What's causing a heart to beat slowly?

Michael was 29 and fit. A government office worker, he played football for hours every week in Fairmount Park with his friends.

Normally, he could make the climb to his second-floor apartment without a problem. But suddenly, he found himself short of breath, gasping for air at the slightest exertion.

He tried to power through for three days until his wife persuaded him to go to the emergency room.

When they first examined Michael, the doctors were puzzled. He looked well. He had no fever or cough. When they listened to his heart and lungs, they heard only the usual healthy sounds and none of the worrisome swooshes and crackles that indicate something is wrong.

While completing a thorough physical exam, they found an alarming problem. His heart was beating only 30 times per minute. Unusually slow, even for an athlete.

The doctors ordered an electrocardiogram (EKG) to track the electrical impulses of Michael's heart. In a normal heart, the spark plug at the top of the heart - the sinoatrial node - fires about 60 to 70 beats a minute. (For a marathon runner at rest, normal may be only in the high 40s.)

In a healthy heart, the electrical current travels through a kind of doorway on its journey to the lower part of the heart - the big pumping chamber called the ventricle, which sends the blood coursing through the body.

Michael's EKG showed that for some reason, the doorway - called the AV node - was blocked. The electrical impulse was being sent but could not get through.

How was Michael still alive?

The ventricle has a backup generator.

When the big pumping chamber fails to receive a signal from above, a secondary spark plug in the AV node kicks in. At 30 beats a minute, it was giving Michael just enough blood to survive.

The challenge now was to figure out what was blocking that electrical doorway.

Three weeks earlier, Michael told his doctors, he had come down with a fever of 102 that lasted three days. About the same time, he noticed a rash in his groin. He assumed it was a fungal rash from all the football he'd been playing. When he was a college athlete, he would sometimes get rashes just like it - red, circular patches. He put antifungal cream on the hot spots, but the rash spread to his abdomen, back, and thighs. After 10 days, it disappeared.

What was going on?

Michael's doctors immediately gave him high doses of antibiotics and steroids.

Why?

He had Lyme disease.

Although Michael had never found a tick on his body, his symptoms were classic. A summer flu-like illness followed by a 10-day rash, called erythema migrans. Lyme (not Lyme's as many people mistakenly call it) is transmitted by ticks, tiny spiderlike creatures that carry the bacteria in their saliva and inject it into humans when they bite.

In its initial stage, the infection causes a fever and rash in about 80 percent of patients.

Later, they may also suffer symptoms from a long, miserable menu of possibilities. Pains that migrate from joint to joint. Neurological problems like partial paralysis of the face (Bell's palsy). Muscle weakness from inflamed nerves. Eye inflammation. Hepatitis. And like Michael, conduction abnormalities in the heart.

Michael never found a tick on himself. His doctors, however, had enough clues to be almost certain that he had Lyme. So rather than wait until they received the results of the Lyme test, they started treating Michael right away on high doses of antibiotics to kill the bacteria.

After three days in the ICU, Michael began to show signs of improvement and he was moved to a cardiac ward where he was monitored carefully but could walk around the corridors, take showers, and visit with family.

Although Michael was feeling much better, his heart rate was still only about 50 beats per minute. His doctors, frustrated by his slow progress, put him on steroids, (not to buff him up, but to decrease inflammation in the heart's AV node.) Within 24 hours, his heart had resumed a normal sinus rhythm.

As his doctors were signing his release papers, they received the result of his Lyme test.

It was positive.