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.

Validation of Cardiac Output as Reported by a Permanently Implanted Wireless Sensor

2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Michael Tree ◽  
Jason White ◽  
Prem Midha ◽  
Samantha Kiblinger ◽  
Ajit Yoganathan
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Measurement Accuracy ◽  
Circulatory System ◽  
Left Heart Failure ◽  
Mock Circulatory System ◽  
System A ◽  
Reference Flow ◽  
Relevant Range

The CardioMEMS heart failure (HF) system was tested for cardiac output (CO) measurement accuracy using an in vitro mock circulatory system. A software algorithm calculates CO based on analysis of the pressure waveform as measured from the pulmonary artery, where the CardioMEMS system resides. Calculated CO was compared to that from reference flow probe in the circulatory system model. CO measurements were compared over a clinically relevant range of stroke volumes and heart rates with normal, pulmonary hypertension (PH), decompensated left heart failure (DLHF), and combined DHLF + PH hemodynamic conditions. The CardioMEMS CO exhibited minimal fixed and proportional bias.

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 Predictors of Procedural Success in Patients With Degenerated Surgical Valves Undergoing Transcatheter Aortic Valve-in-Valve Implantation

2021 ◽  
Vol 8 ◽  
Author(s):  
Abdelrahman I. Abushouk ◽  
Omar Abdelfattah ◽  
Anas Saad ◽  
Toshiaki Isogai ◽  
Medhat Farwati ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Pressure Gradient ◽  
Peak Pressure ◽  
Left Ventricular ◽  
Severe Aortic Regurgitation ◽  
Transcatheter Aortic Valve ◽  
Echocardiographic Parameters ◽  
Valve In Valve ◽  
Procedural Success ◽  
Valve Implantation

Background: Valve-in-Valve transcatheter aortic valve implantation (ViV-TAVI) is a growing alternative for redo-surgery in patients with degenerated surgical valves. To our knowledge, data are lacking on the determinants on ViV-TAVI procedural success in patients with degenerated surgical valves.Methods: All consecutive patients undergoing ViV-TAVI for degenerated surgical valves at the Cleveland Clinic were analyzed. Data were extracted from our patient registry on baseline patient characteristics, echocardiographic parameters, and procedural details. To identify possible predictors of ViV-TAVI procedural success, we employed a multivariate logistic regression model.Results: A total of 186 patients who underwent ViV-TAVI were analyzed, with procedural success (VARC-2 device success and absence of periprocedural MACCE) reported in 165 (88.7%) patients. Patients with successful ViV-TAVI were significantly younger and had more frequent utilization of the transfemoral access than those with failed procedure. Other baseline and procedural characteristics were comparable between both groups. In terms of echocardiographic parameters, the procedural success group had a significantly lower AV peak pressure gradient (62.1 ± 24.7 vs. 74.1 ± 34.6 mmHg; p = 0.04) and lower incidence of moderate-to-severe aortic regurgitation [AR] (30.4 vs. 55%; p = 0.04). However, no significant differences between both groups were noted in terms of AV mean pressure gradient and left ventricular measurements. In multivariate analysis, lower AV peak pressure gradient (OR = 0.97, 95% CI: 0.95–0.99) and absence of moderate-to-severe AR (OR = 0.65, 95% CI: 0.44–0.95) at baseline emerged as independent predictors of ViV-TAVI procedural success.Conclusion: Valve-in-Valve TAVI for degenerated surgical valves is a feasible approach with high success rates, especially in those with lower AV peak pressure gradient and absence of moderate-to-severe AR. Studies with larger sample size and longer follow-up are required to further characterize the predictors of ViV-TAVI success and other clinical outcomes.

135 In vitro antithrombogenic testing for centrifugal blood pumps using a mock circulatory system

2008 ◽  
Vol 2007.20 (0) ◽  
pp. 275-276
Author(s):  
Osamu MARUYAMA ◽  
Daisuke SUGIYAMA ◽  
Yosuke TOMARI ◽  
Ryo KOSAKA ◽  
Masahiro NISHIDA ◽  
...  
Keyword(s):  
Circulatory System ◽  
Mock Circulatory System ◽  
Blood Pumps

Aortic Pressure Estimation With Electro-Mechanical Circulatory Assist Devices

1993 ◽  
Vol 115 (2) ◽  
pp. 187-194 ◽  
Author(s):  
J. F. Gardner ◽  
M. Ignatoski ◽  
U. Tasch ◽  
A. J. Snyder ◽  
D. B. Geselowitz
Keyword(s):  
Initial Conditions ◽  
Circulatory System ◽  
Time History ◽  
Aortic Pressure ◽  
Operating Conditions ◽  
Observer Performance ◽  
Mean Deviation ◽  
Mock Circulatory System ◽  
The Mean

An adaptive technique for the estimation of the time history of aortic pressure (from applied voltage and position feedback) has been designed, implemented, and bench tested using the Penn State Electric Ventricular Assist Device (EVAD). This method, known in the field of automatic control as a dynamic observer, utilizes gains which were determined using experimental data collected while the EVAD was running on a mock circulatory system. An adaptive scheme provides the observer with a method of changing its initial conditions on a stroke-by-stroke basis which improves observer performance. In both determining the feedback gains and developing the adaptation scheme, a range of beat rates and pressure loads was taken into account to yield satisfactory observer performance over a range of operating conditions. The observer was implemented, its performance was verified in vitro and results are reported. In the six experimental operating conditions, the beat rate ranged from 56-104 beats per minute (bpm) and the span of the mean systolic aortic pressure was 10.7-18.7 kPa (80–140 mmHg). For these cases, the mean deviation between the actual and estimated aortic pressure during the latter two-thirds of systole was 0.41 kPa (3.1 mmHg).

scholarly journals Three-dimensional printing for cardiovascular diseases: from anatomical modeling to dynamic functionality

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Hao Wang ◽  
Hongning Song ◽  
Yuanting Yang ◽  
Quan Cao ◽  
Yugang Hu ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Circulatory System ◽  
3D Models ◽  
Function Evaluation ◽  
Anatomical Models ◽  
Mock Circulatory System ◽  
Flow Reserve ◽  
Traditional Pattern

Abstract Three-dimensional (3D) printing is widely used in medicine. Most research remains focused on forming rigid anatomical models, but moving from static models to dynamic functionality could greatly aid preoperative surgical planning. This work reviews literature on dynamic 3D heart models made of flexible materials for use with a mock circulatory system. Such models allow simulation of surgical procedures under mock physiological conditions, and are; therefore, potentially very useful to clinical practice. For example, anatomical models of mitral regurgitation could provide a better display of lesion area, while dynamic 3D models could further simulate in vitro hemodynamics. Dynamic 3D models could also be used in setting standards for certain parameters for function evaluation, such as flow reserve fraction in coronary heart disease. As a bridge between medical image and clinical aid, 3D printing is now gradually changing the traditional pattern of diagnosis and treatment.

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.

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