Clinical Significance of the Forsaken aVR in Evaluation of Tachyarrhythmias: A Reminder.

Abstract

Mechanism of a regular, monomorphic Wide QRS Complex Tachycardia (WCT) is an important diagnostic challenge in day to day practice for the clinicians and affects further management and prognosis. Many of the WCT and Narrow Complex Tachycardia (NCT) produce certain characteristic changes in lead aVR by which we can differentiate between them. The present study was aimed to evaluate tachyarrhythmias in relation to lead aVR and to highlight the clinical significance of lead aVR, "The Neglected Lead". This is prospective study in which 55 consecutive cases of tachyarrhythmias excluding sinus tachycardia, atrial fibrillation and atrial flutter were taken for the study admitted in from ICCU of Department of Medicine at S.S. Medical College and S.G.M. Hospital Rewa (M.P.), India, during July 2014 to September 2015, fulfilling the required study protocol. The data was collected regarding detailed history, physical examination; necessary investigations (including ECG and echocardiography) were done. Among 55 patients, 30 were of WCT and 25 were of NCT. The most common cause of WCT was Ventricular Tachycardia (VT) (83.3%) and rest were Supra Ventricular Tachycardia (SVT) with aberrancy (16.7%). The most common cause of NCT was Atrioventricular Nodal Tachycardia (AVNRT) (84%) followed by Atrioventricular Reciprocating Tachycardia (AVRT) (16%). The present study observed that 38.1% of the AVNRT cases and 50% of AVRT cases showed positive 'p' wave in lead aVR. The present study observed that 75% cases of AVRT showed ST segment elevation in lead aVR while only 33.3% cases of AVNRT showed ST elevation. In the present study 80% of the patients with WCT were diagnosed to have VT using Brugada algorithm while using Vereckei's new aVR algorithm, 83.3% were diagnosed to have VT. Lead aVR, one of the most neglected leads on 12 lead ECG, is a very important diagnostic tool for identification and categorization of different type of tachyarrhythmias. The presence of ST elevation in lead aVR on ECG showing NCT is relatively sensitive for diagnosing AVRT. New aVR algorithm by Vereckei is more sensitive for differential diagnosis of WCT. One should pay careful attention to lead aVR which provides essential diagnostic information.