Percutaneous treatment of ischaemic mitral regurgitation in sheep.

A percutaneous mitral annuloplasty device for implantation in the coronary sinus was evaluated in surviving sheep with ischaemia-induced mitral regurgitation.Microspheres were injected in the left coronary artery of thirty-seven sheep. The treatment was repeated in one month intervals until the resulting myocardial infarctions caused significant mitral regurgitation. Fourteen animals developed a mitral regurgitation degree 2 or higher after 130+/-16 days and 3.4+/-0.4 treatments. The annuloplasty device was implanted percutaneously within the coronary sinus and the animals were followed 97+/-6 days (n=14) with monthly intracardiac echocardiograms. The MR grade (0-4) decreased from 3.1+/-0.2 at the time for implantation to 0.8+/-0.2 (p=0.0005) at the 3 month follow up. The vena contracta decreased from 6.5+/-0.4 mm to 2.0+/-0.7 mm after 3 months (p=0.0007). The mitral septo-lateral diameter was reduced after insertion of the device, from 38+/-1 mm before implantation to 35+/-1 mm after 3 months (P=0.0322). Angiography showed no signs of impairment of the coronary arteries. No thrombosis was observed.These results indicate that experimentally induced ischaemic mitral regurgitation can be significantly reduced by means of a percutaneous catheter technique from the coronary sinus in surviving sheep.