Role of Imaging in Adults with Congenital Heart Disease: State-of-Art Review

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Approximately 40,000 infants are born each year with a congenital heart disease (CHD) in the United States. CHD is defined as any abnormality that affects the cardiac anatomy or physiology, with some forms manifesting at birth, or during infancy, as cyanosis, failure to thrive, or heart failure (HF), while others are discovered in adulthood or incidentally. Newer imaging modalities, improved surgical techniques and medical care, have increased the survival rate of these patients [1]. In the year 2000, it was estimated that there were 485,000 adults with complex CHD and 300,000 with simple CHD in the United States [2]; these numbers have been increasing exponentially over the years. As these patients grow older, they may develop arrhythmias, HF, shunts, conduit failures, valvular insufficiency, and pulmonary hypertension (PHT). In addition, they are 25-100 times more likely to experience sudden cardiac death than the general population [3]. Also, adult women with surgically repaired complex CHD often encounter additional problems during pregnancy.....

Detection of intracardiac shunts is imperative to prevent paradoxical thromboembolism and heart strain from a shunt’s additional flow. Multiple modalities are used to detect shunts, including echocardiography, MRI, CC, and nuclear modalities. Echocardiography is the initial imaging modality for ASD, VSD, and PDA. In ASD and VSD, TEE, 3DE and MRI play a complementary role and can help to determine the suitability for percutaneous closure. Percutaneous closure is being increasingly used for ASD and PDA repair, while percutaneous VSD repair still remains in the experimental stage.

Obstructive lesions impede the flow through the left-sided chambers and the left ventricular outflow. These lesions are cor triatriatum, congenital mitral stenosis, aortic coarctation, and subvalvular, valvular, and supravalvular aortic stenosis. In cor triatriatum and congenital mitral stenosis, echocardiography has a primary imaging role, with MRI and CC supplementing to help detect anomalous pulmonary veins and detect pressure gradients, respectively. TTE is the initial imaging for supravalvular and subvalvular aortic stenosis and MRI is utilized when TTE is non-diagnostic. Echocardiography plays a primary role in valvular aortic stenosis ,and MRI and CT are complementary for evaluating aortic aneurysms and coarctation. Because aortic coarctation is an extracardiac lesion, both MRI and CT can better visualize the defect and are therefore the primary imaging modalities.

Tetralogy of Fallot, Transposition of the Great Arteries, and the Fontan circulation comprise some of the most common congenital cyanotic lesions encountered in practice. Tetralogy can be repaired initially, if the lesion is severe enough, with a systemic-to-pulmonary shunt to augment pulmonary blood flow. Then the definitive repair closes the VSD and enlarges the RV outflow tract. TTE is the initial imaging study of choice for Tetralogy, however, MRI and sometimes CT complement to assess conduits and post-op pulmonary valve insufficiency. d-TGA is characterized by ventriculoarterial discordance and initially was repaired by an atrial switch and is now repaired by an arterial switch. CCTGA has atrioventricular in addition to ventriculoarterial discordance and therefore does not usually necessitate surgical repair. Initial imaging is done with TTE, but TEE, MRI, and CT are frequently required to image the baffle from an atrial switch repair. Contrast angiography is used during percutaneous intervention to repair baffle stenosis. The Fontan circulation is the result of a series of surgeries to repair single ventricle anatomies. TTE is the initial imaging moda lity, but MRI is usually needed to visualize the entire Fontan circuit. CT and TEE are sometimes used as alternatives.

Ebstein’s anomaly is an abnorma lity of the tricuspid valve in which there is a failure of delamination, resulting in tethering of septal and posterior leaflets, apical displacement of the functional annulus and atrialization of the RV. TTE complemented by 3DE is used to diagnose and evaluate for surgical repair. Several congenital heart defects also concomitantly have anomalous origin of their coronary arteries. Some anomalous coronaries, such as an anomalous coronary arising from the opposite sinus, are associated with sudden cardiac death, making their detection imperative. TTE often fails to visualize the coronary arteries. TEE has increased sensitivity, but MRI and MR and CT angiography is the standard to detect anomalous coronaries and elucidate their course.