Heart Disease – Pacemaker

Transcript

“If you look at any one of us, none of us are plugged into the wall, but yet we have electricity in our body. Moving your fingers, speaking, your heart beating, is all electrical, and electrical signals are not by wires but by electrolytes, by sodium, potassium, calcium, magnesium currents in our body. Our heart cells particularly have great automaticity and the ability to fire spontaneously. If you ever were a child and you experimented, you could take heart cells out of certain, you know, animals that you dissected that were live cells and put it in saline. And you could see those cells contract. That’s the automaticity of the heart cells. And our hearts have very particular, very organized structures that help in the conduction of the electricity from one chamber to the other, such that there’s very precise and organized contraction. So when the sinus node in the atrium fires, that electricity goes through a very organized tissue in a very precise manner through the atrial ventricular node and then into the ventricle, and then both ventricles simultaneously contract.

And this is organized pumping activity of the heart, and it does this for our entire life. But for some of us, either because of medications or because of other complications, heart attack, or aging, the conduction system ages such that the heart’s not able to beat on its own. So for these patients, we offer them a pacemaker and we don’t wait for their heart to stop when their heart slows down or when they show a symptoms of dizziness and find this activity on testing, or when they pass out, we start thinking about treating this low heart rate before it turns into a complete, you know, a systole or lack of contraction or death. Now, there are rare people that present with such, and then we’re still able to revive them and then put in a pacemaker. But for majority of people, we find them with conduction system relatively early.

And when we know that they have enough conduction system disease, then we offer them a pacemaker. What’s a pacemaker? It’s basically a little battery generator that sits in your chest wall, underneath the skin with wires, one or two, depending on your situation, that basically sits there and watches, and basically looks, is the heart having a beat? Or the number of beats per minute? What they expect? If the beats per minute is above the threshold for the pacemaker, there’s no pacing. So if your heart rate is 70 and the pacemaker’s set for 60, there’s going to be no pacing. Because our pacemaker sees a beat coming, at least at an interval of every 60, and it’s not going to fire. But when that falls below 60, even at 59, the pacer might start to fire. And that’s what a pacemaker is supposed to do. A lot of patients go, well, how come my father has this arrhythmia and his pacemaker? How come the pacemaker doesn’t treat that arrhythmia? Pacemaker only treats arrhythmias that are related to slow heartbeat or no heartbeat. So a pacemaker replaces your heart’s pacing by providing pacing so that your heart can continue to beat. A pacemaker does not treat arrhythmias typically. So if you have a fast heart rate at 180, the pacemaker is going to do nothing because it’s already seeing electricity that’s coming greater than 60 beats per minute or whatever it’s set at.”