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Literatura académica sobre el tema "Pressure Volume catheter"

Autor: Grafiati

Publicado: 11 de marzo de 2023

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Artículos de revistas sobre el tema "Pressure Volume catheter"

Imbesi, S. G. y C. W. Kerber. "Pressure Measurements across Vascular Stenoses". Interventional Neuroradiology 5, n.º 2 (junio de 1999): 139–44. http://dx.doi.org/10.1177/159101999900500205.

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We describe and analyze pressure measurements across vascular stenoses in an atherosclerotic human carotid bulb replica using catheters of different diameters. Replicas of an atherosclerotic human carotid bulb were created using the lost wax technique, and were placed in a circuit of pulsating non-newtonian fluid. Flows were adjusted to replicate human physiologic flow profiles. Common carotid artery total flow volume of 600 milli-liters/minute was studied. A pressure recording device was calibrated; data were received from catheters placed longitudinally in the common carotid artery and internal carotid artery. The internal carotid artery pressures were obtained both through the stenosis as is usually performed in the angiography suite and through the vessel side-wall beyond the stenosis as a control. Internal carotid artery flow volumes were also measured with and without the catheter through the stenosis. Multiple pressure recordings and volume measurements were obtained in the replica using 7 French, 5 French, and 2.5 French catheters. Measurements of the replica showed a 58% diameter stenosis and an 89% area stenosis of the carotid bulb. All longitudinal pressure measurements in the common carotid artery agreed with control values regardless of the diameter of the catheter used. Pressure measurements were also in agreement with control values in the internal carotid artery using the 2.5 French catheter. However, when larger diameter catheters were employed, pressures measured with the catheter through the stenosis fell when compared to control values. Additionally, internal carotid artery flow volumes were also decreased when the larger diameter catheters were placed across the stenosis. Large diameter catheters when placed across vascular stenoses may cause an occlusive or near-occlusive state and artifactually increase the measured transstenotic vascular pressure gradient as well as decrease forward vascular flow.

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Antony, Kathleen, Diana Racusin, Michael Belfort y Gary Dildy. "Under Pressure: Intraluminal Filling Pressures of Postpartum Hemorrhage Tamponade Balloons". American Journal of Perinatology Reports 07, n.º 02 (abril de 2017): e86-e92. http://dx.doi.org/10.1055/s-0037-1602657.

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Objective Uterine tamponade by fluid-filled balloons is now an accepted method of controlling postpartum hemorrhage. Available tamponade balloons vary in design and material, which affects the filling attributes and volume at which they rupture. We aimed to characterize the filling capacity and pressure-volume relationship of various tamponade balloons. Study Design Balloons were filled with water ex vivo. Intraluminal pressure was measured incrementally (every 10 mL for the Foley balloons and every 50 mL for all other balloons). Balloons were filled until they ruptured or until 5,000 mL was reached. Results The Foley balloons had higher intraluminal pressures than the larger-volume balloons. The intraluminal pressure of the Sengstaken-Blakemore tube (gastric balloon) was initially high, but it decreased until shortly before rupture occurred. The Bakri intraluminal pressure steadily increased until rupture occurred at 2,850 mL. The condom catheter, BT-Cath, and ebb all had low intraluminal pressures. Both the BT-Cath and the ebb remained unruptured at 5,000 mL. Conclusion In the setting of acute hemorrhage, expeditious management is critical. Balloons that have a low intraluminal pressure-volume ratio may fill more rapidly, more easily, and to greater volumes. We found that the BT-Cath, the ebb, and the condom catheter all had low intraluminal pressures throughout filling.

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Brown, I. G., P. A. McClean, P. M. Webster, V. Hoffstein y N. Zamel. "Lung volume dependence of esophageal pressure in the neck". Journal of Applied Physiology 59, n.º 6 (1 de diciembre de 1985): 1849–54. http://dx.doi.org/10.1152/jappl.1985.59.6.1849.

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There is conflicting evidence in the literature regarding tissue pressure in the neck. We studied esophageal pressure along cervical and intrathoracic esophageal segments in six healthy men to determine extramural pressure for the cervical and intrathoracic airways. A balloon catheter system with a 1.5-cm-long balloon was used to measure intraesophageal pressures. It was positioned at 2-cm intervals, starting 10 cm above the cardiac sphincter and ending at the cricopharyngeal sphincter. We found that esophageal pressures became more negative as the balloon catheter moved from intrathoracic to cervical segments, until the level of the cricopharyngeal sphincter was reached. At total lung capacity, esophageal pressures were -10.5 +/- 2.9 (SE) cmH2O in the lower esophagus, -18.9 +/- 3.0 just within the thorax, and -21.3 +/- 2.73 within 2 cm of the cricopharyngeal sphincter. The variation in mouth minus esophageal pressure with lung volume was similar in cervical and thoracic segments. We conclude that the subatmospheric tissue pressure applied to the posterior membrane of the cervical trachea results in part from transmission of apical pleural pressure into the neck. Transmural pressure for cervical and thoracic tracheal segments is therefore similar.

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Mukerji, Nitin, Julian Cahill, Desiderio Rodrigues, Savithru Prakash y Roger Strachan. "Flow dynamics in lumboperitoneal shunts and their implications in vivo". Journal of Neurosurgery 111, n.º 3 (septiembre de 2009): 632–37. http://dx.doi.org/10.3171/2009.2.jns08912.

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Object Lumboperitoneal shunting is the standard treatment for pseudotumour cerebri or idiopathic intracranial hypertension. Complications are common, particularly the problem of overdrainage leading to low pressure symptoms. The authors designed a simple experiment using catheters of different lengths that drained at different pressure heads and with different vertical drops to study the flow characteristics in these shunts and determine the optimal catheter placement and length that would reduce the occurrence of low pressure headaches. Methods The flow rates through catheters of 3 different lengths (60, 83, and 100 cm) with the same internal radius, at 3 different pressure heads (15, 25, and 35 cm H2O to simulate 3 different placements in the lumbar theca), and 3 different vertical drops (10, 20, and 30 cm to simulate the possible effect of siphoning) were measured and the results analyzed. Results Application of Poiseuille's law and Bernoulli's principle to the experimental design shows that the volume of flow is directly proportional to the sum of the pressure head and the vertical drop and inversely proportional to the length of the catheter. The flow rate through the standard catheter lengths over the course of 24 hours can be abnormally high. An attempt to predict the optimal catheter length was made. Conclusions Although the catheter position in the theca and abdomen cannot be altered significantly and the internal radius of the tube cannot be reduced further without increasing the risk of blockage, the length of the tube can be increased to combat overdrainage. The authors suggest that currently available catheters are too short.

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Brand, Paul H., Nianning Qi, Patricia J. Metting y Steven L. Britton. "A self-powered constant infusion device for use in unrestrained rats". American Journal of Physiology-Heart and Circulatory Physiology 278, n.º 6 (1 de junio de 2000): H2157—H2162. http://dx.doi.org/10.1152/ajpheart.2000.278.6.h2157.

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We developed a device that delivers fluid through a catheter at a constant rate and can be used in conscious animals to solve a variety of problems. For example, this device can be used for delivering drugs and maintaining intravascular catheter patency. The device provides infusions at low flows (1.0–1.5 ml/day), so that experimental agents may be administered with minimal volume loading of the rat. Arterial and venous catheter patency is maintained by infusion of heparinized saline through indwelling catheters attached to the device. The catheters exit from the rat in the intrascapular area and are routed through a protective spring to the device, which is suspended above the cage. The catheters may be attached to pressure transducers, blood may be sampled, and injections or infusions may be made without disturbing the rat. Because the device is self-contained, it can be suspended by a fluid-free swivel that rotates through 360°, providing minimal restraint. The device has been used successfully to measure arterial and central venous blood pressures in two studies using rats.

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Ito, H., M. Takaki, H. Yamaguchi, H. Tachibana y H. Suga. "Left ventricular volumetric conductance catheter for rats". American Journal of Physiology-Heart and Circulatory Physiology 270, n.º 4 (1 de abril de 1996): H1509—H1514. http://dx.doi.org/10.1152/ajpheart.1996.270.4.h1509.

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Left ventricular (LV) volume (V) is an essential parameter for assessment of the cardiac pump function. Measurement of LVV in situ by a conductance catheter method has been widely used in dogs and humans but not yet in small experimental animals such as rats. We instituted a miniaturized six-electrode conductance catheter (3-F) for rat LVV measurement and its signal processing apparatus. We compared stroke volumes (SVs) simultaneously measured with this conductance catheter introduced into the LV through the apex and an electromagnetic flow probe placed on the ascending aorta during gradual decreases in LVV by an inferior vena caval occlusion. A high and linear correlation (r = 0.982) was obtained between these differently measured by SVs pooled from six rats. In another group of three rats, LV pressure was simultaneously measured with a 3-F catheter-tip micromanometer introduced into the LV through the apex. We obtained the slope of the end-systolic pressure-volume (P-V) relationship (Emax) by a gradual ascending aortic occlusion. After administration of propranolol, Emax obviously decreased with no change in volume intercept of the P-V relationship. The conductance volumetry proved to be useful in rats.

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Szwarc, Richard S. y Howard A. Ball. "Simultaneous LV and RV volumes by conductance catheter: effects of lung insufflation on parallel conductance". American Journal of Physiology-Heart and Circulatory Physiology 275, n.º 2 (1 de agosto de 1998): H653—H661. http://dx.doi.org/10.1152/ajpheart.1998.275.2.h653.

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One aspect in the measurement of ventricular volume using the conductance catheter technique is the assessment of parallel electrical conductivity of structures extrinsic to the ventricular blood pool. Because it is sometimes necessary to make volume measurements during ventilation or spontaneous respiration, the extent to which parallel conductance may vary with lung insufflation was investigated. Anesthetized pigs (11–15 kg) were ventilated and instrumented with both left (LV) and right ventricular (RV) conductance and pressure-tip catheters and end-hole catheters for injection of hypertonic saline into the inferior vena cava and pulmonary artery. Data were recorded during ventilation with tidal volumes of 10 and 20 ml/kg, and the associated fluctuations to LV and RV end-diastolic (EDV) and stroke (SV) volumes were measured. With the use of a saline dilution technique, parallel conductance (Vc) was determined for each ventricle with the ventilator off and lungs insufflated to 0, 10, and 20 ml/kg. Whereas ventilation caused marked oscillations in LV and RV EDV and SV, these variations could not be attributed to Vc, which remained statistically unchanged from their baseline values of 34.1 ± 3.1 in the LV and 31.1 ± 4.4 in the RV. These results indicate that the fluctuations that occur in conductance catheter-derived LV and RV volume signals with ventilation are not caused by any significant changes to parallel conductance.

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Szwarc, R. S., D. Laurent, P. R. Allegrini y 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, n.º 4 (1 de abril de 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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Biais, Matthieu, Karine Nouette-Gaulain, Alice Quinart, Stéphanie Roullet, Philippe Revel y François Sztark. "Uncalibrated Stroke Volume Variations Are Able to Predict the Hemodynamic Effects of Positive End-Expiratory Pressure in Patients with Acute Lung Injury or Acute Respiratory Distress Syndrome after Liver Transplantation". Anesthesiology 111, n.º 4 (1 de octubre de 2009): 855–62. http://dx.doi.org/10.1097/aln.0b013e3181b27fb2.

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Background Positive end-expiratory pressure (PEEP) may reduce cardiac output and total hepatic blood flow after liver transplantation. Pulse pressure variation is useful in predicting the PEEP-induced decrease in cardiac output. The aim of the study was to examine the relationships between stroke volume variations (SVV) obtained with the Vigileo monitor (Edwards Lifesciences, Irvine, CA), and the hemodynamic effects of PEEP. Methods Over 2 yr, patients presenting an acute lung injury or an acute respiratory distress syndrome in the 72 h after liver transplantation were prospectively enrolled. Patients were monitored with a pulmonary artery catheter (stroke volume) and with the Vigileo system (stroke volume and SVV). Measurements were performed in duplicate, first during zero end-expiratory pressure and then 10 min after the addition of 10 cm H2O PEEP. Results Twenty-six patients were included. Six patients were excluded from analysis. On PEEP, SVV and pulse pressure variation increased significantly and stroke volume decreased significantly. PEEP-induced changes in stroke volume measured by pulmonary artery catheter were significantly correlated with SVV (r = 0.69; P < 0.001) and pulse pressure variation on zero end-expiratory pressure (r = 0.66, P < 0.001). PEEP-induced decrease in stroke volume measured by pulmonary artery catheter > or = 15% was predicted by an SVV > 7% (sensitivity = 100%, specificity = 80%) and by a pulse pressure variation > 8% (sensitivity = 80%, specificity = 100%). PEEP-induced changes in stroke volume measured by pulmonary artery catheter and Vigileo device were correlated (r = 0.51, P < 0.005). Conclusions SVV obtained with Vigileo monitor is useful to predict decrease in stroke volume induced by PEEP. Moreover, this device is able to track changes in stroke volume induced by PEEP.

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Yaksh, T. L., P. A. Durant y C. R. Brent. "Micturition in rats: a chronic model for study of bladder function and effect of anesthetics". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, n.º 6 (1 de diciembre de 1986): R1177—R1185. http://dx.doi.org/10.1152/ajpregu.1986.251.6.r1177.

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The volume-evoked micturition reflex (VEMR) and the effects of anesthetics on the VEMR were studied in a chronic unanesthetized rat model. The bladder catheter was implanted chronically through a laparotomy and externalized percutaneously. An intrathecal (IT) catheter was implanted chronically in animals scheduled for an IT injection. By 2 days after implantation, infusion of saline (200 microliter/min) in the bladder reliably resulted in a low base-line pressure (BP) followed by a transient increase in bladder pressure, an opening of the sphincter (bladder opening pressure, BOP) corresponding to expression of urine (volume of urination, V), then a further rise in pressure (peak pressure, PP) and a subsequent return to base line. Seven days after implantation, values (means +/- SE) for BP, BOP, PP, and V were 10 +/- 0.3, 30 +/- 2, 67 +/- 6 cmH2O, and 1.0 +/- 0.1 ml, respectively. Residual volumes were reliably less than 2-4% of the expressed volume. The VEMR was reliably evoked up to 28 days after implantation. V values in unimplanted and implanted animals were not different. In implanted animals, VEMR parameters were not different during infusion or during spontaneous urination after oral fluid load. Administration of pentobarbital sodium (50 mg/kg ip), alpha-chloralose (130 mg/kg ip), ketamine (100 mg/kg im), halothane (in air 2%), and local anesthetics (2-chloroprocaine 3% or bupivacaine 0.75%, 10 microliter IT) produced a complete blockade of the VEMR and overflow incontinence at pressures significantly higher than BOP values. To compare overflow pressures and passive compliance of the bladder, unanesthetized animals were decapitated.(ABSTRACT TRUNCATED AT 250 WORDS)

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Tesis sobre el tema "Pressure Volume catheter"

Carlsson, Camilla. "Development of a thin, soft, single segment conductance catheter for monitoring left ventricular pressure and volume". Licentiate thesis, KTH, Physics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1441.

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Knowledge of the leftventricular (LV) pressure-volume relation, along withparameters derived from this relation, have led to newpossibilities for the characterisation of cardiac pumpfunction, in both experimental studies and clinicalsettings.

The pressure-volume diagram is apowerful tool for visualising LV performance, but in order tobe clinically useful it is necessary to make plots continuouslyand on-line. The conductance catheter technique offers thispossibility. The conductance catheter system has experiencedgrowing interest among cardiologists, physiologists, surgeons,and anaesthesiologists around the world as a powerful newresearch tool, but the invasiveness of this technique has beena limiting factor for most clinical applications. The catheterneeds to be thinner and softer in order to make this techniquemore suitable for human use.

This thesis reports of a newthin and soft conductance catheter for continuously and on-linemeasurements of LV pressure and volume.

One way to reduce both cathetersize and stiffness is to decrease the number of electrodes onthe catheter. Theoretical calculations shown in this thesisproves that it is possible to obtain the same performance witha single segment catheter as with a five-segment catheter. Thethin catheter has been tested and compared to a commercialfive-segment conductance catheter in animal studies.

We conclude that the thin singlesegment conductance catheter can measure left ventricularvolume and pessure. The regression coefficient between the twomethods is good independent of loading condition and duringbaseline conditions the catheters produce very similar volumecurves. During preload reduction the estimated volume reductionis different in the two systems.

Our thin catheter does notdisturb the heart's normal electrophysiology, neither by thecatheter current nor by any mechanical stimuli. The resultsdemonstrates that our thin, soft, single segment conductancecatheter has performance characteristics which warrant furtherdevelopment, with the goal to make the method available forhuman use.

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Loeffler, Kathryn Rose. "Development of an implantable system to measure the pressure-volume relationship in ambulatory rodent hearts". 2012. http://hdl.handle.net/2152/20018.

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The design, fabrication, and in-vivo testing of an implantable device to measure the pressure-volume (PV) relationship in the hearts of conscious, untethered rats is presented. Volume is measured using a tetrapolar catheter positioned in the left-ventricle which emits a 20kHz current field across the LV blood pool and parallel heart tissue and measures the resulting voltage. The admittance method is used to instantaneously remove the contribution of the parallel heart muscle and Wei’s non-linear blood conductance-to-volume equation is used to calculate volume. Pressure is measured with a strain gauge sensor at the tip of the catheter. The implant was designed to be small, light, and low-power. An average implant occupies 5 cm3, weighs 8g, and on a single charge collects data for 2 months taking 43 samples per day. Collected data is transmitted wirelessly via RF to a base station where it is recorded. The functionality of the implant and measurement system was verified in six rat experiments. In all experiments, ambulatory PV loops were measured on implantation day. Viable pressure data was recorded for 11 days in one rat; in another rat viable admittance data was collected for 10 days. Changing catheter position and non-constant blood resistivity are considered as sources of error in the volume measurement. Pressure drift due to changing atmospheric pressure is considered as a source of error in the pressure measurement. Lastly, alternative uses for the implant and directions for future improvement are considered.
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Chen, Chieh-En y 陳傑恩. "A Real-time Ventricular Pressure-Volume Loop Measurement System with the Conductance Catheter". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04084867098924944471.

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碩士
國立成功大學
電機工程學系碩博士班
96
Electrical impedance measurement technique is widely used in biomedical researchers and applications, such as a conductance catheter. The conductance catheter is used to measure real-time ventricular impedance, and then the measured impedance is converted to ventricular volume. While incorporating with pressure signals, a real-time ventricular pressure-volume loop plot can be obtained, which is a standard tool for researchers and doctors to evaluate the cardiac functions. The main purpose of my research is to develop a real-time measurement system for the conductance catheter. Instead of traditional instrument designed with analog elements for processing, a high speed DSP chip, TMS320F2812 made by Texas Instrument, is used to be the core for digital signal processing. Besides, peripheral analog circuits are needed for signal sensing. Moreover, a graphic user interface, implemented by LabView and a data acquisition card, is designed to illustrate the measurement result immediately. Next, some other equipments are designed to verify the system and finally the in-vivo experiment is performed. (1) An emulator that can mimic the special measured voltage signals is constructed. During the system development stage, the emulator is served as a benchmark to test the functionality and bandwidth of the system. (2) A ventricle-imitated environment is constructed that can test if the system can work for real situation. (3) In vivo Rat experiment that can test the system whether it can work for in-vivo measurement. According to the measurement results, the designed system does work well.

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RUNGATSCHER, Alessio. "Cardioprotective role of S-Nitroso Human Serum Albuminduring regional myocardial ischemia-reperfusion". Doctoral thesis, 2010. http://hdl.handle.net/11562/344722.

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BACKGROUND: The early period of reperfusion after myocardial ischemia is critical for endothelial dysfunction and the impairment of nitric oxide synthesis plays a critical role. We investigated the cardioprotective effect of S-NO-HSA in a regional myocardial ischemia/reperfusion rat model reproducing clinical scenarios. METHODS AND RESULTS: Male Wistar rats (n: 120) underwent reversible occlusion of the left anterior descending artery for 30 minutes and subsequent reperfusion for 24 hours. The animals were randomly treated with S-NO-HSA (0.3 μmol/kg/h) or human serum albumin (HSA) infusion. The infusion started 15 minutes before the beginning of ischemia in a group (Pre-I) whereas it starter 15 min after the initiation of ischemia in the other group (Post-I). The infusion continued until the first 30 minutes of reperfusion in both groups. Ventricular systolic and diastolic function was evaluated during early and late reperfusion (120 min and 24 h) in vivo at different preloads by a Millar microtip P-V conductance catheter. Hearts were excised after reperfusion to determine infarct size (IS) and area at risk (AR). Biopsies were obtained to measure high-energy phosphates, the expression of endothelial nitric oxide synthase (eNOS) and inducile nitric oxide synthase (iNOS) and the production of NFkB. Treatment with S-NO-HSA had a significative effect in reducing IS (42.2% +/-3.5 vs. 65.3 +/-4.2; p<0.05), the maximum effect is produced when the drug is administered before ischemia. S-NO-HSA effect on LV systolic function is evident considering the preload independent contractility parameters: maximal slope of the systolic pressure increment end diastolic volume relationship (dP/dtMAX-EDV), the slope EMAX of the end-systolic P-V relationship and the preload recruitable stroke work (PRSW) were significantly increased during reperfusion in all treated animals and after ischemia only in the pre-treated group (Pre-I). The LV diastolic function was improved by S-NO-HSA treatment. Tau-Weiss (index of ventricular relaxation), LV end-diastolic pressure (LVEDP) and end-diastolic P-V relationship (EDPVR) (indexes of ventricular stiffness) were significantly decreased with S-NO-HSA both in Pre-I and Post-I group after ischemia and during the 24 h reperfusion. NO supplementation by S-NO-HSA led to partial and in Pre-I group to total preservation of high energy phosphates. Phosphocreatine (CrP) content was preserved in Pre-I group (5.25 +/- 1.65 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) and in Post-I group (3.85 +/- 1.12 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) after 24 h reperfusion. Indeed energy charge was significantly higher only in the Pre-I group (0.62 +/- 0.07 vs 0.30 +/- 0.07). S-NO-HSA did not change the constitutive eNOS expression (measured by immunohistochemistry), instead it prevent the NFkB activation (quantified by EMSA) and therefore the iNOS mRNA expression (measured by Northern Blot). CONCLUSIONS: S-NO-HSA limits the infarct size, improves diastolic and systolic function and the energetic reserve of the heart after regional myocardial ischemia/reperfusion. These results suggest that S- NO-HSA might be an interesting option for patients undergoing regional myocardial ischemia reperfusion.
BACKGROUND: The early period of reperfusion after myocardial ischemia is critical for endothelial dysfunction and the impairment of nitric oxide synthesis plays a critical role. We investigated the cardioprotective effect of S-NO-HSA in a regional myocardial ischemia/reperfusion rat model reproducing clinical scenarios. METHODS AND RESULTS: Male Wistar rats (n: 120) underwent reversible occlusion of the left anterior descending artery for 30 minutes and subsequent reperfusion for 24 hours. The animals were randomly treated with S-NO-HSA (0.3 μmol/kg/h) or human serum albumin (HSA) infusion. The infusion started 15 minutes before the beginning of ischemia in a group (Pre-I) whereas it starter 15 min after the initiation of ischemia in the other group (Post-I). The infusion continued until the first 30 minutes of reperfusion in both groups. Ventricular systolic and diastolic function was evaluated during early and late reperfusion (120 min and 24 h) in vivo at different preloads by a Millar microtip P-V conductance catheter. Hearts were excised after reperfusion to determine infarct size (IS) and area at risk (AR). Biopsies were obtained to measure high-energy phosphates, the expression of endothelial nitric oxide synthase (eNOS) and inducile nitric oxide synthase (iNOS) and the production of NFkB. Treatment with S-NO-HSA had a significative effect in reducing IS (42.2% +/-3.5 vs. 65.3 +/-4.2; p<0.05), the maximum effect is produced when the drug is administered before ischemia. S-NO-HSA effect on LV systolic function is evident considering the preload independent contractility parameters: maximal slope of the systolic pressure increment end diastolic volume relationship (dP/dtMAX-EDV), the slope EMAX of the end-systolic P-V relationship and the preload recruitable stroke work (PRSW) were significantly increased during reperfusion in all treated animals and after ischemia only in the pre-treated group (Pre-I). The LV diastolic function was improved by S-NO-HSA treatment. Tau-Weiss (index of ventricular relaxation), LV end-diastolic pressure (LVEDP) and end-diastolic P-V relationship (EDPVR) (indexes of ventricular stiffness) were significantly decreased with S-NO-HSA both in Pre-I and Post-I group after ischemia and during the 24 h reperfusion. NO supplementation by S-NO-HSA led to partial and in Pre-I group to total preservation of high energy phosphates. Phosphocreatine (CrP) content was preserved in Pre-I group (5.25 +/- 1.65 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) and in Post-I group (3.85 +/- 1.12 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) after 24 h reperfusion. Indeed energy charge was significantly higher only in the Pre-I group (0.62 +/- 0.07 vs 0.30 +/- 0.07). S-NO-HSA did not change the constitutive eNOS expression (measured by immunohistochemistry), instead it prevent the NFkB activation (quantified by EMSA) and therefore the iNOS mRNA expression (measured by Northern Blot). CONCLUSIONS: S-NO-HSA limits the infarct size, improves diastolic and systolic function and the energetic reserve of the heart after regional myocardial ischemia/reperfusion. These results suggest that S- NO-HSA might be an interesting option for patients undergoing regional myocardial ischemia reperfusion.

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Begle, Marilyn Sorenson. "The effect of pediatric suction catheter size and suction pressure on negative airway pressure in paralyzed rabbits". 1985. http://catalog.hathitrust.org/api/volumes/oclc/12415119.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1985.
Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-71).

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Libros sobre el tema "Pressure Volume catheter"

Alkhalidi, Abdul Hakam Qasem. The conductance catheter as a method for studying factors influencing pressure-volume relationships in the left ventricle of the heart. Birmingham: University of Birmingham, 1999.

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Cordioli, Ricardo Luiz y Laurent Brochard. Respiratory system compliance and resistance in the critically ill. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0074.

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Under mechanical ventilation, monitoring of respiratory mechanics is fundamental, especially in patients with abnormal mechanics. In order to appropriately set the ventilator, clinicians need to understand the relationship between pressure, volume and flow. To move air in and out the thorax, energy must be dissipated against elastic and resistive forces. Elastance is the pressure to volume ratio and necessitates an end inspiratory occlusion to measure the so-called plateau pressure. Resistance is the ratio between pressure dissipated and mean gas flow. Finally, the total positive end expiratory pressure must be measured with an end expiratory occlusion. Volume-controlled ventilation is the recommended mode to assess respiratory mechanics of a passive patient. Clinicians must be aware that both chest wall and lung participate in forces imposed by the respiratory system. An oesophageal catheter can estimate pleural pressure, and used to partition the respective role of the lung and the chest wall.

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Magee, Patrick y Mark Tooley. Intraoperative monitoring. Editado por Jonathan G. Hardman. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780199642045.003.0043.

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Chapter 25 introduced some basic generic principles applicable to many measurement and monitoring techniques. Chapter 43 introduces those principles not covered in Chapter 25 and discusses in detail the clinical applications and limitations of the many monitoring techniques available to the modern clinical anaesthetist. It starts with non-invasive blood pressure measurement, including clinical and automated techniques. This is followed by techniques of direct blood pressure measurement, noting that transducers and calibration have been discussed in Chapter 25. This is followed by electrocardiography. There then follows a section on the different methods of measuring cardiac output, including the pulmonary artery catheter, the application of ultrasound in echocardiography, pulse contour analysis (LiDCO™ and PiCCO™), and transthoracic electrical impedance. Pulse oximetry is then discussed in some detail. Depth of anaesthesia monitoring is then described, starting with the electroencephalogram and its application in BIS™ monitors, the use of evoked potentials, and entropy. There then follow sections on gas pressure measurement in cylinders and in breathing systems, followed by gas volume and flow measurement, including the rotameter, spirometry, and the pneumotachograph, and the measurement of lung dead space and functional residual capacity using body plethysmography and dilution techniques. The final section is on respiratory gas analysis, starting with light refractometry as the standard against which other techniques are compared, infrared spectroscopy, mass spectrometry, and Raman spectroscopy (the principles of these techniques having been introduced in Chapter 25), piezoelectric and paramagnetic analysers, polarography and fuel cells, and blood gas analysis.

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Capítulos de libros sobre el tema "Pressure Volume catheter"

Villanueva, P. A. "Intracranial Balloon Catheter for ICP and Pressure/Volume Monitoring". En Intracranial Pressure VI, 199–202. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-70971-5_37.

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Sakata, Tomoki, Renata Mazurek, Spyros A. Mavropoulos, Francisco J. Romeo, Anjali J. Ravichandran y Kiyotake Ishikawa. "Assessing the Effect of Cardiac Gene Therapy Using Catheter-Based Pressure–Volume Measurement in Large Animals". En Methods in Molecular Biology, 313–21. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2707-5_24.

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Leatherman, G. F., T. L. Shook, S. M. Leatherman y Wilson S. Colucci. "Use of a conductance catheter to detect increased left ventricular inotropic state by end-systolic pressure-volume analysis". En Inotropic Stimulation and Myocardial Energetics, 247–56. Heidelberg: Steinkopff, 1989. http://dx.doi.org/10.1007/978-3-662-07908-9_24.

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Ziegler, Tilman, Karl-Ludwig Laugwitz y Christian Kupatt. "Left Ventricular Pressure Volume Loop Measurements Using Conductance Catheters to Assess Myocardial Function in Mice". En Methods in Molecular Biology, 33–41. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0668-1_3.

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Sionis, Alessandro, Etienne Gayat y Alexandre Mebazaa. "Pathophysiology and clinical assessment of the cardiovascular system (including pulmonary artery catheterization)". En The ESC Textbook of Intensive and Acute Cardiovascular Care, editado por Marco Tubaro, Pascal Vranckx, Eric Bonnefoy-Cudraz, Susanna Price y Christiaan Vrints, 115–26. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780198849346.003.0012.

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The underlying pathophysiological derangements of the cardiovascular system in many medical conditions are often complex. Acute circulatory dysfunction can be related broadly to a cardiogenic cause leading to acute heart failure or be secondary to hypovolaemia or vascular dysfunction (e.g. sepsis). Different mechanisms may be involved, including left ventricular diastolic and/or systolic dysfunction and/or right ventricular dysfunction. Many aspects of left ventricular function are explained by considering ventricular pressure–volume characteristics. Epidemiological studies show that clinical signs at admission, morbidity, and mortality differ between the main scenarios of acute heart failure: left ventricular diastolic dysfunction, left ventricular systolic dysfunction, right ventricular dysfunction, and cardiogenic shock. Although echocardiography is usually the first investigation used to assess the mechanism of cardiac dysfunction, in selected cases (in particular, in cases of refractory shock secondary to both vascular and heart dysfunction or in cases of refractory haemodynamic instability associated with severe hypoxaemia), the pulmonary artery catheter can help to assess and monitor the cardiovascular status and evaluate response to treatments.

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Waldmann, Carl, Andrew Rhodes, Neil Soni y Jonathan Handy. "Cardiovascular monitoring". En Oxford Desk Reference: Critical Care, 105–36. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780198723561.003.0007.

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Cardiovascular instability is one of the main reasons for admission to intensive care. Situations such as hypovolaemia, heart failure, and vasoplegia are often mixed, between them making the diagnosis more challenging. Attention to details and careful monitoring are essential at this stage. This chapter discusses cardiovascular monitoring and includes discussion on electrocardiograph monitoring, arterial pressure monitoring, insertion of central venous catheters, common problems with central venous access, pulmonary artery catheters, echocardiography, clinical applications of echocardiography in the intensive care unit, Doppler, pulse pressure algorithms, non-invasive methods, monitoring mean systemic filling pressure, and detection of volume responsiveness.

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Potpara, Tatjana. "Atrial premature beats". En ESC CardioMed, 2050–52. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0477.

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Atrial premature beats (APBs), also referred to as atrial or supraventricular extrasystoles, represent premature atrial depolarization occurring earlier than the next expected regular sinoatrial activation, usually from a site outside the sinus node. Premature depolarizations originating from the atrioventricular node or His bundle are termed atrioventricular junctional premature beats. In general, APBs occur in adults of any age, with or without structural heart disease. Increased atrial volume and/or pressure, or increased sympathetic tone are associated with increased frequency of APBs, while in individuals without structural heart disease APBs often originate from the pulmonary veins and may precipitate atrial fibrillation. Patients with APBs are often asymptomatic, or experience palpitations, dizziness, or even presyncope. Significant haemodynamic compromise due to APBs is uncommon. Physical examination may reveal pulse irregularity, and surface electrocardiograms (ECGs) usually show premature P waves which differ from the sinus P morphology, followed by a normal, shortened, or prolonged PR interval (depending on the APB site of origin) and narrow QRS complex. Ambulatory ECG (Holter) monitoring helps to establish the diagnosis when symptoms are sporadic or to quantify the frequency of APBs. Counselling and reassurance would suffice in most minimally symptomatic or asymptomatic patients with APBs, but any underlying cardiovascular disorder must be treated. Beta blockers or class III antiarrhythmic drugs (or class IC in patients without significant structural heart disease) can be used to attenuate symptoms or suppress the APBs facilitating other tachyarrhythmias. Catheter ablation could be considered in selected patients.

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Maughan, W. Lowell y David A. Kass. "Left Ventricular Pressure-Volume Relationships in Patients Measured with the Conductance Catherer and Inferior Vena Caval Balloon Occlusion". En Analysis and Simulation of the Cardiac System — Ischemia, 37–49. CRC Press, 2020. http://dx.doi.org/10.1201/9781003068341-4.

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Abdelwahab Elarref, Mohamed, Mogahed Ismail Hassan Hussein, Muhammad Jaffar Khan y Noran Mohamed Elarif. "Airway Management in Aviation, Space, and Microgravity". En Special Considerations in Human Airway Managements [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96603.

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Although medical services in aviation have evolved over years based on our understanding of physiology, advancement in monitoring technology but airway management was only recently studied with a focus on space environment. The barometric pressure of ambient air declines as altitude increases, while the volume of air in a confined space will increase according to Boyle law, and therefore oxygen concentration remains at a constant 21%. Altitude sensitive equipment includes endotracheal and tracheostomy cuffs, pneumatic anti shock garments, air splints, colostomy bags, Foley catheters, orogastric and nasogastric tubes, ventilators, invasive monitors, and intra-aortic balloon pumps. The microgravity reduces the body compensation capacity for hemorrhage, while the redistribution of the blood can affect intubation by causing facial edema. Another change is the decreased gastric emptying during aviation. Acute respiratory failure, hypoxemia or inadequate ventilation and protection of the airway in a patient with impaired consciousness are common indications for advanced airway management in aviation. Airway management requires adequate training to maintain excellent medical care during aviation. Tracheal intubation using laryngoscopy would be difficult in microgravity, since the force exerted by the laryngoscope causes the head and neck move out of the field of vision by lever effect exerted on the head and generated through the laryngoscope blade by hand generating a lack of stability, resulting in the difficulty to insert the tracheal tube. While on the ground with the help of gravity, an adequate positioning of the patient is facilitated to achieve alignment of the laryngeal, pharyngeal and oral axes, which is known as sniffing position that allows visualization of the vocal cords and supraglottic structures allowing the introduction of an endotracheal tube.

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Actas de conferencias sobre el tema "Pressure Volume catheter"

Majerus, Steve J. A., Brett Hanzlicek, Yaneev Hacohen, Dario Cabal, Dennis Bourbeau y Margot S. Damaser. "A Catheter-Free Bladder Pressure-Volume Sensor". En 2022 IEEE Sensors. IEEE, 2022. http://dx.doi.org/10.1109/sensors52175.2022.9967317.

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Chia-Ling Wei, Chung-Dann Kan, Jieh-Neng Wang, Yi-Wen Wang y Mei-Ling Tsai. "Impact of stroke volume determination on pressure-volume relations measured by conductance catheter". En 2012 IEEE Biomedical Circuits and Systems Conference (BioCAS 2012). IEEE, 2012. http://dx.doi.org/10.1109/biocas.2012.6418437.

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Thaijiam, Chanchai, Wutthinan Jeamsaksiri, Karoon Saejok, Charndet Hruanun y Amporn Poyai. "A study of cardiac function using pressure-volume conductance catheter measurements". En 2013 6th Biomedical Engineering International Conference (BMEiCON). IEEE, 2013. http://dx.doi.org/10.1109/bmeicon.2013.6687721.

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Salafian, Iman y Christopher G. Rylander. "Burst, Leakage, and Constant Pressure Infusion Testing of a Convection Enhanced Drug Delivery System for Glioblastoma Treatment". En 2022 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/dmd2022-1060.

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Abstract Convection-enhanced delivery (CED) through an arborizing microneedle catheter system is an experimental drug delivery technique used to treat glioblastoma by providing a higher drug volume dispersed (Vd) of therapeutics directly to larger regions of brain tissue. A convection-enhanced thermo-chemotherapy catheter system (CETCS) can simultaneously deliver fluid and thermal energy to the infected area. The CETCS developed in our Medical Device Design lab comprises a bundle of 6 microneedles made from fiber optic capillary tubing, passed through a rigid cannula and individually arborized (branch-out). We are preparing CETCS for regulatory pathway application to advance it further toward clinical and human trials. In this paper, we performed three performance tests: infusion pressure, leakage, and constant pressure flow rate tests required by the FDA to file a traditional 510(K) based upon a potential predicate device. The high-pressure burst and leakage test showed that the CETCS can withstand an internal pressure of 100 psi with no leakage or failure in any connections and attachments, resulting in a substantial equivalency to the predicate devices. The constant pressure flow rate test showed a flow rate average of 0.64 ml/h under 0.7 psi and 1.69 ml/h under 2.1 psi of constant pressure using distilled water column, resulting in substantial equivalency to the predicate devices.

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Zaffora, Adriano, Paola Bagnoli, Roberto Fumero y Maria Laura Costantino. "Computational Fluid Dynamic Analysis of an Instrumented Endotracheal Tube for Total Liquid Ventilation to Optimize Pressure Transducer Positioning". En ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206457.

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Despite advances in respiratory care, the treatment of critical neonatal patients with conventional mechanical ventilation (CMV) techniques has still many drawbacks. To address this issue, Total Liquid Ventilation (TLV) with liquid perfluorocarbons (PFC) has been investigated as an alternative respiratory modality [1,2]. A dedicated TLV ventilator supplies PFC tidal volumes (TV) through an endotracheal tube (ETT) inserted into the trachea. In experimental studies, TLV proved to be able to support pulmonary gas exchange while preserving lung structure and function. Moreover, PFC properties make these liquids an optimal medium to treat neonatal respiratory failure [1–3]. However, different aspects of TLV have to be further investigated for a safe transition from the laboratory experience to the clinical application. One of these aspects is the possible airway and lung injury that may be caused by the peculiar fluid dynamics developed when using an incompressible and viscous liquid instead of air as a respiratory medium. To overcome this issue, continuous reliable real-time monitoring of airway pressure during TLV is crucial. Thus, the instrumentation of the ETT with a pressure transducer (PT) is mandatory to perform a safe TLV treatment [4–6]. At present, no commercial instrumented ETTs designed for TLV are available; thus during TLV experimental animal trials [4–6] ETT prototypes instrumented with homemade PT-equipped catheters are currently used. However, the positioning of this catheter has to be optimized in order to reduce fluid dynamic disturbances that can alter pressure measurements. Aim of this study is to investigate on the PFC fluid-dynamic patterns in the presence of the catheter by computational fluid dynamic (CFD) analysis, in the view of the development of a TLV dedicated instrumented ETT. In particular, the effect of two different positioning of the PT catheter on the PFC fluid dynamics and airway pressure measurement was evaluated for a neonatal ETT.

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Discher, Dennis y Adam Engler. "Mesenchymal Stem Cell Injection After Myocardial Infarction Improves Myocardial Compliance". En ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176754.

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Cellular therapy for myocardial injury has improved ventricular function in both animal and clinical studies, though the mechanism of benefit is unclear. This study was undertaken to examine the effects of cellular injection after infarction on myocardial elasticity. Coronary artery ligation of Lewis rats was followed by direct injection of human mesenchymal stem cells (MSC) into the acutely ischemic myocardium. Two weeks post-infarct, myocardial elasticity was mapped by atomic force microscopy. MSC-injected hearts near the infarct region were two-fold stiffer than myocardium from non-infarcted animals but softer than myocardium from vehicle-treated infarcted animals. After eight weeks, the following variables were evaluated: MSC engraftment and left ventricular geometry by histologic methods; cardiac function with a pressure-volume conductance catheter; myocardial fibrosis by Masson trichrome staining; vascularity by immunohistochemistry; and apoptosis by TUNEL assay. The human cells engrafted and expressed a cardiomyocyte protein but stopped short of full differentiation and did not stimulate significant angiogenesis. MSC-injected hearts showed significantly less fibrosis than controls, as well as less left ventricular dilation, reduced apoptosis, increased myocardial thickness, and preservation of systolic and diastolic cardiac function. In summary, MSC injection after myocardial infarction did not regenerate contracting cardiomyocytes but reduced the stiffness of the subsequent scar and attenuated post-infarction remodeling, preserving some cardiac function. Improving scarred heart muscle compliance could be a functional benefit of cellular cardiomyoplasty.

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