When most people think about problems with the heart’s rhythm, they think of a pacemaker, which is a simple device to speed up a slow heartbeat. But there is an entire field called cardiac electrophysiology that specializes in treating a variety of heart rhythm disorders, or arrhythmias.
Science Life recently spoke to Hemal Nayak, MD, a leading expert in cardiac electrophysiology at the University of Chicago Medicine, about the range of treatments his team can offer. We also visited with him in the electrophysiology lab at the Center for Care and Discovery (video above) to see how they work together to get patients back to normal, healthy heart rhythms.
The field of electrophysiology is a lot more than just pacemakers. What are some of the other major treatments?
Our most common procedure is catheter ablation. During catheter ablation, thin electrodes are threaded up the large veins in the leg and positioned in the heart. Through these electrodes, we are able to stimulate the heart and bring on or induce abnormal heart rhythms. Once we find the abnormal electrical tissue responsible for these arrhythmias, we deliver radiofrequency energy or heat to destroy these electrical cells. In many cases, catheter ablation is a curative procedure.
Atrial fibrillation or A-fib is a common arrhythmia. It is the most common arrhythmia leading to hospitalization in the United States and it’s a leading cause of stroke. We see A-fib more commonly in patients with high blood pressure, diabetes, sleep apnea and heart failure. It is also a disease of aging, so we encounter it in older folks. A-fib causes a lot of symptoms like palpitations, shortness of breath and fatigue. It can also lead to heart failure and stroke. We use catheter ablation to treat atrial fibrillation.
At the University of Chicago we’ve been performing catheter ablation for over 25 years, and most recently we have acquired new technology that makes the procedure more successful, and importantly, a lot safer for patients.
What are some of the ways UChicago Medicine is advancing the field of heart rhythm management?
Here at the University of Chicago, we have been researching and applying the latest techniques for A-fib treatment. We’re using special catheters that allow us to know how much force we’re applying onto the tissue, and that’s been shown to improve the success rate for the procedure. We are one of only a handful of centers in the US which use a new mapping system called Rhythmia. It allows us to create a detailed 3-D reconstruction of the heart allowing us to customize the procedure for each patient.
I mentioned that we use radiofrequency energy or heat in most of our catheter ablation procedures. We have begun to use cryo-energy or freezing. Cryoablation gives great results in patients with paroxysmal A-fib or A-fib that comes and goes.
One of the newest things I’m excited about for A-fib management involves what we offer to patients who have been in atrial fibrillation for a long period of time. We have patients who come to us who have been in A-fib for eight or nine years. Traditionally, these patients don’t do well with the standard techniques of ablation. In fact, catheter ablation only works about 40-50 percent of the time.
So I’ve been partnering with my surgical colleague, Dr. Husam Balkhy, who is a robotic heart surgeon with a particular interest in atrial fibrillation and arrhythmia. We have devised an ablation protocol to treat persistent A-fib. We offer a collaborative approach whereby he performs an ablation procedure on the outer surface (epicardium) of the left upper chamber using a minimally invasive approach. Part of his procedure also involves removing something called the left atrial appendage, which is a small pouch where most clots form. By removing this pouch, one could potentially reduce risk of stroke.
After 6-12 weeks, I perform a catheter ablation to complete the treatment. So by burning on both the inside and outside surface of the left upper chamber, we’re hoping that we’ll be able to get these patients who have persistent or chronic forms of atrial fibrillation into normal rhythm. That’s the newest thing we’re doing, and we’re very optimistic about it.
How has prognosis changed for patients as this technology develops?
There are obviously patients who have A-fib who experience symptoms like fatigue, inability to exercise, weakness, or shortness of breath. Some patients with A-fib develop congestive heart failure or heart attacks. These patients need aggressive therapy.
There are patients who don’t even know they have A-fib. We get a number of consultations on patients who present with an abnormal EKG recording A-fib, but without symptoms. In this situation, it is not clear what should be done. Certainly if one is elderly and asymptomatic, an important thing I can do as a heart rhythm specialist is to make sure the heart rate is under good control, in that it’s not too fast or too slow. A number of these patients may need a pacemaker or medication. The most important intervention I make for these patients is to recommend and prescribe blood thinners to reduce stroke risk.
But if a patient is relatively young and in A-fib, research has shown us that patients with A-fib, even those without symptoms, have a shorter lifespan than patients without A-fib. If we are able to get these patients into normal rhythm, and keep them there, we hope that translates into an improvement in survival and long-term quality of life.
What are some of the different devices you can use to treat arrhythmia?
Aside from the pacemaker that you mentioned, which is a very simple device used to treat patients with slow heartbeats, we have devices for patients who have suffered an out-of-hospital cardiac arrest or who are at high risk for one. We implant something called a defibrillator. We implant traditional defibrillators, where we place a lead or leads inside the heart. The lead and defibrillator unit function in tandem to shock the heart in the event of a cardiac arrest. UChicago Medicine, has been a leader in something called the subcutaneous defibrillator. The advantage of the subcutaneous defibrillator relates to the fact the entire system (lead and unit) is implanted under the skin. There is nothing inside the heart. This is the newest type of defibrillator available and is especially useful for younger patients, patients with kidney failure who have limited vascular access and patients who are at a higher risk of infection.
Is that the same concept as the portable devices EMS uses?
Well in a way. Most of us have seen medical shows on television where someone yells out, “Give me the paddles!” Those paddles are attached to an external defibrillator. But nothing works faster than an implantable defibrillator.
Imagine if you suffered a cardiac arrest in the city of Chicago. You have to hope that someone realizes that you’ve collapsed. You have to hope that somebody knows CPR. You have to hope that somebody calls 911. You have to hope that the rescue squad gets to you in time. You have to hope they can get your heart re-started. You have to hope that all of this gets done quickly so that you don’t suffer any brain damage. So even though it’s a good idea to have these automatic external defibrillators in supermarket parking lots or sports arenas, unfortunately they don’t work very quickly. So an implantable defibrillator is far better in reducing the risk of sudden cardiac arrest.
How does it work?
The implantable defibrillator or ICD for short, monitors every heartbeat. If the heart were to go into cardiac arrest, it recognizes it and either delivers rapid pacing or an electrical jolt to stop or terminate the dangerous arrhythmia.
Can these devices stay in forever, or do they require maintenance?
Most units last 7-12 years after which they require replacement with a simple procedure. ICDs need to be checked every 3-6 months and this can be done using remote monitors from home.
Over 95 percent of devices that are currently implanted have some kind of lead, or wire, attached to them. Unfortunately leads can fail, and we have seen a number of leads fracture, or develop breaks in the insulation. Lead failure is serious problem.
At UChicago, we’re experts in lead management. We’re a referral center in the Midwest for this condition because we are one a few centers that perform lead extraction or lead removal. As you can imagine, when leads are placed inside the body, over many years, the body forms scar tissue around them to hold them in place. They’re not easy to remove. We have special techniques, one of which utilizes a laser to remove leads safely. In our hands it’s a very safe procedure.
In the past if someone had a problem with leads, did they just leave them in?
The easiest thing for doctors to do, and this still happens today, is to leave the lead in place and just add more leads. For some patients that may be a reasonable option, but for most it’s not, because you’re adding more hardware to hardware. Over time the vessels can clog up, and we have seen a number of patients who come in with facial swelling and clots in their hearts because of an excessive number of leads. Less than thirty years ago, if we wanted to remove leads, the only choice was open-heart surgery. With the advent of these lead extraction technologies we can remove leads using a significantly less invasive approach.
What other new developments are you excited about?
We know patients with A-fib have higher stroke risk, but what if they can’t receive or tolerate blood thinners because of excessive bleeding? What do you do for those patients? We’re excited that in the near future, UChicago is going to be able to offer something called the Watchman Device, which is an occluder of the left atrial appendage. It is shaped like a shield, and it occludes or covers up the pouch called the appendage, and prevent clots that form within it from entering into the left upper chamber of the heart. It’s been shown in studies to reduce risk of stroke. We also offer therapies to exclude the appendage. We perform a procedure where we place a loop around the left atrial pouch to exclude it from the left atrium.
We also participate in a lot of clinical trials and studies. One of the trials that I’m participating in involves the leadless pacemaker. A traditional pacemaker has a wire or a lead attached to the heart. A leadless pacemaker, which is about the size of a AAA battery does not require a lead. We actually screw in the entire unit into an area in the right lower chamber of the heart. That’s new and exciting, and we’re part of a multi-center national studying whether this new miniaturized device is safe and effective. In fact, we are one of only 2 centers in Illinois that’s participating.