Haystack Principle - Its Importance in Unearthing the Electrocardiogram in a Patient with Unexplained Syncope

Abstract

The "haystack principle" is of great diagnostic and therapeutic importance to unearth the obscure P waves which gives clue to underlying diagnosis. Here, we report a case of 72-year-old women who came to outdoor department for evaluation of repeated episodes of loss of consciousness. Electrocardiogram revealed complete right bundle branch block pattern with bizarre T wave in lead II, III, and aVF. P wave were not discernible. However, lead aVR revealed well formed P wave with second-degree atrioventricular block. Patient was successfully managed with implantation of permanent pacemaker. Therefore, whenever one is faced with the problem of finding elusive P wave, lead showing the smallest electrical deflection should always be carefully examined to clinch the diagnosis.