GIANT Flutter Waves in ECG Lead V1: a Marker of Pulmonary Hypertension.

Atrial flutter (AFl) may exist with or without underlying structural heart disease. Typical AFl presents as a "sawtooth" pattern on the ECG - with inverted flutter (F) waves in the inferior leads and upright F waves in V1. This morphology offers no direct clues as to the underlying cardiac disorder, if any. Occasionally we have encountered giant F waves, most prominently in lead V1, reaching 5 mv or more in height - sometimes exceeding the QRS voltage. The significance of this pattern has not been investigated and reported on. To determine if giant F waves in V1 provide any insight into the presence/type/absence of specific underlying cardiac pathology, the history of 6 consecutive patients with giant F waves was reviewed. Upon review, the only factor common to each patient was the presence of or history of pulmonary hypertension. Right ventricular dilation and/or dysfunction and right atrial enlargement with or without tricuspid insufficiency were present in each by echocardiography. Giant F waves appear to occur in the setting of right heart dysfunction in patients with a history of or the continued presence of pulmonary hypertension. Their detection should indicate the need for right heart evaluation.