Magnetic Resonance Angiography of Criss-Cross Heart
A 29-year-old man presented with a history of cyanotic congenital heart disease. During childhood, cardiac catheterization and angiography had demonstrated atrial situs solitus, L-ventricular loop, l-transposition of the great arteries, and criss-cross atrioventricular connections. The patient had a Mustard procedure at age 13 that improved the cyanosis. He was now reporting decreasing exercise tolerance.
The patient underwent cardiac MRI with magnetic resonance angiography (MRA) as the first step in his evaluation. MRI showed l-transposition of the great arteries and an L-ventricular loop (inversion of the ventricles). The ventricles also had a superior/inferior relationship, in which the morphological right ventricle was to the left of and superior to the morphological left ventricle (Figure 1). The atria were normally positioned (atrial situs solitus), and the atrioventricular connections were concordant. The concordant atrioventricular connections occurred because the pulmonic and systemic blood streams crossed in the midheart, so that the normally positioned atria supplied the appropriate but abnormally positioned ventricles. This type of atrioventricular relation-ship has been called the “criss-cross heart,” or “twisted atrioventricular connection.”
Many patients with criss-cross atrioventricular connections have discordant ventriculoarterial connections, as did this patient. This patient was cyanotic at birth, despite the presence of an L-ventricular loop and l-transposition, which usually cause a physiological correction and an acyanotic state. With the criss-cross atrioventricular relationship, the right atrium remained connected to the right ventricle, causing systemic venous (desaturated) blood to flow to the right ventricle and into the aorta (Figure 2). Thus, systemic venous blood flow was rerouted by the Mustard procedure across the mitral valve, into the left ventricle, and out the pulmonary artery.
In cases of complex congenital heart disease such as the current case, MRI has the advantage of a large field-of-view and the ability to image in multiple planes. This capability has been increased with the advent of gadolinium-enhanced, breath-hold MRA (Figure 3). Gadolinium-enhanced MRA images have a higher spatial resolution than most conventional MR sequences and lend themselves to 3D reconstructions.