Vahid Sadri, Prem A. Midha, Immanuel David Madukauwa-David, Norihiko Kamioka, Phillip M. Trusty, Priya J. Nair, Samuel Cohen, Vrishank Raghav, Rahul Sharma, Vasilis Babaliaros, Ajit P. Yoganathan
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引用次数: 0
Abstract
Purpose
Neo-sinus flow stasis has ben correlated with transcatheter heart valve (THV) thrombosis severity and occurrence. Standard benchtop flow field quantification techniques require optical access or modified prosthesis models that may not reflect the true nature of the original valve. En face and fluoroscopic videodensitometry enable visualization of washout in regions otherwise unviewable.
Methods
This study compares two in vitro methods of assessing flow stasis in scenarios with insufficient optical access for traditional techniques such as particle image velocimetry (PIV). A series of seven paired experiments were conducted using a previously described laser-enhanced video densitometry (LEVD) and fluoroscopic video densitometry (FVD). Both sets of experiments were analyzed to calculate washout time as a measure of flow stasis. A novel flow stasis measure termed contrast attenuation ratio (CAR) is proposed as a viable single measure of flow stasis obtainable from only a small number of cardiac cycles of in vitro or in vivo fluoroscopic data. Retrospective fluoroscopic datasets (n = 72) were analyzed to assess the feasibility of obtaining this metric from routine clinical practice and its ability to stratify results.
Results
Neo-sinus flow stasis calculated from in vitro fluoroscopy was well correlated with LEVD (r2 = 0.77, p = 0.009). The newly proposed CAR metric showed good agreement with the commonly used “washout time” measure of flow stasis (r2 = 0.91, p < 0.001) while allowing for assessment with incomplete or truncated data. As a proof of concept, CAR was measured in 72 consecutive retrospective fluoroscopic datasets. CAR averaged 10.6 ± 4.6% with a range of 1.5–20.3% in these patients.
Conclusions
This study demonstrates two in vitro methods that can be used to assess relative flow stasis in otherwise optically inaccessible regions surrounding cardiac or vascular implants. In addition, the fluoroscopic benchtop technique was used to validate a metric that allows for extension to routine clinical fluoroscopy. This contrast attenuation ratio (CAR) metric was found to be both accurate and clinically obtainable, and potentially offers a new method for valve thrombosis risk stratification.
期刊介绍:
Cardiovascular Engineering and Technology is a journal publishing the spectrum of basic to translational research in all aspects of cardiovascular physiology and medical treatment. It is the forum for academic and industrial investigators to disseminate research that utilizes engineering principles and methods to advance fundamental knowledge and technological solutions related to the cardiovascular system. Manuscripts spanning from subcellular to systems level topics are invited, including but not limited to implantable medical devices, hemodynamics and tissue biomechanics, functional imaging, surgical devices, electrophysiology, tissue engineering and regenerative medicine, diagnostic instruments, transport and delivery of biologics, and sensors. In addition to manuscripts describing the original publication of research, manuscripts reviewing developments in these topics or their state-of-art are also invited.