Intraoperative transesophageal echocardiographic evaluation of mitral regurgitation

Usefulness of intraoperative transesophageal echocardiography in predicting the degree of mitral regurgitation secondary to atrioventricular defect in children

The objectives of this study were to determine the validity of the grade of mitral regurgitation (MR) as imaged by intraoperative transesophageal echocardiography (TEE) in predicting the grade of MR at follow-up. Intraoperative TEE and corresponding follow-up transthoracic studies were retrospectively reviewed and the regurgitant jet area to left atrial area ratio was used to quantify the MR. Patient records were reviewed to identify factors contributing to the development of a certain grade of MR. Intraoperative TEE was useful in detecting severe MR that required further repair at the same time. However, discrepancy in the grade of MR at follow-up was noted in 47% of patients (21 of 47) and unchanged grade of MR was found only in 53% of patients (26 of 47). Blood pressures were significantly lower and heart rates higher intraoperatively. Initial preoperative grade of MR and type of atrioventricular canal defect did not predispose for a particular grade of MR at follow-up. The grade of MR by intraoperative TEE does not predict the grade of MR at follow-up as imaged by transthoracic echocardiography.

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation

OBJECTIVES

To develop and validate an automated noninvasive method to quantify mitral regurgitation.

BACKGROUND

Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR).

METHODS

First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied.

RESULTS

In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml).

CONCLUSIONS

We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.