Five years of experience with mitral valve homografts

INTRODUCTION: The main advantages of mitral homografts are preservation of the subvalvular apparatus and avoidance of life-long anticoagulation. In this communication, we will present our five-year experience using mitral homografts in mitral valve surgery.

PATIENTS AND METHODS: Since 1996, 14 patients (mean age 46 +/- 8 years, range 27 - 65 years have had mitral homografts implanted. Thirteen patients had mitral valve replacement; the septal leaflet of the tricuspid valve was replaced in one case. The indications were mitral (n = 6) or tricuspid endocarditis (n = 1), mitral valve stenosis (n = 3), and combined mitral valve disease (n = 4). Complete mitral homografts were implanted in eight patients; partial homografts were used in six cases. Preoperatively, the dimensions of the left ventricle and the mitral valve were measured by transoesophageal echocardiography (TOE). The mean left ventricular ejection fraction was 56 +/- 9%, the mean end-diastolic diameter 58 +/- 6 mm. The technique described by Acar/Carpentier was adapted for implantation; a Carpentier ring was implanted in all cases for annular stabilization. The patients had anticoagulative therapy which was discontinued when stable sinus rhythm was present after three months postoperatively. Follow-up included clinical examination, ECG, and echocardiography, and was initiated six months postoperatively and continued on a yearly basis. The following parameters were determined by echocardiography--left atrial size, left ventricular end-diastolic and end-systolic diameter, pressure gradient across the mitral valve (c/w Doppler, Bernoulli's equation), and mitral regurgitation.

RESULTS: All patients survived surgery; the mean operation-time was 281 +/- 37 minutes. Intraoperative TOE revealed a first degree insufficiency in 7 patients. Follow-up was completed in all patients, with a mean period of 30 months (6 - 60 months). Two patients had an acute endocarditis two years postoperatively, requiring repeat valve replacement with a mechanical prosthesis. An additional patient had to be reoperated due to chordal rupture three years postoperatively. All three patients had mitral valve stenosis as the initial indication for surgery and had received a complete homograft. In the remaining eleven patients, the morphological and functional state of the implanted grafts remained unchanged during follow-up. The freedom from valve-related events was 93% after one year, 86% after two years, and 79% after three years. At six-month follow-up, ECG and echocardiography revealed sinus rhythm and sufficient atrial contractions in 13 cases. At the last follow-up, the pressure gradients were 3.4 +/- 0.6 mmHg for complete homografts and 2.8 +/- 0.6 mmHg for partial homografts. In five cases, a mild insufficiency was documented, while six patients presented with competent grafts.

CONCLUSIONS: Mitral homografts can be used with acceptable mid-term results in selected cases with good left ventricular function and only slightly dilated left ventricles. Partial mitral homografts represent an additional technique, especially for mitral valve repair in patients with acute endocarditis. The susceptibility to bacterial infections of a homograft makes strict prophylaxis against endocarditis mandatory.