基于术前CTA构建的计算机仿真模型探究收缩期异常尖波对非体外循环下冠状动脉旁路移植桥血管流量及近中期通畅率的影响

A computer simulation model based on preoperative CTA to investigate the effect of abnormal systolic sharp wave on graft flow and early and mid-term patency rate in off-pump coronary artery bypass grafting

目的:使用基于冠状动脉(冠脉)CT血管造影(CTA)图像构建的冠脉旁路移植(CABG)流体仿真模型,通过无创手段获得患者CABG术后桥血管血流动力学参数,并与术中实际测量瞬时桥流量参数进行对比,探讨异常尖波存在的临床意义。方法:选取2018年9月-2019年9月于我院心外科实施首次单纯非体外循环下CABG患者21例。术前完善冠脉CTA检查,术中移植后通过即时血流测量仪(transit time flow measurement,TTFM)完成桥血流测定并记录数据。对术前冠脉CTA资料进行计算机仿真处理,构建个体化模型,计算各个靶血管位点流体力学参数,并与实际手术方案桥流量进行对比。术后1周全部患者出院前完成冠脉CTA复查,术后1年完成冠脉CTA患者16例(76.2%),术后两年完成冠脉CTA复查患者9例(42.9%),术后3年完成冠脉CTA复查患者5例(23.8%)。结果:共11例患者13支桥血管存在异常尖波。通过计算机仿真模型模拟的桥血管流量与术中TTFM实测流量相比差异无统计学意义[(32.58±26.52)mL/min vs(26.66±20.94)mL/min,P=0.160]。按照有无异常尖波分组,异常尖波组中模拟流量明显高于实测流量[(17.91±15.58)mL/min vs(40.68±33.00)mL/min,P=0.006]。异常尖波组术后冠脉CT提示桥血管狭窄甚至闭塞5例(38.46%),非尖波组存在狭窄3例(6.81%),两组狭窄发生率比较差异有统计学意义(P=0.011)。结论:TTFM中收缩早期的异常尖波很可能是一种非正常血流波形,可能对桥流量存在影响,并会加剧桥血流震荡,降低远期通畅率。

Objective:To explore the clinical significance of abnormal sharp waves by using a fluid simulation model based on coronary CT angiography(CTA)images to obtain the hemodynamic parameters of the grafts by non-invasive methods,and to compare with the actual instantaneous graft flow measured during the operation by transit time flow measurement(TTFM)in coronary artery bypass grafting(CABG).Methods:A total of 21 patients who underwent the first off-pump CABG in the Department of Cardiology of our hospital from September 2018 to September 2019 were enrolled.Coronary CTA examination was completed before the operation,and the graft blood flow was measured and recorded by TTFM after CABG.The preoperative coronary CTA data were processed by computer simulation,and the individual model was constructed.The fluid dynamics parameters of each target site were calculated and compared with the actual surgical plan.All patients completed coronary CTA one week after the operation before discharge,16 patients(76.2%)completed coronary CTA one year after the operation,9 patients(42.9%)completed coronary CTA two years after the operation,and 5 patients(23.8%)completed coronary CTA three years after the operation.Results:A total of 13 grafts from 11 patients had abnormal sharp waveforms.There was no significant difference between the flow measured by TTFM and the flow simulated by the computer model([32.58±26.52]mL/min vs[26.66±20.94]mL/min,P=0.160).Grouped according to the presence or absence of abnormal sharp waveform,the simulated flow was significantly higher than the measured flow by TTFM in the abnormal sharp wave group([40.68±33.0]mL/min vs[17.91±15.58]mL/min,P=0.006).There were 5 cases of graft stenosis or even occlusion in the abnormal sharp waveform group and 3 cases of graft stenosis in the non-sharp waveform group,the difference between the two groups was statistically significant(38.46%vs 6.81%,P=0.011).Conclusion:The abnormal sharp waveform in the early systolic phase of TTFM is an abnormal blood flow waveform,which may affect graft flow and exacerbate graft blood flow turbulence,reducing long-term patency.