A pacemaker is a medical device that keeps the heart beating normally, commonly implanted in patients with bradycardia. Bradycardia causes an unusually slow or irregular heartbeat.
In a healthy heart, the beat begins in the right atrium or upper chamber as an electrical impulse. This impulse travels through the heart tissues to the ventricle or lower chambers. Here the heart muscles contract in response to the beat, pumping oxygen-rich blood throughout the body and lung tissues. If blood is pumped too slowly for the body's needs, dizziness, lightheadedness and fainting can occur. A pacemaker alleviates this problem by regulating the heartbeat.
A pacemaker is a small, battery operated, titanium device with one or more highly flexible pacing leads. It is implanted in the chest area with the lead(s) running down to the heart. A lead might be inserted into a vein that feeds into the desired chamber, or it might be affixed to the outside of the heart if the heart is still growing as in the case of children. The tip of the lead is fitted with an electrode and the device contains a computerized program that can stimulate a heartbeat through sending a pacing pulse to the electrode.
Bradycardia can manifest in one of two ways that might affect the type of device used. In some cases, the heart's own pacemaker -- the sinus node -- simply does not generate enough beats per minute, creating low blood pressure and an abnormally slow heartbeat. This is known as sick sinus syndrome.
In other patients, only some of the heartbeats that are generated reach the ventricle chamber, and thus no blood is pumped for the missed beat. This condition is known as heart block and can be caused by scar tissue, heart disease or other abnormalities that interfere with the travel of the impulse, creating an irregular heartbeat.
If bradycardia is present as one of the above conditions, a single-chamber pacemaker might be used to stimulate the faulty chamber. If both sick sinus syndrome and heart block are present, a double-chamber pacemaker can be used to generate beats in the atrium and initiate contraction for pumping blood in the ventricle.
An external programming unit retained by the physician can communicate with the device during checkups. Information about the condition and health of the heart can be relayed and the pacemaker's internal program can be altered as necessary without surgery.
These devices have been used since the 1950s and come in various models. Older styles were designed to deliver beats at a predetermined rate. Other models use sensors that monitor the heart, only generating a pace or beat when the heart's own beat becomes too slow or irregular. Dual-chamber pacemakers monitor both upper and lower chambers, ensuring they remain synchronized in a natural rhythm. The most advanced devices are rate-responsive. These monitor the body's needs so that the heartbeat quickens on demand —- say for strenuous exercise —- and automatically slows when the body is at rest and demands are low.
A pacemaker can make life immeasurably better for someone living with bradycardia, allowing an active life without feeling tired or lacking in energy. With advanced technology in micro circuitry, these devices are becoming smaller and more powerful. Speak to your physician about the options available for your specific needs.
