Benchtop Flow Stasis Quantification: In Vitro Methods and In Vivo Possibilities

• Published in: Cardiovascular engineering and technology 2024-09, Vol.15 (6), p.749-759
• Main Authors: Sadri, Vahid, Midha, Prem A., Madukauwa-David, Immanuel David, Kamioka, Norihiko, Trusty, Phillip M., Nair, Priya J., Cohen, Samuel, Raghav, Vrishank, Sharma, Rahul, Babaliaros, Vasilis, Yoganathan, Ajit P.
• Format: Article
• Language: English
• Subjects: Aged; Aortic Valve - diagnostic imaging; Aortic Valve - physiopathology; Aortic Valve - surgery; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedical Engineering/Biotechnology; Biomedicine; Blood Flow Velocity; Cardiology; Feasibility Studies; Female; Fluoroscopy; Heart Valve Prosthesis; Hemodynamics; Humans; Male; Models, Cardiovascular; Original Article; Predictive Value of Tests; Prosthesis Design; Reproducibility of Results; Retrospective Studies; Rheology; Thrombosis - diagnostic imaging; Thrombosis - physiopathology; Time Factors; Transcatheter Aortic Valve Replacement - instrumentation
• ISSN: 1869-408X; 1869-4098; 1869-4098
• DOI: 10.1007/s13239-024-00750-1

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 (r 2  = 0.77, p  = 0.009). The newly proposed CAR metric showed good agreement with the commonly used “washout time” measure of flow stasis (r 2  = 0.91, p