This is the commonest congenital cyanotic heart disease producing cyanosis at birth. In this condition the great arteries have an abnormal connection with right and left ventricles. The right ventricle pumps blood into aorta which comes from the systemic veins and left ventricle pumps blood into pulmonary arteries which comes from pulmonary veins. Thus for survival there must be some communication on two sides of heart through patent foramen ovale, ASD, VSD, PDA etc. When transposition is associated with PS patient may present with features resembling Fallot’s tetralogy. Patient’s condition becomes downhill when in early infancy the ductus closes.

CLINICAL FEATURES

1. Central cyanonis, dyspnoea, weakness, fatigue.
2. Biventricular or RV enlargement is present.
3. ECG shows biventricular or RV hypertrophy.
4. X-ray shows egg-shaped configuration of cardiac shadow with narrow base. Echocardiogram shows aorta lying on the top of the pulmonary artery. Surgical correction (Mustard’s operation) is done when dyspnoea and cyanosis are severe

CORRECTED TRANSPOSITION

When transposition of great vessels is physiologically corrected aorta arises from embryonic right ventricle and pulmonary trunk arises from embryonic left ventricle. Here the systemic venous return goes to the lungs through the anatomic left ventricle and the blood from pulmonary veins goes to the systemic circulation through aorta from the anatomic right ventricle. The A-V valves are transposed so that mitral valves have tricuspid and tricuspid valves have bivalve mitral shape. Associated anomalies include VSD, PS (infundibular), Ebstein’s anomaly of AV valves and complete heart block. Features include loud S2 over left 2nd interspace, congenital complete heart block. X-ray shows a smooth convexity on the upper part of left border of heart due to displaced ascending aorta. Two-dimensional echocardiography will show the accurate morphology of the ventricle, Due to inversion of the ventricles and the conduction system, ECG will show Q in Vi and absence of q in V5.6 In surgically treated cases the long-term complications include different types of cardiac arrhythmias and conduction defects.

TRANSPOSITION GREAT ARTERIES