Abstract 15372: The Lewis Lead

The Lewis lead is a modified ECG configuration that can enhance the amplitude of the atrial electrical activity and is useful when the atrial activity cannot be discerned in the standard ECG. The configuration involves applying the right arm electrode on the manubrium, left arm electrode to the 5th intercostal space on the right sternal border, left leg electrode over the right lower costal margin and right leg electrode in the standard position. The ECG is then interpreted in lead I and II. Herein we present a case where the Lewis lead aided in the diagnosis of complete heart block with underlying atrial fibrillation. Case Presentation: A 75 year old female with severe tricuspid regurgitation was admitted for tricuspid valve replacement. She had previous paroxysmal atrial fibrillation status post pulmonary vein isolation. The preoperative ECG revealed normal sinus rhythm. Postoperatively, ECG demonstrated a narrow complex ventricular rhythm at 70 beats per minute. No atrial activity could be clearly discerned (Image 1). The epicardial atrial wire placed intraoperatively was not functioning, therefore atrial electrogram could not be obtained. It was unclear from repeat ECGs if there was sinus arrest or atrial fibrillation in the atria. The Lewis lead was then utilized and revealed underlying atrial fibrillation (Image 1); together, this was consistent with atrial fibrillation and complete heart block with a junctional escape rhythm. The rhythm did not recover and there was progressive conduction system disease with widening of the QRS and episodes of severe bradycardia. She underwent pacemaker implantation. Discussion: By utilizing the Lewis lead we were able to establish the atrial rhythm and differentiate between atrial fibrillation and sinus arrest. The Lewis lead can also help narrow the differential for wide complex tachycardia by magnifying the p wave, thus making it easier to detect ventriculoatrial dissociation, a hallmark feature of ventricular tachycardia.