Original article
Cardiovascular
Transit-Time Flow Measurement is Essential in Coronary Artery Bypass Grafting

https://doi.org/10.1016/j.athoracsur.2004.06.010Get rights and content

Background

Patent bypass grafts are fundamental to successful coronary artery bypass grafting. Intraoperative flow measurement through newly constructed grafts is a test of patency. We studied the use of transit-time flow measurement to determine its ability to detect technical errors in grafts, to measure the mean flow norms for Asian patients, and to compare arterial and vein grafts.

Methods

From January 1, 2001, to June 30, 2002, 116 patients underwent isolated primary coronary artery bypass grafting. Sixty-seven patients underwent conventional coronary artery bypass grafting and 49 patients underwent off-pump coronary artery bypass grafting. There were 125 arterial and 197 vein grafts. Transit-time flow measurement was carried out on all completed grafts. Graft patency was assessed using flow curves, mean flow, and pulsatility index. Average of mean flows was calculated to determine mean flow norms. Arterial and vein grafts were compared by statistical analysis between the variables mean flow and pulsatility index.

Results

In 6 patients with seven grafts, intraoperative graft assessment detected technical errors, which were corrected. Average mean flow was 37.4 ± 23.5 mL/min for left anterior descending coronary artery–to–left internal mammary artery grafts, and values ranging from 21.2 to 36.0 mL/min for the rest. There were no statistically significant differences in mean flow or pulsatility index between arterial and vein grafts.

Conclusions

Transit-time flow measurement enables technical problems to be diagnosed accurately, allowing prompt revision of grafts. It should be mandatory in coronary artery bypass grafting to improve surgical outcomes.

Section snippets

Patients and Methods

From January 1, 2001, to June 30, 2002, 116 patients underwent primary isolated CABG within a single surgical service. Sixty-seven patients (58%) underwent conventional CABG, and 49 (42%) underwent off-pump CABG. There were 84 men and 32 women, of which there were 17 Malays, 11 Indians, 85 Chinese, and 3 Eurasians. Mean age was 60.7 ± 9.5 years, and mean body surface area was 1.69 ± 0.18 m2. There were 125 IMA grafts and 197 saphenous vein grafts (SVGs). The mean number of grafts was 2.9 per

Results

Of the 116 patients, 6 patients had seven grafts in which a high PI, low mean flow, unsatisfactory flow curve, or all of them were detected using the transit-time flowmeter. Problems included IMA that was occluded or stretched, or SVGs that were kinked, twisted, or stenosed at anastomotic sites. In all cases the problems were corrected at the time of surgery, resulting in satisfactory flows. When an unsatisfactory flow was observed in the vein graft, the graft was carefully inspected for the

Comment

Transit-time flow measurement gives important and accurate intraoperative information about the status and patency of each individual graft. It enables technical problems such as kinked, twisted, or stenotic grafts to be diagnosed accurately, thereby allowing prompt revision of the constructed grafts before the patient leaves the operating room. Thus, hemodynamic instability during the early postoperative period is possibly prevented and the probability of early graft failure is minimized

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