The Björk-Shiley Tilting Disc Valve in Isolated Mitral Lesions

During the period September 1969 to August 1971, 103 consecutive patients underwent mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis. Forty-four of these patients had isolated mitral lesions. They were studied pre- and postoperatively in a long-term clinical and haemodynamic follow-up. The valve, which had a Delrin disc occluder and opened at an angle of 50°, was placed in a subannular position with isolated mattress sutures and with the larger opening directed towards the ventricular septum. Early and late mortality rates were 5 and 16%, respectively. Thrombo-embolic complications occured in 25% of the cases, half of which were without sequelae. All patients received anticoagulant treatment (Dicoumarol). Thirty-six patients were evaluated at this Clinic 6-12 months postoperatively and 30 of them were catheterized. Subjective improvement was seen in 34/36 and functional improvement (NYHA) in 30/36 patients. Careful haemodynamic evaluation revealed central circulatory improvment, but postoperative haemodynamic abnormalities remained. The mean diastolic pressure difference over the valve prosthesis was 4.3 mmHg at rest and rose to 11.7 mmHg during exercise, corresponding to a calculated valve orifice area of 2.5 cm2. No paravalvular leakage was encountered of such significance that it necessitated re-operation. The results of and problems involved in mitral valve replacement are discussed.