Introduction to Pediatric Electrophysiology: Interview with Beth Bubolz, MD

Dr. Bubolz is located at Children's Mercy Hospital in Kansas City, Missouri. Please describe your medical background. What made you choose pediatric electrophysiology? I graduated from medical school at the University of Texas in Houston, and from there I trained in pediatrics at Baylor College of Medicine in Houston. After that, I went to the Medical University of South Carolina for my pediatric cardiology and electrophysiology training. I trained under Drs. Paul Gillette and Chris Case there. I have been here at Children s Mercy for about two years. I decided on pediatric electrophysiology because I found cardiology fascinating. I liked the techniques for imaging the heart. Actually, the strange thing was that I knew they had electrophysiology for adults since I had been on that rotation as a medical student, but I had no idea that they could do the same thing for kids. Although I really liked treating arrhythmias in adults, I didn t want to do adult medicine. When I figured out that this subspecialty was available in pediatrics, it was kind of a no-brainer for me. What are some of the most common pediatric EP conditions you treat? What age range do you treat? The most common condition would be supraventricular tachycardia. The youngest patients we treat would be babies before they re born, so we treat fetal tachycardias. We also treat rhythm problems in patients who have congenital heart disease who are now well into adulthood. Patients with structural heart disease tend to have pretty complicated rhythm problems. They do not tolerate abnormal rhythms as well as people with normal hearts. The combination of abnormal anatomy and abnormal rhythms make these patients unique. In fact, I have one patient who is about 28 years old who was born with a single ventricle. We have treated this patient s rhythm problems using catheter ablation, medication and also pacemaker implantation. We frequently can terminate her tachycardia by programming her pacemaker. Therefore, we use a multi-faceted approach. We take care of these patients indefinitely. How many of your patients receive pharmacological therapy versus ablation or implants? I would say that in my practice, the large majority, although not all, would have medication treatment first. That is because of: 1) the patient s size; 2) because many times the babies might outgrow their tachycardia so we treat them first with medications; or 3) a lot of the time I will use medication as a bridge to radiofrequency (RF) ablation. RF ablation is an elective procedure in almost all cases. Using medication first gives the parents time to think about it, ask questions, and make a reasonable decision. It gives us an idea of how the child will do on medication, before we go into the lab. Does your hospital utilize cryoablation as well? We have not used cryoablation here, although we have looked into it. What sorts of complications do you run into during pediatric EP cases (versus doing the same types of procedures for adult cases)? The complication rate in RF ablation in kids is quite low; if you added up all the complications, probably what we would see most frequently is bruising in the groin. If you also add in complications that are more serious but are much less frequent, such as perforation of the heart and complete heart block you still have less than 1%. Adults will more frequently have problems with strokes, post-ablation; this is almost unheard of in kids when you use good technique. Adults probably have a higher risk of myocardial infarction than kids, and definitely have a higher risk of atrial fibrillation than kids. However, for adults and kids, the overall complication rate is really quite low. How does the age of patients factor into how cases are handled? What advice would you recommend to someone in the medical field who is working with children? I would say that if you look at the range of EP treatments, it covers a huge area. If you look at RF ablation, success rates are probably the same in patients who are 7-8 years old as they are with older and bigger kids. Complication rates are probably the same in that age group as in older patients. With babies, there are several factors: 1) you have to keep in mind the possibility that their arrhythmia may be outgrown or they may not have it for the rest of their life. So the natural history of, for example, supraventricular tachycardia, is that one-third of the babies that have it may outgrow it in the first year of life and will never have another problem. If the condition is not life-threatening and it is completely controlled by medication, it is not really feasible to go to the cath lab to do RF ablation. With babies who don t outgrow their tachycardia, one-third may have a honeymoon period in which they don t have any problems until pre-adolescence (about age 8). Therefore, it makes good sense to get these patients through their first year of life and then often they can discontinue and stay off the medications and not have a recurrence until much later. The last group of infants with SVT may continue to have problems in infancy, throughout the first year of life, and beyond. For this group, it depends on how well the medication controls them, how fast they are growing, and when it would be advisable to pursue catheter ablation. With device therapy and pacemakers in particular, we can put pacemakers in small, tiny babies. For example, 2 kg babies can have pacemakers. These are not implanted in the EP lab like adults and older kids, but in the operating room. They are attached surgically to the surface of the heart. The third major procedure we do is implantation of defibrillator devices. In pediatrics we consider the disease state, the current symptoms and natural history of the disease. These are balanced with the patient s size and age in order to time implantation for the child. The devices are really quite small and the decision to implant is rarely based on size alone. What technology is offered to pediatric EP patients at Children s Mercy? What we have started utilizing is home telemetry, which is very new and exciting technology for us. In the past few months we have started using it in patients who have rhythm problems that need to be diagnosed or in patients who who we would like to monitor, but who may not meet criteria for implantation of a defibrillator device. Home telemetry is a commercially available service in which a central monitoring station will monitor a patient s EKG. We have employed this in several babies while they sleep. When they are awake, a parent would recognize symptoms, but at night children may be at risk for arrhythmia which would be undetected. A parent will hook up the child to an EKG monitor when they go to bed; this is connected to a transmitter in the home that uses the phone line and transmits data to a central monitoring station that's actually located out of state. At the central monitoring station, there is someone watching the telemetry monitors at all times, and if this child were to have an arrhythmia, they would notify 911 in that patient s area immediately as well as calling the parents so they could initiate treatment. This is to protect the child from having an undetected event while sleeping. This is actually a new application of old technology that has been available in hospitals for decades. We have used the same home telemetry monitoring for teenagers. There is one that is based on cell phone technology, where they can carry around a little transmitter. If they have symptoms, it will transmit their rhythm while they are having symptoms you don t have to worry about them activating some sort of monitor or catching an event during a 24-hour period they simply wear it all the time and the information is transmitted to a central telemetry monitoring unit. We have been using this either to diagnose rhythms or to monitor patients who have long QT or uncontrolled SVT at home. What new trial research information in this field do you find promising? What clinical trials in pediatric EP are upcoming? We are not involved in any multicenter trials at this time. The problem with pediatrics is that there is not the same amount of trials like there are in adult clinical trials. The Pediatric EP Society has made efforts to try and collaborate amongst centers and such. The most recent information that we follow and watch are things about long QT. There is not necessarily multicenter trials, but efforts have been ongoing as far as genetic testing for long QT. One of the outcomes in the last six months is that testing has become available commercially for prolonged QT. Researchers had studied one family who had a strong history of prolonged QT and cardiac death, and they had actually identified the gene in one member of the family. That was a huge step. The only problem is that it is only 75% effective there is still a 25% chance that that patient might have long QT. However, I think this will help the testing to come down in price and be covered by insurance companies, and to be a big help to us clinically in the future. if you are interested in looking at the website, the company is called Family Ion: https://familion.com/. It has been very helpful to know it s genetic and to have such a good family tree. It is something that we are starting to use to help us learn more about these patients and I look forward to when it will give us lab support to answer critical questions more specifically. How do you see treatments for pediatric EP patients changing in the future? I think that just like in adult medicine, we are learning more about heart failure. Heart failure mechanisms and causes and underlying conditions are very different from the pediatric side, because you are drawing from the adult literature. The devices are small enough now, so we have about three or four patients who are using biventricular pacing, but I think that a lot of our information still comes down from the adult literature. From this literature, we then use it on teenagers first, and it works its way on down as needed. However, a lot of it is taking out treatment options like biventricular pacing and finding out which pediatric patients it works best on as well as its different applications for these patients. Is there anything else you d like to add? I think although it might not be as exciting as a new procedure in a cath lab might be, home telemetry may have long-term implications for kids. That is the new thing that we have been trying out here at Children s Mercy a new application of an old technology. For more information about Children s Mercy Hospital, please visit: www.childrens-mercy.org