YOUR HEALTH - MEDICINE 101

PACEMAKERS

"I got rhythm, I got music, I got my girl - who could ask for anything more?"

Medically speaking, all of us are born with rhythm - the regular beating of your heart day in and day out. It's amazing really. The thing starts beating about 10 weeks into a pregnancy - it sounds like this " dot, dot dot" You can see its tiny tap-tap tapping on ultrasound even when the would-be baby is only about 2 1/2 inches long.

It's a remarkable and complicated system. There is the basic resting rhythm that your heart needs to pump blood around to all of the cells in your body. The rate goes up when you climb stairs - you need more blood because blood carries the oxygen to the muscles - and the rate goes back down when you rest. Amazingly, we regularly skip a beat or two when we fall in love.

The heart itself has an inherent rhythm - even hearts removed at surgery continue to beat for sometime afterwards. The beat begins in the atrium - the collecting chamber on the left side of the heart - right up here. In this area there are a group of cells that have what is called an inherent pacemaker - a regularly discharging electrical signal. The impulse travels down through the atrium, pushing blood into the waiting ventricle below. Next, the electrical impulse pauses for a fraction of a second and then spreads quickly throughout the ventricle, causing it to contract, pumping blood out into the body. Sixty beats a minute, 86 thousand 400 beats a day, 31 million 536 thousand beats a year for the rest of your life. It's AMAZING!

But sometimes the system fails. The built-in pacemaker doesn't work properly, or the impulse can't travel down the usual pathway to make the ventricle contract because of damage to the heart. The heart rate falls disastrously, sometimes to as low as twenty beats per minute. Patients often have fainting spells, because this low heart rate is not enough to pump adequate blood flow to the brain.

The treatment is an artificial pacemaker. It's a compact battery pack that is usually surgically inserted in the skin just in the front of the chest wall, and connected to a thin wire. The tip sits within the heart . If the heart is beating adequately - let's say at a rate of 68 beats per minute, the pacemaker does nothing. If the heart rate goes below a pre-set rate (it's usually 60) then the pacemaker sends a small electrical charge back down the wire to start a contraction. You can see it on this cardiogram. (X_RAY) And, if your heart beat is abnormal, you can also add a small defibrillator to the pacemaker. It will deliver a charge just like those paddles that you see on TV and set up a normal rhythm,

They really are wonderful instruments, sensing and solving this most dangerous of cardiac problems without you even being aware. You can laugh, dance, you can sing - especially the song - I've got rhythm, I got batteries, who could ask for anything more.