Intraoperative transesophageal echo-Doppler evaluation of stentless aortic xenografts. Incidence and significance of moderate gradients.

Background: The aim of this study was to assess the utility of intraoperative transesophageal echocardiography (TEE) in the evaluation of patients undergoing aortic valve replacement with the CryoLife-O'Brien (CLOB) Stentless Porcine Aortic Bioprosthesis.
Methods: Between May 1994 and March 1995, 26 patients (15 men, mean age 68.4+/-10.78 years) had a CLOB valve in the aortic position. Transprosthetic gradients and valve regurgitation were detected by intraoperative TEE. Prosthetic regurgitation and transvalvular gradients were evaluated at six-month intervals using transthoracic echo-Doppler (TTE).
Results: The majority of implants resulted in low gradients (83.7%), with only four patients exhibiting a moderate gradient (15.3%). Color flow Doppler imaging showed central aortic regurgitation in only four of 25 patients (trivial, n=4; mild, n=1). There was one paravalvular leak (trivial, n=1). At follow-up examination (mean 37+/-12 months), 24 of 25 patients exhibited low mean gradients (7.25+/-2.81 mmHg). At follow-up one patient who had low velocities in the LVOT at perioperative evaluation exibited a moderate gradient (45 mmHg) with an effective orifice area of 0.8-0.9 cm(2).
Conclusions: Intraoperative TEE was effective in assessing prosthetic stentless valve function.