Congenital heart disease
One of the first applications of Cardiac MR (magnetic resonance) was the evaluation of congenital heart disease (CHD), and this remains as one of the leading indications for the procedure. The primary goals of the exam are to provide the morphologic details of the lesion as well as the sequelae of the disease.
In pediatric patients, Cardiac MR offers several advantages over conventional modalities such as echo and angiography when evaluating CHD: there is no use of nephrotoxic contrast agents, no exposure to ionizing radiation, and lesions which cannot be completely characterized by echo such as aortic coarctation can be clearly depicted.
In adult patients with CHD, the MR exam can be used to evaluate multiple aspects of the disease. It depicts not only the lesion but also the morphological changes in chamber size and configuration that result from the disease. In patients with congenital bicuspid aortic valve, for example, Cardiac MR functional studies can evaluate for aortic regurgitation or stenosis as well as left ventricular hypertrophy. Cardiac MR is also frequently requested to evaluate for stenosis in h3. post-operative shunts, and velocity mapping techniques can be used to estimate gradients in these shunts.
Key Points
- The most common congenital lesion is bicuspid aortic valve, occurring in approximately one to two percent of individuals. MR exams can clearly demonstrate the lesion as well as quantify the significance of aortic stenosis or regurgitation using velocity encoding techniques.
- Coarctation of the aorta is the most common symptomatic lesion of the aorta, and Cardiac MR has demonstrated several advantages in depicting this lesion: collateral circulation in the anterior chest wall or intercostal arteries is frequently seen, helping to distinguish congenital coarctation from “pseudo” coarctation; the hemodynamic severity of the lesion may be quantified; and Cardiac MR can be used to followup post-operative patients to evaluate for recurrent stenosis or dilatation.
- Intracardiac shunts can be clearly delineated by the cardiac exam. Cine MRI can demonstrate the defect. 1st pass imaging can show the direction of the shunt, and flow quantification studies can determine the shunt fraction.
- For complex CHD, the MR exam can characterize cardiac chamber morphology, atrioventricular and ventriculoarterial connections, and abnormal branchings of the aorta or vascular rings. It can also identify sequelae of these anomalies, such as pulmonary arterial hypertension, ventricular hypertrophy, and valvular disease.
Case in Point
MR Angiogram of the aorta and pulmonary arteries showing aysmmetric flow.
29 year old male status post repair of transposition of the great arteries with persistent shunt.
For Further Reading
- Boxt LM, Rozenshtein A. MR imaging of congenital heart disease. Magn Reson Imaging Clin N Am. 2003 Feb;11(1):27-48.
- Araoz PA, Reddy GP, Higgins CB. Congenital heart disease: morphology and function. Cardiovascular MRI & MRA, Lippincott 2003, pp. 307-338.