Cardiac MRI and Pulmonary MR Angiography of Sinus Venosus Defect and Partial Anomalous Pulmonary Venous Connection in Cause of Right Undiagnosed Ventricular Enlargement

OBJECTIVE. Patients may be referred for cardiology assessment because of an enlarged right ventricle (RV) with no cause apparent on echocardiography. Cardiac MRI can contribute to the management of these patients by detecting sinus venosus defect or partial anomalous pulmonary venous connection (PAPVC). We sought to show how often sinus venosus defect or PAPVC was detected on MRI in patients with an enlarged RV without a previously established definite diagnosis. MATERIALS AND METHODS. First cardiac MRI scans obtained over a 4-year period in adults with an undiagnosed cause of RV enlargement were searched for the MRI diagnosis of sinus venosus defect or PAPVC. RESULTS. Thirty-seven patients (25 female, 12 male) met the study criteria. Nineteen patients had a cardiac MRI diagnosis of sinus venosus defect, with PAPVC being present in 95% of those patients. All PAPVCs associated with sinus venosus defect were from the right side. Eleven of the 19 patients with sinus venosus defect underwent surgery at our institution. Sinus venosus defect was confirmed in all 11 cases. Of the 37 patients, 36 had PAPVC, which was right-sided in 27 patients (75%), left-sided in seven patients (19.4%), and bilateral in two patients (5.6%). Three patients had scimitar veins. The common defects associated with PAPVC were sinus venosus defect in 18 patients (50%) and secundum atrial septal defect in six patients (17%). CONCLUSION. This article about cardiac MRI in adults with sinus venosus defect and PAPVC shows that cardiac MRI can reliably detect and quantify these lesions when other methods have not provided a complete diagnosis for the cause of right heart enlargement.