When Normal Electrocardiogram is not Normal?

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Dear Editor,. A 26‑year‑old female presented with Ebstein's anomaly and recurrent palpitations. Her electrocardiogram (ECG) revealed a manifest accessory ...

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When Normal Electrocardiogram is not Normal? Dear Editor, A   26‑year‑old   female presented with Ebstein’s anomaly and recurrent palpitations. Her electrocardiogram (ECG) revealed a manifest accessory pathway (Panel A) Figure 1. Negative delta wave in lead V1 with negative delta waves in lead aVf localized this pathway to the right posteroseptal pathway as per Arruda’s et al. criteria.[1] Electrophysiology study confirmed the pathway which was successfully ablated using radiofrequency energy. Ablation resulted in a normal looking ECG (Panel B) without any preexcitation, giving an impression of successful procedure. Intracardiac electrograms were also not suggestive of any preexcitation, with normal HV interval and no VA conduction. However, the absence of right bundle branch block (RBBB) in a patient with Ebstein’s anomaly raised suspicion of the presence of another pathway. Incremental atrial pacing resulted in manifestation of Mahaim pathway (Panel C) with classical left bundle branch block pattern and superior QRS axis. Successful radiofrequency ablation of this Mahaim pathway resulted in complete RBBB pattern in ECG  (Panel D), a classical finding of Ebstein’s anomaly. The absence of RBBB in Ebstein’s anomaly is very sensitive and specific marker of accessory pathway even if other markers of preexcitation (Short PR interval and delta wave) are absent.[2] Abnormal intra‑atrial conduction and presence of long and slowly conducting pathways are two important reasons for normal PR interval in these patients. RBBB in Ebstein’s anomaly is secondary to the developmental defects and is

masked by the presence of right‑sided accessory pathways. An orthodromic tachycardia or radiofrequency ablation of the accessory pathway will unmask the abnormal right bundle conduction.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship Nil.

Conflicts of interest

There are no conflicts of interest. Neeraj Parakh, Nitish Naik, Rajnish Juneja Department of Cardiology, All India Institute of Medical Sciences, New Delhi, India Address for correspondence: Dr. Neeraj Parakh, Department of Cardiology, All India Institute of Medical Sciences, New Delhi, India. E‑mail: [email protected]

References 1. Arruda MS, McClelland JH, Wang X, Beckman KJ, Widman LE, Gonzalez MD, et al. Development and validation of an ECG algorithm for identifying accessory pathway ablation site in Wolff‑Parkinson‑white syndrome. J Cardiovasc Electrophysiol 1998;9:2‑12. 2. Iturralde P, Nava S, Sálica G, Medeiros A, Márquez MF, Colin L, et al. Electrocardiographic characteristics of patients with Ebstein’s anomaly before and after ablation of an accessory atrioventricular pathway. J Cardiovasc Electrophysiol 2006;17:1332‑6. This is an open access article distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as the author is credited and the new creations are licensed under the identical terms.

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DOI: 10.4103/jpcs.jpcs_53_17

Figure 1: Electrocardiogram of the patient during ablation. 174

How to cite this article: Parakh N, Naik N, Juneja R. When normal electrocardiogram is not normal?. J Pract Cardiovasc Sci 2017;3:174.

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