Assessing shunts

Appropriate care for patients with shunt lesions mandates an exact understanding of their anatomy and haemodynamics. While echocardiography remains the first-line imaging tool and is frequently sufficient in the evaluation of shunts, there are situations in which the anatomical delineation remains incomplete and the shunt magnitude is uncertain. Cardiovascular magnetic resonance (CMR) demonstrates the anatomy of intra- and extra-cardiac shunts and is the gold standard for the quantification of shunt magnitude and ventricular volume loading. Particularly in complex shunt lesions and patients with insufficient acoustic windows, CMR is a valuable diagnostic tool. Short-cut communications between the pulmonary and systemic circulation shunts occur in isolation or as part of complex congenital heart disease. This chapter explores how CMR aids in the diagnosis, workup, and interventional planning of shunt lesions.