Electrocardiogram # 8


Ten month old male infant with complete Transposition of the great arteries


Right atrial enlargement (Tall P waves in Leads 11, 111, and aVF)

Right Ventricular Hypertrophy (Right Axis Deviation, Deep S in V6 and upright T in V1).

Right Ventricular Hypertrophy is due to systemic overloading of the right ventricle, as this ventricle is now connected to high systemic pressures in the Aorta. The left ventricular forces are decreased as the left ventricle is not the systemic ventricle and is pumping against the lower pressures in the pulmonary circuit. The left ventricle mass therefore melts quite rapidly within the first month of birth. It is therefore critical that the arterial switch operation for correction of this condition be done as soon after birth as possible before the left ventricular mass diminishes and can no longer take over the role as the systemic ventricle