An intra-annular 'hemispherical' annuloplasty frame for aortic valve repair

Abstract

Background and aim of the study: A 'Hemispherical' model of aortic valve geometry was developed in which normal human cadaveric aortic valve leaflets could be represented as three hemispheres nested within a cylindrical aorta. By mathematically describing the junction between the leaflets and aorta, the normal three-dimensional annular geometry of the aortic valve could be defined. In this study, a prototype annuloplasty frame based on this model was tested as a repair device in isolated porcine aortic root preparations.

Methods: Eight isolated porcine aortic roots were perfused with water at a constant pressure of 75 mmHg, and valve leakage was measured before and after the vertical incision of one to three sub-commissural areas to create valve incompetence. Annuloplasty frames then were sutured directly to the valve annuli, and the degree of leakage re-determined. The model predicted that the leaflet free-edge length could be used to define the valve diameter necessary to create competence, and this interaction was tested by varying frame size within the protocol. Post-repair leaflet function also was evaluated using high-speed video. Differences were assessed using a two-tailed paired t-test.

Results: All eight normal porcine aortic valves had negligible baseline leak. With sub-commissural incision, the mean (+/- SD) regurgitant volume was increased to 522 +/- 378 ml/min. After annuloplasty frame insertion, the measured leak decreased to 52 +/- 40 ml/min (p = 0.004). The best results were obtained with a frame diameter 5-6 mm smaller than the leaflet free-edge length. Data recorded using high-speed video suggested a normal dynamic valve function after frame insertion.

Conclusion: A three-dimensional 'Hemispherical' intra-annular annuloplasty frame was developed for aortic valve repair. Insertion of the frame into the disrupted porcine valve annuli routinely and effectively restored valve competence. These positive initial results support the continued testing and application of this aortic annuloplasty device.