The human heart is an electro-mechanical pump with a lifetime warranty. Built to operate every minute of every day, it actually gets stronger with hard work.
Among the heart’s most amazing features is its pacemaker, known as the sinus node. A small mass of specialized cells, the sinus node generates electrical impulses that spread throughout the four chambers of the heart, causing them to contract in a coordinated way. The result is a steady delivery of blood to all parts of the body.
Occasionally, this pacemaker can malfunction, causing a beat that’s too slow, too fast or too irregular to keep blood pumping efficiently. In the past, such a malfunction in the pacing of the heart created a constant risk of a heart attack or sudden death. Since the 1960s, however, doctors have had a relatively simple non-invasive solution–implantation of an artificial pacemaker.
A pacemaker consists of a thin metal case containing a pulse generator plus flexible insulated wires, with electrodes at the tip, that are placed at strategic spots within the heart. The pulse generator has a battery-powered computer programmed to produce electrical impulses that set or correct the heart’s rhythm and pace.
You’re probably most concerned when your heart starts to race, but an abnormally slow pace is generally more worrisome and more likely to require help from a pacemaker because it generally means that organs such as the brain, kidneys and liver do not get the oxygen and nutrients they need. The result may be chronic tiredness and occasional fainting.
A slowed heart rate, known as bradycardia, can result from a heart attack, diseases affecting the sinus node, aging or certain medications. “Heart block” refers to a delay or interruption in the signals sent by the sinus node because of a problem in the conductive pathways. A block can be either partial or complete; the latter can have severe consequences.
Another common reason for needing an artificial pacemaker is atrial fibrillation, an arrhythmia in which the two upper chambers of the heart occasionally quiver or flutter rather than contract in a regular rhythm.
About 2.2 million Americans, including three to five percent of persons age 60 and over, suffer from atrial fibrillation. At times, the heart beat may become abnormally rapid, but since blood is not completely pumped out of the upper chambers, it tends to pool and clot, creating a high risk of a heart attack or stroke.
Symptoms of atrial fibrillation include palpitations, a flopping feeling in the chest, lightheadedness, confusion, shortness of breath and chest pain. Many individuals, however, have no symptoms.
Implantation of a pacemaker is performed by a specialist in a hospital or specialized heart facility, usually under local anesthesia. Wires are inserted through a vein near the shoulder and threaded to the correct location in the heart. The pulse generator is then implanted into the chest, under skin and fat but on top of muscle tissue. An overnight stay is usually required to make sure the pacemaker is working properly, but recovery is relatively rapid.
Pacemakers today are powered by lithium batteries that last 5 to 15 years, depending on how often the pacemaker has to work. Replacement requires implanting a new pulse generator, but existing leads are usually kept in place indefinitely.
A doctor can monitor and set a pacemaker without using needles or removing it from the body. And some functions can be checked remotely through an internet or phone connection.
Most persons with pacemakers can resume a normal life, including strenuous exercise. Electrical and magnetic devices that could interfere with proper functioning of a pacemaker include microwaves, cell phones, iPods, industrial welders, metal detectors, high-tension wires and electrical generators.
Cell phones do not cause interference when held in a normal position, but it’s a good idea to use the ear on the opposite side of the body from the pacemaker and to avoid placing the phone in a pocket directly over the pacemaker.
When encountering electromagnetic security systems at airports and courthouses, doctors advise moving through the system at a normal pace. Avoid sitting or standing next to one.
Having a pacemaker is not quite the same as being a bionic man or woman. But it does give you the electronic power to bypass or override any malfunctions in the electromechanical pump known as your heart.
