A case report of isolated levocardia without intracardiac anomalies associated with sick sinus syndrome.

A 42-year-old female with cardiomegaly showed bradycardia without syncope. Clinical data showed that she had an isolated levocardia with interruption of the inferior vena cava. Isolated levocardia was defined as a normally placed heart associated with situs ambiguus of other viscera. She did not have intracardiac anomalies. Isolated levocardia without intracardiac anomalies, as in this case, has only been reported in 13 other cases. Isolated levocardia is often accompanied by severe complex intracardiac anomalies and, therefore, most of the patients have a short life span. Situs ambiguus, especially left isomerism, is frequently associated with deteriorated sinus node function, and an interruption of the inferior vena cava may also be an indication of this phenomenon. Therefore, the patient's sinus node function was examined using an electrophysiological study and a 24-hour ambulatory electrocardiogram. Sick sinus syndrome was finally confirmed.