Accessory Pathway with Decremental Conduction Properties
Arrhythmia 2015;16(1):59-64 ECG & EP CASES Accessory Pathway with Decremental Conduction Properties Yong Seog Oh, MD, PhD Division of Cardiology, Depeartment of Internal Medicine, Catholic University of Korea Received: December 25, 2014 Revision Received: February 18, 2015 Accepted: March 26, 2015 Correspondence: Yong-Seog Oh, MD, PhD, Director of Electrophysiology, Division of Cardiovascular Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, College of Medicine, 505 Banpo-Dong, SeochoKu, Seoul, 137-040, Republic of Korea Tel: +82-2-2258-6031, Fax: +82-2-592-3810 E-mail: [email protected] ABSTRACT Permanent junctional reciprocating tachycardia (PJRT) is an orthodromic atrioventricular tachycardia mediated by a concealed accessory pathway with slow conduction and decremental property. The accessory pathway in PJRT is most often located in the posteroseptal region, especially around the coronary sinus ostium. Here I describe a case of clinical tachycardia with a long RP interval due to slow retrograde conduction. Key Words: supraventricular tachycardia, accessory pathway Copyright © 2015 The Official Journal of Korean Heart Rhythm Society Editorial Board & MMK Co., Ltd. Introduction echocardiography, with an ejection fraction of 62%. Twenty-fourhour Holter monitoring showed repeated induction of Narrow-QRS tachycardia with a long RP interval presents interesting supraventricular tachycardia (SVT), with intervening periods of diagnostic challenges. A correct diagnosis is essential for performing safe sinus rhythm lasting a few minutes. I administered IV adenosine, and effective catheter ablation. The differential diagnosis of verapamil injection, and DC cardioversion several times in an narrow-QRS tachycardia with a long RP interval includes atypical attempt to terminate the tachycardia, but after few seconds in atrioventricular nodal reentrant tachycardia (AVNRT), ectopic sinus rhythm the tachycardia was reinduced and sustained. To atrial tachycardia, and atrioventricular reentrant tachycardia (AVRT) maintain sinus rhythm I prescribed 240 mg of verapamil or 150 with a decremental property. I present a case of permanent junctional mg of atenolol per os; however, the patient continued to exhibit reciprocating tachycardia (PJRT) with a long RP interval that exhibited a the same drug-refractory tachycardia. decremental property. The patient was scheduled for electrophysiological study and catheter ablation. In the electrophysiology lab she showed SVT Case with intermittent short periods of sinus rhythm. The SVT could be easily induced by one premature ventricular contraction A 65-year-old woman was referred to our hospital for sustained (PVC), and was also inducible in sinus rhythm without any AH palpitations and general weakness. The electrocardiogram (ECG) jump (Figure 2). For the differential diagnosis, I applied a PVC showed narrow QRS tachycardia of ~120 /min, with an inverted during SVT. In contrast to orthodromic AVRT without a P wave in leads II, III, aVF, and a long RP interval in all precordial decremental property, after the PVC the AA interval was leads (Figure 1). She had normal left ventricular function on prolonged from 467 ms to 494 ms (Figure 3). To ablate the 59 Arrhythmia 2015;16(1):59-64 A B Figure 1. (A) Electrocardiogram in tachycardia, (B) Electrocardiogram in sinus rhythm. accessory pathway, I identified the earliest activation site of A in diagnosis was the atrial response to a PVC during the His the right posteroseptal area (Figure 4, Figure 5). After 4 seconds of refractory period. Since the atrial activation was delayed by the radiofrequency application, the SVT terminated and showed PVC, AVNRT could be excluded.1 ventriculoatrial dissociation (Figure 6). The patient remained in PJRT is an orthodromic AVRT mediated by a concealed and hospital for two days after the catheter ablation and was slow-conducting accessory pathway. The clinical course of PJRT is discharged in sinus rhythm. not always benign. Many patients try multiple antiarrhythmic drugs and ultimately require catheter ablation. Radiofrequency Discussion catheter ablation is a safe and effective therapy.2 However, the higher recurrence rate of PJRT, compared with that of reentry In this case, no preexcitation was observed. During the with no decremental property, may be explained by the long, tachycardia, the earliest atrial activation was observed around the tortuous course of the accessory pathway. The most important coronary sinus ostium. The critical finding for the differential complication of incessant PJRT is tachycardia-induced 60 Accessory Pathway with Decremental Conduction Properties A B Figure 2. (A) Electrocardiogram showing induction of supraventricular tachycardia (SVT) by a premature ventricular contraction (PVC), (B) Electrogram showing SVT induction by PVC. 61 Arrhythmia 2015;16(1):59-64 A B Figure 3. (A) Electrocardiogram showing induction of supraventricular tachycardia (SVT) in sinus rhythm, (B) Electrogram showing SVT induction in sinus rhythm. 62 Accessory Pathway with Decremental Conduction Properties Figure 4. The earliest atrial activation site in supraventricular tachycardia. RAO LAO Figure 5. Catheter in fluoroscopic view. RAO, right anterior oblique projection; LAO, left anterior oblique projection. 63 Arrhythmia 2015;16(1):59-64 A B Figure 6. (A) Electrogram showing termination of supraventricular tachycardia, (B) Electrogram showing ventriculoatrial dissociation. cardiomyopathy, which has been observed in 18% of patients with 2) Meiltz A, Weber R, Halimi F, Defaye P, Boveda S, Tavernier R, PJRT. Slower conduction through the accessory pathway has a Kalusche D, Zimmermann M. Permanent form of junctional wider excitable gap. In most cases of PJRT, the accessory pathway reciprocating tachycardia in adults: peculiar features and results of is located in the posteroseptal region. radiofrequency catheter ablation. Europace. 2006;8:21-28. 3 3) Bensler JM, Frank CM, Razavi M, Rasekh A, Saeed M, Haas PC, References 1) Ho RT, Frisch DR, Pavri BB, Levi SA, Greenspon AJ. Greenspon. Electrophysiological features differentiating the atypical atrioventricular node- dependent long RP supraventricular tachycardias. Circ Arrhythm Electrophysiol. 2013;6:597-605. 64 Nazeri A, Massumi A. Tachycardia-mediated cardiomyopathy and the permanent form of junctional reciprocating tachycardia. Tex Heart Inst J. 2010;37:695-698.
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