Intraoperative Fluorescence Imaging after Transit-Time Flow Measurement during Coronary Artery Bypass Grafting

Objective This report describes the complementary use of transit-time flow measurement (TTFM) and intraoperative fluorescence imaging (IFI) during off-pump coronary artery bypass grafting (OPCAB) and compares their results with those of subsequent coronary angiography. Methods The subjects were 159 OPCAB patients, with a total of 435 grafts at a single center between April 2009 and November 2011. During surgery, all grafts were assessed initially by both TTFM and IFI. Transit-time flow measurement was used for screening grafts for possible revision, then IFI was applied to check patency. For IFI, indocyanine green was injected into the superior vena cava, then the presence and timing of fluorescent enhancement were monitored in coronary and graft vessels. Results Twelve grafts were revised after poor TTFM scores. Despite some poor TTFM scores even after revision, subsequent IFI showed that all grafts were enhanced. However, two grafts showed delayed enhancement. In one internal thoracic artery (ITA), delay was caused by competitive flow from a mildly stenotic native coronary artery. The other delayed-enhancement ITA was revised. Reanastomosis was constructed with shorter ITA at the larger lumen size. After about 1 week, all patients underwent coronary angiography (plain angiography for 31, computed tomography angiography for 128). These demonstrated that all 385 arterial grafts, and 48 out of 50 venous grafts, were patent. Conclusions Our OPCAB series using TTFM and IFI achieve extremely high graft patency in the early graft assessments. “Delayed enhancement” of one ITA in comparison with the other suggested either native competitive flow or a bypass graft problem.

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The Accuracy of Transit Time Flow Measurement in Predicting Graft Patency after Coronary Artery Bypass Grafting

Innovations Technology and Techniques in Cardiothoracic and Vascular Surgery ◽

10.1097/imi.0000000000000021 ◽

2013 ◽

Vol 8 (6) ◽

pp. 416-419 ◽

Cited By ~ 14

Author(s):

Patrick F. Walker ◽

William T. Daniel ◽

Emmanuel Moss ◽

Vinod H. Thourani ◽

Patrick Kilgo ◽

...

Keyword(s):

Coronary Artery ◽

Coronary Artery Bypass Grafting ◽

Transit Time ◽

Pulsatility Index ◽

Flow Measurement ◽

Artery Bypass ◽

Graft Patency ◽

Bypass Grafting ◽

Flow Measurements ◽

Time Flow

Objective Transit time flow measurement (TTFM) is a method used to assess intraoperative blood flow after vascular anastomoses. Angiography represents the criterion standard for the assessment of graft patency after coronary artery bypass grafting (CABG). The purpose of this study was to compare flow measurements from TTFM to diagnostic angiography. Methods From October 9, 2009, to April 30, 2012, a total of 259 patients underwent robotic-assisted CABG procedures at a single institution. Of these, 160 patients had both TTFM and either intraoperative or postoperative angiography of the left internal mammary artery to the left anterior descending coronary artery graft. Transit time flow measurements were obtained after completion of the anastomosis and after administration of protamine before chest closure. Transit time flow measurement assessment included pulsatility index, diastolic fraction, and flow (milliliters per minute). Angiograms were graded according to the Fitzgibbon criteria. The patients were grouped according to angiographic findings, with perfect grafts defined as FitzGibbon A and problematic grafts defined as either Fitzgibbon B or O. Results Overall, there were 152 (95%) of 160 angiographically perfect grafts (FitzGibbon A). Of the eight problematic grafts, five were occluded (Fitzgibbon O) and three had significant flow-limiting lesions (FitzGibbon B). Two patients had intraoperative graft revision after completion angiography, one had redo CABG during the same hospitalization, and five were treated with percutaneous coronary intervention. A significant difference was seen in mean ± SD flow (34.3 ± 16.8 mL/min vs 23.9 ± 12.5 mL/min, P = 0.033) between patent and nonpatent grafts but not in pulsatility index (1.98 ± 0.76 vs 1.65 ± 0.48, P = 0.16) or diastolic fraction (73.5% ± 8.45% vs 70.9% ± 6.15%, P = 0.13). Conclusions Although TTFM can be a useful tool for graft assessment after CABG, false negatives can occur. Angiography remains the criterion standard to assess graft patency and quality of the anastomosis after CABG.

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