Pathological Case of the Month

Figure 1. An echocardiogram in the subxiphoid view shows prominent left ventricular trabeculations with deep intertrabecular recesses involving especially the apex and free wall. RA indicates right atrium; RV, right ventricle; and LV, left ventricle.

Figure 2. A coronal section of the heart, with the left ventricle on the right side, shows interstices deep within the hypertrophied left ventricular free wall.

Figure 3. The endothelium of the left ventricular trabeculae and interstices shows fibroelastosis (hematoxylin-eosin, original magnification×40).

This boy had isolated noncompaction of the left ventricular myocardium (also known as persistence of spongy myocardium), a rare form of congenital cardiomyopathy in which the left ventricular wall fails to become flattened and smoother as it normally would during the first 2 months of embryonic development.^2,3 This developmental arrest results in decreased cardiac output with subsequent left ventricular hypertrophy. The aberrant left ventricular trabeculae predispose to abnormal cardiac conduction and potentially fatal cardiac arrhythmias. The interstices within the trabeculated left ventricle predispose to thrombus formation with secondary systemic embolic events. Fibroelastosis of the adjacent ventricular endocardium (Figure 3) is a secondary phenomenon resulting from the abnormal blood flow pattern in the left ventricular chamber. No evidence of systemic embolic events was found at autopsy; however, hemosiderin-laden macrophages in the lungs indicate evolving congestive heart failure.

The echocardiographic and computed tomographic appearance of this entity in nonlethal cases has been described.^4,5 Reported cases range from 11 months to 44 years and occur in both sexes. Associated facial dysmorphology and a variety of structural cardiac anomalies have been found in some cases.^6,7 Familial cases suggest autosomal dominant inheritance of a sporadic new mutation.

Treatment consists of anticoagulants, antiarrhythmic medications, and avoidance of strenuous exercise. Echocardiographic screening of surviving siblings is recommended.

Accepted for publication May 1, 1997.

Reprints: Mark A. Lovell, MD, Associate Professor of Pathology and Pediatrics, Box 168, University of Virginia Health Sciences Center, Charlottesville, VA 22908 (e-mail: mal3u@virginia.edu).