OBJECTIVE To determine the haemodynamic behaviour, at rest and during exercise, of aortic valve pericardial bioprostheses and different 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 effective 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.