Grading Aortic Valve Stenosis With Dimensionless Index During Pre-cardiopulmonary Bypass Transesophageal Echocardiography: A Comparison With Transthoracic Echocardiography

Abstract

Objective: The authors hypothesized that grading valvular aortic stenosis (AS) with dimensionless index (DI) during intraoperative pre-cardiopulmonary bypass (pre-CPB) transesophageal echocardiography (TEE) would match the grade of AS during preoperative transthoracic echocardiography (TTE) for the same patients more often than when using peak velocity (V_p), mean pressure gradient (PG_m), or aortic valve area (AVA).

Design: Retrospective, observational.

Setting: Single university hospital.

Participants: The participants in this study included 123 cardiac surgical patients with any degree of AS, who underwent open cardiac surgery between 2010 and 2016 at the Medical University of South Carolina and had V_p, PG_m, AVA, and DI values available from reporting databases or archived imaging.

Interventions: None.

Measurements and main results: When using DI, pre-CPB TEE grading of AS severity was 1 grade higher 21.1% of the time and 1 grade lower 13.0% of the time compared with TTE, for an overall disagreement rate of 34.1%. The overall disagreement rates between pre-CPB TEE and TTE for V_p, PG_m, and AVA were 39.8%, 33.3%, and 33.3%, respectively.

Conclusions: The authors could not demonstrate that DI was better than V_p, PG_m, or AVA at matching AS grades between intraoperative pre-CPB TEE and preoperative TTE. When DI was used, pre-CPB TEE was more likely to overestimate than underestimate the severity of AS compared with TTE. However, when V_p or PG_m was used, pre-CPB TEE was more likely to underestimate the severity of AS compared with TTE. A comprehensive approach without overemphasis on 1 parameter should be used for AS assessment by intraoperative TEE.

Keywords: aortic stenosis; dimensionless index; grading; intraoperative transesophageal echocardiography; pre-cardiopulmonary bypass transesophageal echocardiography.

Fig 1.

Flow diagram illustrating selection of study population. AI, aortic insufficiency; AS, aortic stenosis; AV, aortic valve; MR, mitral regurgitation; RV, right ventricle; TEE, transesophageal echocardiography; TR, tricuspid regurgitation; TTE, transthoracic echocardiography.

Fig 2.

TTE images showing (A) LVOT diameter measurement in a parasternal long-axis aortic valve view, (B) LVOT-VTI by pulsed-wave Doppler in an apical view, and (C) AV-VTI by continuous-wave Doppler in an apical view. AV, aortic valve; LVOT, left ventricular outflow tract; TTE, transthoracic echocardiography; VTI, velocity-time integral.

Fig 3.

TEE images in the same patient as Fig 2 showing (A) LVOT diameter measurement in a midesophageal long-axis view, (B) LVOT-VTI by pulsed-wave Doppler in a deep transgastric long-axis view, and (C) AV-VTI by continuous-wave Doppler in a deep transgastric long-axis view. Note the lower V_p (labeled AV V_max on the image), PG_m, LVOT-VTI, and AV-VTI values compared with transthoracic echocardiography in Fig 2. AV, aortic valve; LVOT, left ventricular outflow tract; PG_m, mean pressure gradient; TEE, transesophageal echocardiography; V_p, peak velocity; VTI, velocity-time integral.

Fig 4.

Scatter plots of TTE (y-axis) by TEE (x-axis) for each metric. The 45° line represents perfect agreement with TEE. Points above the line represent participants for whom values during TTE > TEE and points below the line represent participants for whom values during TTE < TEE. The Pearson’s correlation between TEE and TTE also is provided on each plot. All correlations were significant at p < 0.001. TEE, transesophageal echocardiography; TTE, transthoracic echocardiograph.