Coronary artery fistulas and anomalous coronary artery origin

Imaging description Coronary artery fistulas are defined by an abnormal connection between a coronary artery and another vessel or cardiac chamber in the absence of an intervening capillary bed. Coronary fistulas are thought to be abnormal remnants of primitive sinusoids and vessels of fetal life that persist into adulthood. At echocardiography, cardiac CT, or cardiac MRI a tortuous and possibly dilated vessel with abnormal drainage will be identified. Fistulas may connect to the cardiac chambers (coronary–cameral fistulas), pulmonary arteries, coronary sinus, pulmonary veins, or superior vena cava (Figures 37.1 and 37.2). Fistulas draining to low pressure right-sided structures are the most common. Anomalous coronary artery origin from the pulmonary artery, also known as Bland-Garland-White syndrome, is an entity distinct from coronary artery fistula. Unlike fistulas, which are anomalies of coronary termination, Bland-Gar-land-White syndrome is an abnormality of coronary artery origination. The left coronary artery is the most commonly affected, and is also known by the acronym ALCAPA (anomalous left coronary artery from the pulmonary artery). The imaging appearance is similar to coronary fistulas with dilated and tortuous coronary arteries on cross-sectional imaging (Figure 37.3). Unlike fistulas, however, the entire coronary tree is usually involved and the abnormal origin of a coronary artery from the pulmonary artery will be present. Importance Although most patients are asymptomatic, large coronary artery fistulas with significant shunting can result in congestive heart failure. Fistulas have also been associated with stroke, arrhythmias, myocardial infarction, and endocarditis. Patients with an anomalous origin of the coronary artery from the pulmonary artery are much more symptomatic, usually presenting in infancy due to significant shunting or myocardial ischemia from a steal phenomenon. However, delayed presentation until adulthood has been reported and can be a cause of sudden cardiac death. Typical clinical scenario Coronary artery fistulas are rare, with an incidence estimated at 0.3–0.8% at angiography. Most are congenital; however, post-traumatic and iatrogenic fistulas may occur.