Morphometric analysis of myocardial bridges in children with ventricular hypertrophy.

The nuclear cross-sectional area of the muscular fibers from a series of myocardial bridges was analyzed and compared to both the adjacent and underlying myocardial fibers. The series came from 12 hearts of children, ranging in age from 24 h to 2 years, with diverse forms of congenital heart disease, which caused left ventricular hypertrophy and had a myocardial bridge in the path of the anterior interventricular coronary artery. The cross-sectional areas of myocardial nuclei were measured for the bridging myocardial fibers, the adjacent myocardium, and the myocardial fibers underlying the bridged coronary artery. A significant statistical difference between the bridging muscular fibers and those underlying the submerged artery was observed, as well as between the bridging fibers and its adjacent ones. This findings suggests that myocardial bridges not only represent an anatomical abnormality, but probably imply different functional behavior as well.