摘要

随着我国人口老龄化的加速和不良生活方式等危险因素的广泛流行，冠状动脉粥样硬化性心脏病（Coronary artery atherosclerotic heart disease, CHD）简称冠心病的患病率和死亡率逐年增加，预计未来10年仍处于持续上升阶段。冠状动脉旁路移植手术（Coronary artery bypass grafting, CABG）是通过重建血运通道增加有效灌注，改善心肌供血，缩小梗死面积，恢复顿抑或冬眠心肌功能，进而改善心脏整体和局部功能。CABG按照是否使用体外循环辅助技术分为体外循环CABG和非体外循环CABG。体外循环CABG需在主动脉阻断、心脏停搏的前提下进行，提供较为清晰的手术视野和相对静止的手术条件，但该术式易诱发系统性炎症反应，造成心肌缺血再灌注损伤，导致术后并发症发生风险增高。非体外循环CABG术中心脏持续跳动，避免激活炎症反应，降低体外循环所引起的多脏器功能损伤和神经系统并发症，减少了手术的出血量及输血量，但术中易发生血流动力学波动，可能造成血管化不完全。目前大量的已经发表的研究探讨了体外循环和非体外循环CABG的孰优孰劣，但仍然没有明确的共识。关于两种术式孰优孰劣讨论日益激烈，目前大量的临床资料综合比较和短期远期随访仍在进行。

超声心动图是一种简便、无创、可重复性强的检查方式，具有良好的时间和空间分辨率，可以反映心脏的解剖特点并评估心脏功能。斑点追踪显像技术（Speckle tracking imaging, STI）可灵敏地反映心肌微结构和功能，广泛地应用于心血管疾病的风险分层和预后评估。目前超声心动图联合STI在体外循环和非体外循环CABG的综合比较报道较少。两种术式对心脏结构和心肌功能的影响，及术后心功能恢复情况尚不明确，仍有待进一步研究。因此，本研究旨在探讨超声心动图联合STI对CABG患者进行综合的术前评估和术后短期及中期疗效评价，以期揭示体外循环CABG和非体外循环CABG在围术期及术后短期、中期心功能的改善及差异，为临床指导治疗和判断预后提供重要信息。

第一部分 超声心动图联合斑点追踪技术评价体外循环和非体外循环冠状动脉旁路移植术围术期心功能

目的：评估体外循环CABG和非体外循环CABG围术期心功能的变化。

方法：收集在中国医学科学院阜外医院于2019年12月-2021年1月完成择期单独CABG治疗的625例患者的临床资料和超声心动图图像，根据手术方式分为体外循环CABG组和非体外循环CABG组。分析超声心动图参数和心肌应变测量值，比较两组围术期心功能相关指标的变化。

结果：本研究患者平均年龄61.50 ± 8.88岁，男性79.36%（n=496），根据术中是否使用体外循环辅助技术，分为体外循环CABG组366例（58.56%）和非体外循环CABG组259例（41.44%）。两组患者基线资料除体表面积、心率、NYHA分级和血清肌钙蛋白-I（cTn I）外，均无明显统计学差异。术前冠脉造影结果显示，左主干动脉病变和三支病变无明显差异。体外循环CABG组比非体外循环CABG组患者有更多的桥血管数目（3.37 ± 0.80 vs 3.17 ± 0.91, P = 0.006），且两组术后峰值N末端B型利钠肽原（NT-proBNP）和cTn I 水平均较术前显著增加（P <0.01）。两组术前超声心动图常规参数和心肌应变测量值比较无明显统计学差异（P >0.05），术后早期左室射血分数和左室整体长轴应变较术前降低。同时术后早期左心室舒张末期容积指数、左心室舒张末期内径指数、左心室每搏量指数、左心室质量指数；左心房内径、左心房容积指数、右心室内径和左心房储备应变、左心房导管应变、左心房泵应变、右心室整体长轴应变、右心室游离壁应变，均较术前减小（P <0.05）。而左心室舒张末期容积指数、左心室舒张末期内径指数和左心室收缩末期内径指数存在组间差异，非体外循环CABG组高于体外循环CABG组（P <0.05）。

结论：体外循环和非体外循环CABG患者在术后早期均出现了整体和局部心功能降低，心功能的恢复仍需随访观察。

【关键词】冠状动脉旁路移植术；体外循环；超声心动图；斑点追踪技术

第二部分 超声心动图联合斑点追踪技术评价体外循环和非体外循环冠状动脉旁路移植术后3个月心功能

目的：评估体外循环CABG和非体外循环CABG术后3个月心功能的变化。

方法：收集在中国医学科学院阜外医院于2019年12月-2021年1月完成择期单独CABG治疗的508例患者术后3个月的超声心动图图像。分析超声心动图参数和心肌应变测量值，比较两组术后3个月心功能相关指标的变化。

结果：本研究根据术中是否使用体外循环辅助技术，分为体外循环CABG组296例（58.27%）和非体外循环CABG组212例（41.73%）。术后3个月平均左心室射血分数和左心室整体长轴应变分别为 58.87 ± 7.75%、-12.47 ± 4.55%，均比术后早期升高且与术前水平相近。同时两组超声心动图参数左室舒张末期内径指数、左室每搏量指数、左心房内径和左心房储备应变（LASr）、左心房导管应变、左心房泵应变（LASct）、右心室整体长轴应变（RVGLS）、右心室游离壁应变（RVFWS），均较后早期明显增大（P <0.05）。其中体外循环CABG组中LASr、LASct、RVGLS和RVFWS大于非体外循环CABG组（P <0.05）；而左心房容积指数在非体外循环CABG组多于体外循环CABG组（P <0.05）。

结论：术后3个月，体外循环CABG组比非体外循环CABG组左心房功能恢复的更显著，但两组均存在不同程度的右心室功能障碍，仍需长期观察。

【关键词】冠状动脉旁路移植术；体外循环；超声心动图；斑点追踪技术；左心房功能

第三部分 超声心动图联合斑点追踪技术评价体外循环和非体外循环冠状动脉旁路移植术后1年心功能

目的：评估体外循环CABG和非体外循环CABG术后1年心功能的变化。

方法：收集在中国医学科学院阜外医院于2019年12月-2021年1月完成择期单独CABG治疗的431例患者的术后1年超声心动图图像。分析超声心动图参数和心肌应变测量值，比较两组术后1年心功能相关指标的变化。

结果：本研究根据术中是否使用体外循环辅助技术，分为体外循环CABG组245例（56.84%），非体外循环CABG组186例（43.16 %）。术后1年平均左心室射血分数和左心室整体长轴应变分别为58.90 ± 8.28%、-12.70 ± 4.19%，与术前水平相近。两组常规超声心动图参数左心室质量指数和左心室重构指数均较术前减低，其中体外循环CABG组变化更明显（P <0.05）。非体外循环CABG组的左心房储备应变和左心房泵应变与术前水平相近。右心室整体长轴应变和右心室游离壁应变在体外循环CABG和非体外循环CABG组差异无明显统计学意义（P >0.05），但均低于术前水平（P <0.05）。

结论：右心室功能障碍在术后早期出现，至术后1年仍然存在，与是否使用体外循环无关。

【关键词】冠状动脉旁路移植术；体外循环；超声心动图；斑点追踪技术；右心室功能

Abstract

Coronary artery atherosclerotic heart disease (CHD) is a common cardiovascular disease, with increased prevalence and mortality rate, and the acceleration of population aging and widespread prevalence of risk factors make it possible to continue to rise in the next 5 years. Coronary artery bypass grafting (CABG) is an effective common revascularization treatment for severe coronary artery disease to reduce the risk of sudden cardiac death and improve myocardial function. This operation was primarily conducted with using of cardiopulmonary bypass (on-pump CABG), providing convenient way to access accurate coronary anastomosis in good version on the arrested heart. Performing CABG on the bearing heart (off-pump CABG) is less invasive approach, along with less complications caused by cardiopulmonary bypass (CPB) and manipulation of the aorta. Previous studies have shown postoperative serum myocardial enzymes levels were lower in the off-pump CABG than the on-pump CABG group, suggesting reduction in the degree of myocardial necrosis without CPB early after surgery. Some other studies have reported off-pump CABG was associated with higher long-term risk of death, increased risk of incomplete revascularization and rates of repeat revascularization than on-pump CABG. The question of whether on-pump CABG or off-pump CABG offers better myocardial function early and late after surgery, remains controversial and requires further investigations.

The strategy for evaluation preoperative heart function and myocardial function recovery at early and late after revascularization is critically important for patients underwent CABG. Magnetic resonance imaging is considered a standard technique for this purpose and can accurately investigate mechanical characteristics of myocardial deformation. However, The nature of high cost and timing-consuming limits wide use. Echocardiography is a novel, inexpensive and noninvasive modality to assess global and regional myocardial function. Speckle tracking echocardiography (STE) is based on echocardiography and developed to calculate the speed, displacement of selected region to calculate myocardial tissue motion, with less dependent on geometric assumptions and loading conditions than conventional echocardiographic parameters. Several studies have shown left ventricular global longitudinal strain (LVGLS) was more sensitive than LV ejection fraction (LVEF) to earlier find minor myocardial damage, and an independent predictor of cardiovascular outcomes.

Therefore, this study aimed to using echocardiography and strain measurements to investigate the effect of on-pump versus off-pump CABG surgery on perioperative and postoperative myocardial function.

Part I. Speckle-Tracking Echocardiography to monitor the effect of on-pump versus off-pump coronary artery bypass grafting on myocardial structure and function on perioperative period

Objective: CABG is an effective common revascularization treatment performed worldwide for severe coronary artery disease, with using CPB or not. The strategies of on-pump or off-pump CABG are still debatable and have been compared in many clinical trials, using different methods and emphasizing on specific parameters. This study aims to compare the myocardial function between on-pump and off-pump CABG during perioperative period.

Methods: This study enrolled 625 patients underwent elective isolated CABG between December 2019 and January 2021, by means of echocardiography and strain measurements, to investigate the effects of the revascularization treatment with both on-pump and off-pump techniques on myocardial function and monitor changes on myocardial function after selective isolated CABG surgery during perioperative period.

Results: The mean age of the total study population was 61.50 ± 8.88 years and 79.36% were men, divided into the on-pump CABG group (n =366, 58.56%) and the off-pump CABG group (n =259, 41.44%). There were no statistically significant differences between two groups, except for body surface area, heart rate, New York Heart Association (NYHA) functional classification and serum troponin I (cTn I). The on-pump CABG group had more grafts (3.37 ± 0.80 vs 3.17 ± 0.91, P = 0.006). Preoperative echocardiographic parameters and strain measurements were similar between two groups, the mean LVEF was 58.83 ± 9.24% in on-pump group and 59.74 ± 8.75% in off-pump group. After surgery, LVEF in off-pump group decreased to 57.84 ± 8.06% (P <0.05), while the decline in on-pump group was not statistical difference. The volumetric parameters (LVEDVI, SVI, LAVI), size parameters (LVEDDI, LAD, RVD) and LVMI decreased significantly in both groups (P <0.05) early after surgery. Meanwhile, all strain measurements in both groups were lower than its preoperative level (P <0.05). In addition, LVEDVI, LVEDDI and LVESDI were higher in off-pump group, compared with on-pump group (P <0.05).

Conclusions: The decline in myocardial function occurs early after on-pump or off-pump CABG, and the recovery of global and regional functions still requires follow-up studies.

Key words：CABG, CPB, echocardiography, strain measurements

Part Ⅱ. Speckle-Tracking Echocardiography to monitor the effect of on-pump versus off-pump coronary artery bypass grafting on myocardial structure and function by 3-month follow-up

Objective: This study aims to compare the myocardial function between on-pump and off-pump CABG at short-term follow-up (3 months).

Methods: This study used echocardiography and strain measurements to investigate the effects of the revascularization treatment with both on-pump and off-pump techniques on myocardial function and monitor changes on myocardial function after selective isolated CABG surgery at short-term follow-up (3 months).

Results: Patients was divided into the on-pump CABG group (n =296, 58.27%) and the off-pump CABG group (n =212, 41.73%). The mean LVEF and LVGLS were respectively 58.87 ± 7.75% and -12.47 ± 4.55%, which increased in both groups by 3 months. The volumetric parameters (SVI), size parameters (LVEDDI, LAD) and strain measurements (LASr, LAScd, LASct, RVGLS, RVFWS) increased in both groups  at short-term follow-up, compared with the early postoperative level (P <0.05). In addition, LAScd, LASct, RVFWS and RVGLS were higher in the on-pump group than off-pump group, while LAVI was lower in the on-pump group (P <0.05).

Conclusions: The decline in myocardial function occurs early after on-pump or off-pump CABG, and relatively reversible at 3 months. The recovery of left atrial function was earlier in the on-pump than off-pump CABG group. While both groups have different levels of right ventricular dysfunction and still need the follow-up observations.

Key words：CABG, CPB, echocardiography, strain measurements, left atrium

Part Ⅲ. Speckle-Tracking Echocardiography to monitor the effect of on-pump versus off-pump coronary artery bypass grafting on myocardial structure and function by 1-year follow-up

Objective: This study aims to compare the myocardial function between on-pump CABG and off-pump CABG by 1-year follow-up.

Methods: This study used echocardiography and strain measurements to investigate the effects of the revascularization treatment with both on-pump and off-pump techniques on myocardial function and monitor changes on myocardial function after selective isolated CABG surgery at 1-year after surgery.

Results: The study cohorts were divided into the on-pump group (n =245, 56.84%) and the off-pump group (n =186, 43.16%). The mean LVEF and LVGLS were respectively 58.90 ± 8.28% and -12.70 ± 4.19%, which were similar with its level at 3 months. The LV remodeling index decreased in both groups compared with its preoperative levels (P <0.05), while the decline of LVMI only in the on-pump CABG group showed statistical significance (P <0.05). The LASr and LASct in the off-pump CABG group were similar with its preoperative level. In addition, there are no significant intergroup difference regarding RVFWS and RVGLS, both significantly lower than preoperative level by 1 year follow-up (P <0.05).

Conclusions: Right ventricular dysfunction occurred early after surgery and remains up to 1 year, which was independent of the surgical technique.

Key words：CABG, CPB, echocardiography, strain measurements, right ventricle