pacemaker

Pacemaker
A pacemaker is a small device, about the size of a pocket watch, that s placed under the skin near the heart to help control heartbeat. People may need a pacemaker for a variety of reasons — mostly due to one of a group of conditions called arrhythmias, in which the heart s rhythm is abnormal. Normal aging of the heart may disrupt the heart rate, making it beat too slowly. Heart muscle damage resulting from a heart attack is another common cause of disruptions of the heartbeat. Some medications can affect heart rate as well. For some, genetic conditions cause an abnormal heart rate. Regardless of the underlying cause of an abnormal heart rate, a pacemaker may fix it. A pacemaker can often be implanted in the chest with a minor surgery. Client may need to take some precautions in his daily life after pacemaker is installed. Pacemakers consist of two components: an electronic pulse generator and pacemaker electrodes, which are located on leads or wires. The generator contains the circuitry and batteries that generate the rate (measured in beats per minute) and the strength (measured in milliamperes [mA]) of the electrical stimulus delivered to the heart Leads can be threaded through a major vein into the right ventricle (endocardial leads), or they can be lightly sutured onto the outside of the heart and brought through the chest wall during open heart surgery (epicardial wires). The epicardial wires are always temporary and are removed by a gentle tug within a few days after surgery. The complete code consists of five letters, but only the first three are commonly used. The first letter of the code identifies the chamber or chambers being paced—that is, the chamber containing a pacing electrode. The letter characters for this code are A (atrium), V (ventricle), or D (dual, meaning both A and V). The second letter describes the chamber or chambers being sensed by the pacemaker generator. Information from the electrode within the chamber is sent to the generator for interpretation and action by the generator. The possible letter characters are A (atrium), V (ventricle), D (dual), and O (indicating that the sensing function is turned off).