PSVT Ablation - A Sweet Addition to Our Treatment Options
NOVEMBER 28, 2010
Ed Pullen, MD
This article originally appeared online at DrPullen.com, part of the HCPLive network.
For years PSVT (paroxysmal supra-ventricular tachycardia) has been a common and difficult problem for primary care physicians and cardiologists to manage. PSVT ablation is now commonly used with a high success rate in eliminating the problem for patients where recurrent episodes significantly affect their lives.
First let’s be sure you understand PSVT
PSVT is a condition where there is a tiny bundle of heart muscle cells that connect the atria of the heart to the ventricles of the heart in a place they do not belong. In the normal heart there is a separation of the atria from the ventricles by fibrous tissue called the atrioventricular septum. Unlike muscle tissue where when an adjacent muscle cell fires and contracts stimulating adjacent cells to also fire and contract, these fibrous cells are not contractile, and keep the atria heart muscle cells from triggering the ventricular heart muscle cells. The only place where the electrical signal can pass from the atria to the ventricles is the Atrioventricular node (AV node) also called the Bundle of His. This specialized bundle of heart muscle cells has the unique property of more slowly transmitting electrical stimulation of contracting myocardial cells so there is a momentary delay between the contraction of the atria and the contraction of the ventricles. When there is an additional connection of cells between the atria and the ventricles the stimulus to the heart muscles to contract can circle back to the atria. This can cycle over and over again very quickly leading to a very rapid heart rate. This is called supraventricular tachycardia; tachycardia meaning fast heart rate, and supraventricular, meaning “above” the ventricles. Because these episodes happen in sudden episodes, or paroxysms, the name paroxysmal supraventricular tachycardia is used. It is also called PAT for paroxysmal atrial tachycardia, but generally PSVT is more commonly used.
Non-surgical treatment of PSVT
When a patient does have an episode of PSVT techniques to increase the tone of the vagus nerve, and thereby slow the AV node conduction are the usual things patients are taught to do to interrupt episodes of PSVT. Techniques to provide vagal stimulation include carotid massage, the Valsalva maneuver whereby a patient holds their breath and grunts down hard with the diaphragm to increase intra-abdominal tone, and applying a cold washcloth to the face. Sometimes these methods are effective at breaking an episode of PSVT. If these interventions do not work adenosine can be infused intravenously to abort attacks. This is the most common emergency room intervention. Rarely, it is urgent that an attack be stopped, for example when a patient is having angina pectoris (chest pain caused by lack of oxygen and ischemia to the heart muscle) from the extremely rapid heart rate, or if heart failure is occurring from the rapid heart rate, electrical defibrillation can be done in the ER.
In the past the only ways to treat PSVT with medications preventatively have been using medications to slow the heart rate response when PSVT attacks do occur, like using beta blockers, calcium channel blockers, or digoxin. All of these drugs can have side effects, and often are not very effective.
Today with the advances in cardiac catheterization and the use of endocardial mapping by cardiologists specializing in electrophysiology procedures to locate the aberrant fibers, techniques to destroy them have been developed. This is usually done with a technique called radiofrequency ablation. In this technique a high-frequency radio wave energy is applied to the abnormal cells, heating them to a temperature that they are destroyed. This technique is effective in approximately 90% of cases where an aberrant connection is located, and is about as invasive as a routine cardiac catheterization. In some cases where the cyclic rhythm originates within the AV node, treatment is more difficult because of the risk of inducing complete heart block if the AV node is treated with radiofrequency ablation. In these cases alternative methods of ablation are sometimes used. Sports fans may recall that Carlos Silva, a major league pitcher for the Chicago Cubs had endocardial ablation for PSVT in the middle of the 2009 season.
If you are having frequent or prolonged episodes of PSVT that lead to emergency room visits maybe you need to discuss endometrial ablation for your PSVT with a cardiologist who specialized in electro-physiologic mapping and treatments.
Ed Pullen, MD, is a board-certified family physician practicing in Puyallup, WA. He blogs at DrPullen.com – A Medical Bog for the Informed Patient.