Preserved hyperaemic response in (distal) string sign left internal mammary artery grafts

Objective: To correlate supraclavicular ultrasonography at rest and in hyperaemic response with angiographically patent and (distal) 'string sign' left internal mammary artery (LIMA) to left anterior descending (LAD) area grafts. Methods: Fifty-three patients with LIMA to LAD area grafting were prospectively entered in a follow-up study. Arteriography (native and LIMA) was performed at 1.4 ± 0.8 years postoperatively and ultrasonography was performed at rest, in hyperaemic response and 2 min after hyperaemic response at 1.8 ± 0.8 years postoperatively and was compared to arteriography. Ultrasonographic parameters analysed were systolic and diastolic peak velocity, systolic and diastolic velocity integral, diastolic/systolic peak velocity ratio and diastolic/total velocity integral ratio. Results: One patient was excluded because obesity hampered ultrasonography. Arteriography demonstrated functional grafts in 43 patients (group I), sequential distal 'string sign grafts' in 4 patients (group II) and total 'string sign grafts' in 5 patients (group III). Between the groups all ultrasonographic velocities showed a significant linear relation (p ≤ 0.013) at rest and during maximal hyperaemic response all velocities increased significantly within all groups (p ≤ 0.018). A significant decrease was found 2 min after hyperaemic response and diastolic velocities showed a significant linear relation (p ≤ 0.032). Conclusions: String sign LIMA grafts' were found in 9/52 (17.3%) patients. All patent and all 'string sign grafts' showed a shift towards a coronary flow profile in the proximal segment postoperatively. The study revealed the 'functionality' of the patent and the (distal) 'string sign LIMA graft' in regard to myocardial oxygen demand. 'String sign grafts' are 'recruitable' on demand.

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