Occult Anomalous Pulmonary Venous Drainage
The Clinical Value of Cardiac Magnetic Resonance Imaging
A 59-year-old male with hypertension, who had occasional chest pressure with moderate activities, was evaluated for an abnormal ECG showing right bundle branch block and left-axis deviation. A transthoracic echocardiogram revealed a mildly hypertrophied left ventricle with good systolic function. The right atrium and ventricle were inexplicably dilated; the latter was contracting satisfactorily. There was moderate tricuspid regurgitation, with a transtricuspid gradient of 36 mm Hg. Subsequent transesophageal echocardiography failed to detect any primary tricuspid valve anomaly or any atrial or ventricular septal defect despite multiple contrast injections. The pulmonary veins were not adequately visualized due to distortion by the enlarged right atrium. Right heart catheterization recorded a pulmonary arterial systolic pressure of 32 mm Hg, and oximetric studies indicated a left-to-right shunt at the right atrial level. Coronary angiography was normal. Magnetic resonance study was performed, which clinched the anatomical diagnosis as well as supply crucial functional information. Cine imaging confirmed right-sided chamber dilatation (Figure 1). First-pass contrast-enhanced magnetic resonance angiography acquired images during the pulmonary arterial (Figure 2) and pulmonary venous (Figure 3) phases. The arterial phase image showed dilated pulmonary arteries. The pulmonary venous phase image revealed anomalous drainage of the right upper and lower pulmonary veins via a large common vein into the inferior vena cava. Magnetic resonance pulmonary (Qp) and aortic (Qs) flow mapping recorded a Qp:Qs ratio of 2.7:1 (Figure 4). Patient is due for further study in anticipation of an operative repair of the shunt.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St.Luke's Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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