V. PERMANENT PACEMAKERS
A dual-chamber pacemaker is the treatment of choice in patients with pacemaker syndrome. Maintenance of AV synchrony is important in these patients as VAconduc-tion causes hemodynamic derangements that raise atrial
decrease cardiac output with associated
3. Pacemaker Malfunction
Malfunctions include:
Sensing malfunction (see Fig. 6)
Oversensing
Pacing malfunction
Lead fracture
Pulse generator malfunction
Pacemaker infection.
D. Temporary Pacing
It may be necessary to insert a temporary pacemaker in patients where a heart attack has disturbed the electrical conducting system of the heart and spontaneous recovery is expected within a few days. This procedure is a simple one. The temporary pacemaker consists of a pacing wire that is inserted through a vein in the neck, usually the subclavian vein. The skin over the vein is infiltrated with a local anesthetic so that the procedure is not painful. A pacing catheter is threaded through the vein to reach the inside of the right ventricle. The passage of the pacing catheter is usually done under fluoroscopic (x-ray) control because the wire is radio-opaque and can be seen on x-ray. Occasionally this procedure is done with the assistance of an ECG and the final position of the catheter is verified by x-ray. The external end of the wire catheter is connected to a battery-operated pulse gene¬rator (see Fig. 3). The pulse generator is set, for example, at 65 beats per minute and commences pacing if the heartbeat falls below this set rate. The pacemaker works (fires) only when it is required. Complications are very few for the insertion and maintenance of a temporary pacemaker.