Echo doppler evaluation of patients with acute mitral regurgitation: Superiority of transesophageal echocardiography with color flow imaging

Acute mitral regurgitation is a medical emergency that requires prompt, accurate diagnosis and urgent therapy. Although the use of echo Doppler imaging has been described in these patients, preliminary observations have suggested that color flow Doppler performed from the standard transthoracic windows may underestimate the severity of mitral insufficiency in this setting. The aim of this study was to compare transesophageal color Doppler quantitation of regurgitation with results obtained from standard transthoracic windows in patients with acute, severe mitral regurgitation. Two-dimensional echocardiography with pulsed, continuous, and color flow Doppler was performed by both transthoracic and transesophageal methods in 16 consecutive patients who were documented to have acute severe mitral insufficiency by catheterization. Transthoracic and transesophageal scans were reviewed by two blinded observers and assessed for the detection of mitral regurgitation by transthoracic pulsed wave (81%), continuouswave (100%), and color flow Doppler (81%) compared with transesophageal color flow imaging (100%; p = NS). Severity of mitral regurgitation was graded as none, mild, moderate, or severe on the basis of existing transthoracic pulsed wave and color flow criteria and compared with transesophageal color flow grading. At first examination patients were critically ill, with elevated pulmonary wedge pressures (mean 27 ± 7 mm Hg) and V waves (mean 45 ± 10 mm Hg). Fifteen of the patients underwent emergency surgery, and the overall hospital mortality rate was 12%. Maximal color flow jet areas were significantly greater on transesophageal scanning (mean 10.5 cm2) compared with transthoracic color jets (mean 2.3 cm2). Indeed, although all 16 patients had severe mitral regurgitation by catheterization, transthoracic pulsed wave and color flow methods underestimated the grade in each case: 3 patients had none, 11 mild, 2 moderate, and 0 severe. However, transesophageal color flow techniques graded the same lesions as moderate in 2 and severe in 14 (p < 0.0001). Examination of the duration of color flow jets revealed the flow disturbance to be present in only 38% ± 15% of systolic color frames but was visualized in 87% ± 6% of transesophageal color frames (p < 0.001). Transesophageal echo imaging also allowed the definitive clinical cause of regurgitation to be determined in 9 (56%) of the patients in whom conventional surface scanning was inadequate: torn chordae (2 patients), ruptured papillary muscle (2), flail porcine leaflet (3), and myocardial infarction (2). These results indicate that, although transthoracic echo with conventional and color flow Doppler is useful for the detection of mitral regurgitation, quantitation of severity by these methods yielded a consistent underestimation of grade when compared with angiography, probably because of technical limitations such as attenuation and scanning depth. Transesophageal echo with color flow imaging was far superior to surface scanning in giving the cause and predicting the severity of the mitral regurgitation. Thus transesophageal imaging should be considered in all patients suspected of having acute, severe mitral regurgitation.