Advanced Cardiac Imaging in Adults With Congenital Heart Disease: The Great Wave

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Excerpt

Congenital heart disease (CHD) is the most commonly occurring birth defect, affecting approximately 1% of live births.1,2 Many of these abnormalities are relatively minor; yet, 10% to 15% of congenital cardiac anomalies are more severe, with life-long hemodynamic sequelae.2 Given that many patients with severe CHD born before 1960 died young, previous generations of cardiac imagers encountered adult CHD survivors only on rare occasions. With advances in cardiopulmonary bypass and deep hypothermic circulatory arrest in the 1950s to 1970s, cardiac imagers practicing near the turn of the millennium gradually began to see more adults with postsurgical anatomy. Techniques for neonatal surgery were introduced in the 1980s, drastically improving survival among infants born with the most severe forms of CHD. In a recent study from Canada, the prevalence of severe CHD increased by 57% between 2000 and 2010, with adults accounting for 66% of the CHD population in 2010.2 As a result, current and future generations of cardiac imagers are tasked with performing and evaluating studies on a rapidly growing number of adult CHD patients. Because of substantial improvements in medical technology and surgical skills, the complexity of the cardiovascular anatomy in these patients is increasing as well. Fortunately, the imaging armamentarium available to evaluate this population has also advanced exponentially during this era.3–5
In this symposium, an overview of advanced cardiac imaging in the adult CHD population is presented, along with specific indications and techniques for imaging using cardiovascular magnetic resonance imaging and computed tomography.6–10 The contributions included in the symposium are the results of tight-knit collaborations among radiologists, adult cardiologists, and pediatric cardiologists. We believe that this collaborative approach is essential in creating the optimal imaging environment for this complex patient population, a notion that is supported by societal guidelines.11,12 With the wide array of techniques available for advanced cardiac imaging in patients with CHD, the most beneficial diagnostic information is obtained only by tailoring the imaging to each patient’s specific diagnosis and clinical characteristics. This demands a broad, multidisciplinary knowledge of the patient’s history, CHD-specific findings, natural history, and potential interventions, in addition to the acquisition protocols and technical parameters available for the chosen imaging technique.
For instance, consider a 45-year-old patient with a diagnosis of a double-inlet left ventricle (DILV) who is referred for a cardiac magnetic resonance imaging (or computed tomography) because of exercise intolerance. First, one must be familiar enough with the spectrum of CHD to recognize that DILV almost universally results in single-ventricle physiology and that most adults with single-ventricle physiology have undergone a Fontan procedure.13 Then, consideration must be given to the various types of Fontan procedures utilized over the years, along with the spectrum of inherent complications.14 Based on that information, the differential diagnosis for this patient should include stenosis or thrombosis within the Fontan pathway or pulmonary arteries, arterial or venous collateral vessels, and pulmonary arteriovenous fistulae. It should also be considered that a majority of patients with DILV are born with transposition of the great arteries, resulting in an aorta that arises from an incomplete right ventricle.15 If the ventricular septal defect was restrictive at birth, it is likely that some form of aortic arch augmentation was required. Thus, the imager must ensure adequate evaluation of the aortic arch. The ventricular septal defect could have become restrictive with time, and therefore subaortic stenosis should also be considered. Finally, ventricular dysfunction, valvar stenosis/regurgitation, and atherosclerotic coronary artery disease are always high on the differential for any patient with exercise intolerance, and patients with single-ventricle physiology are no exception.

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