Biventricular Pacemaker: What is Cardiac Resynchronization Therapy?
Guest: Dr. Michael Gold - Cardiology
Host: Dr. Bill Spencer – Cardiology
Dr. Bill Spencer: I am Dr. Bill Spencer and with me is Dr. Michael Gold who is professor of Medicine and chief of the division of Cardiology at the Medical University of South Carolina. Michael is going to talk to us today about a pacemaker which treats heart failure, which is recent innovation. Michael, welcome.
Dr. Michael Gold: Thank you.
Dr. Bill Spencer: I hope you can tell us a little about the evolution of pacemakers and heart failure. I have had patients ask me, doctor, you are going to put a pacemaker in me? Will it make my heart stronger?
Dr. Michael Gold: That is a very good question. Traditionally we have used pacemakers to treat slow heart rhythms. They simply keep the heart from stopping or going too slowly. They do not help the symptoms of shortness of breath or heart failure. However, we have discovered that certain groups of patients with very damaged hearts, we can put special pacemakers in where we pace both sides of the heart simultaneously. That is called biventricular pacing, or CRT, and that can help heart failure very dramatically sometimes.
Dr. Bill Spencer: What is CRT?
Dr. Michael Gold: CRT stands for cardiac resynchronization therapy, a fancy word for pacing both sides of the heart so we can get the heart to beat in a more coordinated fashion.
Dr. Bill Spencer: What is the problem related to a less coordinated fashion? What is the problem with the heart to begin with?
Dr. Michael Gold: Well, it is always someone who has had a damaged heart, typically either from a heart attack, a viral infection or high blood pressure that was not well controlled. Not only do these patients have a damaged heart, they often have an abnormality on their EKG, that one of the wires that conducts the heartbeat from the top to the bottom has been broken so that the heart is not being electrically activated. One side gets activated before the other.
Dr. Bill Spencer: It sounds like it is sort of like a motor that is out of tune.
Dr. Michael Gold: I think that is probably a good analogy. Not only is the motor not working well, it is also the left side rather than the right side. The spark may be may going sooner there so that you get a discoordinated contraction of the heart.
Dr. Bill Spencer: So, you are becoming more like mechanic who fine tunes the heart then.
Dr. Michael Gold: With electrical therapy though.
Dr. Bill Spencer: Tell us about the evolution of this therapy.
Dr. Michael Gold: Well, this is a rather recent therapy that was only developed around 1992, or 1993, so it has been recent that we have had this. Fortunately, I happened to be in Baltimore at the time when this was first developed there and we were involved in some of the earlier studies. Now, at MUSC, we have been involved with the newer development and the newer techniques for these studies.
Dr. Bill Spencer: Well, I imagine the field has advanced very rapidly.
Dr. Michael Gold: Yes, it is very exciting. It used to be, back in the early 90s, you would have to have cardiac surgery and have your chest opened up to be able to put these wires on the two sides of the heart. Now we can do it directly through a vein. Sometimes these procedures only take about 45 minutes to be able to put in these special pacemakers.
Dr. Bill Spencer: How complicated is it to identify a person who would need one of these?
Dr. Michael Gold: It turns out that it is relatively easy. We normally have an ultrasound or echo test on the heart to know how damaged the heart is. Then, we just talk to the patient to know how limited they are by shortness of breath or fatigue. The last thing we need is an EKG. With those three simple factors, we can identify patients who may benefit from a biventricular pacemaker or CRT device.
Dr. Bill Spencer: How beneficial is it?
Dr. Michael Gold: It can cause some very dramatic benefits. We have seen many patients who were so sick that they were going to have a cardiac transplantation. We not only can prevent their transplantation but they can be back to work after one of these devices.
Dr. Bill Spencer: You are telling me that you are putting extra wires in the heart. Does this present a challenge?
Dr. Michael Gold: They are not the easiest of procedures. It is more difficult than a standard pacemaker. Fortunately, we do a lot of them, so after having done thousands of these procedures, you get better at them. So, about 98 to 99 percent of the time we get these wires where we want them to be and they work very well.
Dr. Bill Spencer: How complicated is the follow-up?
Dr. Michael Gold: Follow-up has become quite simple. Patients only need to see the doctor, typically, about twice a year following one of these implantations. We can do many of the checks over the telephone which makes it very simple for the patient.
Dr. Bill Spencer: Do you have to make a lot of adjustments in the device?
Dr. Michael Gold: We typically can set them up at the time we are actually implanting them, so before the patient even leaves our electrophysiology lab, the room where it is being implanted, we do not have to adjust any further. Twice a year we do check them out to make sure if there has been any changes in any of the amount of voltages or other things that we have to do in the device.
Dr. Bill Spencer: And you say that many people who have this, have heart failure. You know that people who have heart failure are taking many medicines. Does this device take the place of the medicines?
Dr. Michael Gold: No. I think that is a very important point. The medicines are doing, frequently, very different things, protecting the heart and preventing cardiac arrest and helping the heart to get better. So, this device makes it easier for them to take the medicines because the blood pressure will get high or the heart rate may get higher. So, they will tolerate the medicines better. We usually do not stop these medicines because these medicines, independently, are good for the heart.
Dr. Bill Spencer: So, they actually make the medicines work better and that makes the pacemaker work better?
Dr. Michael Gold: Right.
Dr. Bill Spencer: I have to ask you then, at the end, 10 years or 12 years ago, would you have predicted that pacing the heart would improve its function at all?
Dr. Michael Gold: No, not at all. It is quite interesting that, in fact, standard pacemakers, if anything, make the heart function worse. We now try to avoid pacemakers in patients who have heart disease, unless their heart rate is very slow, because it may make it worse. But, these CRT devices actually make them better. We now have combinations of these special pacemakers with defibrillators. So, if patients’ heart beats get too fast, they can get a shock from the defibrillator to prevent cardiac arrest while the pacemaker can make the heart failure better.
Dr. Bill Spencer: Well, I have to say, it has been a pleasant surprise for all of us that it worked as well as it did. Do you agree?
Dr. Michael Gold: Absolutely.
Dr. Bill Spencer: Thank you very much.
Dr. Michael Gold. You are welcome.
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