CLINICAL EVALUATION OF TRANSIT-TIME FLOW MEASUREMENT AS A BIOMEDICAL ENGINEERING TOOL FOR INTRAOPERATIVE QUALITY ASSESSMENT DURING CORONARY ARTERY BYPASS GRAFTING

Abstract

Background: The accuracy intraoperatively measuring whether a bypass graft will function properly is vital in achieving a successful result for coronary artery bypass graft surgery. Traditional assessment of graft quality through visual and tactile examination is subjective and does not always disclose any technical problem until after the chest has been closed. Transit Time flowmetry (TTFM), an ultrasonic flow detection technique, provides an objective measurement of graft blood flow dynamics and has become a useful Biomedical Engineering technology in the assessment of quality during operations. But we are unaware if this technique is beneficial in a quantitative fashion for different left internal mammary artery (LIMA) harvesting methods during CABG. Objective: To evaluate the effectiveness of Transit-Time Flow Measurement as a biomedical engineering technology for intraoperative graft quality assessment during isolated CABG and to determine its ability to objectively characterize graft hemodynamics. Methods: The prospective observational study was carried out on 45 patients undergoing elective isolated CABG at Deptt of cardiovascular & thoracic surgery SKIMS Srinagar. Intrapoperative assessment of the graft was carried out immediately after finishing the coronary anastomosis by means of TTFM Transit Time Flow Measurement. Mean Graft flow, Pulseatility index, diastolioc Filling%, and waveform pattern were measured as objective indicators of graft performance. Statistical comparisons were done using unpaired students t-test &, when necessary, Fisher’s exact test. Results: Transit-Time Flow Measurement yielded meaningful intraoperative evaluation of all patients. The Skeletonized LIMA group experienced significantly higher Mean Graft Flow (46.8 ± 9.3 mL/min versus 37.4 ± 8.1 mL/min; p = 0.001), significantly lower Pulsatility Index (2.1 ± 0.5 versus 2.8 ± 0.7; p = 0.002) and significantly greater Diastolic Filling percentage (72.4 ± 6.8% versus 64.1 ± 7.5%; p < 0.001). The representative waveform analysis showed predictable and acceptable waveforms with consistent predominantly diastolic flow. The objective data generated by TTFM offered a real-time, real-world view of the conduit during surgery. Conclusion: Transit-Time Flow Measurement is a practical biomedical technology for reliable intraoperative qualitative and quantitative evaluation of coronary bypass graft quality. Quantitative evaluation of Mean Graft Flow, Pulsatility Index and Diastolic Filling percentage provides a consistent objective tool that can be used by the surgeon to assist intraoperative assessment and improve quality assurance during CABG, laying the groundwork for an artificial intelligence approach.