Hospital Services

Cardiac Electrophysiology Procedures
(Diagnose and/or Treatment of Heart Rhythm Disorders)

Pacemakers

What is a pacemaker?
o A pacemaker is prescribed for people whose hearts are beating too slowly or irregularly (bradycardia). A pacemaker sends tiny electrical impulses to the heart muscle. The electrical impulses are precisely timed and cause the heart to beat, very similarly to a naturally occurring heart rhythm. When people refer to a pacemaker, they are really discussing a pacing system: a pacemaker, a pacing lead, and a programmer. Two parts of a pacing system are placed inside the body:

• The pacemaker is a small metal case that contains electronics and battery. The pacemaker sends a tiny electrical pulse at a specific time.
• A pacing lead is an insulated wire that carries the tiny electrical pulse to the heart. It can also relay information about the heart's activity back to the pacemaker.
• The third part, the Programmer, is kept in a hospital or clinic. A nurse or doctor uses this specialized computer to monitor and adjust the settings of a pacemaker.
• The three parts of a pacing system work together to make the heart beat at a more normal rate. By restoring the heart rate, the symptoms of bradycardia are often eliminated. This often means patients have more energy and less shortness of breath.

How a Pacing System Works

• A pacing system restores one of the most essential rhythms of life--the rhythm of the human heart. The two parts of the pacing system inside the body, the pacemaker and the pacing lead, work together to perform two main functions: pacing and sensing. The third part of the system, the programmer, is used by a doctor or nurse to communicate with the pacemaker.
• Pacing is when a pacemaker sends tiny electrical signals to the heart through a pacing lead. Each tiny electrical signal is called a pacing pulse (pacing impulse, pace) and it is this pacing pulse that starts a heartbeat. The pacemaker paces (sends a pacing pulse to) the heart when the heart's own rhythm is interrupted, irregular, or too slow.
• A pacemaker may also sense (monitor) the heart's natural electrical activity. If a pacemaker senses a natural heartbeat, it will not deliver a pacing pulse to the heart.

How pacing starts a heartbeat:

• The pacemaker sends a tiny electrical signal, a pacing impulse.
• This impulse travels through the insulated wires of a pacing lead until it reaches the metal electrode at the tip of the lead.
• The electrode, which is in direct contact with the heart, delivers the electrical impulse to the heart.
• The electrical impulse causes the heart tissue to begin a heartbeat.

How a pacemaker knows when to send a pacing impulse:

• The pacing pulses are timed so that the heart beats in a manner very similar to a naturally occurring heart rhythm.
• For some pacemakers, this timing is exactly the same for each heartbeat.
• In other pacemakers, the timing is based on when the heart beats on its own. For these pacemakers, information about the heart's own electrical activity is sent back to the pacemaker through an electrode on the lead. (This is called sensing.)
• If the pacemaker circuitry determines that the heart is beating too slowly, a pacing pulse is sent to start a heartbeat.
• If the pacemaker circuitry determines that the heart is beating at a proper rate, the pacing pulse is withheld.
• In rate responsive pacemakers, a special sensor detects changes in the body such as movement of arms and legs or how often a person breathes. The pacemaker's circuitry interprets these changes and increases the pacing rate (the number of times per minute that a pacing pulse is sent) by either a little or a lot - depending upon the body's need for oxygen.

How the doctor or nurse know what a pacemaker is doing:
During a follow-up visit at a clinic or hospital, a programmer is used by a doctor or nurse to monitor the pacemaker and adjust the pacing and sensing.

Surgery
Pacemaker surgery is often done using a local anesthetic and the person returns home the same day. Occasionally, a patient who requires other surgery, such as a coronary bypass, will have the pacemaker implanted at the same time as the other surgery. The cardiac electrophysiologists of Associated Cardiologists implant the ICD. These are cardiologists with specialized training in the diagnosis and treatment of heart rhythm disorders.

The surgical procedure includes these steps:

• An incision is made for the pacemaker. (This may be on either side of the chest or in the abdomen.
• The leads are inserted into a vein and guided to the heart.
• The leads are connected to the pacemaker.
• The pacemaker and leads are tested.
• The incision is closed.
• The pacemaker is programmed.