Pacemakers

A pacemaker is a medical device implanted to regulate the beating of the heart. It works by using electrical impulses delivered through electrodes to make the heart muscle contract in a controlled, regular rhythm. A pacemaker becomes necessary either when the heart's own natural pacemaker (the sinoatrial node) is not firing fast enough, or when there is a block somewhere in the heart's electrical conducting pathway that stops its signals reaching the muscle properly. The pacemaker system has two main parts: a pulse generator, a sealed unit containing lithium-halide battery cells for power and an electronic circuit that controls the rate and pulse width of each electrical impulse, and an electrode that carries the impulse to the heart muscle. It uses low-energy electrical pulses to keep the heart beating at a normal rate, and the pulse generator itself is implanted under the skin below the collarbone; when its battery eventually runs down it can be surgically replaced. Modern pacemakers can also monitor factors such as blood temperature and breathing rate and automatically adjust the heart rate to match the body's needs. A pacemaker's battery typically lasts 5 to 15 years, averaging around 6 to 7 years, depending on how actively it is used, and its wires may occasionally need replacement over time. A related condition, sick sinus syndrome, is a dysfunction of the sinoatrial node that is often treated by implanting an artificial pacemaker. In terms of normal heart …