Transit-time flow predicts outcomes in coronary artery bypass graft patients: a series of 1000 consecutive arterial grafts

• Published in: European journal of cardio-thoracic surgery 2010-08, Vol.38 (2), p.155-162
• Main Authors: Kieser, Teresa Mary, Rose, Sarah, Kowalewski, Ryszard, Belenkie, Israel
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Algorithms; Arterial grafts; Blood Flow Velocity - physiology; Coronary Artery Bypass - adverse effects; Coronary artery bypass surgery; Female; Humans; Intraoperative Care - methods; Male; Middle Aged; Outcomes; Prognosis; Pulsatile Flow - physiology; Reoperation; Retrospective Studies; Transit-time flow; Treatment Outcome; Vascular Patency - physiology
• ISSN: 1010-7940; 1873-734X
• DOI: 10.1016/j.ejcts.2010.01.026

Objective: This study was undertaken to evaluate transit-time flow (TTF) as a tool to detect technical errors in arterial bypass grafts intra-operatively and predict outcomes. Methods: TTF’s three parameters, pulsatility index (PI, index of resistance), flow (cc min−1) and diastolic filling (DF, proportion of diastole with coronary flow), were measured in 990/1000 (99%) of arterial grafts in 336 consecutive patients, prospectively enrolled in a database. Grafts were revised when TTF findings supported the otherwise suspected graft malfunction. If no other signs/suspicion of graft malfunction existed (normal electrocardiogram (EKG), stable haemodynamics and unchanged ventricular function on trans-oesophageal echocardiography (TEE)), and the PI was >5, grafts were not revised. Major adverse cardiac events (MACEs: recurrent angina, perioperative myocardial infarction, postoperative angioplasty, re-operation and/or perioperative death) were related to TTF measurements. Results: The average number of grafts per patient was 3.02, of which 99% were arterial. Satisfactory grafts were achieved in 916/990 (93%) of the grafts, with flows from 34 to 61 cc min−1, PI ≤5 and DF of 62–85%. Fourteen conduits, 20 grafts (2%) suspected to be problematic, were revised. Patients were divided into two groups: 277 (82%) with at least one graft with PI ≤5 and 59 (18%) with a PI >5. MACE occurred in 25 (7.4%) patients — 15/277 patients with a PI ≤5 (5.4%) and 10/59 with a PI >5 (17%, p = 0.005). Mortality following non-emergent surgery was significantly higher in patients with a PI >5 (5/54, 9%) than in patients with a PI ≤5 (5/250, 2%, p = 0.02). Flow and DF were not predictive of outcomes. Conclusion: A high PI predicts technically inadequate arterial grafts during surgery — even if all other intra-operative assessments indicate good grafts; it also predicts outcomes, particularly mortality.