Journal of Hematology & Thromboembolic Diseases
Open Access

Abstract

Canary in the Cardiac-Valve Coal Mine: Flow Velocity and Inferred Shear during Prosthetic Valve Closure-Predictors of Blood Damage and Clotting

Lawrence N. Scotten*, Rolland Siegel, David J Blundon, Marcus-Andre Deutsch, Terence R.P. Martin, James W. Dutton, Ebrahim M. Kolahdouz, Boyce E. Griffith

Objective: To demonstrate a clear link between predicted blood shear forces during valve closure and thrombogenicity that explains the thrombogenic difference between tissue and mechanical valves and provides a practical metric to develop and refine prosthetic valve designs for reduced thrombogenicity.

Methods: Pulsatile and quasi-steady flow systems were used for testing. The time-variation of Projected Open Valve Area (POVA) was measured using analog opto-electronics calibrated to projected reference orifice areas. Flow velocity determined over the cardiac cycle equates as instantaneous volumetric flow rate divided by POVA. For the closed valve interval, data from quasi-steady back pressure/flow tests was obtained.

Performance ranked by derived maximum negative and positive closing flow velocities, evidences potential clinical thrombogenicity via inferred velocity gradients (shear). Clinical, prototype and control valves were tested.

Results: Blood shear and clot potential from multiple test datasets guided empirical optimization and comparison of valve designs. A 3-D printed prototype valve design (BV3D) purposed for soft closure and reduced thrombogenic potential was assessed.

Conclusions: The relationship between leaflet geometry, flow velocity and predicted shear at valve closure illuminated an important source of prosthetic valve thrombogenicity. With an appreciation for this relationship and based on our experiment generated comparative data, we achieved optimization of valve prototypes with potential for reduced thrombogenicity.

Published Date: 2025-01-18; Received Date: 2023-08-16