International Journal of Cardiology 118 (2007) e48 – e50 www.elsevier.com/locate/ijcard
Letter to the editor
Unusual electrocardiographic presentation of typical atrioventricular nodal re-entrant tachycardia Miguel A. Arias ⁎, Ana M. Sánchez Cardiac Arrhythmia and Electrophysiology Unit, Department of Cardiology, Complejo Hospitalario de Jaén, Jaén, Spain Received 10 November 2006; accepted 31 December 2006 Available online 3 April 2007
Abstract The present case report illustrates an atypical electrocardiographic presentation of typical atrioventricular nodal re-entrant tachycardia. Persistent 2:1 AV block during tachycardia is evident and an spontaneous ventricular premature beat during tachycardia resulted in 1:1 AV conduction. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Electrocardiographic presentation; Typical atrioventricular nodal re-entrant tachycardia; Electrocardiogram
A 45-year-old woman was referred for electrophysiologic study due to episodes of supraventricular tachycardia. The 12-lead electrocardiograms shown in Figs. 1 and 2 were consecutively recorded when the patient was lying down before vascular puncture. Typical (slow/fast) form of atrioventricular nodal re-entrant tachycardia (AVNRT) at a rate of 200 bpm was reproducibly induced by burst atrial pacing and was identical to that registered at the end of the electrocardiogram shown in Fig. 2. Successful radiofrequency ablation of the slow pathway was performed with no inducible tachycardia post ablation. Persistent 2:1 AV block during AVNRT is a rare phenomenon that is evident in Fig. 1. In Fig. 2, resumption to 1:1 AV conduction is observed. Twoto-one AV block during AVNRT is considered a physiologic phenomenon in the majority of patients [1]. In our case an spontaneous ventricular premature beat during AVNRT with 2:1 AV block resulted in 1:1 AV conduction. The more
⁎ Corresponding author. Plaza Curtidores No. 2, 4°Dcha 23007, Jaén, Spain. Tel.: +34 637463857; fax: +34 953270692. E-mail address:
[email protected] (M.A. Arias). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2006.12.057
plausible explanation for this occurrence is that retrograde penetration of the ventricular ectopy into the His bundle resulted in either activating the His bundle earlier than expected allowing it to recovery for excitation or shortening the refractoriness of the Hisian region because of its prematurity and consequently resolving the AV block. This relatively early beat found the left bundle refractory and therefore 1:1 AV conduction resumes but with left bundle branch block for the next 3 beats with following narrow QRS complexes by shortening the refractoriness of the left bundle due to tachycardia. Reference [1] Josephson ME. Clinical cardiac electrophysiology: techniques and interpretations. 3rd ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2002.
M.A. Arias, A.M. Sánchez / International Journal of Cardiology 118 (2007) e48–e50
Fig. 1. Twelve-lead ECG showing an apparent long RP type regular narrow QRS tachycardia, with a cycle length of 570 ms.
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M.A. Arias, A.M. Sánchez / International Journal of Cardiology 118 (2007) e48–e50
Fig. 2. Twelve-lead ECG shows the same tachycardia as in Fig. 1. An ectopic ventricular beat results in change to a narrow complex tachycardia with no visible P waves and a cycle length of 300 ms.
