[An unusual cause of complete atrioventricular block--a case report]

Complete atrioventricular block is a serious disorder, since patients may be asymptomatic. However, it is an important risk for sudden cardiac death.

A 48-year old male patient was admitted to the coronary care unit, due to recurring substernal chest pain. It was followed by fatigue, weakness and confusion, it lasted more than half an hour and occurred twice. Loss of consciousness did not occur. The patient had a tick bite two months earlier. Physical examination was unremarkable, except for low heart rate (50/minute) electrocardiogram showed a complete atrioventricular block with narrow QRS complexes and good ventricular function. Elevation of ST segment was observed in the inferior ECG leads, with reciprocal ST depression in precordial leads; it was highly suspicious for acute myocardial infarction, but markers of myocardial necrosis (Troponin, Creatine kinase-MB) were normal. The chest pain recurred without evolutive changes in the electrocardiogram or increase in markers of myocardial necrosis. Tests for Lyme disease were negative, too. The cause of atrioventricular conduction disturbance was found by transthoracic echocardiography. A giant tumor was found in the right atrium and right ventricle. Further examinations excluded its secondary cause and the patient was sent to surgery. The tumor was inoperable and bled excessively. Although permanent pacing was performed, the patient died suddenly after dismisal.

We can conclude that a giant primary tumor of the heart can be asymptomatic for a long time causing complete atrioventricular block, and in this case it clinically presented as acute myocardial infarction. Echocardiographic examination was the main diagnostic tool in our case.