Assessment of aortic valve pressure overload and leaflet functions in an ex vivo beating heart loaded with a continuous flow cardiac assist device

Aortic valve regurgitation, fusion and thrombosis are commonly reported clinical complications after continuous flow ventricular assist device implantations; however, the complex interaction between reduced pulsatile flow physiology and aortic valve functions has not been studied experimentally. To address this, a continuous flow left ventricular assist device was implanted in four swine ex vivo beating hearts and then operated at baseline (device off, no flow) and at device speeds ranging between 8500 and 11,500 rpm under healthy and experimentally created failing heart conditions.At baseline and after each speed increase, aortic, left ventricular, left atrial and pulse pressure signals were monitored to assess the haemodynamic status of the ex vivo heart, aortic valve opening time and the transvalvular pressure changes. Aortic root and device flows were recorded with flow probes. Left ventricular pressure-volume loops were measured with a conductance catheter. Changes in aortic leaflet motion and end-diastolic aortic root diameter were recorded with epicardial echocardiography.A two-chamber healthy and failing ex vivo beating heart model was successfully created. At increasing device flows, aortic valve open time steadily decreased from 36?7% of the baseline cardiac cycle to 0% at 11,500 rpm in the healthy heart and from 18?16 to 0% in failing heart mode (P