiology 315, no. 1 (July 1, 2018): H6—H17. http://dx.doi.org/10.1152/ajpheart.00701.2017.

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The cardiorespiratory system exhibits oscillations from a range of sources. One of the most studied oscillations is heart rate variability, which is thought to be beneficial and can serve as an index of a healthy cardiovascular system. Heart rate variability is dampened in many diseases including depression, autoimmune diseases, hypertension, and heart failure. Thus, understanding the interactions that lead to heart rate variability, and its physiological role, could help with prevention, diagnosis, and treatment of cardiovascular diseases. In this review, we consider three types of cardiorespiratory interactions: respiratory sinus arrhythmia (variability in heart rate at the frequency of breathing), cardioventilatory coupling (synchronization between the heart beat and the onset of inspiration), and respiratory stroke volume synchronization (the constant phase difference between the right and the left stroke volumes over one respiratory cycle). While the exact physiological role of these oscillations continues to be debated, the redundancies in the mechanisms responsible for its generation and its strong evolutionary conservation point to the importance of cardiorespiratory interactions. The putative mechanisms driving cardiorespiratory oscillations as well as the physiological significance of these oscillations will be reviewed. We suggest that cardiorespiratory interactions have the capacity to both dampen the variability in systemic blood flow as well as improve the efficiency of work done by the heart while maintaining physiological levels of arterial CO2. Given that reduction in variability is a prognostic indicator of disease, we argue that restoration of this variability via pharmaceutical or device-based approaches may be beneficial in prolonging life.

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Zhang, Hua, Pranay Prabhakar, Robert Sealock, and James E. Faber. "Wide Genetic Variation in the Native Pial Collateral Circulation is a Major Determinant of Variation in Severity of Stroke." Journal of Cerebral Blood Flow & Metabolism 30, no. 5 (February 3, 2010): 923–34. http://dx.doi.org/10.1038/jcbfm.2010.10.

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Severity of stroke varies widely among individuals. Whether differences in the extent of the native (preexisting) pial collateral circulation exist and contribute to this variability is unknown. We addressed these questions and probed for potential genetic contributions using morphometric analysis of the collateral circulation in 15 inbred mouse strains recently shown to exhibit wide differences in infarct volume. Morphometrics were determined in the unligated left hemisphere (for native collaterals) and ligated right hemisphere (for remodeled collaterals) 6 days after permanent middle cerebral artery (MCA) occlusion. Variation among strains in native collateral number, diameter, MCA, anterior cerebral artery (ACA), and posterior cerebral artery (PCA) tree territories were, respectively: 56-fold, 3-fold, 42%, 56%, and 61%. Collateral length ( P<0.001) and the number of penetrating arterioles branching from them also varied ( P<0.05). Infarct volume correlated inversely with collateral number ( P<0.0001), diameter ( P<0.0001), and penetrating arteriole number ( P<0.05) and directly with MCA territory ( P<0.05). Relative collateral conductance and MCA territory, when factored together, strongly predicted infarct volume ( P<0.0001). Outward remodeling of collaterals in the ligated hemisphere varied ∼3-fold. These data show that the extent of the native pial collateral circulation and collateral remodeling after obstruction vary widely with genetic background, and suggest that this variability, due to natural polymorphisms, is a major contributor to variability in infarct volume.

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Zhang, Huan-Xin, Qun-Xiong Fan, Shi-Zhen Xue, Min Zhang, and Ji-Xian Zhao. "Twenty-four-hour blood pressure variability plays a detrimental role in the neurological outcome of hemorrhagic stroke." Journal of International Medical Research 46, no. 7 (June 4, 2018): 2558–68. http://dx.doi.org/10.1177/0300060518760463.

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Background Blood pressure variability (BPV) is a modifiable risk factor for stroke. This study was performed to determine the prognostic role of BPV in patients with acute hemorrhagic stroke. Methods The data of 131 hospitalized hypertensive patients with spontaneous intracerebral hemorrhage (sICH) were collected. All patients underwent examinations using several neurological scales (Glasgow Coma Scale, National Institutes of Health Stroke Scale, and modified Rankin scale [mRS]) and BP measurements at different time points. Results Sex, age, hematoma volume, and neurological scores were not significantly different between patients with a favorable and unfavorable prognosis for sICH. However, significant differences were found in hypertension, diabetes, metabolic syndrome, atrial fibrillation, smoking, and stroke history. The standard deviation (SD), coefficient of variation (CV), and maximum–minimum range (Max–Min) of diastolic BP and the mean, SD, CV, and Max–Min of systolic BP significantly differed between the groups. Statistical analysis also demonstrated correlations between the 90-day mRS score and BPV and between systolic BPV and the 90-day mRS score. Conclusion High systolic or diastolic BPV within 24 hours of hemorrhagic stroke onset is associated with the 90-day neurological prognosis. The 24-hour BPV plays a critical role in the neurological outcome of hemorrhagic stroke.

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Tang, Yongquan, Martin J. Turner, Johnny S. Yem, and A. Barry Baker. "Calibration of pneumotachographs using a calibrated syringe." Journal of Applied Physiology 95, no. 2 (August 2003): 571–76. http://dx.doi.org/10.1152/japplphysiol.00196.2003.

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Pneumotachograph require frequent calibration. Constant-flow methods allow polynomial calibration curves to be derived but are time consuming. The iterative syringe stroke technique is moderately efficient but results in discontinuous conductance arrays. This study investigated the derivation of first-, second-, and third-order polynomial calibration curves from 6 to 50 strokes of a calibration syringe. We used multiple linear regression to derive first-, second-, and third-order polynomial coefficients from two sets of 6–50 syringe strokes. In part A, peak flows did not exceed the specified linear range of the pneumotachograph, whereas flows in part B peaked at 160% of the maximum linear range. Conductance arrays were derived from the same data sets by using a published algorithm. Volume errors of the calibration strokes and of separate sets of 70 validation strokes ( part A) and 140 validation strokes ( part B) were calculated by using the polynomials and conductance arrays. Second- and third-order polynomials derived from 10 calibration strokes achieved volume variability equal to or better than conductance arrays derived from 50 strokes. We found that evaluation of conductance arrays using the calibration syringe strokes yields falsely low volume variances. We conclude that accurate polynomial curves can be derived from as few as 10 syringe strokes, and the new polynomial calibration method is substantially more time efficient than previously published conductance methods.

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Li, Huagang, Dong Sun, Dongwei Lu, Junjian Zhang, and Junjie Zeng. "Low Hippocampal Dentate Gyrus Volume Associated With Hypertension-Related Cognitive Impairment." American Journal of Alzheimer's Disease & Other Dementiasr 35 (January 1, 2020): 153331752094978. http://dx.doi.org/10.1177/1533317520949782.

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Hypertension increases the risk of cognitive impairment independent of detectable stroke or cerebral lesions. However, the principal pathophysiological basis of this increase has not been fully elucidated. The present study investigates the relationships among blood pressure, hippocampal subfields volume, and cognitive function in a relatively young non-stroke population. A total of 59 non-stroke non-dementia subjects (mean age, 57.2 ± 4.9 years) were enrolled. All subjects were subjected to complete assessment of vascular risk factors including 24-hour blood pressure monitoring, various neuropsychological tests, and 3D-T1 MR scan. Freesurfer V6.0 was used for segmentation of hippocampal subfields. Our analyses revealed that both 24-hour and daytime mean systolic blood pressure (SBP) were significantly associated with the low volume of the left DG. Higher coefficient of variation (CV) of daytime SBP was significantly associated with lower volume of the left Cornu Ammonis 4 and dentate gyrus (DG) region. Both higher CV of 24-hour mean SBP and daytime SBP were significantly associated with lower performance in both executive and linguistic function. The low volume of the left DG was significantly associated with the low performance in linguistic function. Our findings support that reduced DG volume and increased SBP variability associated with hypertension-related cognitive impairment.

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Elstad, Maja, and Lars Walløe. "Heart rate variability and stroke volume variability to detect central hypovolemia during spontaneous breathing and supported ventilation in young, healthy volunteers." Physiological Measurement 36, no. 4 (March 23, 2015): 671–81. http://dx.doi.org/10.1088/0967-3334/36/4/671.

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Janot, J., R. Robergs, J. Bell, C. Vella, and L. Kravitz. "INTERINDIVIDUAL VARIABILITY OF CARDIAC OUTPUT, STROKE VOLUME, AND HEART RATE RESPONSES DURING INCREMENTAL EXERCISE TO VO2MAX." Medicine & Science in Sports & Exercise 35, Supplement 1 (May 2003): S277. http://dx.doi.org/10.1097/00005768-200305001-01537.

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Kaeferlein, B., R. C. Serfass, A. J. Walker, D. C. Rao, J. S. Skinner, J. H. Wilmore, J. Gagnon, C. Bouchard, and A. S. Leon. "THE EFFECT OF EXERCISE TRAINING ON HEART RATE VARIABILITY AND STROKE VOLUME: THE HERITAGE FAMILY STUDY." Medicine & Science in Sports & Exercise 30, Supplement (May 1998): 216. http://dx.doi.org/10.1097/00005768-199805001-01234.

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Duschek, Stefan, Alexandra Hoffmann, Casandra I. Montoro, and Gustavo A. Reyes del Paso. "Autonomic Cardiovascular Dysregulation at Rest and During Stress in Chronically Low Blood Pressure." Journal of Psychophysiology 33, no. 1 (January 1, 2019): 39–53. http://dx.doi.org/10.1027/0269-8803/a000204.

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Abstract. Chronic low blood pressure (hypotension) is accompanied by symptoms such as fatigue, reduced drive, faintness, dizziness, cold limbs, and concentration difficulties. The study explored the involvement of aberrances in autonomic cardiovascular control in the origin of this condition. In 40 hypotensive and 40 normotensive subjects, impedance cardiography, electrocardiography, and continuous blood pressure recordings were performed at rest and during stress induced by mental calculation. Parameters of cardiac sympathetic control (i.e., stroke volume, cardiac output, pre-ejection period, total peripheral resistance), parasympathetic control (i.e., heart rate variability), and baroreflex function (i.e., baroreflex sensitivity) were obtained. The hypotensive group exhibited markedly lower stroke volume, heart rate, and cardiac output, as well as higher pre-ejection period and baroreflex sensitivity than the control group. Hypotension was furthermore associated with a smaller blood pressure response during stress. No group differences arose in total peripheral resistance and heart rate variability. While reduced beta-adrenergic myocardial drive seems to constitute the principal feature of the autonomic impairment that characterizes chronic hypotension, baroreflex-related mechanisms may also contribute to this state. Insufficient organ perfusion due to reduced cardiac output and deficient cardiovascular adjustment to situational requirements may be involved in the manifestation of bodily and mental symptoms.

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LAITINEN, Tomi, Hanna HUOPIO, Ilkka VAUHKONEN, Cyril CAMARO, Juha HARTIKAINEN, Markku LAAKSO, and Leo NISKANEN. "Effects of euglycaemic and hypoglycaemic hyperinsulinaemia on sympathetic and parasympathetic regulation of haemodynamics in healthy subjects." Clinical Science 105, no. 3 (September 1, 2003): 315–22. http://dx.doi.org/10.1042/cs20030079.

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The effects of hypoglycaemia during hyperinsulinaemia, occurring under various pathophysiological conditions, on the cardiovascular regulatory system and vasculature are largely unknown. The aim of the present study was to investigate regulatory and haemodynamic responses to acute hyperinsulinaemia and consequent hypoglycaemia in 18 healthy subjects. Blood sampling and 5 min ECG and blood pressure recordings were performed at baseline and during the euglycaemic and hypoglycaemic phases of a hyperinsulinaemic clamp. Heart rate variability (HRV) and blood pressure variability (BPV) were assessed by using power spectral analysis, and baroreflex sensitivity (BRS) was assessed using the cross-spectral method. Stroke volume was assessed from the non-invasive blood pressure signal by the arterial pulse contour method. Euglycaemic hyperinsulinaemia did not change plasma catecholamine concentrations, HRV, BPV, BRS, heart rate, blood pressure, stroke volume, cardiac output or peripheral resistance. However, hyperinsulinaemic hypoglycaemia resulted in an 11.7-fold increase in the plasma adrenaline concentration (from 0.19±0.03 to 1.68±0.32 nmol/l; P<0.001), and a modest 1.3-fold increase in the plasma noradrenaline concentration (from 1.74±0.22 to 2.02±0.19 nmol/l; P<0.05) compared with baseline. Furthermore, we observed significant decreases in diastolic blood pressure (from 68±3 to 60±3 mmHg; P<0.05) and peripheral resistance (from 24.1±1.2 to 18.5±1.1 mmHg·min-1·l-1; P<0.01). Stroke volume and cardiac output increased markedly from the euglycaemic to the hypoglycaemic period only (P<0.01 for both). Hypoglycaemia did not influence HRV, BPV or BRS. Our findings indicate that hyperinsulinaemic hypoglycaemia is characterized by a significant increase in the plasma adrenaline concentration and by decreases in peripheral resistance and blood pressure. Counter-regulation during hyperinsulinaemic hypoglycaemia involves selective adrenomedullary sympathetic activation, and does not influence cardiac parasympathetic regulation or baroreflex control of heart rate.

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Goyal, Mayank, Johanna M. Ospel, Bijoy Menon, Mohammed Almekhlafi, Mahesh Jayaraman, Jens Fiehler, Marios Psychogios, et al. "Challenging the Ischemic Core Concept in Acute Ischemic Stroke Imaging." Stroke 51, no. 10 (October 2020): 3147–55. http://dx.doi.org/10.1161/strokeaha.120.030620.

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Endovascular treatment is a highly effective therapy for acute ischemic stroke due to large vessel occlusion and has recently revolutionized stroke care. Oftentimes, ischemic core extent on baseline imaging is used to determine endovascular treatment-eligibility. There are, however, 3 fundamental issues with the core concept: First, computed tomography and magnetic resonance imaging, which are mostly used in the acute stroke setting, are not able to precisely determine whether and to what extent brain tissue is infarcted (core) or still viable, due to variability in tissue vulnerability, the phenomenon of selective neuronal loss and lack of a reliable gold standard. Second, treatment decision-making in acute stroke is multifactorial, and as such, the relative importance of single variables, including imaging factors, is reduced. Third, there are often discrepancies between core volume and clinical outcome. This review will address the uncertainty in terminology and proposes a direction towards more clarity. This theoretical exercise needs empirical data that clarify the definitions further and prove its value.

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Nishiyasu, T., N. Tan, K. Morimoto, M. Nishiyasu, Y. Yamaguchi, and N. Murakami. "Enhancement of parasympathetic cardiac activity during activation of muscle metaboreflex in humans." Journal of Applied Physiology 77, no. 6 (December 1, 1994): 2778–83. http://dx.doi.org/10.1152/jappl.1994.77.6.2778.

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We measured the changes in heart rate (HR) variability estimated from the standard deviation of the R-R intervals to evaluate cardiac parasympathetic tone noninvasively before and during activation of muscle metaboreflex induced by postexercise muscle ischemia. Eight healthy male subjects performed sustained handgrip at 50% maximal voluntary contraction followed by forearm occlusion. Mean arterial pressure, cardiac stroke volume, and ratio of cardiac preejection period to left ventricular ejection time (PEP/LVET) were also measured. During the 2-min occlusion after 60 s of handgrip with voluntary respiration, HR variability and mean arterial pressure were significantly increased from baseline (54.4 +/- 6.1 to 80.1 +/- 12.8 ms and 81 +/- 1 to 99 +/- 3 mmHg, respectively) and PEP/LVET was decreased from resting level of 0.404 +/- 0.022 to 0.363 +/- 0.036. During occlusion and recovery, HR did not change from baseline level in any experiment. There was no influence of occlusion itself or of cessation of exercise per se on any parameters. Although overall enhanced HR variability was seen, probably due to lower breathing frequency and larger tidal volume, similar results were also obtained from an experiment with controlled respiration, showing that the increase in HR variability was not due to the changes in tidal volume or breathing frequency during occlusion. In conclusion, the HR variability is increased during activation of the muscle metaboreflex induced by postexercise muscle ischemia in humans. This finding shows that the parasympathetic cardiac tone is enhanced during activation of the muscle metaboreflex in humans and balances enhanced cardiac sympathetic activity to result in an unchanged HR.(ABSTRACT TRUNCATED AT 250 WORDS)

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Zuo, Zhi, Anne Subgang, Alireza Abaei, Wolfgang Rottbauer, Detlef Stiller, Genshan Ma, and Volker Rasche. "Assessment of Longitudinal Reproducibility of Mice LV Function Parameters at 11.7 T Derived from Self-Gated CINE MRI." BioMed Research International 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/8392952.

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The objective of this work was the assessment of the reproducibility of self-gated cardiac MRI in mice at ultra-high-field strength. A group of adult mice (n=5) was followed over 360 days with a standardized MR protocol including reproducible animal position and standardized planning of the scan planes. From the resulting CINE MRI data, global left ventricular (LV) function parameters including end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and left ventricular mass (LVM) were quantified. The reproducibility of the self-gated technique as well as the intragroup variability and longitudinal changes of the investigated parameters was assessed. Self-gated cardiac MRI proved excellent reproducibility of the global LV function parameters, which was in the order of the intragroup variability. Longitudinal assessment did not reveal any significant variations for EDV, ESV, SV, and EF but an expected increase of the LVM with increasing age. In summary, self-gated MRI in combination with a standardized protocol for animal positioning and scan plane planning ensures reproducible assessment of global LV function parameters.

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Chemaly, Elie R., Antoine H. Chaanine, Susumu Sakata, and Roger J. Hajjar. "Stroke volume-to-wall stress ratio as a load-adjusted and stiffness-adjusted indicator of ventricular systolic performance in chronic loading." Journal of Applied Physiology 113, no. 8 (October 15, 2012): 1267–84. http://dx.doi.org/10.1152/japplphysiol.00785.2012.

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Load-adjusted measures of left ventricle (LV) systolic performance are limited by dependence on LV stiffness and afterload. To our knowledge, no stiffness-adjusted and afterload-adjusted indicator was tested in models of pressure (POH) and volume overload hypertrophy (VOH). We hypothesized that wall stress reflects changes in loading, incorporating chamber stiffness and afterload; therefore, stroke volume-to-wall stress ratio more accurately reflects systolic performance. We used rat models of POH (ascending aortic banding) and VOH (aorto-cava shunt). Animals underwent echocardiography and pressure-volume analysis at baseline and dobutamine challenge. We achieved extreme bidirectional alterations in LV systolic performance, end-systolic elastance (Ees), passive stiffness, and arterial elastance (Ea). In POH with LV dilatation and failure, some load-independent indicators of systolic performance remained elevated compared with controls, while some others failed to decrease with wide variability. In VOH, most, but not all indicators, including LV ejection fraction, were significantly reduced compared with controls, despite hyperdynamic circulation, lack of heart failure, and preserved contractile reserve. We related systolic performance to Ees adjusted for Ea and LV passive stiffness in multivariate models. Calculated residual Ees was not reduced in POH with heart failure and was reduced in VOH, while it positively correlated to dobutamine dose. Conversely, stroke volume-to-wall stress ratio was normal in compensated POH, markedly decreased in POH with heart failure, and, in contrast with LV ejection fraction, normal in VOH. Our results support stroke volume-to-wall stress ratio as a load-adjusted and stiffness-adjusted indicator of systolic function in models of POH and VOH.

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DRITSAS, ATHANASE, JAYSHREE JOSHI, STUART C. WEBB, GEORGE ATHANASSOPOULOS, CELIA M. OAKLEY, and PETROS NIHOYANNOPOULOS. "Beat-to-Beat Variability in Stroke Volume During VVI Pacing as Predictor of Hemodynamic Benefit from DDD Pacing." Pacing and Clinical Electrophysiology 16, no. 8 (August 1993): 1713–18. http://dx.doi.org/10.1111/j.1540-8159.1993.tb01042.x.

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Holme, Nathalie Linn Anikken, Erling Bekkestad Rein, and Maja Elstad. "Cardiac stroke volume variability measured non-invasively by three methods for detection of central hypovolemia in healthy humans." European Journal of Applied Physiology 116, no. 11-12 (September 10, 2016): 2187–96. http://dx.doi.org/10.1007/s00421-016-3471-2.

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AGOSTONI, Pier Giuseppe, Karlman WASSERMAN, Giovanni B. PEREGO, Marco GUAZZI, Gaia CATTADORI, Pietro PALERMO, Gianfranco LAURI, and Giancarlo MARENZI. "Non-invasive measurement of stroke volume during exercise in heart failure patients." Clinical Science 98, no. 5 (April 4, 2000): 545–51. http://dx.doi.org/10.1042/cs0980545.

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The objective of the present study was to determine the variability of the arterio–venous O2 concentration difference [C(a–v)O2] at anaerobic threshold and at peak oxygen uptake (VO2) during a progressively increasing cycle ergometer exercise test, with the purpose of assessing the possible error in estimating stroke volume from measurements of VO2 alone. We sampled mixed venous and systemic arterial blood every 1 min during a progressively increasing cycle ergometer exercise test and measured, in each blood sample, haemoglobin concentration and blood gas data. Ventilation, VO2 and CO2 uptake were also measured continuously. We studied 40 patients with normal haemoglobin concentrations and with stable heart failure due to ischaemic or idiopathic cardiomyopathy. Mean values (±S.D.) for C(a–v)O2 were 7.8±2.6, 13.0±2.4 and 15.0±2.7 ml/100 ml at rest, anaerobic threshold and peak VO2 respectively. The patients with heart failure were divided into classes according to their peak VO2. Classes A, B and C contained patients with peak VO2 values of > 20, 15–20 and 10–15 ml·min-1·kg-1 respectively. At anaerobic threshold, C(a–v)O2 was 12.3±1.3, 13.1±2.7 and 13.5±2.6 ml/100 ml for classes A, B and C respectively (class A significantly different from classes B and C; P < 0.05). At peak exercise C(a–v)O2 was 13.6±1.4, 15.6±2.5 and 15.4±3.2 ml/100 ml for classes A, B and C respectively (class A significantly different from classes B and C; P < 0.05). Stroke volume was estimated for each subject using the mean values of the measured C(a–v)O2 in each functional class and individual values of VO2 and heart rate using the Fick formulation. The average difference between the stroke volume estimated from mean C(a–v)O2 and that obtained using the patient's actual C(a–v)O2 value was 9.2±9.7, 1.0±8.8 and -0.2±6.1 ml at anaerobic threshold, and -1.9±11.3, 0.9±10.0 and -2.3±8.5 ml at peak exercise, in classes A, B and C respectively. Among the various classes, the most precise estimation of stroke volume was observed for class C patients. We conclude that stroke volume during exercise can be estimated with the accuracy needed for most purposes from measurement of VO2 at the anaerobic threshold and at peak exercise, and from population-estimated mean values for C(a–v)O2 in heart failure patients.

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Martusevich, Andrew, Ivan Bocharin, Natalia Ronzhina, Solomon Apoyan, Levon Dilenyan, and Maxim Gurjanov. "The Peculiarities of Heart Rate Variability in Student Athletes." International Journal of Biomedicine 11, no. 2 (June 5, 2021): 169–72. http://dx.doi.org/10.21103/article11(2)_oa9.

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The aim of this research was to study the peculiarities of heart rate variability (HRV) and microcirculation in students, depending on their sport specialization. Methods and Results: Our study included the results of a survey of 96 students from 18 to 21 years of age who were the members of the national teams of their universities in athletics (n=49) and floorball (n=47). For ECG registration and analysis of hemodynamic findings, including those characterizing the HRV, we used the “Medical Soft” sports testing system (“MS FIT Pro”). For monitoring, we used the standard hemodynamic patterns (blood pressure, HR, stroke volume, cardiac output, and others), statistical and spectral indicators of the HRV, as well as an integral criterion of the state of microcirculation. The studied HRV parameters in most students generally were within the age range. At the same time, track and field athletes have large adaptive resources and, consequently, a more optimal level of myocardial fitness, in comparison with floorball players. Conclusion: The orientation of sports training among students affects heart condition.

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Hoff, Ingrid Elise, Lars Øivind Høiseth, Jonny Hisdal, Jo Røislien, Svein Aslak Landsverk, and Knut Arvid Kirkebøen. "Respiratory Variations in Pulse Pressure Reflect Central Hypovolemia during Noninvasive Positive Pressure Ventilation." Critical Care Research and Practice 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/712728.

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Background. Correct volume management is essential in patients with respiratory failure. We investigated the ability of respiratory variations in noninvasive pulse pressure (ΔPP), photoplethysmographic waveform amplitude (ΔPOP), and pleth variability index (PVI) to reflect hypovolemia during noninvasive positive pressure ventilation by inducing hypovolemia with progressive lower body negative pressure (LBNP).Methods. Fourteen volunteers underwent LBNP of 0, −20, −40, −60, and −80 mmHg for 4.5 min at each level or until presyncope. The procedure was repeated with noninvasive positive pressure ventilation. We measured stroke volume (suprasternal Doppler), ΔPP (Finapres), ΔPOP, and PVI and assessed their association with LBNP-level using linear mixed model regression analyses.Results. Stroke volume decreased with each pressure level (−11.2 mL, 95% CI −11.8, −9.6,P<0.001), with an additional effect of noninvasive positive pressure ventilation (−3.0 mL, 95% CI −8.5, −1.3,P=0.009). ΔPP increased for each LBNP-level (1.2%, 95% CI 0.5, 1.8,P<0.001) and almost doubled during noninvasive positive pressure ventilation (additional increase 1.0%, 95% CI 0.1, 1.9,P=0.003). Neither ΔPOP nor PVI was significantly associated with LBNP-level.Conclusions. During noninvasive positive pressure ventilation, preload changes were reflected by ΔPP but not by ΔPOP or PVI. This implies that ΔPP may be used to assess volume status during noninvasive positive pressure ventilation.

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Kitamura, Juri, Hiroki Ueno, Michiaki Nagai, Naohisa Hosomi, Kie Honjo, Masahiro Nakamori, Tomoya Mukai, et al. "Blood Pressure Variability in Acute Ischemic Stroke: Influence of Infarct Location in the Insular Cortex." European Neurology 79, no. 1-2 (2018): 90–99. http://dx.doi.org/10.1159/000486306.

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Background: The aim of this study was to elucidate the influence of insular infarction on blood pressure (BP) variability and outcomes according to the region of the insular cortex affected. Methods: A total of 90 patients diagnosed with acute unilateral ischemic stroke were registered. The BP variability was calculated over 24 h after admission (hyperacute) and for 2–3 days after admission (acute). Patients were classified into groups of right and left, and then right anterior, right posterior, left anterior, and left posterior insular infarction. Results: Patients with insular infarction showed a significantly larger infarct volume, higher modified Rankin scale scores, and lower SD and coefficient of variation (CV) of systolic BP in the hyperacute phase than shown by patients without insular infarction (p < 0.01, p < 0.01, p = 0.02, and p = 0.03, respectively). The SD and CV of systolic BP in the hyperacute phase showed significant differences among the 3 groups with right insular infarction, with left insular infarction, and without insular infarction (p < 0.05 and p < 0.05, respectively). There was a tendency for the systolic BP variability to be lower in patients with right anterior insular infarction than in patients with infarcts in other areas. Conclusion: The right insular cortex, especially the anterior part, might be a hub for autonomic nervous regulation.

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Tsai, Jang-Zern, Syu-Jyun Peng, Yu-Wei Chen, Kuo-Wei Wang, Hsiao-Kuang Wu, Yun-Yu Lin, Ying-Ying Lee, et al. "Automatic Detection and Quantification of Acute Cerebral Infarct by Fuzzy Clustering and Histographic Characterization on Diffusion Weighted MR Imaging and Apparent Diffusion Coefficient Map." BioMed Research International 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/963032.

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Determination of the volumes of acute cerebral infarct in the magnetic resonance imaging harbors prognostic values. However, semiautomatic method of segmentation is time-consuming and with high interrater variability. Using diffusion weighted imaging and apparent diffusion coefficient map from patients with acute infarction in 10 days, we aimed to develop a fully automatic algorithm to measure infarct volume. It includes an unsupervised classification with fuzzy C-means clustering determination of the histographic distribution, defining self-adjusted intensity thresholds. The proposed method attained high agreement with the semiautomatic method, with similarity index 89.9 ± 6.5%, in detecting cerebral infarct lesions from 22 acute stroke patients. We demonstrated the accuracy of the proposed computer-assisted prompt segmentation method, which appeared promising to replace the laborious, time-consuming, and operator-dependent semiautomatic segmentation.

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Evans, Joyce M., Michael G. Ziegler, Abhijit R. Patwardhan, J. Blaine Ott, Charles S. Kim, Fabio M. Leonelli, and Charles F. Knapp. "Gender differences in autonomic cardiovascular regulation: spectral, hormonal, and hemodynamic indexes." Journal of Applied Physiology 91, no. 6 (December 1, 2001): 2611–18. http://dx.doi.org/10.1152/jappl.2001.91.6.2611.

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The autonomic nervous system drives variability in heart rate, vascular tone, cardiac ejection, and arterial pressure, but gender differences in autonomic regulation of the latter three parameters are not well documented. In addition to mean values, we used spectral analysis to calculate variability in arterial pressure, heart rate (R-R interval, RRI), stroke volume, and total peripheral resistance (TPR) and measured circulating levels of catecholamines and pancreatic polypeptide in two groups of 25 ± 1.2-yr-old, healthy men and healthy follicular-phase women (40 total subjects, 10 men and 10 women per group). Group 1 subjects were studied supine, before and after β- and muscarinic autonomic blockades, administered singly and together on separate days of study. Group 2 subjects were studied supine and drug free with the additional measurement of skin perfusion. In the unblocked state, we found that circulating levels of epinephrine and total spectral power of stroke volume, TPR, and skin perfusion ranged from two to six times greater in men than in women. The difference (men > women) in spectral power of TPR was maintained after β- and muscarinic blockades, suggesting that the greater oscillations of vascular resistance in men may be α-adrenergically mediated. Men exhibited muscarinic buffering of mean TPR whereas women exhibited β-adrenergic buffering of mean TPR as well as TPR and heart rate oscillations. Women had a greater distribution of RRI power in the breathing frequency range and a less negative slope of ln RRI power vs. ln frequency, both indicators that parasympathetic stimuli were the dominant influence on women's heart rate variability. The results of our study suggest a predominance of sympathetic vascular regulation in men compared with a dominant parasympathetic influence on heart rate regulation in women.

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Vidwan, Param, and George A. Stouffer. "Biventricular Pulsus Alternans." Cardiology Research and Practice 2009 (2009): 1–3. http://dx.doi.org/10.4061/2009/703793.

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Pulsus alternans is a rare hemodynamic condition characterized by beat-to-beat variability in systolic pressure. It is attributed to variations in stroke volume with alternate cardiac cycles and is typically seen in patients with advanced myopathic conditions. Left ventricular pulsus alternans is rare, and right ventricular pulsus alternans is even less common. There are only a few reports of biventricular pulsus alternans. We report the case of a 62-year-old female with a recent anterior wall myocardial infarction who had biventricular pulsus alternans at the time of cardiac catheterization.

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McLean, Jack R. L., and David P. Inwald. "The utility of stroke volume variability as a predictor of fluid responsiveness in critically ill children: a pilot study." Intensive Care Medicine 40, no. 2 (December 5, 2013): 288–89. http://dx.doi.org/10.1007/s00134-013-3171-x.

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Adkins, Amy N., Julius P. A. Dewald, Lindsay P. Garmirian, Christa M. Nelson, and Wendy M. Murray. "Serial sarcomere number is substantially decreased within the paretic biceps brachii in individuals with chronic hemiparetic stroke." Proceedings of the National Academy of Sciences 118, no. 26 (June 25, 2021): e2008597118. http://dx.doi.org/10.1073/pnas.2008597118.

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A muscle’s structure, or architecture, is indicative of its function and is plastic; changes in input to or use of the muscle alter its architecture. Stroke-induced neural deficits substantially alter both input to and usage of individual muscles. We combined in vivo imaging methods (second-harmonic generation microendoscopy, extended field-of-view ultrasound, and fat-suppression MRI) to quantify functionally meaningful architecture parameters in the biceps brachii of both limbs of individuals with chronic hemiparetic stroke and in age-matched, unimpaired controls. Specifically, serial sarcomere number (SSN) and physiological cross-sectional area (PCSA) were calculated from data collected at three anatomical scales: sarcomere length, fascicle length, and muscle volume. The interlimb differences in SSN and PCSA were significantly larger for stroke participants than for participants without stroke (P = 0.0126 and P = 0.0042, respectively), suggesting we observed muscle adaptations associated with stroke rather than natural interlimb variability. The paretic biceps brachii had ∼8,200 fewer serial sarcomeres and ∼2 cm2 smaller PCSA on average than the contralateral limb (both P < 0.0001). This was manifested by substantially smaller muscle volumes (112 versus 163 cm3), significantly shorter fascicles (11.0 versus 14.0 cm; P < 0.0001), and comparable sarcomere lengths (3.55 versus 3.59 μm; P = 0.6151) between limbs. Most notably, this study provides direct evidence of the loss of serial sarcomeres in human muscle observed in a population with neural impairments that lead to disuse and chronically place the affected muscle at a shortened position. This adaptation is consistent with functional consequences (increased passive resistance to elbow extension) that would amplify already problematic, neurally driven motor impairments.

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Sugawara, Jun, Hidehiko Komine, Taiki Miyazawa, Tomoko Imai, James P. Fisher, and Shigehiko Ogoh. "Impact of chronic exercise training on the blood pressure response to orthostatic stimulation." Journal of Applied Physiology 112, no. 11 (June 1, 2012): 1891–96. http://dx.doi.org/10.1152/japplphysiol.01460.2011.

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Exercise training elicits morphological adaptations in the left ventricle (LV) and large-conduit arteries that are specific to the type of training performed (i.e., endurance vs. resistance exercise). We investigated whether the mode of chronic exercise training, and the associated cardiovascular adaptations, influence the blood pressure responses to orthostatic stimulation in 30 young healthy men (10 sedentary, 10 endurance trained, and 10 resistance trained). The endurance-trained group had a significantly larger LV end-diastolic volume normalized by body surface area (vs. sedentary and resistance-trained groups), whereas the resistance-trained group had a significantly higher LV wall thickness and aortic pulse wave velocity (PWV) compared with the endurance-trained group. In response to 60° head-up tilt (HUT), mean arterial pressure (MAP) rose in the resistance-trained group (+6.5 ± 1.6 mmHg, P < 0.05) but did not change significantly in sedentary and the endurance-trained groups. Systolic blood pressure (SBP) decreased in endurance-trained group (−8.3 ± 2.4 mmHg, P < 0.05) but did not significantly change in sedentary and resistance-trained groups. A forward stepwise multiple regression analysis revealed that LV wall thickness and aortic PWV were significantly and independently associated with the MAP response to HUT, explaining ∼41% of its variability ( R2 =0.414, P < 0.001). Likewise, aortic PWV and the corresponding HUT-mediated change in stroke volume were significantly and independently associated with the SBP response to HUT, explaining ∼52% of its variability ( R2 = 0.519, P < 0.0001). Furthermore, the change in stroke volume significantly correlated with LV wall thickness ( r = 0.39, P < 0.01). These results indicate that chronic resistance and endurance exercise training differentially affect the BP response to HUT, and that this appears to be associated with training-induced morphological adaptations of the LV and large-conduit arteries.

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Gattringer, Thomas, Maria Valdes Hernandez, Anna Heye, Paul A. Armitage, Stephen Makin, Francesca Chappell, Daniela Pinter, et al. "Predictors of Lesion Cavitation After Recent Small Subcortical Stroke." Translational Stroke Research 11, no. 3 (November 8, 2019): 402–11. http://dx.doi.org/10.1007/s12975-019-00741-8.

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Abstract Morphologic evolution of recent small subcortical infarcts (RSSI) ranges from lesion disappearance to lacune formation and the reasons for this variability are still poorly understood. We hypothesized that diffusion tensor imaging (DTI) and blood-brain-barrier (BBB) abnormalities early on can predict tissue damage 1 year after an RSSI. We studied prospectively recruited patients with a symptomatic MRI-defined RSSI who underwent baseline and two pre-specified MRI examinations at 1–3-month and 1-year post-stroke. We defined the extent of long-term tissue destruction, termed cavitation index, as the ratio of the 1-year T1-weighted cavity volume to the baseline RSSI volume on FLAIR. We calculated fractional anisotropy and mean diffusivity (MD) of the RSSI and normal-appearing white matter, and BBB leakage in different tissues on dynamic contrast-enhanced MRI. Amongst 60 patients, at 1-year post-stroke, 44 patients showed some degree of RSSI cavitation on FLAIR, increasing to 50 on T2- and 56 on T1-weighted high-resolution scans, with a median cavitation index of 7% (range, 1–36%). Demographic, clinical, and cerebral small vessel disease features were not associated with the cavitation index. While lower baseline MD of the RSSI (rs = − 0.371; p = 0.004) and more contrast leakage into CSF (rs = 0.347; p = 0.007) were associated with the cavitation index in univariable analysis, only BBB leakage in CSF remained independently associated with cavitation (beta = 0.315, p = 0.046). Increased BBB leakage into CSF may indicate worse endothelial dysfunction and increased risk of tissue destruction post RSSI. Although cavitation was common, it only affected a small proportion of the original RSSI.

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Iwasaki, Ken-Ichi, Rong Zhang, Julie H. Zuckerman, James A. Pawelczyk, and Benjamin D. Levine. "Effect of head-down-tilt bed rest and hypovolemia on dynamic regulation of heart rate and blood pressure." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 279, no. 6 (December 1, 2000): R2189—R2199. http://dx.doi.org/10.1152/ajpregu.2000.279.6.r2189.

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Adaptation to head-down-tilt bed rest leads to an apparent abnormality of baroreflex regulation of cardiac period. We hypothesized that this “deconditioning response” could primarily be a result of hypovolemia, rather than a unique adaptation of the autonomic nervous system to bed rest. To test this hypothesis, nine healthy subjects underwent 2 wk of −6° head-down bed rest. One year later, five of these same subjects underwent acute hypovolemia with furosemide to produce the same reductions in plasma volume observed after bed rest. We took advantage of power spectral and transfer function analysis to examine the dynamic relationship between blood pressure (BP) and R-R interval. We found that 1) there were no significant differences between these two interventions with respect to changes in numerous cardiovascular indices, including cardiac filling pressures, arterial pressure, cardiac output, or stroke volume; 2) normalized high-frequency (0.15–0.25 Hz) power of R-R interval variability decreased significantly after both conditions, consistent with similar degrees of vagal withdrawal; 3) transfer function gain (BP to R-R interval), used as an index of arterial-cardiac baroreflex sensitivity, decreased significantly to a similar extent after both conditions in the high-frequency range; the gain also decreased similarly when expressed as BP to heart rate × stroke volume, which provides an index of the ability of the baroreflex to alter BP by modifying systemic flow; and 4) however, the low-frequency (0.05–0.15 Hz) power of systolic BP variability decreased after bed rest (−22%) compared with an increase (+155%) after acute hypovolemia, suggesting a differential response for the regulation of vascular resistance (interaction, P < 0.05). The similarity of changes in the reflex control of the circulation under both conditions is consistent with the hypothesis that reductions in plasma volume may be largely responsible for the observed changes in cardiac baroreflex control after bed rest. However, changes in vasomotor function associated with these two conditions may be different and may suggest a cardiovascular remodeling after bed rest.

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Floras, John S., Gary C. Butler, Shin-Ichi Ando, Steven C. Brooks, Michael J. Pollard, and Peter Picton. "Differential sympathetic nerve and heart rate spectral effects of nonhypotensive lower body negative pressure." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281, no. 2 (August 1, 2001): R468—R475. http://dx.doi.org/10.1152/ajpregu.2001.281.2.r468.

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Lower body negative pressure (LBNP; −5 and −15 mmHg) was applied to 14 men (mean age 44 yr) to test the hypothesis that reductions in preload without effect on stroke volume or blood pressure increase selectively muscle sympathetic nerve activity (MSNA), but not the ratio of low- to high-frequency harmonic component of spectral power (PL/PH), a coarse-graining power spectral estimate of sympathetic heart rate (HR) modulation. LBNP at −5 mmHg lowered central venous pressure and had no effect on stroke volume (Doppler) or systolic blood pressure but reduced vagal HR modulation. This latter finding, a manifestation of arterial baroreceptor unloading, refutes the concept that low levels of LBNP interrogate, selectively, cardiopulmonary reflexes. MSNA increased, whereas PL/PH and HR were unchanged. This discordance is consistent with selectivity of efferent sympathetic responses to nonhypotensive LBNP and with unloading of tonically active sympathoexcitatory atrial reflexes in some subjects. Hypotensive LBNP (−15 mmHg) increased MSNA and PL/PH, but there was no correlation between these changes within subjects. Therefore, HR variability has limited utility as an estimate of the magnitude of orthostatic changes in sympathetic discharge to muscle.

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Yamaguchi, I., E. Komatsu, and K. Miyazawa. "Intersubject variability in cardiac output-O2 uptake relation of men during exercise." Journal of Applied Physiology 61, no. 6 (December 1, 1986): 2168–74. http://dx.doi.org/10.1152/jappl.1986.61.6.2168.

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Intersubject variability in the relation between cardiac output (Q) and O2 uptake (VO2) was examined during supine cycling up to the maximum level in 40 normal untrained men age 27 +/- 4 (SD) yr. In individual subjects, Q increased linearly against VO2 in the submaximum exercise range. The SD of Q on VO2 was so small (0.47 +/- 0.25 l/min) that Q could be given by a linear function of VO2 as Q = K(VO2 - VO2 r) + Qr, where K, VO2 r, and Qr are the slope of the regression line, the resting VO2, and resting Q, respectively. K varied widely among the subjects studied, ranging from 5.5 to 10.3 and was independent of both physical characteristics and Qr, which ranged from 3.7 to 8.3 l/min. However, K correlated significantly with changes in heart rate, stroke volume, mean arterial pressure, and systemic vascular conductance. From these results, we concluded that the intersubject variability in the Q-VO2 relation was caused independently by individual variations in resting hemodynamics and in cardiovascular response to exercise.

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Liu, Fangfang, Sihai Zhu, Qing Ji, Weiyan Li, and Jian Liu. "The impact of intra-abdominal pressure on the stroke volume variation and plethysmographic variability index in patients undergoing laparoscopic cholecystectomy." BioScience Trends 9, no. 2 (2015): 129–33. http://dx.doi.org/10.5582/bst.2015.01029.

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Kerr, Andrew J., Mark B. Simmonds, and Ralph A. H. Stewart. "Influence of heart rate on stroke volume variability in atrial fibrillation in patients with normal and impaired left ventricular function." American Journal of Cardiology 82, no. 12 (December 1998): 1496–500. http://dx.doi.org/10.1016/s0002-9149(98)00693-6.

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Wajima, Zen’ichiro, Toshiya Shiga, Kazuyuki Imanaga, and Tetsuo Inoue. "Assessment of the effect of rapid crystalloid infusion on stroke volume variation and pleth variability index after a preoperative fast." Journal of Clinical Monitoring and Computing 24, no. 5 (August 31, 2010): 385–89. http://dx.doi.org/10.1007/s10877-010-9259-8.

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Groeneveld, A. B. Johan, Remco R. Berendsen, Anton J. Schneider, Ioannis A. Pneumatikos, Leo A. Stokkel, and Lambertus G. Thijs. "Effect of the mechanical ventilatory cycle on thermodilution right ventricular volumes and cardiac output." Journal of Applied Physiology 89, no. 1 (July 1, 2000): 89–96. http://dx.doi.org/10.1152/jappl.2000.89.1.89.

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The purpose of this study was to evaluate right ventricular (RV) loading and cardiac output changes, by using the thermodilution technique, during the mechanical ventilatory cycle. Fifteen critically ill patients on mechanical ventilation, with 5 cmH2O of positive end-expiratory pressure, mean respiratory frequency of 18 breaths/min, and mean tidal volume of 708 ml, were studied with help of a rapid-response thermistor RV ejection fraction pulmonary artery catheter, allowing 5-ml room-temperature 5% isotonic dextrose thermodilution measurements of cardiac index (CI), stroke volume (SV) index, RV ejection fraction (RVEF), RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) indexes at 10% intervals of the mechanical ventilatory cycle. The ventilatory modulation of CI and RV volumes varied from patient to patient, and the interindividual variability was greater for the latter variables. Within patients also, RV volumes were modulated more by the ventilatory cycle than CI and SV index. Around a mean value of 3.95 ± 1.18 l · min−1 · m−2 (= 100%), CI varied from 87.3 ± 5.2 (minimum) to 114.3 ± 5.1% (maximum), and RVESV index varied between 61.5 ± 17.8 and 149.3 ± 34.1% of mean 55.1 ± 17.9 ml/m2 during the ventilatory cycle. The variations in the cycle exceeded the measurement error even though the latter was greater for RVEF and volumes than for CI and SV index. For mean values, there was an inspiratory decrease in RVEF and increase in RVESV, whereas a rise in RVEDV largely prevented a fall in SV index. We conclude that cyclic RV afterloading necessitates multiple thermodilution measurements equally spaced in the ventilatory cycle for reliable assessment of RV performance during mechanical ventilation of patients.

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Journal articles on the topic 'Stroke volume variability'

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