Ablation Therapy of Supraventricular Tachycardia in Elderly Persons

Leonard S. Dreifus, MD; Scott J. Pollak, MD

Disclosures

Am J Geriatr Cardiol. 2005;14(1):20-25. 

In This Article

AVNRT and AVRT

The AV node is an integral link in the atrioventricular node-dependent tachycardias. The two most common forms of these mechanisms are AVRT, which also uses a separate AV pathway in addition to the AV node, and AVNRT, which incorporates perinodal tissue as a link to the reentry mechanism.[6,7] The AVNRT tachycardias are described as typical when the posterior input from the crista terminalis functions as the slow (slow-fast) pathway and the anterior or interatrial septum acts as the fast pathway. The atypical form functions in the reverse manner (fast-slow), although rarely there are other combinations of re-entry such as slow-slow. This group of tachycardias is the most common of the paroxysmal atrial mechanisms and is seen most frequently in women. In elderly patients, presyncope and syncope can occur in addition to palpitations, weakness, and shortness of breath. Persistence of these tachycardias may lead to a cardiomyopathy and congestive heart failure. Infrequent episodes are best treated by pharmacologic therapy, utilizing a 1C or III antiarrhythmic agent. A pill in a patient's pocket can often be successful in the management of persons with only infrequent episodes of rapid heart action. Radiofrequency ablation is necessary in tachycardias lasting more than 30 seconds. Clinical judgment and patient preference must be considered in the definitive management program. A new rapid ablation technique utilizing electroanatomical mapping targeting the preferable posterior slow pathway is described. This procedure was devised by one of the authors (Scott J. Pollack, MD) and is utilized in our institution. In these patients the following protocol was utilized:

  1. The His bundle electrograms are marked, particularly the more proximal ones (large atrial electrograms with smaller His electrograms).

  2. The roof and floor of the coronary sinus are then tagged. The coronary sinus OS can be identified by a combination of electrograms, fluoroscopic appearance of the catheter tip, and continuous impedance measurements.

  3. The middle cardiac vein is tagged and located by the fluoroscopic appearance of the catheter tip being wedged, a larger ventricular electrogram, and continuous impedance measurements.

  4. The right anterior oblique (RAO) and left anterior oblique views are utilized for the ablation procedure. In the right lateral view, ablation is then performed at the right angle intersection of the proximal His electrogram and the floor of the coronary sinus OS (Figures 1 and 2). The left anterior oblique view is used to make sure the catheter tip is directed toward the septum. During the ablation radiofrequency application is terminated if the catheter tip moves significantly. In the authors' experience, junctional rhythm and successful modification is achieved by approximately 90% during the first radiofrequency application at the point of the intersection. An example of AVNRT tachycardia is shown in Figure 1. The P waves are hidden within the QRS complex, as this is a slow-fast type of reentry mechanism.

Electrocardiogram showing atrioventricular node re-entry tachycardia.

Demonstration of tagging of the His bundle (HIS), coronary sinus (CS) and middle cardiac vein. Ablation of the tachycardia was performed at the right angle intersection of lines drawn from the His and coronary sinus sites in the right lateral view.

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