Collateral Flow Measurement by Phase-contrast Magnetic Resonance Imaging for the Assessment of Systemic Venous Baffle Patency After Atrial Switch Repair for Transposition of the Great ArteriesMuzzarelli, Stefano MD; Ordovas, Karen Gomes MD; Higgins, Charles B. MD; Meadows, Alison Knauth MD, PhDJournal of Thoracic Imaging: May 2012 - Volume 27 - Issue 3 - p 175–178 doi: 10.1097/RTI.0b013e31823fb9a0 Original Articles Abstract Author Information Purpose: We aimed to describe and compare azygos vein flow patterns of patients with obstructed and unobstructed systemic venous baffle after atrial switch repair for d-transposition of the great arteries (TGA). We hypothesized that phase-contrast magnetic resonance imaging would enable characterization of retrograde collateral flow across the azygos vein in cases of systemic venous baffle obstruction. Materials and Methods: This is a retrospective, cross-sectional study. Twelve patients with atrial switch repair for TGA were examined. Azygos flow index was measured with phase-contrast magnetic resonance imaging; comparison was made between patients with documented systemic venous baffle obstruction (n=3) and a control group of patients without baffle obstruction (n=9). Results: Patients with systemic venous baffle obstruction had a distinctive azygos flow pattern that was retrograde and an increased amount of azygos flow compared with patients without obstruction [median (range), −436 (−455/−399) vs. 103 (51/125) mL/min/m2; P=0.01]. Conclusions: Patients with systemic venous baffle obstruction have a characteristic collateral flow across the azygos vein. Azygos vein flow measurement may be used for the assessment of baffle patency in patients after atrial switch repair for TGA. However, diagnostic accuracy needs to be tested in a larger population. Department of Radiology, University Hospital of California, San Francisco, CA Dr Stefano Muzzarelli is supported by the Swiss National Science Foundation (Grant PBBSP3-125579, Berne, Switzerland). The authors declare no conflicts of interest. Reprints: Stefano Muzzarelli, MD, Division of Cardiology, Fondazione Cardiocentro Ticino, Via Tesserete 48, CH-6900 Lugano, Switzerland (e-mail: email@example.com). © 2012 Lippincott Williams & Wilkins, Inc.