scholarly journals In Vitro Study of Flow Regulation for Pulmonary Insufficiency

2006 ◽  
Vol 129 (2) ◽  
pp. 284-288 ◽  
Author(s):  
T. A. Camp ◽  
K. C. Stewart ◽  
R. S. Figliola ◽  
T. McQuinn
Keyword(s):  
Pulmonary Circulation ◽  
Circulatory System ◽  
In Vitro Study ◽  
Mechanical Valve ◽  
Pulmonary Insufficiency ◽  
Regurgitant Fraction ◽  
Mock Circulatory System ◽  
Mechanical Valves ◽  
The Right

Given the tolerance of the right heart circulation to mild regurgitation and gradient, we study the potential of using motionless devices to regulate the pulmonary circulation. In addition, we document the flow performance of two mechanical valves. A motionless diode, a nozzle, a mechanical bileaflet valve, and a tilting disk valve were tested in a pulmonary mock circulatory system over the normal human range of pulmonary vascular resistance (PVR). For the mechanical valves, regurgitant fractions (RFs) and transvalvular pressure gradients were found to be weak functions of PVR. On the low end of normal PVR, the bileaflet and tilting disk valves fluttered and would not fully close. Despite this anomaly, the regurgitant fraction of either valve did not change significantly. The values for RF and transvalvular gradient measured varied from 4 to 7% and 4to7mmHg, respectively, at 5lpm for all tests. The diode valve was able to regulate flow with mild regurgitant fraction and trivial gradient but with values higher than either mechanical valve tested. Regurgitant fraction ranged from 2 to 17% in tests extending from PVR values of 1to4.5mmHg∕lpm at 5lpm and with concomitant increases in gradient up to 17mmHg. The regurgitant fraction for the nozzle increased from 2 to 23% over the range of PVR with gradients increasing to 18mmHg. The significant findings were: (1) the mechanical valves controlled regurgitation at normal physiological cardiac output and PVR even though they failed to close at some normal values of PVR and showed leaflet flutter; and (2) it may be possible to regulate the pulmonary circulation to tolerable levels using a motionless pulmonary valve device.

In Vitro Study of Flow Regulation for Pulmonary Insufficiency Using Diode Valves

2007 ◽  
Author(s):  
Tiffany A. Camp ◽  
Stephanie Hequembourg ◽  
Richard S. Figliola ◽  
Tim McQuinn
Keyword(s):  
Pulmonary Valve ◽  
Pulmonary Regurgitation ◽  
Circulatory System ◽  
In Vitro Study ◽  
Pulmonary Insufficiency ◽  
Pressure Gradients ◽  
Right Heart ◽  
Mock Circulatory System ◽  
The Right

The operating pressures in the right heart are significantly lower than those of the left heart and with marked differences in the circulation impedances. The pulmonary circulation shows a tolerance for mild regurgitation and pressure gradient [1]. Pulmonary regurgitation fractions on the order of 20% and transvalvular pressure gradients of less than 25mm Hg are considered mild [4]. Given this tolerance, we examine the concept of using a motionless valve to regulate flow in the pulmonary position. In a previous study, the use of fluid diodes was shown to be a promising concept for use as a pulmonary valve [2]. In this study, we test two different diode designs. For each diode valve, flow performance was documented as a function of pulmonary vascular resistance (PVR) and compliance. Tests were done using a pulmonary mock circulatory system [3] over the normal adult range of PVR and compliance settings.

scholarly journals P1591Assessment of flow disturbances in the right ventricle: an in vitro study using a novel heart model

EP Europace ◽  
2017 ◽  
Vol 19 (suppl_3) ◽  
pp. iii339-iii339
Author(s):  
U. Gulan ◽  
AM. Saguner ◽  
D. Akdis ◽  
C. Brunckhorst ◽  
M. Holzner ◽  
...  
Keyword(s):  
Right Ventricle ◽  
In Vitro Study ◽  
Vitro Study ◽  
Heart Model ◽  
Flow Disturbances ◽  
The Right

scholarly journals In vitro study of trileaflet polytetrafluoroethylene conduit and its valve-in-valve transformation

2020 ◽  
Vol 30 (3) ◽  
pp. 408-416 ◽  
Author(s):  
Te-I Chang ◽  
Kang-Hong Hsu ◽  
Chi-Wen Luo ◽  
Jen-Hong Yen ◽  
Po-Chien Lu ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Stent Graft ◽  
Peak Pressure ◽  
Circulatory System ◽  
Valve Design ◽  
Mock Circulatory System ◽  
Valved Conduit ◽  
Valve In Valve ◽  
In Vitro Performance

Abstract OBJECTIVES Handmade trileaflet expanded polytetrafluoroethylene valved conduit developed using the flip-over method has been tailored for pulmonary valve reconstruction with satisfactory outcomes. We investigated the in vitro performance of the valve design in a mock circulatory system with various conduit sizes. In our study, the design was transformed into a transcatheter stent graft system which could fit in original valved conduits in a valve-in-valve fashion. METHODS Five different sizes of valved polytetrafluoroethylene vascular grafts (16, 18, 20, 22 and 24 mm) were mounted onto a mock circulatory system with a prism window for direct leaflets motion observation. Transvalvular pressure gradients were recorded using pressure transducers. Mean and instant flows were determined via a rotameter and a flowmeter. Similar flip-over trileaflet valve design was then carried out in 3 available stent graft sizes (23, 26 and 28.5 mm, Gore aortic extender), which were deployed inside the valved conduits. RESULTS Peak pressure gradient across 5 different sized graft valves, in their appropriate flow setting (2.0, 2.5 and 5.0 l/min), ranged from 4.7 to 13.2 mmHg. No significant valve regurgitation was noted (regurgitant fraction: 1.6–4.9%) in all valve sizes and combinations. Three sizes of the trileaflet-valved stent grafts were implanted in the 4 sizes of valved conduits except for the 16-mm conduit. Peak pressure gradient increase after valved-stent graft-in-valved-conduit setting was <10 mmHg in all 4 conduits. CONCLUSIONS The study showed excellent in vitro performance of trileaflet polytetrafluoroethylene valved conduits. Its valved stent graft transformation provided data which may serve as a reference for transcatheter valve-in-valve research in the future.

scholarly journals P2834An in vitro study on the influence of increased heart rate on the right ventricular kinetic energy and shear stresses

2018 ◽  
Vol 39 (suppl_1) ◽  
Author(s):  
U Gulan ◽  
A M Saguner ◽  
D Akdis ◽  
A Denegri ◽  
M X Miranda ◽  
...  
Keyword(s):  
Heart Rate ◽  
Kinetic Energy ◽  
Right Ventricular ◽  
In Vitro Study ◽  
Vitro Study ◽  
Shear Stresses ◽  
The Right

Abnormal Action Potential Responses to Halothane in Heart Muscle Isolated from Malignant Hyperthermia-susceptible Pigs

1995 ◽  
Vol 82 (4) ◽  
pp. 947-953. ◽  
Author(s):  
Norbert Roewer ◽  
Clemens Greim ◽  
Eckhart Rumberger ◽  
Jochen Schulte am Esch
Keyword(s):  
Malignant Hyperthermia ◽  
Action Potentials ◽  
Myocardial Function ◽  
In Vitro Study ◽  
Resting Potential ◽  
Cardiac Symptoms ◽  
Cardiac Dysrhythmias ◽  
Malignant Hyperthermia Susceptible ◽  
The Right

Background During human and porcine malignant hyperthermia (MH), cardiac dysrhythmias and altered myocardial function can be observed. It is unknown whether a primary abnormality in cardiac muscle contributes to the cardiac symptoms during MH. An abnormal response to halothane has recently been demonstrated in action potentials (APs) from MH-susceptible (MHS) human skeletal muscles. We investigated the electrophysiologic properties in trabeculae isolated from the right ventricles of normal (MHN) and MHS pigs. Methods The experiments were performed on electrically stimulated (1 Hz) trabeculae isolated from the right ventricles of MHS and MHN pigs. Resting membrane potentials, APs, and tension were measured with and without the presence of 1% halothane. In addition, the halothane-equilibrated muscles were exposed to caffeine in increasing doses (1, 2, and 4 mM). Results In the absence of halothane, resting potential and AP characteristics in MHS and MHN muscles did not differ significantly. Halothane did not alter resting potentials but produced different alterations in the APs in MHS and MHN muscles, whereas the decrease in twitch tension was identical. In contrast to reductions in the AP amplitude and duration in MHN muscle, halothane produced an enlargement of the APs in MHS muscle. The addition of caffeine caused nearly identical prolongations of AP duration in MHS and MHN muscles. Conclusions This in vitro study demonstrates that halothane produces abnormal alterations in the dynamic electric properties of the ventricular excitable membrane from MHS pigs. These results suggest a latent defect in the myocardium of MHS pigs that becomes apparent in the presence of MH-triggering agents.

scholarly journals Mitral Prosthesis Opening and Flow Dynamics in a Model of Left Ventricle: An In Vitro Study on a Monoleaflet Mechanical Valve

2005 ◽  
Vol 5 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Frederic Mouret ◽  
Lyes Kadem ◽  
Eric Bertrand ◽  
Jean G. Dumesnil ◽  
Philippe Pibarot ◽  
...  
Keyword(s):  
Left Ventricle ◽  
In Vitro Study ◽  
Mechanical Valve ◽  
Flow Dynamics ◽  
Vitro Study ◽  
Mitral Prosthesis
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