We conclude that despite undeniable recent improvements in the design of artificial heart valves, 19 mm aortic prostheses continue to create significant obstruction of the left ventricular outflow tract and, possibly as a consequence of this, fail to bring about significant reduction in left ventricular hypertrophy.

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Objective-To determine the haemodynamic behaviour, at rest and during exercise, of aortic valve pericardial bioprostheses and diVerent sizes of bileaflet prosthesis. Design-Observational study. Setting-Tertiary medical centre. Patients and interventions-74 patients (33 women, 41 men; mean age 64 years) in whom 40 pericardial bioprostheses and 34 bileaflet prostheses sized 19, 21, or 23 mm had been implanted to replace aortic valves. Main outcome measures-Doppler echocardiography at rest and at peak exercise, between 12 and 47 months after surgery. Results-All patients achieved a significant increase in heart rate, systolic blood pressure, and cardiac output with exercise. Transvalvar pressure fall, valve area, and left ventricular systolic and diastolic function indices also underwent significant changes with exercise. Reductions in peak and mean transvalvar pressure, at rest and at peak exercise, were greater in patients with small valves (p < 0.05). Valve areas and eVective area index were greater in the patients with larger valves (p < 0.001). There were no significant differences between patients with mechanical and biological prostheses with regard to transvalvar pressure fall and valve areas at rest and at peak exercise. Conclusions-19 mm and 21 mm aortic prostheses and bioprostheses continue to create significant obstruction, particularly with exercise. (Heart 1999;82:149-155)

Between January 1977 and January 1989, 465 pericardial bioprostheses were implanted in 424 patients. The mean age of patients was 59.1 years (range 16-81 y.) At the time of surgery, 68% of the patients suffered from chronic atrial fibrillation. Mitral valve replacement was performed in 167 patients, aortic valve replacement in 216, multiple replacement in 40 (36 mitral and aortic, 3 mitral and tricuspid, and 1 mitral, aortic and tricuspid), and 1 pulmonary valve replacement. The different types of pericardial valve used were: Ionescu-Shiley 408, Mitral Medical 23, Bioflo 30, and Hancock 4. Hospital mortality was 10.1% with an attrition rate of 1.8 episodes per 100 patients/year. The 12-year actuarial survival rate was 65.1%. No patient underwent long-term anticoagulant treatment. The first 144 patients undergoing mitral and multiple valve replacements received temporary anticoagulation for the first 8 weeks after surgery. There was no valve thrombosis observed. Altogether 19 thromboembolic events (6 early and 13 late) were clinically documented. One patient died after an embolic event. The linearized rates of thromboembolism were 1.64 episodes per 100 patients/year for mitral and multiple valve replacements and 0.33 episodes per 100 patients/year for aortic valve replacement, with an overall rate of 1.0 episodes per 100 patients/year. Excluding early thromboembolism, the linearized rate was 1.02 episodes per 100 patients/year overall. The actuarial freedom from embolism was 92.4% overall, 88.2% for the mitral and multiple valve replacement group, and 97.6% for the aortic valve replacement group at a maximum follow-up of 12 years.(ABSTRACT TRUNCATED AT 250 WORDS)