Images in cardiovascular medicine. Himalayan P-waves in a patient with tricuspid atresia.

An 8-month-old female infant was diagnosed with tricuspid atresia in utero by an ultrasound and the diagnosis was confirmed at birth. She underwent a modified Blalock-Tausig shunt at the age of 2 months to treat increasing cyanosis. She did well and is waiting to complete single ventricle palliation. On her recent follow-up, she was asymptomatic, with a systemic arterial saturation of 80% at room air. On examination, she had normal and symmetric pulses in her extremities, a normal S1, single S2, a grade 3/6-continuos murmur (due to shunt) at base, and a grade 2/6 ejection systolic murmur at the mid-left sternal border. Her abdominal examination was normal. Her cardiothoracic ratio was 0.60 on chest X-ray. Her recent 12-lead ECG (Figure) demonstrates important diagnostic information and classic signs of tricuspid atresia. It shows a normal sinus rhythm, superior axis ( 15), right atrial enlargement, and an adult pattern of QRS progression over the precordial leads (V1 through V6). This pattern of QRS is characterized by absent right ventricular forces and well-developed left ventricular forces consistent with left ventricular hypertrophy. The P-waves are tall ( 5 mm) and peaked in lead II. These types of P-waves are called giant P-waves or Himalayan P-waves and are indicative of a dilated right atrium due to a restrictive atrial communication.