UAB Cardiologists Seek and Destroy Arrhythmias
By Tara Hulen
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UAB specialists are focused on correcting heart arrhythmias as well as on preventing the most dangerous heart rhythm issues. |
When the heart skips a beat, it may not be love. A little too much coffee, a just-missed fender bender, or a strange sound in the middle of the night can all cause a heart to flutter, race, and pound. But when those sensations are frequent, last more than a few seconds, or cause dizziness, fatigue, or fainting, it’s time to see an expert to find out why.
Cardiac arrhythmias—the term for abnormal heart rhythms—affect more than 14 million Americans, says Tom McElderry, M.D., a cardiologist in the electrophysiology program at the UAB Heart and Vascular Center.
Arrhythmias, in simple terms, are caused by faulty wiring. They occur when the electrical pathways that make each part of the heart beat in sequence develop short circuits or other irregularities, which can make the heart inefficient and reduce the amount of blood it pumps through the rest of the body.
The consequences are often relatively benign. “For most people who have not had heart attacks in the past and don’t have cardiomyopathy or a weak heart, palpitations are typically only a nuisance,” McElderry says. People with mild or infrequent symptoms might simply need to avoid caffeine, certain cold medicines, and similar triggers. Or they may benefit from starting medications such as beta blockers or calcium channel blockers.
But some heart rhythms—including atrial fibrillation and ventricular tachycardia—can signal a greatly increased risk of stroke, heart failure, and death, McElderry says. At the Heart and Vascular Center, electrophysiologists specialize in finding and fixing the source of the trouble. Meanwhile, in UAB’s Cardiac Rhythm Management Laboratory (CRML), researchers are searching for better ways to treat and prevent the most dangerous heart rhythm issues—and to increase our understanding of what causes the problems in the first place.
See how UAB electrophysiologists repaired one patient's heart in this video. Story continues below video
Looking for Trouble
Finding the source of abnormal heart rhythms usually starts with standard tests such as an electrocardiogram and various rhythm monitoring devices. Because arrhythmias can be sporadic, patients are sometimes given a small monitor to take home that they can activate whenever they feel an episode start. For highly symptomatic or frequent arrhythmias, UAB’s electrophysiologists perform a test that maps the heart’s electrical impulses to find the location and type of issue triggering the problems, McElderry says.
The test, known as an electrophysiology study (EPS), begins with thin catheters inserted into a blood vessel in the patient’s leg and/or neck. Using fluoroscopic imaging, electrophysiologists guide the catheter into the heart chamber, where they record electrical activity and pinpoint the problem.
Treatments include blood thinners to help negate the risk for stroke, along with other medications. But now electrophysiologists also have a weapon in their arsenal to provide a cure for atrial fibrillation and other dangerous arrhythmias: radiofrequency ablation. High-frequency energy is applied directly to the abnormal electrical pathways, cauterizing them and restoring normal heart rhythms.
Survival Strategies
UAB has been a leader in the use of ablation to prevent atrial fibrillation, says Raymond Ideker, M.D., Ph.D., director of the CRML. Now Ideker is conducting research on the best methods to treat an even more dangerous type of arrhythmia: sudden cardiac arrest.
One out of five Americans dies from the condition, Ideker says. Some patients have clear warning signs, he notes, but this only accounts for “a very small amount of the people who have sudden cardiac arrest.”
When cardiac arrest does occur, there is very little time to respond. “For roughly every minute you’re in fibrillation, your odds of survival go down by 10 percent,” Ideker says. “If it’s been more than 10 minutes, the odds of getting somebody back are not good.”
In Alabama, survival rates are “horrible,” Ideker says. UAB researchers are seeking to improve those numbers as part of a consortium of 10 universities from different regions across the United States. “Of those 10 areas of the country, Alabama’s survival rate was the lowest,” Ideker notes. That is in part because emergency medical response times are often quicker in other parts of the country, he says. Seattle, for example, has ambulances on the road constantly, and states with better survival rates also have portable defibrillators commonly placed in public buildings, with more of the general public trained in how to use them.
Of the several known causes of cardiac arrest, the CRML is currently focusing on ventricular fibrillation, which is generally preceded by ventricular tachycardia—both of which involve errant electrical signals. “Instead of a coordinated electrical signal going through the heart, it’s a highly disorganized signal, where the heart doesn’t contract in any kind of synchronous form,” Ideker says. “If you don’t do something, then you’re going to die within a matter of minutes.”
Why So Sudden?
The mystery of what ultimately causes arrhythmias and heart failure is the research focus of CRML’s Steven Pogwizd, M.D., an expert in electrophysiology and cellular mechanisms of arrhythmias. “Our interest is in understanding why people with heart failure drop dead,” Pogwizd says.
“In heart failure, cell-to-cell communication is altered,” he notes.
“We are trying to understand these alterations and then identify key targets to provide the foundation for the next generation of anti-arrhythmic drugs.”
One great frustration of researchers and clinicians is that for most conditions, current treatments have limitations, Pogwizd says. For example, implantable defibrillators can shock the heart out of ventricular fibrillation, “but they don’t prevent the arrhythmia from occurring,” he says—and not all patients are candidates for the devices.
“There is a long way to go for us to use pharmacological approaches to prevent sudden death,” he says. “So developing effective pharmacological or medical therapy for patients with heart failure is really an important goal.”
The Value of Experience
UAB electrophysiologists credit the program’s focus on research with its success in bringing the most up-to-date treatments to arrhythmia patients. The UAB Heart and Vascular Center performs 1,000 to 1,200 procedures each year in its four state-of-the-art labs. With that volume comes the experience that leads to successful outcomes for patients, McElderry says. “It is very important that if you have one of these irregular heartbeats that you see your doctor,” he adds. “You may require blood thinners to help negate your risk of stroke, and there are other medicines and the ablation procedure we can do to treat the condition.”
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