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Types of Permanent Pacemakers

The need to place a permanent pacemaker comes up as a result of conditions or diseases that altered your heart's rate or rhythm. The pacemaker is a small, low-energy device that emits impulses in response to a heart rate that is too fast, too slow or irregular. The impulse discharged, or fired, from the pacemaker keeps the heart beating with a regular rhythm. Cardiologisdts can program different types of pacemakers to respond to a particular condition within your heart's electrical conduction system.

  1. Types

    • The single-chamber pacemaker operates with one lead wire in the upper chamber of the heart, called the atrium, or one lead wire in the lower chamber, called the ventricle. A dual-chamber pacemaker works with one lead placed in the atrium and one lead in the ventricle. A biventricular pacemaker operates with three leads: one lead placed in the right atrium, one lead in the right ventricle and one lead in the left ventricle.

    Sub-Types

    • Sub-typing within pacemaker settings includes fixed-rate pacemakers, demand mode pacemakers and rate-responsive pacemakers. Fixed-rate delivers a specific preset heart rate and does not change with activity levels. Demand mode only delivers impulses when your heart rate drops to a rate less than a preset rate. Rate-responsive units adapt to your heart rate in reaction to activity.

    Implantable Cardioverter Defibrillator

    • The implantable cardioverter defibrillator, also know as the ICD, operates on low-energy levels like a pacemaker, to regulate heart rate and rhythm. The ICD also uses high-energy impulses when needed for rhythms that are dangerous, such as ventricular fibrillation and ventricular tachycardia. Both ventricular rhythms, left untreated, can be fatal. Additional uses for the ICD include responding to heart diseases, conditions and disorders that lead to cardiomyopathy, chronic heart failure, sudden cardiac death and long QT syndrome.

    Function

    • A pacemaker consists of a tiny generator that contains a miniature computer and a battery. Lead wires carry the pacemaker impulses to the heart muscle, but also monitor the electrical action of your heart. A cardiologist can connect one to three lead wires to the generator, depending on the heart problem requiring treatment. Each time the generator sends out an impulse along the lead wires, the heart muscle contracts in response and produces a heartbeat.

    Precautions

    • After pacemaker placement, certain precautions avoid damaging the electronics. Keep away from areas of high-voltage, radiation and magnetic force fields. Additionally, high-tension wires, magnets for large industrial operations and arc welding machines produce serious malfunction within the pacemaker generator. Microwave ovens used to be a concern, but with safety mechanisms implanted within the pacemaker, interference is no longer a problem. Metal detectors do not damage pacemakers, but always carry your card to help explain the alarm. Avoid magnetic resonance imaging, or MRI testing, as the magnet does damage pacemakers. Feeling dizzy, faint, short of breath or having irregularities in your heart rate are symptoms of a malfunctioning pacemaker.

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