Rest and exercise hemodynamics of an extended stentless aortic bioprosthesis

Aortic valve surgery in patients with a narrow aortic root remains a clinical problem. The Extended Biocor Stentless porcine bioprosthesis was specifically designed to allow widening of the aortic annulus in patients with narrow aortic roots. The aim of this prospective study was to evaluate the hemodynamic performance of this prosthesis.

Serial Doppler echocardiography was used in 50 patients (mean age 77 years, range: 60 to 87 years) during a 15-month follow up after aortic valve replacement. Valve hemodynamics were also assessed in 30 patients at 15 months after surgery, during increased flow rates induced by a supine bicycle exercise test.

Of these patients, 60% received valves sized 23 mm or smaller. The mean pressure difference before hospital discharge was 13.8 +/- 5.8 mmHg and this decreased by 40% during the first six months. During the same period there was a significant increase in effective orifice area and a decrease in left ventricular mass. Symptom-limited supine exercise increased cardiac output by 65% while the mean pressure difference increased only slightly (from 8.1 +/- 3.2 to 11.9 +/- 3.6 mmHg). Trivial aortic regurgitation (grade 1+) was detected in 12% of patients at 15 months follow up. All patients who were in NYHA functional class III or IV before surgery were in class I or II after surgery.

We conclude that the Extended Biocor Stentless prosthesis shows low Doppler-derived transvalvular pressure gradients both at rest and during exercise, and also when small-sized valves are employed. Doppler echocardiography, showing low incidence of aortic regurgitation and early regression of left ventricular hypertrophy, demonstrate the beneficial hemodynamic performance of this valve.