犬急性心肌梗死早期冠状动脉旁路移植术对左室壁运动的影响

目的 探讨犬急性心肌梗死早期冠状动脉旁路移植术对室壁运动的影响及其在唤醒冬眠心肌中的意义.方法 结扎犬冠状动脉前降支制备心肌梗死模型(30只).按手术日期随机分组,分别在心肌梗死后1、2、4、6周行冠状动脉旁路移植术作为实验组,其中第2周4只,其余每组6只;对每个实验组分别设立心肌梗死对照组(不进行冠状动脉旁路移植术),每组2只.实验组在冠状动脉旁路移植术前及冠状动脉旁路移植术8周后开胸利用多巴酚丁胺超声负荷试验结合组织多普勒成像技术标记冬眠心肌,并测定室壁运动记分;对照组在相同时间点同样的方法标记冬眠心肌并测定室壁运动记分.每只犬处死后分别测定心肌梗死面积.结果 每个实验组各存活4只,对照组均存活.1、2周实验组较4、6周实验组及对照组梗死区心肌室壁运动记分的变化明显减小(0.03±0.06,0.05 ±0.09,0.23 ±0.08,0.27±0.06,0.32 ±0.05,P＜0.05),所有实验组较对照组心肌室壁运动记分的变化明显减小(1.195±0.09,1.25±0.18,1.30±0.18,1.36 ±0.11,1.65 ±0.17,P＜0.05),所有实验组较对照组唤醒更多的冬眠心肌(0.27 ±0.12,0.22±0.04,0.31±0.09,0.23±0.03,0.03 ±0.04,P＜0.05).1、2周实验组较4、6周实验组及对照组心肌梗死范围明显减小[(20.75±2.63)％,(21.25±2.5)％,(27.25±1.71)％,(27.75±2.22)％,(26.50±0.71)％,(29.00±1.41)％,(27.00±1.41)％,(28.50±0.71)％,P＜0.05)].结论 犬急性心肌梗死早期冠状动脉旁路移植可以明显改善心肌室壁运动,唤醒更多的冬眠心肌,尤其2周内行冠状动脉旁路移植术可以最大限度地减少梗死心肌对室壁运动的影响,并可以减少心肌梗死范围.     

心肌缺血/再灌注后多巴酚丁胺最佳应用时间探讨

目的 制作大鼠离体心脏缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)模型,比较再灌注后不同时间点给予多巴酚丁胺对心功能和心肌损伤的影响,以探索心肌缺血/再灌注(ischemia/reperfusion,I/R)后给予多巴酚丁胺的最佳时间.方法 雄性SD大鼠36只,按完全随机法分为4组(每组9只),各组在Langendorff灌注装置上建立离体心脏I/RI模型.平衡灌注15 min,缺血30 min,再灌注60 min,于再灌注期采取不同处理措施.单纯I/R组(I/R组)再灌注期全程以克-亨氏(Kreb'sHenseleit,K-H)液灌注;多巴酚丁胺一组(D1组)再灌注5 min时给予多巴酚丁胺灌注30 min,其余时间以K-H液灌注;多巴酚丁胺二组(D2组)再灌注15 min时给予多巴酚丁胺灌注30 min,其余时间以K-H液灌注;多巴酚丁胺三组(D3组)再灌注25 min时给予多巴酚丁胺灌注30 min,其余时间以K-H液灌注.其中,多巴酚丁胺输注剂量均为10 μg· kg-1·min-1.记录各组平衡灌注末(T0),再灌注10 min(T1)、20min(T2)、30min(T3)、60 min(T4)时的血流动力学指标:HR、左室舒张末压(left ventricular end diastolic pressure,LVEDP)、左室发展压(left ventricular developed pressure,LVDP)、左室内压上升/下降最大速率(the maximum rate of left ventricular pressure change,±dp/dtmax)及冠状动脉流量(coronary flow,CF).留取T0～T4各时点冠状动脉流出液,使用乳酸脱氢酶(lactate dehydrogenase,LDH)和肌酸磷酸激酶(creatine kinase,CK)试剂盒测定冠状动脉流出液中LDH和CK的活性.2,3,5-氯化三苯基四氮唑(2,3,5-triphenyl tetrazolium chloride,TTC)染色法测定心肌梗死面积(myocardial infarct size,MIS).Western blot法检测肌浆网钙泵(sarcoendoplasmic reticulum Ca2+-ATPase,SERCA2a)和兰尼碱受体(ryanodine receptors,RyR2)蛋白表达量. 结果 D1组在给予多巴酚丁胺后,HR、LVEDP、LDH、CK、MIS均比I/R组高,差异有统计学意义(P＜0.05);D2组、D3组在给予多巴酚丁胺后,HR、CF、LVDP、±dp/dtmax均高于I/R组,差异有统计学意义(P＜0.05),而LVEDP、LDH、CK、MIS比较,差异无统计学意义(JP＞0.05).多巴酚丁胺各组SERCA2a蛋白表达量和I/R组比较,差异无统计学意义(P＞0.05),而RyR2蛋白表达量则高于I/R组(P＜0.05).D2组与D3组相比在给予多巴酚丁胺后上述指标比较,差异均无统计学意义(P＞0.05). 结论 大鼠心肌FR 15 min时应用多巴酚丁胺要优于其他时间点.在这一时间点用药可以及时而有效地提高大鼠HR,增加CF,改善心肌收缩功能,且不会加重心肌损伤.     

瑞芬太尼预处理对冠状动脉旁路移植术患者体外循环期间的脑保护作用

目的 探讨瑞芬太尼预处理对冠状动脉旁路移植术患者体外循环期间的脑保护作用.方法 择期行体外循环(CPB)冠状动脉旁路移植术的患者40例,ASA Ⅱ或Ⅲ级,随机分为4组(n=10):对照组(C组)和不同剂量瑞芬太尼预处理组(R_(1～3)组).R_(1～3)组于麻醉诱导后30 min时分别静脉输注瑞芬太尼0.6、1.2和1.8 μg·kg~(-1)min~(-1),输注时间5 min,重复3次,间隔5 min;C组以生理盐水代替瑞芬太尼.于麻醉诱导前(T_0)、CPB开始前(T_1)、CPB 30 min(T_2)、CPB结束(T_3)时取颈内静脉血样3 ml,采用ELISA法测定血浆S-100β蛋白浓度,采用比色法测定血浆超氧化物歧化酶(SOD)活性和丙二醛(MDA)浓度.结果 与T_0时比较,T_(1～3)时各组血浆S-100β蛋白和MDA浓度升高,SOD活性降低(P<0.05或0.01);与C组比较,R_3组T_(2,3)时血浆S-100β蛋折和MDA浓度降低,SOD活性升高(P<0.05),R_1组和R_2组上述指标差异无统计学意义(P>0.05).结论 瑞芬太尼(1.8μg·kg~(-1)min~(-1))预处理可减轻冠状动脉旁路移植术患者CPB诱发脑损伤,其机制可能与抑制脑脂质过氧化反应有关.     

七氟醚预处理对体外循环冠状动脉旁路移植术病人围术期心肌的保护作用

目的探讨七氟醚预处理对体外循环(CPB)下冠状动脉旁路移植术(CABG)病人心肌的保护作用。方法择期CPB下CABG病人40例,ASAⅡ级或Ⅲ级,随机分为2组(n=20):七氟醚组(S组)或异丙酚组(P组)。麻醉维持:P组靶控输注异丙酚,血浆靶浓度2～3μg/L,静脉输注芬太尼2～3μg·kg~(-1)·h~(-1);S组夹闭主动脉前,吸入0.5%～2%七氟醚,静脉输注芬太尼2～3μg·kg~(-1)·h~(-1),夹闭主动脉后靶控输注异丙酚,血浆靶浓度2～3μg/L,静脉输注芬太尼2～3μg·kg~(-1)·h~(-1)。于切皮前即刻、CPB前即刻、CPB后即刻、回ICU后即刻、6、12h记录心率(HR)、平均动脉压(MAP)、肺动脉楔压(PCWP)、中心静脉压(CVP)、心脏指数(CI)、体循环血管阻力指数(SVRI)。于麻醉诱导前、回ICU后即刻、6、12、24h采集静脉血,测定血清心肌肌钙蛋白I(cTnI)浓度。记录术后不良事件的发生情况。结果2组各时点MAP、PCWP、CVP、HR和SVRI比较差异无统计学意义(P>0.05);与切皮前即刻和P组比较,S组回ICU后各时点CI升高(P<0.05)。与P组比较,S组回ICU后各时点cTnI浓度降低(P<0.05)。2组病人术后均无死亡;2组心肌梗塞、房颤和心肌缺血的发生率差异无统计学意义(P>0.05);S组cTnI浓度>2ng/ml的发生率低于P组(P<0.05)。结论七氟醚预处理对体外循环下冠状动脉旁路移植术病人围术期心肌具有一定的保护作用。     

心脏移植长期存活患者冠状动脉病变一例

目的　探讨 1例心脏移植长期存活患者冠状动脉病变的原因、诊断和处理。方法　对1例心脏移植术后存活 8年的患者进行长期随访。结果　术后患者生活质量好 ,恢复正常工作 ;血液生化正常 ;心电图无心肌缺血改变 ;肱动脉内皮依赖性血管舒张功能正常 ;心内膜心肌活检未见急性排斥反应征象 ;同位素心肌显像提示左室壁心肌放射性分布进行性减低 ;冠状动脉造影显示左冠状动脉弥漫性狭窄、右冠状动脉近段有一局限性严重狭窄 (>90 % )、远端为轻度弥漫性狭窄 ,行右冠状动脉近段成形和支架植入 ,同位素心肌显像示左室壁心肌放射性分布明显改善。结论　慢性排斥反应可能是导致移植心冠状动脉病变的重要原因 ;定期行同位素心肌显像检查有助于了解心肌血液供应 ;严重的局限性冠状动脉病变可应用冠状动脉成形和支架植入予以治疗。     

异丙酚对大鼠两侧脑半球各皮质脑电互近似熵的影响

目的 探讨异丙酚对大鼠两侧脑半球顶叶、额叶和枕叶皮质脑电互近似熵(C-ApEn)的影响.方法 雄性SD大鼠36只,体重300～350 g,随机分为3组(n=12),分别于左右顶叶(Ⅰ组)、额叶(Ⅱ组)和枕叶(Ⅲ组)埋置硬膜外电极,连续监测自发腩电.于大鼠清醒状态下连续记录20 min脑电图,取最后2 min的脑电图进行后期分析并记为基础值;然后静脉输注异丙酚,初始输注速率为400μg·kg~(-1)·min~(-1),每次递增100 μg·kg~(-1)·min~(-1),直至900μg·kg~(-1)·min~(-1),每个速率持续输注10 min,取最后2 min的脑电图进行后期分析,计算不同异丙酚输注速率时两侧脑半球的C-ApEn.于埋置电极前1周时测定不同异丙酚输注速率时大鼠翻正反射和夹尾反射消失情况.结果 所有大鼠异丙酚500～600μg·kg~(-1)·min~(-1)时翻正反射消失,800～900 μg·kg~(-1)·min~(-1)时夹尾反射消失.各组给予异丙酚后的C-ApEn均低于清醒状态时,且随异丙酚剂量的增加C-ApEn逐渐降低(P<0.05).结论 异丙酚可剂量依赖性地降低两侧脑半球顶叶、额叶和枕叶皮质的信息交流和联系.C-ApEn是与异丙酚麻醉效应相关的敏感的非线性腩电参数.     

瓣膜置换术患者心肺转流后多巴酚丁胺与米力农对心肌应变力的影响

目的探讨瓣膜置换术后早期多巴酚丁胺与米力农对心肌应变力的影响。方法择期心肺转流(CPB)下行瓣膜置换术患者55例,男27例,女28例,年龄40～75岁,ASAⅡ或Ⅲ级,NYHA心功能Ⅱ或Ⅲ级。采用随机数字表法将患者分为三组:多巴酚丁胺组(D组,n=18)、米力农组(M组,n=20)和对照组(C组,n=17)。三组术中麻醉维持均采用全凭静脉麻醉,D组于停CPB15min后经微量注射泵静注多巴酚丁胺4μg·kg~(-1)·min~(-1)至1h结束,M组于同一时点开始经微量注射泵静注米力农0.4μg·kg~(-1)·min~(-1)至1h结束,C组于同一时点开始经微量注射泵静注等量生理盐水至1h结束。分别于麻醉诱导后劈胸骨前(T0)和停CPB后15min(T1)、泵药后30min(T2)和1h(T3)记录血流动力学指标:HR、CVP、CO、LVEF、右室面积变化分数(RVFAC)、心脏指数(CI)、外周血管阻力指数(SVRI)和应变力参数:左室长轴全局纵向应变力(S-LVL)、左室短轴全局环向应变力(S-LVM)和右室长轴全局纵向应变力(S-RV)。结果 T2、T3时D组HR明显快于M组,T3时D组HR明显快于C组(P0.05);T2时D组CI明显高于C组和M组(P0.05)。T2、T3时D组和M组左室短轴环向应变力S-LVM明显高于C组(P0.05);T3时D组S-LVL与M组S-RV明显高于C组(P0.05)。结论 CPB后静脉输注小剂量多巴酚丁胺能够改善S-LVL与S-RV,米力农有助于增加S-LVm与S-RV。     

速度向量成像技术对梗死心肌和缺血心肌纵向运动的研究

目的 应用速度向量成像(velocity vector imaging,VVI)技术分析梗死心肌和缺血心肌纵向运动特点,评价VVI技术测定心肌运动功能的价值.方法选择2007年12月-2008年1月行超声心动图检查者,其中梗死组6例,均为急性前肇心肌梗死;缺血组9例,前降支狭窄＞70%,有心绞痛症状;正常对照组16例.应用Sequoia 512超声成像仪在VVI技术模式下采集心尖左心室长轴和左心室两腔心切面动态图像.采用Syngo US workplace工作站对图像进行脱机分析,定量分析左心室前壁和前间隔梗死节段、缺血节段和正常节段的纵向速度、位移、应变和应变率. 结果 正常对照组左心室前壁和前间隔纵向收缩期峰值速度(Vs)和峰值位移(D)自基底段向心尖段递减,差异有统计学意义(P＜0.05):峰值应变(S)和收缩期峰值应变率(SRs)在基底段、中间段和心尖段上差异无统计学意义(P＞0.05).梗死组心肌各项指标均较正常对照组和缺血组减低,S和SRs减低更明显,差异均有统计学意义(P＜0.05).缺血组心肌仅前壁基底段和中间段的S显著低于正常对照组(P＜0.05).以任意节段S＜-6.94%作为诊断急性心肌梗死的临界值,敏感度和特异度均为100%;以任意节段SRs＜-0.81%作为诊断急性心肌梗死的临界值,敏感度为100%,特异度为80%;以任意节段SRs＜-0.46%作为诊断急性心肌梗死的临界值,其敏感度为83%,特异度为100%. 结论 VVI技术具有准确定量评价急性心肌梗死的临床应用价值,尤其足应变和应变率能提供更多有价值的信息.     

非体外循环与改良灌注体外循环下冠状动脉旁路移植术对心肌损伤影响558例的回顾性队列研究

目的 探讨体外循环下冠状动脉旁路移植术(ONCAB)与非体外循环冠状动脉旁路移植术(OPCAB)对心肌损伤的差异.方法 2017～2019年北京安贞医院对558例冠状动脉粥样硬化性心脏病患者施行了冠状动脉旁路移植术,根据是否应用改良灌注的体外循环,将患者分为两组.OPCAB组(OP组):465例,男282例、女183例...     

耐受ProSeal喉罩成人所需雷米芬太尼的ED50

目的 测定患者在保持自主呼吸、清醒状态下耐受Proseal喉罩所需雷米芬太尼的半数有效量(ED50).方法 择期全麻手术患者60例,按照随机、双盲原则分为六组,每组10例.雷米芬太尼剂量分别为0.061、0.048、0.039、0.03、0.025和0.02 μg·kg~(-1)·min~(-1),在喉罩置入5 min后开始输注.开始持续输注前每位患者先给予单剂量的雷米芬太尼0.25 μg/kg.持续输注25 rnin后观察喉罩耐受反应.分别计算雷米芬太尼的ED50.结果 保持自主呼吸、清醒状态下的患者耐受喉罩所需的雷米芬太尼ED60为0.027 μg·kg~(-1)·min~(-1),95%可信区间为0.023～0.030 μg·kg~(-1)·min~(-1).结论 持续输注小剂量雷米芬太尼可以使患者在清醒状态下耐受喉罩的刺激,且保持血流动力学稳定.     

Changes in regional myocardial function after coronary artery bypass graft surgery are predicted by intraoperative low-dose dobutamine echocardiography

BACKGROUND: Left ventricular dysfunction is often reversed after coronary artery bypass graft (CABG) surgery; however, this change is not easily predicted. The authors hypothesized that functional changes after a low dose of dobutamine (5 microgram. kg-1. min-1) intraoperatively would predict functional changes when complete revascularization was achieved. METHODS: The authors analyzed 560 segments in 40 patients scheduled for elective CABG surgery for regional wall motion (1-5 scoring system) at four stages: baseline (after induction and intubation), with administration of low-dose dobutamine before cardiopulmonary bypass, after separation from cardiopulmonary bypass (early), and after administration of protamine (late). Two independent observers scored the myocardial regions according to a 16-segment model in multiple imaging planes. For each segment, the response to dobutamine was dichotomized as improved or not improved from baseline and analyzed with logistic regression. The influence of covariates (ejection fraction, myocardial infarction, diabetes mellitus, and beta blockers) was also determined with logistic regression models. P < 0.05 was considered significant. RESULTS: Changes in myocardial function after low-dose dobutamine were highly predictive for early (P < 0.0001) and late (P < 0.0001) changes in myocardial function from baseline regional scores. The overall odds ratio for early and late improvement increased by 20.7 and 34.6, respectively, when improvement was observed after low-dose dobutamine was administered. The overall positive predictive value of improved regional wall motion after CABG did not vary with left ventricular ejection fraction, a history of myocardial infarction, or beta blocker use, and it varied little with diabetic status (range, 0.86-0.96) if regional wall motion improved with low-dose dobutamine before CABG. The overall negative predictive value was 0.70; however, the range varied with diabetic status (i.e., lowest in diabetic patients and highest in nondiabetic patients). CONCLUSION: Intraoperative low-dose dobutamine is a reliable method to predict myocardial functional reserve and to determine functional recovery expected after coronary revascularization.     

Changes in Regional Myocardial Function after Coronary Artery Bypass Graft Surgery Are Predicted by Intraoperative Low-dose Dobutamine Echocardiography

Background: Left ventricular dysfunction is often reversed after coronary artery bypass graft (CABG) surgery; however, this change is not easily predicted. The authors hypothesized that functional changes after a low dose of dobutamine (5 [mu]g [middle dot] kg-1 [middle dot] min-1) intraoperatively would predict functional changes when complete revascularization was achieved.

Methods: The authors analyzed 560 segments in 40 patients scheduled for elective CABG surgery for regional wall motion (1-5 scoring system) at four stages: baseline (after induction and intubation), with administration of low-dose dobutamine before cardiopulmonary bypass, after separation from cardiopulmonary bypass (early), and after administration of protamine (late). Two independent observers scored the myocardial regions according to a 16-segment model in multiple imaging planes. For each segment, the response to dobutamine was dichotomized as improved or not improved from baseline and analyzed with logistic regression. The influence of covariates (ejection fraction, myocardial infarction, diabetes mellitus, and [beta] blockers) was also determined with logistic regression models. P < 0.05 was considered significant.

Results: Changes in myocardial function after low-dose dobutamine were highly predictive for early (P < 0.0001) and late (P < 0.0001) changes in myocardial function from baseline regional scores. The overall odds ratio for early and late improvement increased by 20.7 and 34.6, respectively, when improvement was observed after low-dose dobutamine was administered. The overall positive predictive value of improved regional wall motion after CABG did not vary with left ventricular ejection fraction, a history of myocardial infarction, or [beta] blocker use, and it varied little with diabetic status (range, 0.86-0.96) if regional wall motion improved with low-dose dobutamine before CABG. The overall negative predictive value was 0.70; however, the range varied with diabetic status (i.e., lowest in diabetic patients and highest in nondiabetic patients).     

Is there a long-term predictive value of intraoperative low-dose dobutamine echocardiography in patients who have coronary artery bypass graft surgery with cardiopulmonary bypass?

In patients with coronary artery disease, chronic regional left ventricular systolic dysfunction at rest may be caused by hibernating or by infarcted myocardium. Intraoperative low-dose dobutamine (LDD) echocardiography reliably predicts the immediate recovery of regional myocardial function after coronary artery bypass graft (CABG) surgery. We sought to determine whether intraoperative LDD echocardiography would also predict recovery of regional function after 1 yr. Twenty-five patients with coronary artery disease who underwent CABG surgery with intraoperative LDD echocardiography were evaluated 1 yr later with a follow-up transthoracic echocardiogram. The covariates of left ventricular ejection fraction, old myocardial infarction, and diabetes mellitus were considered in an analysis of regional wall motion (RWM). A 16-segment model and a 1-5-point scoring system were used to evaluate 350 myocardial segments. Multiple logistic regression analysis was performed to determine whether response to intraoperative LDD echocardiography (5 microg. kg(-1). min(-1)) predicted changes in regional function at 1 yr. A segment was defined as stunned if the RWM score obtained during LDD infusion deteriorated after cardiopulmonary bypass but recovered in the 1-yr follow-up echocardiogram. A response to intraoperative LDD predicted changes in regional function at 1 yr. The overall odds of improvement in regional function were 2.22 times greater (95% confidence interval = 1.29, 3.82; P = 0.0039) with a positive response to intraoperative LDD. The positive predictive value of intraoperative LDD echocardiography for improvement in myocardial function was 0.81 and the negative predictive value was 0.34. The predictive values did not vary with the examined covariates. Of segments with unexpected deterioration of RWM immediately after cardiopulmonary bypass, 87% recovered at the time of the 1-yr follow-up echocardiogram. Contractile reserve demonstrated by intraoperative LDD echocardiography predicts regional function at 1 yr; however, the test cannot predict which segment will not recover. Most of unexpected regional ventricular systolic dysfunction immediately after CABG surgery can be attributed to myocardial stunning. IMPLICATIONS: In patients undergoing coronary artery bypass graft surgery, intraoperative low-dose dobutamine echocardiography has only limited value for the prediction of regional myocardial function at 1 yr. Small-dose dobutamine echocardiography predicts regional myocardial function at 1 yr when baseline regional wall motion abnormalities improve with dobutamine; however, the test cannot be used to predict which segment will not recover at 1 yr.     

Does intraoperative evaluation of left ventricular contractile reserve predict myocardial viability? A clinical study using dobutamine stress echocardiography in patients undergoing coronary artery bypass graft surgery

To determine the contractile reserve of the left ventricle during reperfusion as a predictor of myocardial viability in patients undergoing coronary artery bypass graft surgery, we measured the response of left ventricular regional wall motion and thickening by using dobutamine stress echocardiography (DSE) after myocardial revascularization. All patients were monitored with radial and pulmonary arterial catheters, transesophageal echocardiography, standard five-lead clinical electrocardiography, and three-channel Holter electrocardiography. Immediately after separation from cardiopulmonary bypass, dobutamine was administered IV starting at 5 microg. kg(-1). min(-1), with increases in rate every 3 min to 10, 20, 30, and 40 microg. kg(-1). min(-1). Within 1 wk after surgery, resting and redistribution thallium-201 myocardial perfusion imaging (thallium studies) was performed to assess the relationship between the intraoperative contractile response and myocardial viability. One-hundred patients completed DSE up to 10 microg. kg(-1). min(-1), and 85 patients received the larger escalating doses of the DSE. Seventy-two patients had postoperative thallium studies. At the completion of the small-dose dobutamine infusion, 689 (97.7%) of 705 segments had a normal response (improvement), and 16 segments (2.3%) had a positive response (deterioration). During large-dose dobutamine infusion, 577 (95.8%) of 602 segments had a normal response, and 25 segments (4.2%) had a positive response. Myocardial segments that had a positive response during large-dose DSE (48%) were more likely to be considered as nonviable on postoperative thallium studies compared with segments that had a normal response (14.7%) (P < 0.00001). By using thallium studies as the reference standard, the sensitivity of DSE was low (31% and 48% for small- and large-dose DSE, respectively) in predicting nonviable myocardium. However, the specificity was higher (86% and 85% for small- and large-dose DSE, respectively). In a separate analysis of patients who developed new regional wall motion abnormalities (RWMA) in the early intraoperative reperfusion period, 15 (75%) of 20 abnormally contracting myocardial segments had normal postoperative thallium studies. Our results demonstrate that a normal response to DSE is highly specific for viable myocardium; however, a positive response to DSE has low sensitivity in predicting nonviable myocardium. The majority of new postbypass regional wall motion abnormalities appear to be related to stunned myocardium.     

Transesophageal echocardiography during coronary bypass surgery]

The early diagnosis of intraoperative myocardial ischemia is important because such ischemia can lead to myocardial infarction. Clinical effectiveness of transesophageal echocardiography (TEE) was evaluated for detecting intraoperative myocardial ischemia and for observing the recovery of cardial motion at the end of cardiopulmonary bypass (CPB) in 20 patients who had undergone CABG. After endotracheal intubation, the TEE transducer was introduced into the esophagus to obtain a short axis cross-sectional view of the left ventricle at the level of the papillary muscles. Global LV function was assessed by measuring end-diastolic and end-systolic areas, which were calculated automatically, and the fractional area change (FAC). Regional endocardial wall motion was also analyzed by subdivision into four anatomical segments. The mean FACs were 48% after intubation, 47% after skin incision and 48% after sternotomy. Thereafter it increased significantly to 59% 30 minutes after CPB and 56% at the end of the operation. Thus, global LV function was improved significantly by revascularization. TEE could detect myocardial ischemia more sensitively than ECG. In 9 patients, FAC decreased significantly and new regional wall motion abnormality (RWMA) appeared around the time of sternotomy, but no ECG changes were detected. In another 7 patients, new RWMAs were detected without either a decrease in the FAC or ECG changes. It was found that myocardial ischemia took place more frequently before the initiation of CPB than expected. The recovery of left ventricular wall motion from cardioplegic arrest was able to be monitored visually during the period of weaning from CPB and the TEE could facilitated prompt and exact judgement of weaning from CPB.(ABSTRACT TRUNCATED AT 250 WORDS)     

Echocardiographic analysis of dysfunctional and normal myocardial segments before and immediately after coronary artery bypass graft surgery.

Echocardiography has revealed evidence of "subnormal" regional contraction patterns that result from myocardial ischemia and are often accompanied by nonadjacent "hyperkinetic" regions. Whether these regions of hyperkinetic wall motion persist unchanged or revert to normal after coronary artery bypass graft (CABG) surgery has not been studied in humans. Using echocardiography, we evaluated both dysfunctional and normal myocardial regions for changes in segmental wall motion and percent of systolic wall thickening that occurred immediately after CABG surgery in 32 patients. Segmental wall motion analysis before CABG surgery in these patients revealed that 170 (66%) of 256 myocardial segments were subnormal, of which 115 (67%) improved and 102 (60%) returned to normal immediately after CABG surgery. Eleven myocardial segments that were hyperkinetic before CABG surgery returned to normal after CABG surgery. Preoperatively, 162 (63%) of 256 myocardial segments had systolic wall thickening less than 30%, which increased from 11.8% +/- 8.9% to 24.3% +/- 14.3% (mean +/- SD) (P less than 0.01) postoperatively. Conversely, a reverse trend was found when systolic wall thickening was greater than 30% before CABG surgery: thickening decreased from 46.2% +/- 13.8% to 33.4% +/- 14.8% after CABG surgery (P less than 0.01). Thus, we conclude that immediately after CABG surgery, there is a recovery of function in some myocardial segments and a reduction in function in others. Furthermore, we conclude that the semiquantitative assessment of percent of systolic wall thickening is a more reliable (consistent) echocardiographic index of myocardial function compared with the qualitative assessment of segmental wall motion immediately after CABG surgery.     

Factors excercising an influence on recovery of hibernating myocardium after coronary artery bypass grafting.

OBJECTIVE: Coronary artery bypass grafting (CABG) in patients with endstage coronary disease (CAD) significantly improves symptoms and prolongs life expectancy. Left ventricular function is also improved in some patients, but not in others. Factors which influence functional recovery of hibernating myocardium after revascularization are at present under investigation. METHODS: From 3/2000 to 8/2002, we analyzed 41 patients with an ejection fraction (EF) of < or =30%, who underwent CABG, prospectively. All patients received low-dose dobutamine echocardiography (DE), dobutamine myocardial scintigraphy with SPECT, dobutamine magnetic resonance tomography (MRI), contrast-enhanced MRI and, when necessary, positron emission tomography (PET). Hibernating myocardium (area of interest) was identified with these diagnostic tools preoperatively and biopsy samples were taken intraoperatively. RESULTS: All patients received complete coronary revascularization. Early mortality was 2.4%. Three patients died during follow-up. Six months after the operation DE, MRI and SPECT were repeated. EF increased in 23 patients (group I) by at least >or =5%, and in 14 patients (group II) it did not improve. The wall motion score in the area of interest had increased during preoperative DE in group I significantly. The score did not change in group II. In addition the diastolic-systolic wall thickness increase in the area of interest rose >15% during DE in group I preoperatively; the increase was < or =15% in group II. MRI hyperenhancement of the left ventricle was significantly lower in group I compared to group II preoperatively. SPECT showed myocardial viability in the area of interest in all 37 patients. There were no significant differences between group I and II seen in SPECT. When the area of interest was located in the anterior wall the patients more frequently showed ventricular improvement postoperatively than patients with an area of interest located in the inferior, lateral or posterior wall. Light microscopy showed more severe myocardial cell hypertrophy (>19 microm) and less severe destruction of myocardial cell architecture in biopsies of group I compared to group II (myocardial cell hypertrophy < or =17 microm). Electron microscopy showed mitochondrial abnormalities in size and shape, lack of contractile material and large areas containing nonspecified cytoplasm, lipid droplets, and large glycogen-filled regions, but no significant differences between the two groups. Gene expresssion of the pro-apoptotic genes BAK and BAX was lowered compared to expression in 'normal' myocardium. The anti-apoptotic gene BCL-XL was significantly more expressed in the 'area of interest' of group II patients than in group I patients. CONCLUSIONS: We conclude that in patients with endstage CAD myocardial recovery after coronary revascularization can be predicted using DE and MRI preoperatively. Myocardial regions without any potential of functional recovery show less adaptation (less pronounced myocardial cell hypertrophy), a more severe degree of myocardial architecture destruction and a higher degree of anti-apoptotic gene expression. We recommend a myocardial biopsy when DE and MRI are not favorable in a patient with end stage coronary artery disease referred to us with the option of heart transplantation or coronary bypass.     

Echocardiographic demonstration of improved myocardial function early after coronary artery bypass graft surgery

The time course of recovery of left ventricular (LV) function after coronary artery bypass grafting (CABG) surgery is largely unknown. We aimed to test the hypothesis that LV function improves shortly after CABG by using echocardiography to elucidate myocardial contractility before and after CABG, and to determine the segmental distribution of viable myocardium. We prospectively studied 42 patients undergoing elective isolated CABG. No selection was done regarding preoperative LV ejection fraction. All patients underwent serial transthoracic two-dimensional echocardiography preoperatively, and at two to four days and six to seven weeks postoperatively. Regional wall motion was evaluated at each examination, and wall motion score index (WMSI) was calculated to assess recovery of contractile function. WMSI improved by surgery (P=0.005), stepwise from preoperatively to two to four days postoperatively (P=0.05) and borderline significantly between the two postoperative examinations (P=0.06). One hundred and one (15%) of 670 segments had abnormal contraction preoperatively; of which 69 were hypokinetic and 32 were akinetic. At six to seven weeks postoperatively a normalization of function was found in 35 (51%) hypokinetic and four (13%) akinetic segments. Our data suggest that CABG improves myocardial contractility within the first days postoperatively. Echocardiographic determination of wall motion is a useful tool to observe LV function.     

Myocardial perfusion correlates with improvement of systolic function of the left ventricle after CABG. Dobutamine echocardiography and Tc-99m-MIBI SPECT study.

OBJECTIVE: The aim of the study was to assess the effect of surgical revascularization [coronary artery bypass grafting (CABG)] on systolic function and perfusion of the left ventricle using dobutamine echocardiography (DE) and Tc-99m-MIBI SPECT (SPECT). METHODS: There were 32 patients mean age 52.2+/-7.2 years in whom DE and SPECT were performed before and 3-4 months after CABG using standard protocols. Wall motion score index (WMSI) and perfusion index (PI) were calculated. RESULTS: Significant improvement of WMSI at rest (1.44+/-0.46 vs 1.33+/-0.41; P=0.03) as well as after maximal dose of dobutamine (1.49+/-0.42 vs 1.39+/-0.44; P=0.02) was observed after CABG as compared to preoperative examination. Similar relation was observed during SPECT study. Perfusion index diminished significantly after revascularization during rest acquisition (2.19+/-0.71 vs 1.93+/-0.70; P=0.0008) and after Dipirydamole administration (2.73+/-0.73 vs 2.20+/-0.69; P=0.0001) as compared to preoperative examination. We found correlation between PI and WMSI at rest before CABG (R=0.46; P=0.01), PI after Dipirydamole and WMSI after maximal dose of Dobutamine before CABG (R=0.37; P=0.04), PI and WMSI at rest after CABG (R=0.39; P=0.03), PI after Dipirydamole and WMSI after dobutamine after CABG (R=0.38; P=0.03). CONCLUSIONS: Surgical revascularization significantly improves both perfusion and contractility. Increased perfusion after CABG correlates with improvement of systolic function of the left ventricle.     

Deterioration of regional wall motion immediately after coronary artery bypass graft surgery is associated with long-term major adverse cardiac events

BACKGROUND: Patients undergoing coronary artery bypass graft (CABG) surgery frequently develop wall motion abnormalities diagnosed by intraoperative transesophageal echocardiography. However, the relation between deterioration in wall motion and postoperative morbidity or mortality is unclear. Therefore, the authors hypothesized that deterioration in intraoperative left ventricular regional wall motion immediately after CABG surgery is associated with a higher risk of adverse cardiac events. METHODS: With institutional review board approval, data were gathered from 1,412 CABG surgery patients. Echocardiographic wall motion score (WMS) was derived using a 16-segment model. Outcomes data were gathered for up to 2 yr after surgery. The primary outcome, major adverse cardiac event, was a composite index of myocardial infarction, need for subsequent coronary revascularization, or all-cause mortality during the follow-up period. RESULTS: Two hundred twenty-one patients (16%) had 254 primary outcome events during follow-up. Postbypass WMS did not change in 812 patients (58%), deteriorated in 219 patients (16%), and improved in 368 patients (26%). Kaplan-Meier analysis showed that patients with deterioration in WMS after CABG experienced significantly lower major adverse cardiac event-free survival than patients with either no change or improvement in WMS (P = 0.004). Cox proportional hazards regression modeling revealed a significant association between deterioration in WMS and the composite adverse outcome (hazard ratio, 1.47 [1.06-2.03]; P = 0.02). CONCLUSIONS: The authors confirmed their hypothesis that deterioration in wall motion detected by intraoperative echocardiography after CABG surgery is associated with increased risk of long-term adverse cardiac morbidity. Worsening wall motion after CABG surgery should be considered a prognostic indicator of adverse cardiovascular outcome.