A novel annuloplasty system with rigid and flexible elements: initial experimental results in sheep and the case for untreated autologous pericardium.

BACKGROUND AND AIMS OF THE STUDY

A precise annuloplasty is difficult to perform with pericardium as the ring material because unwanted plication of the pericardium itself typically occurs when the sutures are tied. A novel annuloplasty system has been developed which should allow a predictably precise measured plication of the annulus without plication of the pericardium itself. A feasibility study was designed to evaluate this new concept.

METHODS

Three juvenile sheep underwent implantation of a new annuloplasty system into the posterior mitral annulus without tissue annulus plication. Small rigid titanium suture-platforms 7 x 3 x 1 mm with two-suture holes 3 mm apart were individually affixed to the posterior mitral tissue annulus each with a single horizontal mattress suture. A longitudinal strip of untreated autologous pericardium, corresponding to the perimeter dimension of the free edge of the anterior leaflet, was sutured to the posterior annulus including both fibrous trigones, covering the suture-platforms with the mesothelial surface up, using two different suture techniques. No postoperative anticoagulation was utilized. Serial transthoracic echocardiograms and necropsy at five to six weeks post implant were performed.

RESULTS

When the pericardium was affixed to the annulus with a continuous suture exposing only the mesothelial surface to the blood, completely covering the suture-platforms and their suture knots or folded in upon itself as a tube above the suture-platforms, it appeared to maintain all of its original implant dimensions and flexibility. There was no functional or anatomical distortion of any part of the mitral apparatus; fibrotic reaction was minimal and there was no thrombus formation with this suture technique.

CONCLUSIONS

This annuloplasty system, combining rigid and flexible elements, 'melts' into the tissue annulus with a low profile, providing overall annular flexibility with no shrinkage of the overlying untreated autologous pericardium, no distortion of any part of the mitral apparatus, minimal fibrous reaction and no thrombus formation.