Background Pacemakers are indicated in children for congenital or acquired dysfunctions of sinus node or atrioventricular node. Congenital complete atrioventricular block is rare and appears in children with normal heart structure, with an incidence of 1/14.000–20000 live newborn. Kearns-Sayre Syndrome is a mitochondrial myopathy that demonstrates chronic progressive ophtalmoplegia, pigmentary retinal degeneration, cerebellar ataxia, diabetes, hypoparathyroidism, hearing loss, renal failure and cardiac conduction defects.

Objective We present two pediatric patients which necessitate pacemaker’s placement.

Material and Method Case 1: 1½ year-old boy was admitted in Pediatric Intensive Care Unit, Emergency Clinical County Hospital Constanta, Romania. He was diagnosed at two weeks of age with congenital complete atrioventricular block with heart rate 45–53 beats/minute, without signs of heart failure in infancy. At admission patient had severely abnormally heart rhythm (ventricular fibrillation, torsade de pointes) and heart failure. He was successfully resuscitated for cardiac arrest. Echocardiography revealed dilated cardiomiopathy, important systolic dysfunction, without congenital heart defects. He was referred to a cardiovascular surgery center were he underwent permanent pacing with epicardial unicameral pacemaker on the left ventricle, at 80 beats/minute frequency. There were no early postoperative complications and the cardiac functions improved rapidly. Case 2: A 15-year old boy diagnosed with Kearns-Sayre Syndrome exhibited cardiac conduction disturbances: complete right bundle branch block with left anterior hemiblock and Mobitz type 2 second degree AV block. He improved by implantation of a permanent endocardial pacemaker.

Conclusion Heart conduction defects necessitate an accurate and early diagnosis in order to refer patients for pacemaker therapy.