A method for cardioverting or defibrillating a human heart, performed by placing a transvenous lead having a cardioversion or defibrillation electrode such that the electrode is located at least partially within the middle cardiac vein of a patient's heart and placing an additional cardioversion or defibrillation electrode in the superior vena cava of the patient's heart and thereafter delivering a cardioversion or defibrillation pulse between the first and second electrodes. The method may be practiced by placing the transvenous such that the defibrillation electrode it carries extends around the apex of the patient's heart, and the transvenous lead may be advanced through one cardiac vein toward the apex of the patient's heart and thereafter advanced upward through a different cardiac vein.