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Clinical Images
Utility of Intravascular Ultrasound in the Diagnosis of Ambiguous Calcific Left Main Stenoses
July 2004
Case Report. A 42-year-old Aboriginal man was transferred from a peripheral hospital for coronary angiography. He presented a week earlier with a small anterolateral non-ST elevation myocardial infarction. He was treated with aspirin, clopidogrel, metoprolol, ramipril and a glyceryl trinitrate patch. His previous medical history included chronic renal failure for which he had been having peritoneal dialysis since 1994. His cardiovascular risk factors included continued cigarette smoking and hypertension.
His coronary angiogram, performed with a GE Medical Systems “flat panel” coronary angiographic imaging system, showed a filling defect in the distal left main coronary artery extending into the left circumflex artery (yellow arrow, panels A and B). His other coronary arteries showed evidence of non-critical, but calcified, disease.
It was felt that this filling defect may represent “pseudo-thrombosis” of a heavily calcified lesion, and thus intravascular ultrasound was utilized to define both the nature and severity of the coronary lesion. Intravascular ultrasound was performed with a 40 mHz CVIS Boston Scientific catheter using an automated pullback device at 0.5 mm.sec-1. Panel C shows the cross-sectional view of the left main coronary artery in its mid-section. The yellow tracing outlines the lumen in both panels C and D, showing a large (area = 15.8 mm2) unobstructed area in panel C. Panel D shows the IVUS image at the distal left main, where a very small residual lumen only remains (area = 2.8 mm2), due to a heavy burden of severely calcific atherosclerosis. Note that the acoustic shadowing due to the calcification makes it impossible to accurately discern the outer vessel wall structures.
Summary. This highlights the utility of IVUS in the diagnosis of uncertain pathology in the left main coronary artery and in this case the patient was able to be appropriately referred for coronary artery graft surgery. Despite improvements in coronary angiographic image quality with the advent of “flat panel” imaging systems, there clearly remains a role for intravascular ultrasound imaging in the diagnosis of coronary artery pathology.
