A novel system for the treatment of aortic annular dilation : an ex vivo investigation

OBJECTIVES: The main reason for aortic repair failures is recurrent annular dilatation. The fibrous portion of left ventricular outflow tract dilates. A novel device was designed to tackle this problem. METHODS: The device consists of an internal ring applied at the aortic annulus plus an external flexible band at the level of the aortic root. The internal ring has a semi-rigid portion (40%, placed at ventriculo-arterial junction) and a flexible portion to allow it to conform along the curves of the non-coronary/right coronary leaflet and right coronary/left coronary leaflet commissures. The external band acts as a reinforcement to the internal ring. A pulsatile mock loop capable of housing porcine aortic valve was used. Working conditions were 60 bpm of heart rate, 75 of stroke volumes and 120-80mmHg of simulated pressure. Mean gradient, effective orifice area, annular diameter, coaptation height and length were recorded on 11 aortic root units (ARUs). High-speed video and standard echocardiographic images were also recorded. All data were acquired in the following conditions: (i) basal (untreated ARU); (ii) pathological condition (left coronary/non-coronary triangle was dilated by suturing an aortic patch); and (iii) ARU treated with the device. RESULTS: Gradients and effective orifice area were respectively 0.9 ± 0.64mmHg and 3.1 ± 0.7cm2 (pathological) and 3.7 ± 1.1mmHg and 1.5 ± 0.2cm2 (treated, P < 0.05). Left coronary/non-coronary diameter decreased from 2.4 ± 0.2 cm (pathological) to 2.0 ± 0.2 (treated, P < 0.05). Coaptation length and height were fully restored to basal values following treatment. Visual inspection showed proper dynamics of the leaflet, confirmed by high-speed video and echocardiography. CONCLUSIONS: The device allowed for restoring physiologic-like coaptation in the experimental model, without inducing clinically relevant worsening of the haemodynamics of the treated ARU.