Snipping key nerves may help life-threatening heart rhythms
December 19, 2011
Estimated read time: 5 minutes
What do sweaty palms and abnormal heart rhythms have in common? Both can be initiated by the nervous system during an adrenaline-driven "flight-or-fight" stress reaction, when the body senses danger.
Hyperhidrosis, an abnormal flight-or-fight response of the sympathetic nervous system that causes excessively sweaty palms may also contribute to problems like dangerous irregular rhythms from the lower chambers of the heart, known as ventricular arrhythmias.
UCLA cardiologists have now found that surgery to snip nerves associated with the sympathetic nervous system on both the left and right sides of the chest may be helpful in stopping dangerous, incessant ventricular arrhythmias — known as an "electrical storm" — when other treatment methods have failed. This same type of surgery has been used for years to alleviate hyperhidrosis.
The UCLA team's findings are reported in the Dec. 27–Jan. 3 issue of the Journal of the American College of Cardiology. The study is one of the first to assess the impact of bilateral cardiac sympathetic denervation (BCSD), surgery on both sides of the heart, to control arrhythmias. The research builds on previous work at UCLA in which a similar procedure was performed only on the left side. But for some patients to obtain relief, the researchers said, it must be done bilaterally.
Many people suffer from ventricular arrhythmias, one of the leading causes of death in the U.S. (400,000 deaths per year). These arrhythmias can usually be controlled by using medications, an implantable cardioverter defibrillator that automatically shocks the heart back into normal rhythm, or a procedure called catheter ablation, which involves a targeted burn to the tiny area of the heart causing the irregular heart beat.
"When these treatment options fail, especially for a patient experiencing a life-threatening electrical storm, the situation becomes critical," said the study's senior author, Dr. Kalyanam Shivkumar, director of the UCLA Cardiac Arrhythmia Center and co-director of the Oppenheimer Family Center for Neurobiology of Stress at UCLA. "We are always seeking additional options to help patients."
The UCLA findings add to a growing field of research on the sympathetic nervous system's impact on stress and its possible role in disease. Shivkumar noted that this research may provide a unique opportunity; if snipping the cardiac sympathetic nerve proves to effectively alleviate irregular heart rhythms, perhaps the treatment could be initiated early, before the condition manifests itself.
"In the future, we may be able to correct what is wrong with the heart early, like fixing what's broken in an airplane engine before we need a 'parachute,' like an implantable defibrillator," said Shivkumar, who is also a professor of medicine and radiological sciences at the David Geffen School of Medicine at UCLA.
During the procedure, surgeons cut the stellate ganglia, part of the sympathetic nervous system that delivers information to the body about stress and initiates the flight-or-fight response. These ganglia contain thousands of nerve-cell bodies and run along either side of the spinal cord in long chains. From the ganglia, nerves then travel to the heart.
To help control arrhythmias, surgeons snip the stellate ganglion, as well as the three ganglia directly below it, to completely remove the nerves destined for the heart. The procedure can be done on the left, on the right or on both sides of the thorax — the area of the body between the neck and the abdomen that contains organs such as the heart and lungs
For the study, researchers reviewed records from patients at UCLA and a collaborating center in France. The patients all presented with electrical storms. Their average age was 60, and all were poor candidates for heart transplants. After other treatments — including medications, catheter ablation and implantable defibrillators — had failed, the patients underwent surgery to snip the cardiac sympathetic nerves destined for both sides of the heart.
Researchers found that after the surgery, four of the six patients responded completely, with no more arrhythmias. One patient had a partial response, and one had no response at all.
With their heart rhythms stabilized, three of the responding patients received no more shocks from their defibrillators, which would previously occur when the devices tried to normalize irregular rhythms. One of these patients had been experiencing approximately 11 shocks a day. The patient who partially responded to treatment had a shock reduction of more than 50 percent.
All five responding patients survived until hospital discharge; two died after discharge as a result of health issues not related to arrhythmias. No major operative complications occurred in the patients studied, and typical side-effects related to the procedure, such as alterations in sweating or temperature regulation, were not significant. Researchers noted that such side-effects are usually acceptable to seriously ill patients experiencing an electrical storm, considering that the alternatives include continued arrhythmias, defibrillator shocks or death.
According to the researchers, cutting the cardiac sympathetic nerve may interrupt pro-arrhythmic signaling within the heart tissue or stellate ganglion, thus stopping the irregular heart rhythms.
"We are encouraged by this small study's results and plan to further examine the role of this procedure in suppressing arrhythmias in a larger patient population," said Dr. Olujimi Ajijola, a UCLA cardiology fellow and lead author of the study.
"This type of innovative therapy is only possible because of close scientific and clinical collaborations between multiple teams of specialists caring for very sick patients," said co-author Dr. Aman Mahajan, chief of cardiac anesthesia and vice chairman of the UCLA Department of Anesthesia.
The research by this group in this area was supported by the National Heart, Lung and Blood Institute, part of the National Institutes of Health.
Other authors included Dr. Nicholas Lellouche from Henri Mondor Hospital in Creteil, France; Dr. Tara Bourke and Dr. Roderick Tung from the UCLA Cardiac Arrhythmia Center; and Dr. Samuel Ahn from the UCLA Department of Surgery.