S. Silberman et al., Exercise hemodynamics of aortic prostheses: Comparison between stentless bioprostheses and mechanical valves, ANN THORAC, 72(4), 2001, pp. 1217-1221
Citations number
25
Categorie Soggetti
Cardiovascular & Respiratory Systems","Medical Research Diagnosis & Treatment
Background. Nonstented bioprostheses have been associated with lower restin
g gradients than stented bioprostheses or mechanical valves. We compared th
e hemodynamic performance of nonstented bioprostheses and mechanical valves
with normal native aortic valves at rest and exercise.
Methods. Dobutamine echocardiography was used to assess gradients and effec
tive orifice area index at rest and exercise in patients with the Toronto s
tentless porcine valve (TSPV, n = 13; mean implant size 25.7 mm), Medtronic
Freestyle (FR; n = 11; mean implant size 23.9 mm), Sorin Bicarbon (SOR; n
= 11; mean implant size 24.5 mm), St. Jude Medical (SJM; n = 10; mean impla
nt size 21.3 mm), and normal native aortic valves (NOR; n = 10).
Results. All groups demonstrated a major rise in cardiac output at maximal
dobutamine infusion. At rest and exercise, respectively, mean gradients wer
e 5.48 +/- 1.1 mm Hg and 5.83 +/- 0.9 mm Hg for TSPV, 5.68 +/- 1.2 mm Hg an
d 7.50 +/- 1.7 mm Hg for FR, 10.29 +/- 1.4 mm Hg and 20.78 +/- 2.7 mm Hg fo
r SJM, 5.26 +/- 0.8 mm Hg and 11.1 +/- 1.8 mm Hg for SOR, and 1.54 +/- 0.4
mm Hg and 2.18 +/- 0.7 mm Hg for NOR. In comparison with normal valves, bot
h stentless groups showed no change in mean gradient at exercise, whereas b
oth mechanical groups showed an increase in gradient at exercise (P < 0.04)
.
Conclusions. Stentless valves behave similarly to normal aortic valves in t
hat there is almost no increase in gradient at exercise. Both mechanical va
lve groups showed increased gradients at exercise, suggesting that these va
lves obstruct blood flow. Our data add further evidence that stentless valv
es are hemodynamically superior to mechanical valves in the aortic position
. (C) 2001 by The Society of Thoracic Surgeons.