Coronary-Subclavian Steal Syndrome Demonstrated by Cardiovascular Magnetic Resonance
Coronary-subclavian steal syndrome is a well-recognized complication after coronary artery bypass grafting using the internal mammary artery (IMA). It occurs when blood is diverted away from the coronary territory through the IMA to the upper limb as a result of significant stenosis in or occlusion of the proximal subclavian artery. We describe a case that was diagnosed using cardiovascular magnetic resonance (CMR).
A 56-year-old woman presented with a 10-year history of angina pectoris. For this condition she had undergone coronary angioplasty to her proximal left anterior descending coronary artery (LAD). Her angina recurred shortly after and repeat coronary angiography showed ostial LAD restenosis. She subsequently underwent coronary artery bypass grafting during which her left IMA (LIMA) was anastomosed to the LAD. After surgery, she was asymptomatic for &8 years before experiencing a recurrence of progressively worsening angina pectoris. Adenosine stress myocardial perfusion imaging showed a reversible defect in the anteroapical myocardium. Selective coronary angiography showed mild 20% stenosis in the left main stem and minor disease in the proximal LAD. Retrograde flow was present in the LIMA. The circumflex artery was patent and there was diffuse disease in the nondominant right coronary artery. On aortography, there was antegrade as well as retrograde flow in the LIMA, and the left subclavian artery was occluded at its origin. Coronary-subclavian steal syndrome was suspected, and the patient was referred for CMR for further evaluation.
Initial gradient echo imaging clearly showed the positions of the right IMA (RIMA) and the LIMA graft (Figure 1, Movie I). Phase-contrast velocity mapping of these 2 vessels in the transaxial plane (Figure 2, Movie II) showed antegrade caudally directed flow in the RIMA, but predominantly retrograde flow in the cranial direction in the LIMA (Figure 3). Contrast-enhanced magnetic resonance angiography was performed, which revealed occlusion of the proximal 2.5 cm of the left subclavian artery (Figure 4). Proximal left subclavian arterial occlusion and retrograde flow in the LIMA graft were convincing evidence of coronary-subclavian steal syndrome and accounted for the patient’s recurrent chest pain and myocardial perfusion abnormality. This case illustrates the versatility of CMR techniques for demonstrating this well-recognized complication after coronary artery bypass surgery with internal mammary grafts. The use of a variety of magnetic resonance techniques enables anatomic, functional, and flow information to be obtained in a single study.
The online-only Data Supplement, which contains 2 movies, can be found at http://circ.ahajournals.org/cgi/content/full/113/25/e930 /DC1.