SUMMARY Multiple valve replacement with pericardial xenografts (sizes 17 to 31) was undertaken in 76 patients. The incidence of early and late deaths was 10-5 and 3 9 per cent, respectively. Actuarially it is predicted that 94 7+3-9 per cent of hospital survivors will be alive at three and a half years after valve replacement. Though long-term anticoagulants were not used, thrombotic valve obstruction was not seen in this series. A systemic embolus occurred early in one case only (0 95 episodes/100 patient years). Mechanical dysfunction of the pericardial xenograft has not been seen.Haemodynamic studies were performed in seven patients, eight to 21 months after valve replacement. The transvalvular gradients were negligible across the aortic pericardial xenografts. Gradients across mitral and tricuspid xenografts were small. The calculated surface areas ranged from 1P0 to 1-4 cm2 for aortic, 1-7 to 2-1 cm2 for mitral, and 2-0 to 2-4 cm2 for tricuspid valves.These results after multiple valve replacement are comparable to those reported with isolated mitral or aortic pericardial xenografts over a similar period of observation.

SUMMARY Haemodynamic studies were performed in 30 patients at a mean interval of 43-4 (range 27 to 59) months after aortic valve replacements-withpericardial xenografts. Five valve sizes-19, 21, 23, 25, and 27 mm annulus diameter-were used. Of these 30 patients, 16 had preoperative haemodynamic investigations. Comparison of the pre-and postoperative data showed a marginal but significant increase in cardiac output (P < 0.05). There was a significant reduction in the pulmonary wedge and left ventricular end-diastolic pressures at rest and on exercise (P < 0-05 and P < 0-01).At the postoperative study the mean peak systolic gradient was 8-3 mmHg at rest and 12-3 mmHg on exercise in patients with the smallest xenograft inserted (19 mm) and decreased with each corresponding increase in graft size, so that across the 27 mm graft it was hardly measurable. The calculated xenograft surface area ranged from 1 1 to 2 1 cm2 at rest and 1-3 to 2-4cm2 during exercise. Aortic root angiography showed competent valves in all 30 patients, but a grade 1 to 2 perivalvular leak was shown in 8 patients.This long-term study has indicated significant circulatory improvement and very small transvalvular gradients in patients with aortic pericardial xenografts.