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 (PG m ) 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 PG m and AVA values recorded in both pre-CPB TEE and preoperative TTE reporting databases.Interventions: None. Measurements and Main Results: PG m with pre-CPB TEE was lower by 6.6 mmHg (95% confidence interval, -4.0 to -9.3 mmHg; p o 0.001), whereas AVA was higher by 0.10 cm 2 (95% confidence interval, 0.04 to 0.15 cm 2 ; p o 0.001), compared with preoperative TTE values. When using PG m , 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 ¼ 92) of patients.Conclusions: The authors confirmed their hypothesis that pre-CPB TEE generates different PG m and AVA values compared with preoperative TTE. These differences often underestimate AS severity. Hemodynamic standardizations or adjustments of pre-CPB TEE PG m and AVA values may be necessary in anesthetized patients before assigning an AS grade using these parameters. & 2016 Elsevier Inc. All rights reserved.KEY WORDS: aortic stenosis, aortic valve area, discordance, mean gradient, precardiopulmonary bypass (intraoperative) transesophageal echocardiography P RECARDIOPULMONARY BYPASS (pre-CPB) transesophageal echocardiography (TEE) is essential for intraoperative assessment and surgical guidance during cardiac surgery. Although many patients come to the operating room with an extensive cardiac workup, pre-CPB TEE aortic valve assessment can affect surgical decision-making based on new findings during planned or emergency surgeries. According to a large retrospective review of 3,835 patients undergoing isolated coronary artery bypass grafting (CABG), 3.3% of patients had an unplanned aortic or mitral valve procedure added to the surgery based on pre-CPB TEE findings. 1 Of 1,823 patients undergoing mitral valve surgery, 1.0% of patients underwent an unplanned aortic valve procedure based on incidental findings during pre-CPB TEE. 1 Given that surgical decisions can be based on pre-CPB TEE findings, accurate interpretation of grading parameters during the pre-CPB period is imperative.The validated mean gradient (PG m ) and aor...

Comparison of grading of aortic stenosis between transthoracic and transesophageal echocardiography in adult patients undergoing elective aortic valve replacement surgeries: A prospective observational study

“…Based on the study, conducted by Whitener et al .,[7] considering average PGm as 46.0 in pre-induction TTE group and as 39.6 in pre-CPB TEE, with power as 90% and α error as 5%, sample size of 54 patients was derived. Thus, we decided to enroll 60 patients in our study with 30 in each group.…”

“…[6] In a retrospective, observational study preoperative TTE PGm and AVA values were compared with precardiopulmonary bypass (CPB) TEE, and it was found that preCPB TEE often underestimates AS severity. [7] The reason for this disparity is unclear. One of the reasons might be that AS grading was originally defined in spontaneously breathing patients.…”

The Emperor Has No Clothes: Recognizing the Limits of Current Echocardiographic Technology in Perioperative Quantification of Mitral Regurgitation

“…Aortic valve gradients decrease and calculated valve areas increase in the operating room. 21 Left ventricular outflow obstruction in hypertrophic cardiomyopathy frequently improves after induction produces a pharmacologic sympathectomy. 22 Finally, the myocardial depressant effects of inhalation agents affect echocardiographic measurements of ventricular performance.…”

In Pursuit of a Unicorn: Does the Ideal Parameter for Grading of Aortic Stenosis During Intraoperative Transesophageal Echocardiography Exist?

“…1,4 Previous research has shown that V p , PG m , and AVA obtained during precardiopulmonary bypass TEE often underestimates the severity of AS. 5 Additional research has shown that there is more discordance between mean PG m and AVA during precardiopulmonary bypass TEE than during preoperative TTE. 6 In a perfect world, one could perform a TEE examination and have certain parameters be in complete agreement with previously reported studies across all modalities.…”

“…V p and PG m were more likely to underestimate AS severity, which confirmed previous work by this group. 5 So what is a cardiac anesthesiologist to do? Whitener et al again remind us that a comprehensive approach to assessment of AS is necessary and that no single parameter should be used alone.…”