Incidence of myocardial bridges in northwest Indians.

Dissection of hearts obtained at autopsy from 150 adults (110 males, 40 females) and 15 children (10 males, 5 females) showed an incidence of myocardial bridges over the coronary arteries to be 34.5% in the male and 32.5% in female adults (p = NS); in children the incidence was 40% in either sex. A similar incidence was found in the neonates. Such bridges were also present in the fetuses. A bridge over the anterior interventricular artery could be identified as early as 60mm C.R. stage. An examination of serial sections of 3 early embryos indicated that the coronary arteries develop epimyocardially. The myocardial bridges seem to develop concurrently with the development of myocardium. In 63% instances a bridge was present on the anterior interventricular artery, other arteries were involved less frequently.