Comparison of M mode echocardiography and pathologic findings in the hypoplastic left heart syndrome

The M mode echocardiograms and pathologic specimens from 18 infants with the hypoplastic left heart syndrome were compared to determine the accuracy with which the echocardiogram reflects the state of the mitral valve, left ventricle and aortic valve, and its limitations in establishing this diagnosis. Mitral valve echoes were recorded in 7 of the 11 cases with an anatomic mitral valve orifice diameter greater than 3 mm. Ventricular septal echoes were found only in the seven cases in which the mitral valve was recorded. Differences between echocardiographic and anatomic left ventricular internal dimensions were not statistically significant in this small group. When aortic valve echoes were recorded, this valve was always patent in the anatomic specimen. The aortic valve was atretic in 9 of the 11 cases in which no aortic valve echoes were present. The echocardiographic and anatomic aortic root dimensions had a statistically significant correlation (p < 0.05), but there was considerable scatter in the data.None of the 18 infants met all of the previously proposed criteria for the echocardiographic diagnosis of hypoplastic left heart syndrome. An echocardiographic left ventricular dimension of 10 mm or greater was present in five cases (28 percent), and an aortic root dimension of 10 mm or greater in six (33 percent). The most reliable echocardiographic finding was excursion of 5 mm or less of the anterior leaflet of the mitral valve or inability to detect the mitral valve. Noninvasive findings are not always sufficient to establish the diagnosis of hypoplastic left heart syndrome, and further studies may be necessary in some patients.