The beat goes on and on, often with a pacemaker

By Jonathan Turner, Dispatch/Argus Staff writer

Staff The heart beats more than 100,000 times a day, and sometimes needs a regulator like a small pacemaker to keep it on schedule.

Since the 1950s, the pacemaker has revolutionized treatments of irregular heart rates, according to Moline cardiologist Harry Wallner.

However, the best pacemaker ``is the one you're born with,'' he said in a recent interview.

The heart's natural pacemaker, Dr. Wallner said, is the sinoatrial node in the right atrium. It receives messages from the brain and elsewhere, directing the node to initiate an electrical impulse that adjusts the heart rate to meet the body's needs.

Half of cases requiring pacemakers result when that impulse does not get through from the upper to lower heart chambers, Dr. Wallner said. That cuts the heart rate -- or pulse -- in half, slowing the oxygen supply to other parts of the body, he said.

Another reason doctors may prescribe a pacemaker is when the pulse the sinoatrial node initiates causes a persistent, abnormally slow heart rate. Symptoms of irregular heart rate include excess fatigue, weakness, shortness of breath, dizziness or sudden loss of consciousness, Dr. Wallner said.

A pacemaker -- now smaller than a half-dollar coin -- electronically stimulates or ``paces'' the heart. The device has a pulse generator and one or two pacing leads.

The pulse generator includes sophisticated electronic circuitry that monitors the heart's activity and initiates a current when necessary, Dr. Wallner said.

The leads are very thin, insulated wires that carry the impulses to the heart, he said. The pacemaker circuitry also has a memory function where data on heart activity can be stored and retrieved non-invasively by a computer, Dr. Wallner said.

While most patients require pacemakers for slow heart rates, sometimes a suddenly rapid pulse can trigger the need, he said.

Going from a fast to a normal heart rate can cause the heart to stop beating for 3 to 12 seconds, which then ceases pumping blood to the brain, Dr. Wallner said.

While most patients needing pacemakers are generally elderly, children suffering from ``sick sinus syndrome'' may need pacemakers since the disease doesn't initiate a pulse.

According to Dr. Wallner, there are 240,000 patients implanted with pacemakers in the United States each year.

The heart beats more that 100,000 times a day, sending 1,500 gallons of blood through the body's 12,000 miles of veins and arteries.