Winning Abstracts from the 2009 Medical Student Abstract Competition: Unmasking Subclavian Steal Syndrome
Authors: First Author: Roy Lin, Ross University School of Medicine 2010, Second Author: Rakesh Gupta, MD, FACP, Interventional Cardiologist at North Shore LIJ, New York Hospital Queens and Saint Vincent Catholic Medical Center
Subclavian steal syndrome describes a condition where retrograde vertebral artery flow results in cerebral ischemia that is associated with transient neurological symptoms. Retrograde vertebral flow is a result of the lower pressure in the distal subclavian artery receiving flow from the contralateral vertebral artery via the basilar artery.
A 66-year-old man presented to the emergency room with a syncopal episode. The patient described non-radiating chest pain that was 8/10 in intensity, which prompted self-administration of sublingual nitroglycerin. Subsequently, the patient began to feel light-headed and passed out. On admission, the patientís blood pressure was 104/62 mmHg. He was afebrile with normal oxygen saturation and heart rate. ECG monitoring showed normal sinus rhythm of 71 beats per minute with no ST changes. There was no elevation of troponin or CK-MB on serial testing. Head CT was normal. Echocardiogram showed normal LV function with no vegetation or mass. When a more detailed physical examination was performed, the patient was noted to have unequal upper extremity blood pressures with 123/77 on the right arm and 101/72 on the left arm Additional history revealed complaints of left arm pain when lifting heavy objects. Carotid doppler was later performed indicating left subclavian stenosis. Suspicion of subclavian steal syndrome was confirmed via MRI. Left heart catheterization and aortogram with left subclavian angiogram were performed. A stent was placed in the left subclavian artery at the bifurcation of the vertebral artery. Following the procedure the patient remained symptom-free and denied any pain in the left arm when lifting. Blood pressures were equal in both arms. He was discharged on nitroglycerin as needed.
This case describes the importance of pertinent history-taking and a thorough physical examination when patients present with syncope of unknown etiology. As illustrated in this case, the patientís syncopal episode may have easily been attributed to the use of self- administered nitroglycerin. With the findings of his history of arm pain and of unequal upper extremity blood pressures, subclavian steal syndrome was suspected and correctly diagnosed. Recognition of this syndrome allowed for proper intervention, leading to stent placement and, hopefully, the prevention of future syncopal episodes.
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