A Novel Aortic Regurgitation Model from Cusp Prolapse with Hemodynamic Validation Using an Ex Vivo Left Heart Simulator

Abstract

Although ex vivo simulation is a valuable tool for surgical optimization, a disease model that mimics human aortic regurgitation (AR) from cusp prolapse is needed to accurately examine valve biomechanics. To simulate AR, four porcine aortic valves were explanted, and the commissure between the two largest leaflets was detached and re-implanted 5 mm lower to induce cusp prolapse. Four additional valves were tested in their native state as controls. All valves were tested in a heart simulator while hemodynamics, high-speed videography, and echocardiography data were collected. Our AR model successfully reproduced cusp prolapse with significant increase in regurgitant volume compared with that of the controls (23.2 ± 8.9 versus 2.8 ± 1.6 ml, p = 0.017). Hemodynamics data confirmed the simulation of physiologic disease conditions. Echocardiography and color flow mapping demonstrated the presence of mild to moderate eccentric regurgitation in our AR model. This novel AR model has enormous potential in the evaluation of valve biomechanics and surgical repair techniques. Graphical Abstract.

Keywords: Aortic regurgitation; Cusp prolapse; Left heart simulator; Porcine model.

Fig. 1:

(a) A porcine aortic root mounted on a 3D-printed valve conduit mount for evaluation in the left heart simulator. (b) Illustration of the aortic regurgitation model where the commissure supporting the two largest cusps was detached and re-implanted below the native height. (c) Labeled image of the left heart simulator designed to generate physiologic conditions for the aortic valves.

Fig. 2:

(a) Intraoperative example of aortic regurgitation due to right coronary cusp prolapse. The arrow annotates the prolapsed cusp. (b) Porcine aortic regurgitation model induced by lowering the commissure between the two largest leaflets. The arrow annotates the prolapsed cusp.

Fig. 3:

(a) Mean aortic flow confirmed the generation of aortic regurgitation in our aortic regurgitation model as evidenced by the flow reversal observed in diastole. (b) Aortic pressure tracings demonstrated significantly lower pressures throughout the cardiac cycle for the aortic regurgitation model compared with that of controls; mean arterial pressure (62.3±22.1 versus 100.0±0.4mmHg, p=0.042), diastolic pressure (42.2±21.1 versus 82.8±1. mmHg, p=0.031), and systolic pressure (88.4±19.5 versus 121.7±1.5mmHg, p=0.041). Shaded regions represent standard error.

Fig. 4:

Echocardiography color flow mapping image reflecting mild to moderate regurgitation with an eccentric jet in a representative example of our aortic regurgitation model.