What should I expect after implantation of pacemaker or defibrillator?

Please see defibrillator or pacemaker implantation for details. However, unique to biventricular pacing, the left ventricular lead passes very close to a nerve that runs along surface of the heart from the spine all the way down to the diaphragm. This is called the phrenic nerve. If it is stimulated by the left ventricular leave, it can cause a twitch of the left side of the diaphragm with every heartbeat. This is not dangerous, but can be quite aggravating. It can usually be corrected by reprogramming the pacemaker or defibrillator in the office. It is because of the potential for phrenic nerve stimulation that we frequently watch people overnight.