Grading Aortic Stenosis With Mean Gradient and Aortic Valve Area: A Comparison Between Preoperative Transthoracic and Precardiopulmonary Bypass Transesophageal Echocardiography.

Abstract

OBJECTIVE: The authors hypothesized that average precardiopulmonary bypass (pre-CPB) transesophageal echocardiographic (TEE) mean gradient (PGm) and aortic valve area (AVA) values would be significantly different from preoperative transthoracic (TTE) values in the same patients and that these changes would affect pre-CPB TEE grading of aortic stenosis (AS). DESIGN: Retrospective, observational design. SETTING: Single university hospital. PARTICIPANTS: The study comprised 92 patients who underwent aortic valve replacement with or without coronary artery bypass grafting between 2000 and 2012 at Duke University Hospital and who had PGm and AVA values recorded in both pre-CPB TEE and preoperative TTE reporting databases. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: PGm with pre-CPB TEE was lower by 6.6 mmHg (95% confidence interval, -4.0 to -9.3 mmHg; p<0.001), whereas AVA was higher by 0.10 cm(2) (95% confidence interval, 0.04 to 0.15 cm(2); p<0.001), compared with preoperative TTE values. When using PGm, pre-CPB TEE generated an AS severity 1 grade lower 39.1% of the time and revealed no difference 55.4% of the time compared to preoperative TTE. When using AVA by continuity, pre-CPB TEE generated an AS severity 1 grade lower 14.1% of the time and revealed no difference 81.5% of the time compared to preoperative TTE. When using either PGm or AVA, preoperative TTE exhibited moderate or severe AS for all study patients, whereas, pre-CPB TEE demonstrated mild AS in 5.4% (n = 92) of patients. CONCLUSIONS: The authors confirmed their hypothesis that pre-CPB TEE generates different PGm and AVA values compared with preoperative TTE. These differences often underestimate AS severity. Hemodynamic standardizations or adjustments of pre-CPB TEE PGm and AVA values may be necessary in anesthetized patients before assigning an AS grade using these parameters.