scholarly journals Contrast Microsphere Destruction by a Continuous Flow Ventricular Assist Device: An In Vitro Evaluation Using a Mock Circulation Loop

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
David G. Platts ◽  
Nicole Bartnikowski ◽  
Shaun D. Gregory ◽  
Gregory M. Scalia ◽  
John F. Fraser
Keyword(s):  
Signal Intensity ◽  
Continuous Flow ◽  
Ventricular Assist Devices ◽  
Circulation Loop ◽  
Relative Reduction ◽  
Ventricular Assist ◽  
Pump Speed ◽  
Mock Circulation ◽  
Mock Circulation Loop

Objectives. Transthoracic echocardiography (TTE) is fundamental in managing patients supported with ventricular assist devices (VAD). However imaging can be difficult in these patients. Contrast improves image quality but they are hydrodynamically fragile agents. The aim was to assess contrast concentration following passage through a VAD utilising a mock circulation loop (MCL). Methods. Heartware continuous flow (CF) VAD was incorporated into a MCL. Definity® contrast was infused into the MCL with imaging before and after CF-VAD. 5 mm2 regions of interest were used to obtain signal intensity (decibels), as a surrogate of contrast concentration. Results. Four pump speeds revealed significant reduction in contrast signal intensity after CF-VAD compared to before CF-VAD (all p<0.0001). Combined pre- and postpump data at all speeds showed a 22.2% absolute reduction in contrast signal intensity across the CF-VAD (14.8 ± 0.8 dB prepump versus 11.6 ± 1.4 dB postpump; p<0.0001). Mean signal intensity reduction at each speed showed an inverse relationship between speed and relative reduction in signal intensity. Conclusion. Contrast microsphere transit through a CF-VAD within a MCL resulted in significant reduction in signal intensity, consistent with destruction within the pump. This was evident at all CF-VAD pump speeds but relative signal drop was inversely proportional to pump speed.

Hemodynamic performance of a compact centrifugal left ventricular assist device with fully magnetic levitation under pulsatile operation: An in vitro study

2020 ◽  
Vol 234 (11) ◽  
pp. 1235-1242 ◽  
Author(s):  
Tingting Wu ◽  
Hao Lin ◽  
Yuxin Zhu ◽  
Penghui Huang ◽  
Frank Lin ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Circulation System ◽  
Third Generation ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Mock Circulation ◽  
Hemodynamic Performance

Long-term using continuous flow ventricular assist devices could trigger complications associated with diminished pulsatility, such as valve insufficiency and gastrointestinal bleeding. One feasible solution is to produce pulsatile flow assist with speed regulation in continuous flow ventricular assist devices. A third-generation blood pump with pulsatile operation control algorithm was first characterized alone under pulsatile mode at various speeds, amplitudes, and waveforms. The pump was then incorporated in a Mock circulation system to evaluate in vitro hemodynamic effects when using continuous and different pulsatile operations. Pulsatility was evaluated by surplus hemodynamic energy. Results showed that pulsatile operations provided sufficient hemodynamic assistance and increased pulsatility of the circulatory system (53% increment), the mean aortic pressure (65% increment), and cardiac output (27% increment). The pulsatility of the system under pulsatile operation support was increased 147% compared with continuous operation support. The hemodynamic performance of pulsatile operations is susceptible to phase shifts, which could be a tacking angle for physiological control optimization. This study found third-generation blood pumps using different pulsatile operations for ventricular assistance promising.

scholarly journals Response of a physiological controller for ventricular assist devices during acute patho-physiological events: an in vitro study

2017 ◽  
Vol 62 (6) ◽  
pp. 623-633 ◽  
Author(s):  
Anastasios Petrou ◽  
Panagiotis Pergantis ◽  
Gregor Ochsner ◽  
Raffael Amacher ◽  
Thomas Krabatsch ◽  
...  
Keyword(s):  
Valsalva Maneuver ◽  
Constant Speed ◽  
Ventricular Assist Devices ◽  
Moving Window ◽  
Clinical Implementation ◽  
Premature Ventricular Contractions ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Mock Circulation

AbstractThe current paper analyzes the performance of a physiological controller for turbodynamic ventricular assist devices (tVADs) during acute patho-physiological events. The numerical model of the human blood circulation implemented on our hybrid mock circulation was extended in order to simulate the Valsalva maneuver (VM) and premature ventricular contractions (PVCs). The performance of an end-diastolic volume (EDV)-based physiological controller for VADs, named preload responsive speed (PRS) controller was evaluated under VM and PVCs. A slow and a fast response of the PRS controller were implemented by using a 3 s moving window, and a beat-to-beat method, respectively, to extract the EDV index. The hemodynamics of a pathological circulation, assisted by a tVAD controlled by the PRS controller were analyzed and compared with a constant speed support case. The results show that the PRS controller prevented suction during the VM with both methods, while with constant speed, this was not the case. On the other hand, the pump flow reduction with the PRS controller led to low aortic pressure, while it remained physiological with the constant speed control. Pump backflow was increased when the moving window was used but it avoided sudden undesirable speed changes, which occurred during PVCs with the beat-to-beat method. In a possible clinical implementation of any physiological controller, the desired performance during frequent clinical acute scenarios should be considered.

An advanced mock circulation loop for in vitro cardiovascular device evaluation

2020 ◽  
Vol 44 (6) ◽  
Author(s):  
Shaun D. Gregory ◽  
Jo P. Pauls ◽  
Eric L. Wu ◽  
Andrew Stephens ◽  
Ulrich Steinseifer ◽  
...  
Keyword(s):  
Circulation Loop ◽  
Mock Circulation ◽  
Mock Circulation Loop

scholarly journals The Effect of Pump Speed Settings on Suspected Pump Thrombosis in Patients Supported With Continuous-Flow Left Ventricular Assist Devices

2016 ◽  
Vol 22 (8) ◽  
pp. S108-S109
Author(s):  
Christopher T. Sparrow ◽  
David S. Raymer ◽  
Shree L. Radhakrishnan ◽  
Michael E. Nassif ◽  
Justin M. Vader ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Left Ventricular ◽  
Ventricular Assist Devices ◽  
Left Ventricular Assist Devices ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Pump Speed ◽  
Pump Thrombosis ◽  
Left Ventricular Assist

A Compact Mock Circulation Loop for the In Vitro Testing of Cardiovascular Devices

2010 ◽  
Vol 35 (4) ◽  
pp. 384-391 ◽  
Author(s):  
Daniel L. Timms ◽  
Shaun D. Gregory ◽  
Nicholas A. Greatrex ◽  
Mark J. Pearcy ◽  
John F. Fraser ◽  
...  
Keyword(s):  
Circulation Loop ◽  
In Vitro Testing ◽  
Cardiovascular Devices ◽  
Mock Circulation ◽  
Mock Circulation Loop
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