The Omni design: evolution of a valve

Abstract

The Lillehei-Kaster prosthesis has been the subject of an engineering evolution to close the gap between engineering expectations and clinical performance. Advanced engineering development in response to users has narrowed this gap with the Omni design (Omniscience titanium and omnicarbon Pyrolite cages). Our studies on mitral Omniscience valves demonstrated that because anatomic and surgical variations, the anterior orientation was more forgiving than the posterior orientation, resulting in lower thrombotic complications (0.5% versus 3.3% patient-year). A subsequent thicker cuff was used to reduce the probability of anatomic interference and incomplete opening after cardiac recovery. Such findings were also incorporated in the Omnicarbon design. Five European centers implanted 354 patients (198 atrial valve replacement, 115 mitral valve replacement, and 41 double valve replacement with Omniscience valves between August 1984 and January 1986. No restrictive patient selection criteria were used. As of June 1987, 96% of the patients at risk were accounted for. Average follow-up was 1.7 +/- 0.4 years (range, 0.3 to 2.8 years), with a total follow-up of 555 years. There were no cases of structural failure or clinically significant hemolysis. Ninety-one percent of the patients improved one or more functional classes. Actuarial analysis of survival probability at 3 years is 92.5% for atrial valve replacement, 97.9% for mitral valve replacement, and 93.6% overall. There were no late deaths from valve thrombosis or thromboembolism. The actuarial freedom from all thromboembolic events (valve thrombosis, thromboembolism, and transient ischemia) is 97.8% at 2 1/2 years. Through close rapport between user surgeons and designers, the evolution of a valve with improved performance becomes a reality.