Shunts, Intracardiac and Intrapulmonary

Shunts, intracardiac and intrapulmonary, are vascular communications that allow mixture of deoxygenated and oxygenated blood within the cardiovascular system. The most common intracardiac shunts encountered in adults allow left (oxygenated) to right (deoxygenated) directional shunting which over time can lead to pulmonary circulation volume overload and pulmonary hypertension. In this chapter, the most common adult intracardiac shunts (atrial septal defects, patent foramen ovale and ventricular septal defects) are discussed. Shunting can also occur at the level of the lung parenchyma with one of the most common examples being a pulmonary arteriovenous malformation (pAVM). PAVMs are very frequently inherited conditions, and their identification has implications both for the patient and immediate family members. The imaging appearances of these intracardiac and intrapulmonary lesions will be discussed.