PMC3292475_01
The side-branch of the mammary graft from left anterior oblique (A) and lateral (B) views. (The white arrow indicates the side-branch, and the black arrow shows the string sign of the mammary main branch.).
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F1
The angiography revealed an unligated thick side-branch of the left mammary artery with a high run-off, which probably contributed to the string sign of the main branch of the mammary graft (Figure 1).
PMC3292475_02
A: String sign of the left internal mammary artery (black arrow). B: Lesion of the native left anterior descending artery (white arrow).
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F2
Coronary angiography showed an almost occluded LIMA graft (string sign) (Figure 2A) with 50-60% stenosis on the proximal part of the LAD (Figure 2B).
Pressure wire measurement of the left anterior descending artery: during the ic. injection of 100 mug of adenosine, only a nonsignificant translesional pressure gradient was provoked. The ratio of the pressure (FFR: fractional flow reserve) detected distally to the stenosis (green line) and the proximal (aortic) pressure (red line) was 0.83.
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F3
The previous myocardial scintigraphy revealed a reversible perfusion defect on the inferior wall, while pressure wire measurement on the LAD proved that the lesion of the LAD was not associated with a significant pressure gradient even during vasodilatation (FFR = 0.83) (Figure 3), suggesting sufficient remaining (competitive) flow in the native LAD.
PMC3292475_03
String sign of the left internal mammary artery graft (black arrow).
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F4
One year later, the repeated coronary angiography detected string sign of the LIMA graft (Figure 4.) and total occlusion of the venous graft.
Quantitative coronary analysis measurement of the left anterior descending artery lesion demonstrated 57% diameter stenosis on the left anterior descending artery. However, the pressure wire sensor (black arrow) detected only a nonsignificant translesional gradient during vasodilatation (FFR = 0.89), indicating appropriate competitive flow in the LAD.
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F5
Despite the 57% diameter stenosis of the LAD lesion (Figure 5.), pressure wire measurement excluded a hemodynamically significant lesion in this coronary artery.
Mammary graft before and after the reoperation with the radial graft: A,B: The left internal mammary artery graft was widely open before the reoperation (black arrow: left internal mammary artery, white arrow: anastomosis of the left internal mammary artery graft to the left anterior descending artey). C: After the reoperation involving a radial graft, the string sign developed on the previously patent left internal mammary artery graft (black arrow). D: The anastomosis of the radial graft is indicated by the white arrow. This radial anastomosis was applied more distally than the anastomosis of the mammary graft. The new bypass was administered on the left anterior descending artery as there was considered to be a significant lesion under the left internal mammary artery graft.
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F6
After 3 years repeated coronary angiography revealed the string sign of the previously patent LIMA graft because the competitive flow of the new radial graft supplied the LAD more intensively than the previous LIMA graft (Figure 6).
PMC3292475_04
String phenomenon of the internal mammary artery graft, caused by competitive flow of the left anterior descending artery because of regression of the left anterior descending artery lesion. A: Severe stenosis (as a consequence of non-occlusive thrombus formation associated with a ruptured plaque) on the left anterior descending artery (black arrow) just under the origin of a well-developed diagonal branch (left striped arrow), and on an obtus marginal of the left circumflex artery (right striped arrow). B: Three years after the bypass surgery, the contrast injection of the left coronary artery shows retrograde filling of the degenerated left internal mammary artery graft (white arrow). There is no significant stenosis at the site of the original lesion (black arrow), presumably because of the healing of the ruptured plaque with resolution of the thrombus. After the bypass surgery, the grafted diagonal and marginal branches became occluded, but the applied venous grafts provided good filling of the run-off (C: striped arrows).
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F7
Coronary angiography showed the string sign of the LIMA graft, while the venous grafts were patent (Figure 7).
PMC3292475_05
The left side shows the tight lesion of the middle left anterior descending artery before the coronary artery bypass grafting, while the right panel reveals the situation 3 years after the operation, with the short open distal part of the left internal mammary artery graft (arrow) bypassing the proximal part of the left anterior descending artery to the distal segment through the diagonal branch. The proximal part of the left internal mammary artery graft has been occluded because of the competitive flow through this connection. A slight regression of the originally very severe lesion may also be observed.
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F8
Only the short distal part of the LIMA graft was open, connecting the proximal part of the LAD to the distal segment through the diagonal branch (Figure 8).