Cardiac catheterization was performed to measure pressure gradients and hemodynamic parameters at rest and during supine bicycle exercise in 37 patients with aortic valve replacements, using allograft valves. Bicer prosthetic valves and SJM prosthetic valves of 19 to 27 mm diameter. Fourteen patients had an allograft valve replacement, 17 a Bicer valve, and 6 a St. Jude Medical valve. Patients were comparable for age, valve size, body surface area and left ventricular systolic function. There were no statistical differences among three groups for body surface area, left ventricular end-systolic and end-diastolic volume indices, exercise cardiac index, exercise heart rate, or workload achieved. In all 37 patients left ventricular and ascending aortic pressures were measured simultaneously according to the Brockenbrough method. In a 21 mm valve size, the mean pressure gradient was higher for Bicer and St. Jude Medical prosthetic valves than for allograft valves, both at rest (8.0 +/- 3.5 mmHg for Bicer, 5.0 +/- 1.4 mmHg for St. Jude Medical versus 0 +/- 0 mmHg for allograft; p < 0.05) and during exercise (11.0 +/- 4.9 mmHg, 10.0 +/- 2.8 mmHg versus 0 +/- 0 mmHg, respectively: p < 0.05). In a 23 mm size, there were no significant differences among three groups for resting mean pressure gradient, but during exercise the mean pressure gradient was higher for Bicer and St. Jude Medical prosthetic valves than for allograft valves (8.4 +/- 9.3 mmHg, 5.5 +/- 4.4 mmHg versus 0 +/- 0 mmHg; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)