Left atrial isomerism: clinicopathologic findings in a 14-year-old boy.

Visceral heterotaxy syndromes have been associated with complex congenital heart disease and several attempts have been made to classify these lesions. One area of controversy that remains is the existence of atrial isomerism. In this case report we provide definite anatomic evidence of the existence of left atrial isomerism, wherein both the atria have smooth walls, finger-like appendages, and absence of the pectinate muscles and sinus node.