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Heart Disease Health Center

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Abnormal Heart Rhythms and Pacemakers

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The normal, healthy heart has its own pacemaker that regulates the rate that the heart beats.

However, some hearts don't beat regularly. A pacemaker can sometimes correct the problem. A pacemaker is a small device that sends electrical impulses to the heart muscle to maintain a suitable heart rate and rhythm. A pacemaker may also be used to treat fainting spells (syncope), congestive heart failure, and hypertrophic cardiomyopathy.

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Pacemakers are implanted just under the skin of the chest during a minor surgical procedure.

The pacemaker has two parts: the leads and a pulse generator. The pulse generator houses the battery and a tiny computer, and resides just under the skin of the chest. The leads are wires that are threaded through the veins into the heart and implanted into the heart muscle. They send impulses from the pulse generator to the heart muscle, as well as sense the heart's electrical activity.

Each impulse causes the heart to contract. The pacemaker may have one to three leads, depending on the type of pacemaker needed to treat your heart problem.

There are different types of pacemakers:

  • Single-chamber pacemakers use one lead in the upper chamber (atria) or lower chamber (ventricles) of the right side of the heart.
  • Dual-chamber pacemakers use one lead in the right atrium and one lead in the right ventricle of your heart.
  • Biventricular pacemakers use three leads: one placed in the right atrium, one placed in the right ventricle, and one placed in the left ventricle (via the coronary sinus vein).

Your doctor will decide what type of pacemaker you need based on your heart condition.

The doctor programs the minimum heart rate. When your heart rate drops below that set rate, your pacemaker generates (fires) an electrical impulse that passes through the lead to the heart muscle. This causes the heart muscle to contract, creating a heartbeat.

Pacemakers are also used to treat the following:

  • Bradyarrythmias, which are slow heart rhythms that may arise from disease in the heart's electrical conduction system (such as the SA node, AV node, or HIS-Purkinje system).
  • Heart failure. This type of treatment is called cardiac resynchronization therapy (CRT) or biventricular pacing.
  • Hypertrophic cardiomyopathy.
  • Syncope (fainting spells).

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