The 12 cc Penn State Pediatric Ventricular Assist Device: A Flow Visualization Study of Bridge-to-Recovery and Weaning
Open Access
- Author:
- Roszelle, Breigh Nonte
- Graduate Program:
- Bioengineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 22, 2010
- Committee Members:
- Keefe Manning, Committee Chair/Co-Chair
Steven Deutsch, Committee Member
William Weiss, Committee Member
Lacy Alexander Holowatz, Committee Member - Keywords:
- particle image velocimetry
ventricular assist device
biofluid mechanics
weaning - Abstract:
- While mechanical circulatory support systems have shown success as bridge-to-transplant devices for end-stage heart failure patients, recent evidence shows that sufficient myocardial recovery may occur during device use to allow for explantation without transplant. As Penn State continues development on a 12 cc pulsatile pediatric ventricular assist device (PVAD), studying the impact of this device in clinically relevant situations, such as bridge-to-recovery and weaning is important. The device fluid mechanics are of importance, because a major problem is thromboembolic events, which can be prevented in pulsatile VADs with adequate wall shear rates (>500 s-1). In order to observe the PVAD flow particle image velocimetry was performed on an acrylic model of the PVAD in a mock circulatory loop. Two flow rate reduction studies were performed. The first used a beat rate reduction protocol, focused on 50 and 75 bpm. This study found that a beat rate reduction led to flow more conducive to thrombus deposition, and would not be recommended for weaning. The second used a stroke volume reduction protocol that incrementally reduced the device output from 100 to 40%, and included two filling methods, a quick and slow fill. The study found that the quick fill method produced desirable flow in the PVAD for stroke volumes of 100% to 60%, and the fluid dynamics were preferable over the beat rate reduction method. The slow fill method showed poor flow and is not recommended. The study also found that regardless of the filling method, a reduction in stroke volume below 60% led to greatly reduced wall shear rates that could increase the thrombogenicity of the device. These conclusions are also based on a newly developed thrombus susceptibility potential metric that incorporates wall shear rate information into a single metric to be used for comparison of device variations. Overall, this study identified an acceptable flow reduction method using stroke volume reduction with a quick fill method.