STENTLESS BIOPROSTHESES FOR THE SMALL AORTIC ROOT

Background and aims of the study: Despite a variety of different artif icial heart valves no ideal prosthesis for the small aortic root is ye t available, Conventional stented valves are hemodynamically disadvant ageous because of higher transvalvular pressure gradients. Stentless b ioprostheses were implanted in such patients to evaluate their perform ance as an alternative to homografts and to conventional mechanical pr ostheses. Materials and methods: We analyzed 57 patients with small ao rtic roots who underwent stentless aortic valve replacement (Toronto S PV(TM)) from March 1993 to November 1995. All but two patients had aor tic stenosis. The mean age at operation was 70.9 (+/- 8.2) years. The annular diameter was 18-23 mm (mean 21.4 +/- 1.1 mm) in all patients. Of the 57 patients, 17 received a 23 mm and 40 patients a 25 mm prosth esis. Results: Using the oversizing technique, valve size was adjusted according to the sinotubular junction diameter, allowing a gain in pr osthesis size of 2-4 mm to be achieved in all patients. On pre-dischar ge echocardiography maximum flow velocity was 2.3 +/- 0.4 mis, maximum pressure gradient was 19.1 +/- 6.8 mmHg, and effective valve orifice area was 1.46 +/- 0.27 cm(2). All patients were in NYHA class I or II at discharge. One patient was reoperated due to a folded annulus cause d by too much oversizing. At six months follow up there was a signific ant reduction in pressure gradients and an increase in effective valve orifice areas in relation to a decrease in pre-existing left ventricu lar hypertrophy. Conclusions: Stentless bioprostheses show excellent h emodynamics due to their comparably large internal diameter and flexib ility. Controlled oversizing is a safe technique without additional co mplications. As larger valve sizes can be implanted, aortic root enlar gement is not necessary. The superior hemodynamic profile of stentless aortic valves is especially advantageous in patients with small aorti c roots.