[Change of defibrillation vector with addition of an azygos vein coil lowers defibrillation threshold].

A 34-year-old male with dilated cardiomyopathy and advanced heart failure was referred for defibrillator implantation for primary prevention of sudden cardiac death. During implantation despite multiple right ventricular (RV) lead positions (outflow tract, septum, apex) and various defibrillation vector combinations (superior vena cava coil on/off, polarity reversal, tilt change), the maximum energy shock (40 J) from the implanted device was unsuccessful in restoring the sinus rhythm. In a straightforward fashion another regular single coil shocking lead was introduced to the azygos vein using telescoping system for coronary sinus cannulation and coronary vein subselection. The terminal pin of the new shocking coil was inserted into the superior vena cava coil port of the device header; the old superior vena cava coil pin and the redundant RV pacing IS-1 pin of the new lead were caped. This resulted in a successful defibrillation with the energy of 30 J and thus in obtaining the required 10 J safety margin. Azygos vein implantation technique was described and it's merits discussed.