Assessment of cor triatriatum dexter and giant eustachian valve with cardiac magnetic resonance.

A 56-year-old man with symptomatic atrial fibrillation (AF) was referred to our arrhythmia center for pulmonary vein isolation by catheter ablation. The patient underwent routine transesophageal echocardiography (TEE) and cardiac magnetic resonance (MR) examination before the catheter ablation. The cardiac MR examination consisted of time-resolved (4-dimensional) contrast-enhanced MR angiog-raphy (TR-MRA), cine imaging with steady-state free preces-sion, and 3-dimensional (3D) late gadolinium enhancement (3D-LGE) sequences. In assessments of cardiac function and thrombus (Figure 1), the TEE image demonstrated the nodu-lar structure adhering to the interatrial septum of right atrium (RA). The cine image revealed a thin membrane dividing the RA into 2 chambers. The proximal and distal chambers of RA were connected to the inferior vena cava (IVC) and superior vena cava (SVC), respectively. The TR-MRA (Figure 2) showed a strongly enhanced distal chamber of RA with restriction of contrast media distribution and an unenhanced proxi-mal chamber RA on the multiple phases of contrast dynamics. The reformatted 3D LGE images (Figure 3) showed a thin and high septum from the eustachian valve (EV) between the IVC and coronary sinus (CS) orifices and an enlargement of IVC and hepatic vein (HV). Sequentially, a catheter-based conventional angiography (Figure 4) was performed for further evaluation of RA. The septum from the EV disrupted the catheter approach to the CS in the cardiac intervention session. The cor triatriatum dexter (CTD) is characterized by the presence of a fibromuscular membrane dividing the RA into proximal and distal chambers and is rarely found in adults. 1 The EV takes the form of a thin ridge-like crescent and generally arises from the anterior rim of the IVC orifice. 2 If its structure and attachment to the atrial septum are large and high enough to define the giant EV, it can give the appearance of CTD. With advanced technique, cardiac MR imaging for the RA especially has become increasingly important to provide a preprocedural roadmap for necessary intervention. TR-MRA involves rapid sequential imaging of an anatomic volume during the dynamic intravascular passage of a contrast bolus and enables the identification of complex vascular flow kinetics. 3 LGE imaging has been widely used for assessing the viability of myocardium because it permits clear visualization of myo-cardial fibrosis. Furthermore, the use of 3D LGE sequence permits acquisition of entire heart data in a single scan and viewing of any desired plane of the heart by reconstruction of the acquired 3D data. …