CT and MR Imaging in Post-operative CHD

With an increasing number of patients reaching adulthood following surgical repair or palliation of congenital heart defects (CHDs), their regular follow-up assumes importance. For identifying complications, planning procedures and for prognostication, imaging in the form of either cardiac magnetic resonance (CMR) or cardiac computed tomography angiography (CTA) has assumed an important role. Two dimensional and Doppler echocardiography, despite being inexpensive and readily available, has its own limitations in the assessment of complicated post-operative anatomy of conduits and shunts, small residual defects and pulmonary venous drainage to name a few. The two imaging modalities (CTA and CMR) available are not only valuable for the anatomical and functional evaluation of post-operative CHDs but also identify the late post-operative sequelae and intra-/extracardiac complications of the palliative and therapeutic procedures. They also act as a guide to early intervention, prognostication and decision-making process. Though the two modalities are complementary and supplementary to echocardiography, CMR has definite advantages over cardiac CTA in the evaluation of post-operative CHDs given its superiority for the evaluation of ventricular and valvular function, assessment of the functional significance of stenosis and diagnosis and haemodynamic evaluation of small residual/recurrent septal defects. The need for multiple imaging follow-ups also tips the balance in favour of CMR, it being a radiation-free modality. However, some centres may still prefer CTA because of its availability, lower cost and faster scan times. In this chapter, common surgical procedures used for palliation and final correction of CHDs and their imaging findings are discussed.