Radiological Diagnosis

TOTAL ANOMALOUS PULMONARY VENOUS CONNECTION [TAPVC]. (SUPRA CARDIAC TYPE)

This is a condition in which all the pulmonary veins fail to terminate in the left atrium. This occurs in approximately 2% of all cardiac anomalies. TAPVC is classified according to the ultimate level of termination of the pulmonary vein, as (1) supracardiac, (2) cardiac, (3) infradiaphragmatic, (4) mixed [1],[2]

In the supracardiac type, which is the most common (33%), all the pulmonary veins connect to a 'common vein' which in turn is drained by an anomalous 'vertical' vein [Figure - 2]. The vertical vein, which is otherwise called the left superior vena cava [1] usually passes anterior to the left hilum, to join the left brachiocephalic vein, then draining via the supeior vena cava to the right atrium [Figure - 1],[Figure - 2]. The right atrium thus becomes the only chamber to receive the total systemic and pulmonary venous return [2]. This condition is invariably associated with an atrial septal defect, or persistent foramen ovale. The right atrium [RA] and right ventricle [RV] are considerably enlarged and left sided chambers are small and displaced backwards [Figure - 1],[Figure 4].

Plain radiograph may show a characteristic 'snowman's heart'. Color Doppler, echocardiography, gated cardiac MR, cardiac catheterization and angiocardiography all help in diagnosis and pre-therapeutic evaluation.

MR is of particular importance in delineating the pathological anatomy of the cardiac chambers, the draining venous pattern, any venous obstruction and the status of pulmonary circulation. MR also helps in the post-operative evaluation of these patients [3].