In-vitro study of a porcine quadricuspid aortic valve

Quadricuspid aortic valve (QAV) is an extremely rare congenital defect in which the valve features an additional fourth cusp. It is often associated with an alteration in valve functionality such as valve regurgitation, stenosis and coronary disease. These associated pathologies entail surgical correction in about 50% of patients at a mean age of 50 years.

A swine QAV was studied in a pulsatile mock loop in the laboratory. Rest (70 bpm) and exercise (100 bpm) conditions were simulated, and opening and closing kinematics were evaluated from a high-speed video. Short- and long-axis echocardiograms were recorded. The pressure drop across the valve, valve competence and effective orifice area were evaluated and compared to data from healthy samples tested in the same experimental apparatus.

Hemodynamic quantities were physiologic-like, despite the QAV showing an altered kinematics (longer closing and opening times compared to healthy samples) and an asynchronous closing phase (the extra cusps reached the closed configuration at the end of systole systematically earlier with respect to the other three cusps). Echocardiographic data showed an increased coaptation height between the left and right coronary cusps, and a mismatch between the lunule of the extra cusp and the non-coronary cusp.

The altered kinematics, together with incorrect coaptation, can alter the biomechanics of the structure, inducing an anomalous distribution of local stress which could lead to structural failure over time.