Electrocardiogram showing right ventricular hypertrophy

Right ventricular hypertrophy due, in this case, to idiopathic pulmonary arterial hypertension. The characteristic features include marked right axis deviation (+210º which is equal to -150º), tall R wave in V1 (as part of a qR complex), delayed precordial transition zone with prominent S waves in leads V5 and V6, inverted T waves and ST depression in V1 to V3 consistent with right ventricular "strain," and peaked P waves in lead II consistent with concomitant right atrial enlargement.

Normal electrocardiogram showing normal sinus rhythm at a rate of 75 beats/minute, a PR interval of 0.14 seconds, a QRS interval of 0.10 seconds, and a QRS axis of approximately 75°.