Deleterious effect of unintentional pacing from the middle cardiac vein in a patient with congenitally corrected transposition of the great arteries and ventricular septal defect. The beneficial effect of cardiac resynchronization therapy after heart surgery.

This report presents a case of a 31-year-old male with congenitally corrected transposition of the great arteries, ventricular septal defect (VSD) and complete heart block who was admitted to our institution because of an exacerbation of heart failure after pacemaker implantation. The ECG and chest radiograph revealed that the ventricular lead was placed in the middle cardiac vein. After cardiosurgical procedure (VSD closure and atrioventricular valves replacement), the clinical symptoms of heart failure were still present. They diminished while the patient was on escape rhythm (40-70 bpm). Therefore, the previously implanted leads were removed and the transvenous, biventricular system was implanted, which resulted in a significant clinical improvement.