The incidental heart sound. Study of clinical diagnostic certainty and possible causes

Abstract

The diagnosis "innocent murmur" is made when there is no evidence for a heart disease either by history nor by examination, auscultation, electrocardiogram or echocardiography. The purpose of the present study was to determine the usefulness of echocardiography for diagnosing of an innocent heart murmur and further to compare the findings of ultrasound with those of the clinical examination. Children were accepted for the study after clinical examination and evaluation of the electrocardiogram (but before echocardiography) only when two independent pediatricians did not realize any symptoms of a heart disease. A total number of 200 children were examined; 121 were male and 79 female. 194 children (97%) had an innocent murmur, six children (3%) a heart disease [atrial septum defect (3), bicuspid aortic valve (1), aortic stenosis (1) or pulmonary stenosis]. The sensitivity and positive predictive value of clinical examination and auscultation ranged from 92% to 99%, the specificity from 50% to 60%. In six cases the initial diagnosis had to be changed after echocardiography. Three times an innocent murmur was diagnosed as a heart disease and another three times a pathological murmur was regarded as innocent. Left ventricular bands were seen in 53 (26,5%) children and they significantly correlated with the musical heart murmur (77%). If there was no false tendon, the murmur was mostly an uncharacteristic one (74% (less than 0,001). The echocardiographic findings were not different of those children without a murmur or heart disease. The average peak velocity in the ascending aorta was 143,1 +/- 23,6 cm/s (87-215 cm/s), the shortening fraction 36,2 +/- 6,3%. We could not find a correlation between velocity, shortening fraction and aortic diameter.