In vivo hemodynamic characteristics of porcine stentless aortic valves.
Jin XY., Westaby S.
The objective of this study was to elucidate the relationship of aortic pressure gradient (mPG) and effective orifice area (EOA) with mean systolic flow rate of left ventricle in patients who received a stentless aortic valve. Two hundred thirteen patients (age: 73 +/- 6 years, 123 men and 90 women) who received a Freestyle stentless valve in subcoronary position for aortic valve diseases were studied. EOA, mPG, and systolic aortic flow rate were determined by Doppler echocardiography at 1 and 20 months after implant. With follow-up, there was a 13% increase in EOA and a 30% decrease in mPG, both P <.01. Although systolic aortic flow did not change, the intercept of EOA-flow relationship increased significantly at late follow-up (0.56 +/- 0.13 v 0.11 +/- 0.13, P <.01). Multiple regression analysis showed that systolic aortic flow accounted for 54%, and mPG for only 27%, variation of EOA. Linear relationship between EOA and systolic aortic flow provides a comprehensive approach to describe stentless valve performance, when mean valve pressure gradient appears to be flow independent. These hemodynamic features distinguish stentless valves from stented or mechanical prosthesis. Ultimately, the variations in aortic root anatomy, surgical experience and their interactions are likely to become major determinants of in vivo performance of stentless aortic valves.