非体外循环冠状动脉旁路移植术后早期血流动力学和心肌损伤的观察

目的观察非体外循环冠状动脉旁路移植术（OPCAB）后早期血流动力学变化及心肌损伤。方法选择20例择期OPCAB患者,连续监测血流动力学变化,并记录麻醉诱导后10min（T0）、血运重建后30min（T1）、2h（T2）、6h（T3）、12h（T4）、24h（T5）的血流动力学参数,同时测定血浆肌酸激酶同功酶（CK-MB）、心肌肌钙蛋白1（cTnI）和N端B型脑钠肽（NT—proBNP）浓度。吻合血管前和血运重建后30min分别取右心房心肌组织透射电镜观察超微结构的变化。结果围术期SBP和DBP无明显变化,但血运重建后HR增快（P〈0．01）、CVP、肺动脉楔压（PCWP）、平均肺动脉压（MPAP）和心指数（cI）升高（P〈0．01）,而体循环阻力（SVR）、体循环阻力指数（SVRI）、每搏数（SV）、每搏指数（SVI）和左室每搏功指数（LVSWI）降低,右室每搏功指数（RVSWI）仅在血运重建后2h降低（P〈0．01）。CK-MB和cTnI从血运重建后持续升高（P〈0．05）,尤以血运重建后24h为明显。NT-proBNP在血运重建后12h内无显著变化,但在血运重建后24h显著升高（P〈0．01）。透射电镜下见血运重建后肌丝结构较术前模糊,线粒体有变形,结构不清晰,嵴模糊。结论OPCAB血运重建后早期存在心肌损伤和左右心功能下降,以左心为著。     

Myocardial injury after off-pump coronary artery bypass grafting operation.

OBJECTIVE: Perioperative myocardial ischemia is less pronounced in off-pump coronary artery bypass (OPCAB) compared to on-pump coronary artery bypass; however, the threshold over which the postoperative release of cardiac troponin I (cTnI) release and creatine kinase-MB (CK-MB) after OPCAB should be considered clinically relevant is unknown. The study was designated to evaluate if perioperative myocardial damage, measured by means of postoperative release of cTnI and CK-MB, has an influence on short- and mid-term outcome after OPCAB operations. METHODS: Two hundred and sixty-one unselected patients undergoing OPCAB had cTnI and CK-MB measured preoperatively and nine times postoperatively. Postoperative peak values were evaluated and the 80th percentiles were used to segregate the population into two groups for each marker. The following cut-offs were used: 7.1 ng/dl for cTnI peak and 36.3 ng/dl for CK-MB peak. RESULTS: Patients with cTnI>7.1 ng/ml (n=51) and CK-MB>36.3 ng/ml (n=48) had a longer mechanical ventilation and ICU length of stay. Nevertheless, hospital mortality did not differ between groups. Survival after 3 years was 92.8+/-2.3% and 81.8+/-6.2 for patients with postoperative cTnI peak7.1 ng/ml, respectively (p=0.003). It was 93+/-2.2% and 80+/-6.8% for patients with CK-MB36.3 ng/ml, respectively (p=0.005). Adjusted hazard ratios for mid-term mortality were HR 2.7 (CI 1-7.6), p=0.05 for cTnI>7.1 ng/dl and HR 3.1 (CI 1-9.1), p=0.04 for CK-MB>36.3 ng/ml. CONCLUSION: Perioperative myocardial damage should not be considered an innocuous event following OPCAB operations since the survival rate over 3 years is significantly worse in patients with the highest postoperative peak release of cTnI and CK-MB.     

A prospective randomized study to evaluate splanchnic hypoxia during beating-heart and conventional coronary revascularization

Objective: Cardiopulmonary bypass (CPB) is associated with gut mucosal hypoxia, which may contribute to gastrointestinal complications. We examined gastric mucosal oxygenation together with whole-body oxygen flux in low-risk patients undergoing coronary artery bypass grafting (CABG) with and without CPB. Methods: Fifty-four patients undergoing primary CABG by the same surgeon were randomized into either on-pump (ONCAB, n=27) or off-pump (OPCAB, n=27) groups. The ONCAB group underwent mild hypothermic (35°C) pulsatile CPB with arterial line filtration. Each patient underwent perioperative monitoring with continuous tonometry and cardiac output devices. Gastric intramucosal pH (pHi), gastric-arterial carbon dioxide partial pressure difference (CO₂ gap), whole-body oxygen delivery (DO₂) and consumption (VO₂) and whole-body oxygen extraction fraction were measured at sequential time-points intraoperatively and up to 6 h postoperatively. Anaesthetic management was standardized. Results: Both groups had similar demographic makeup and extent of revascularization (ONCAB 2.6±0.9 grafts versus OPCAB 2.5±0.8 grafts; P=0.55). The ONCAB group had a mean (±SD) CPB time of 62±25 min and aortic cross-clamp time of 32±11 min. In both groups there was a similar and progressive drop in pHi intraoperatively. Postoperatively, there was a gradual separation between the groups with ONCAB patients showing no further decline in pHi, while further deterioration was observed in the OPCAB group up to 6 h postoperatively. There was a significant difference between the groups over time (P=0.03). There was a corresponding progressive rise in CO₂ gap perioperatively in both groups, with ONCAB patients demonstrating superior preservation of gastric mucosal oxygenation in the early postoperative period. Global oxygen utilization measurements showed superior DO₂ and VO₂ in the OPCAB group throughout the study. Conclusions: Despite superior global oxygen flux associated with beating-heart revascularization, gastric mucosal hypoxia occurred to similar extents in both groups with worsening trends for the OPCAB patients postoperatively. The splanchnic pathophysiology during beating-heart revascularization should be further explored.     

A prospective randomized study of diluted versus non-diluted cardioplegia (minicardioplegia) in primary coronary artery bypass surgery

AIM: Sanguineous (blood) cardioplegia has been established as the prime option for myocardial protection but the choice of dilution (4:1 blood to crystalloid ratio) versus use of blood from the cardiopulmonary bypass alone (minicardioplegia) remains controversial. The purpose of this prospective randomized clinical trial was to compare the clinical outcome and enzymatic endpoints (troponin I, CK-MB isoenzyme release) in patients undergoing primary CABG surgery. METHODS: From June 1999 to October 2000, 59 patients were randomized preoperatively to undergo coronary artery bypass grafting surgery using cardiopulmonary bypass and either diluted (4:1 blood to crystalloid ratio; n=25) or undiluted sanguineous cardioplegia (minicardioplegia; n=4) at the Montreal Heart Institute. Clinical data and biochemical markers of ischemia were recorded. Tepid cardioplegia and moderate hypothermic cardiopulmonary bypass were used in 92% of patients. RESULTS: There were no significant differences in preoperative variables between the 2 groups. There were no statistically significant differences in low output syndrome, stroke rate, arrhythmia or hospital length of stay between both groups. There was no statistically significant difference between minicardioplegia and diluted groups in the release of troponin T 24 hours postoperatively (0.36+/-0.31 versus 0.23+/-0.22, respectively). There was a slightly higher release of troponin T in the minicardioplegia group 48 hours after surgery (0.38+/-0.35 versus 0.20+/-0.16) (p=0.03) and of CK-MB 24 hours postoperatively (22.9+/-18.6 versus 10.2+/-5.3) (p<0.01). CONCLUSION: Clinical outcomes are similar in patients undergoing primary CABG surgery with tepid cardioplegia and moderate hypothermic bypass with diluted or minicardioplegia. Minicardioplegia may be the optimal method of myocardial protection because of low cost, ease of use and lack of hemodilutive effect.     

The supportive value of pre-bypass L-glutamate loading in patients undergoing coronary artery bypass grafting

AIM: Experimental studies have demonstrated that an exogenous supply of glutamate improves mechanical function and recovery of ischemic myocardium. The aim of the present study was to investigate the effect of myocardial pre-bypass loading with glutamate on myocardial protection during global ischemia and reperfusion of patients undergoing coronary artery bypass grafting (CABG). METHODS: The study was double blinded. Twenty patients undergoing elective CABG were randomized to receive L-glutamate (n = 10) or normal saline (n = 10). Intracellular levels of glutamate, ATP and lactate were measured in left ventricular biopsies collected 10 min after aortic clamp release. Hemodynamic data, and postoperative release of CK-MB and troponin T were also measured. RESULTS: Pre-bypass administration of glutamate resulted in myocardial glutamate loading since glutamate levels were significantly higher in the glutamate group of patients than in controls (18.6 +/- 3.1 versus 8.7 +/- 1.2 microg/g tissue, P < 0.001). In the same group ATP levels were also significantly higher (2.4 +/- 0.7 versus 1.5 +/- 0.4 microg/g tissue, P < 0.05) and lactate levels significantly less than in controls (6.9 +/- 1.9 versus 12.0 +/- 2.1 microg/g tissue, P < 0.001). Glutamate patients had statistically significantly superior post-bypass hemodynamic performance (cardiac index, left ventricular stroke work index, systemic vascular resistance and pulmonary vascular resistance). Statistically significantly lower levels of CK-MB (6 h postoperative), total and peak CK-MB, troponin T (24 h postoperative), and total troponin T were found in the glutamate group. CONCLUSIONS: The results of this preliminary study indicate that pre-bypass intravenous administration of glutamate in patients undergoing CABG has a supportive effect on myocardial metabolism during global ischemia and reperfusion, improves patients' postoperative hemodynamic performance and reduces postoperative cardiac enzyme release.     

Comparison of active and passive coronary perfusion in off-pump coronary artery bypass grafting

The myocardial protective effects of active and passive coronary perfusion were compared during off-pump coronary artery bypass grafting (OPCAB) in coronary stenosis model. An internal shunt tube was placed in the proximal left anterior descending arteries of adult dogs to produce a 75% coronary stenosis model. In 10 animals passive coronary perfusion was performed using an internal shunt tube placed in a pseudo-anastomotic site, and active coronary perfusion was performed through an external shunt tube. Ischemia was examined at normal and low blood pressure, based on hemodynamics, regional myocardial blood flow, and oxygen and lactate extraction in the perfused area. With passive perfusion, regional myocardial blood flow decreased and oxygen extraction and regional lactate production increased at normal blood pressure, indicating myocardial ischemia. Regional myocardial blood flow further decreased at low blood pressure. In contrast, regional myocardial blood flow with active perfusion did not change at normal or low blood pressure, and oxygen and lactate extraction were unchanged, indicating prevention of myocardial ischemia. Myocardial ischemia can occur with passive perfusion even at normal blood pressure. Active coronary perfusion that provides sufficient regional perfusion prevents myocardial ischemia during coronary artery anastomosis in OPCAB.     

老年人非体外循环冠状动脉旁路移植术的心肌保护作用

目的比较70岁以上老年人非体外循环冠状动脉旁路移植术(OPCAB)和体外循环冠状动脉旁路移植术(CABG)围术期心肌损伤程度,探讨OPCAB的心肌保护效果。方法30例老年患者分为两组,A组15例,为CABG组,B组15例,为OPCAB组。分别于术前、术中30min、术中1h、术后6h、12h、24h、72h、120h取静脉血标本,分别测定心肌肌钙蛋白I(cTnI)水平和CKMB活性;另外记录围手术期各项临床指标。结果OPCAB组术后辅助呼吸时间较CABG组短(P<0.01),而且主动脉球囊反搏和输血例数较低(P<0.05)。CABG组与OPCAB组cTnI、CKMB的术前水平相,术后6hcTnI即有升高而后下降,术后30min至72h均较OPCAB组明显升高(P<0.05或0.01)。结论与CABG相比,OPCAB的心肌损伤较轻,心肌保护效果较好。     

Cardiac troponin I release after open heart surgery: a marker of myocardial protection?

Background. Unlike creatine kinase MB isoenzyme, cardiac troponin I (cTnI) is a highly specific marker of myocardial injury. Its release has recently been studied after coronary artery bypass grafting operation. However, its significance after open heart surgery (OHS) remains to be determined. This protein release could be a marker of myocardial protection. We sought to study cTnI release after OHS in patients with normal coronary arteries and to compare it with cTnI release in patients after coronary artery bypass graft (CABG) surgery.

Methods. Eighty-five patients undergoing OHS and 86 patients undergoing CABG were enrolled in the study. CTnI concentrations were measured in serial venous blood samples drawn before surgery and immediately, 12 hours, 24 hours, 48 hours, and 5 days after aortic unclamping.

Results. In the OHS group and in the CABG group without acute myocardial infarction (AMI), cTnI peaked at 12 hours postoperatively (6.35 ± 6.5 and 5.38 ± 8.55 ng/mL, respectively) and normalized on day 5 postoperatively (0.57 ± 2 and 0.72 ± 1.62 ng/mL, respectively). CTnI concentration did not differ significantly between the OHS group and the CABG group in the absence of AMI for any samples considered. In the CABG group, 2 patients had AMI. In the OHS group, cTnI levels at 12 hours postoperatively were found to correlate closely with CPB and aortic cross-clamping (ACC) times, contrary to the CABG group, which correlated only with occurrence of AMI. CTnI release was independent of age and ejection fraction in either group.

Conclusions. cTnI release in patients after OHS with normal coronary arteries has the same profile as cTnI release in patients after CABG in the absence of AMI. However, its peak at 12 hours postoperatively is only correlated to ACC and CPB times, which is contrary to cTnI release after CABG surgery. This observation suggests that cTnI could be a marker of myocardial ischemia after OHS.     

Inflammatory response and myocardial injury following coronary artery bypass grafting with or without cardiopulmonary bypass

Objective: In coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB) the inflammatory response is suggested to be minimized. Coronary anastomoses are performed during temporary coronary occlusion. Inflammatory response and myocardial ischaemia need to be studied in a randomized study comparing CABG in multivessel disease with versus without CPB. Methods: Following randomization 30 consecutive patients received CABG either with (n=16) or without CPB (n=14). Primary study endpoints were parameters of the inflammatory response (interleukin (IL)-6, interleukin-10, ICAM-1, P-selectin) and of myocardial injury (myoglobin, creatine kinase-MB (CK-MB), troponin I) (intraoperatively, 4, 8, 16, 24 and 48 h after surgery). The secondary endpoint was clinical outcome. Results: The incidence of major (death: CABG with CPB n=1, not significant (n.s.)) and minor adverse events (wound infection: with CPB n=2, without CPB n=1, n.s.; atrial fibrillation: with CPB n=3, without CPB n=2, n.s.) was comparable between both groups. The release of IL-6 was comparable during 8 h of observation (n.s.). Immediately postoperatively IL-10 levels were higher in the operated group with CPB (211.7±181.9 ng/ml) than in operated patients without CPB (104.6±40.3 ng/ml, P=0.0017). Thereafter no differences were found between both groups. A similar pattern of release was observed in serial measures of ICAM-1 and P-selectin, with no difference between both study groups (n.s.). Eight hours postoperatively the cumulative release of myoglobin was lower in operated patients without CPB (1829.7±1374.5 μg/l) than in operated patients with CPB (4469.8±4525.7 μg/l, P=0.0152). Troponin I release was 300.7±470.5 μg/l (48 h postoperatively) in patients without CPB and 552.9±527.8 μg/l (P=0.0213). CK-MB mass release was 323.5±221.2 μg/l (24 h postoperatively) in operated patients without CPB and 1030.4±1410.3 μg/l in operated patients with CPB (P=0.0003). Conclusions: This prospective randomized study suggests that in low-risk patients the impact of surgical access on inflammatory response may mimic the influence of long cross-clamp and perfusion times on inflammatory response. Our findings indicate that multiregional warm ischaemia, caused by snaring of the diseased coronary artery, causes considerably less myocardial injury than global cold ischaemia induced by cardioplegic cardiac arrest.     

Does warm antegrade intermittent blood cardioplegia really protect the heart during coronary surgery?

OBJECTIVE: Intermittent antegrade blood cardioplegia (IABC) has been standardized as a routine technique for myocardial protection in coronary surgery. However, if the myocardium is known to tolerate short periods of ischemia during hypothermic arrest, it may be less tolerant of warm ischemia, so the optimal cardioplegic temperature of intermittent antegrade blood cardioplegia is still controversial. The aim of this study was to compare the effects of warm intermittent antegrade blood cardioplegia and cold intermittent antegrade blood cardioplegia on myocardial pH and different parameters of the myocardial metabolism. METHODS: Thirty patients undergoing first-time isolated coronary surgery were randomly allocated into two groups: group 1 (15 patients) received warm (37 degrees C) intermittent antegrade blood cardioplegia and group 2 (15 patients) received cold (4 degrees C) intermittent antegrade blood cardioplegia. The two randomization groups had similar demographic and angiographic characteristics. Total duration of cardiopulmonary bypass (108+/-17 and 98+/-21 min) and of aortic cross-clamping (70+/-13 and 65+/-15 min) were similar. The cardioplegic solutions were prepared by mixing blood with potassium and infused at a flow rate of 250 ml/min for a concentration of 20 mEq/l during 2 min after each anastomosis or after 15 min of ischemia. Intramyocardial pH was continuously measured during cardioplegic arrest by a miniature glass electrode and values were corrected by temperature. Myocardial metabolism was assessed before aortic clamping (pre-XCL), 1 min after removal of the clamp (XCL off) and 15 min after reperfusion (Rep) by collecting coronary sinus blood samples. All samples were analyzed for lactate, creatine kinase (MB fraction), myoglobin and troponin I. Creatine kinase and troponin I were also daily evaluated in peripheral blood during 6 days post-operatively. RESULTs: The clinical outcomes and the haemodynamic parameters between the two groups were identical. In group 1, XCL off and Rep were associated with higher coronary sinus release of lactate (5.5 +/- 1.8 and 2.2 +/- 0.5 mmol/l) than in group 2 (2.0 +/- 0.7 and 1.6 +/- 0.3 mmol/l, P < 0.05). Mean intramyocardial pH was lower in group 1 (7.23 +/- 0.08) than in group 2 (7.65 +/- 0.30, P < 0.05). There were no significant differences between the two groups with respect of creatine kinase (MB fraction) either after Rep or during the post-operative period. Lower coronary sinus release of myoglobin was detected at Rep in group 1 (170 +/- 53 microg/l) than in group 2 (240 +/- 95 microg/l, P < 0.05). At day 1, a lower release of troponin I was found in group 1 (0.11 +/- 0.07 g/ml) compared to group 2 (0.17 +/- 0.07 ng/ml, P < 0.05). CONCLUSION: With regards to similar clinical and haemodynamic results, myocardial protection induced by warm IAEX is associated with more acidic conditions (intramyocardial pH and lactate release) and less myocardial injury (myoglobin and troponin I release) than cold intermittent antegrade blood cardioplegia during coronary surgery.     

Intermittent Antegrade Tepid Versus Cold Blood Cardioplegia in Elective Myocardial Revascularization

Background. The ideal temperature for blood cardioplegia administration remains controversial.

Methods. Fifty-two patients who required elective myocardial revascularization were prospectively randomized to receive intermittent antegrade tepid (29°C; group T, 25 patients) or cold (4°C; group C, 27 patients) blood cardioplegia.

Results. The two cohorts were similar with respect to all preoperative and intraoperative variables. The mean septal temperature was higher in group T (T, 29.6° ± 1.1°C versus 17.5° ± 3.0°C; p < 0.0001). After reperfusion, group T exhibited significantly greater lactate and acid release despite similar levels of oxygen extraction (p < 0.05). The creatine kinase-MB isoenzyme release was significantly lower in group T (764 ± 89 versus 1,120 ± 141 U · h/L; p < 0.04). Hearts protected with tepid cardioplegia demonstrated significantly increased ejection fraction with volume loading, improvement in left ventricular function at 12 hours, and decreased need for postoperative inotropic support (p < 0.05). The frequency of ventricular defibrillation after cross-clamp removal was lower in this cohort (p < 0.05). There were no hospital deaths, and both groups had similar postoperative courses.

Conclusions. Intermittent antegrade tepid blood cardioplegia is a safe and efficacious method of myocardial protection and demonstrates advantages when compared with cold blood cardioplegia in elective myocardial revascularization.     

Coronary perfusion methods during off-pump coronary artery bypass: results of a randomized clinical trial

BACKGROUND: Several techniques are being used to perform off-pump coronary artery bypass (OPCAB) grafting. This three-armed clinical trial was performed to determine whether one OPCAB method of coronary perfusion was superior over the others with respect to myocardial protection and performance. METHODS: Over the course of 11 months, 151 consecutive unselected patients underwent elective first-time OPCAB grafting by sternotomy performed by a single surgeon. Patients were prospectively randomized to receive one of three OPCAB coronary perfusion treatments: (1) no coronary perfusion (NCP), ie, OPCAB using no coronary perfusion during the distal anastomosis or graft perfusion after the distal anastomosis until all the proximal anastomoses were completed; (2) passive coronary perfusion (PCP), providing distal coronary perfusion during the anastomosis and immediate graft perfusion after the distal anastomosis by means of a passive cannula from the aorta; or (3) active coronary perfusion (ACP), providing assisted distal coronary perfusion and graft perfusion by means of an in-line pump (perfusion-assisted direct coronary artery bypass. Hemodynamic and biochemical data were recorded to disc continuously throughout the operation and postoperatively. RESULTS: With no statistically significant differences in the three treatment groups with respect to patient age, left ventricular systolic or diastolic function, and extent and distribution of coronary disease or grafts performed, cardiac performance postoperatively was superior in the active coronary perfusion group compared to the groups receiving either passive coronary perfusion or no coronary perfusion (p < 0.001). In addition, troponin I levels were lower in the coronary perfusion groups (PCP and ACP) (p = 0.023). CONCLUSIONS: Providing active coronary perfusion during the anastomosis and after each distal anastomosis by using an in-line pump resulted in superior myocardial protection and performance during OPCAB surgery when compared to either no coronary perfusion or passive coronary perfusion.     

Simultaneous lung resection for cancer and myocardial revascularization without cardiopulmonary bypass (off-pump coronary artery bypass grafting)

Backround

Patients with resectable lung cancer and unstable coronary heart disease are at high risk of postoperative death or severe cardiovascular complications. The aim of this study was to present the early results of radical lung resection for cancer with simultaneous myocardial revascularization on the beating heart (off-pump coronary artery bypass [OPCAB]).

Methods

From 1999 to 2002, thirteen patients (9 men and 4 women, aged 54 to 71 years, mean age 64 yrs) with resectable lung cancer and unstable angina or a recent history of myocardial infarction, were operated on. All of them underwent coronary angiography and neither coronary angioplasty nor stenting were feasible. Eight lobectomies, three pneumonectomies, and two wedge resections were carried out together with aortocoronary graft implantation (mean number of grafts: 1.7 per patient). Myocardial revascularization without cardiopulmonary bypass (OPCAB) preceded the lung resections. The preferred approach to the heart and lung was by sternotomy.

Results

There were no postoperative deaths in this group of patients. The most frequent postoperative complication was prolonged air leakage and one patient required respiratory support for two days. In one patient, significant blood loss was observed with a need for rethoracotomy. Transient supraventricular cardiac arrhythmias occurred in three patients. None of the patients showed evidence of myocardial ischemia after surgery. Patients were followed up for 7 to 36 months. None had acute myocardial infarction. In one patient, who underwent lobectomy, local recurrence was found. In another patient, who underwent pneumonectomy, distant metastases occurred in the third year of observation.

Conclusions

Lung resection carried out simultaneously with OPCAB is a safe and effective method for the treatment of lung cancer and myocardial ischemia.     

Active distal coronary perfusion to prevent regional myocardial ischemia in off-pump coronary artery bypass grafting.

Regional myocardial ischemia during anastomosis in off-pump coronary artery bypass (OPCAB) can occasionally cause hemodynamic instability. To prevent regional myocardial ischemia and stabilize the hemodynamics during the procedure, perfusion of the distal coronary artery to the anastomotic site is necessary as the only reliable method. We have applied an active coronary perfusion method using a servo-controlled pump in selected patients in place of conventional passive perfusion methods (intraluminal shunt and external shunt). We present a case in which the active perfusion method proved useful in avoiding regional myocardial ischemia. A 74-year-old male patient with triple-vessel coronary disease underwent OPCAB for unstable angina. During revascularization of the main right coronary artery, the hemodynamics collapsed due to regional myocardial ischemia. As soon as the distal coronary artery was perfused at a high flow rate around 80 ml/min, the hemodynamics stabilized and the operation was completed successfully. This active coronary perfusion method in OPCAB is particularly useful in cases in which regional myocardial ischemia cause hemodynamic instability.     

On- and off-pump coronary surgery and perioperative myocardial infarction: an issue between incomplete and extensive revascularization.

OBJECTIVE: Complete myocardial revascularization is the standard for coronary artery bypass grafting. It has been shown, however, that off-pump coronary bypass surgery (OPCAB) may reduce completeness of revascularization without affecting perioperative myocardial infarction rates. We evaluated the influence of OPCAB on major postoperative events in a large consecutive cohort of patients, with special emphasis on risk factors for perioperative myocardial infarction. METHODS: From 1995 to 2004, 5935 patients underwent isolated coronary bypass surgery; of these, 4623 (77.9%) and 1312 (22.1%) underwent on-pump coronary surgery (CABG) and OPCAB, respectively. Patients undergoing OPCAB were matched to patients undergoing CABG by propensity score; logistic regression analysis models were used to study predictors of perioperative myocardial infarction. RESULTS: In matched pairs, postoperative mortality, myocardial infarction, stroke, and atrial fibrillation were similar between groups, while reoperation for bleeding, time on ventilator and red blood cell use were lower in patients undergoing OPCAB. The number of distal anastomoses was lower in patients undergoing OPCAB (2.2+/-0.80 in OPCAB vs 2.9+/-0.86 in CABG, p<0.001), as well as complete revascularization rates (61.9% in OPCAB vs 90.0% in CABG, p<0.001). Multivariate analyses, performed on preoperative and intraoperative variables, showed that both incomplete revascularization and increasing numbers of distal anastomoses (even when controlling for completeness of revascularization) were significant predictors of perioperative myocardial infarction, while CABG/OPCAB strategy did not influence it. CONCLUSIONS: The choice of surgical technique did not influence the occurrence of major perioperative complications and of myocardial infarction, which is negatively affected by incomplete or too extensive revascularization strategies.     

非体外循环冠状动脉旁路移植术的心肌保护

目的　比较非体外循环心脏跳动下冠状动脉旁路移植术 (OPCAB)与常规体外循环下冠状动脉旁路移植术 (CABG)的心肌保护效果。方法　将 70例冠状动脉粥样硬化病人分成 2组 ,行非体外循环冠状动脉旁路移植术组 (非体外循环组 35例 ) ,间断冷氧合血心脏停搏液冠状动脉旁路移植术组 (冷血停跳组 35例 )。 2组病人术前心功能、年龄、性别、体质量差异无统计学意义 ;各组于围术期不同时点分别抽血测定肌酸激酶同工酶 (CK MB)、心肌肌钙蛋白T(cTnT)。关胸前每组各随机取 2例病人心尖区心肌 ,行心肌超微结构观察。结果　非体外循环组术中、术后各时间点CK MB、cTnT与冷血停跳组比较差异有显著性 (P <0 0 5 ) ;非体外循环组心肌超微结构表明心肌保护效果明显优于后者。结论　非体外循环组心肌保护效果优于冷血停跳组。与CK MB相比 ,cTnT是评价心肌损害的更特异、更敏感的指标。     

Beating heart coronary artery bypass grafting for acute myocardial infarction

We consider that off-pump coronary artery bypass grafting (CABG) [OPCAB], which results in local myocardial ischemia, is more effective for patients with acute myocardial infarction (AMI) than conventional CABG under cardiac arrest with global myocardial ischemia. Twenty-one patients (15 males, 6 females) received OPCAB for AMI, among whom surgery was performed following percutaneous coronary intervention (PCI) failure in 4 and PCI was performed prior to OPCAB in 2, while PCI was not performed in the remaining 15. Preoperatively, 16 patients had intraaortic balloon pumping (IABP), and 4 had IABP and percutaneous cardiopulmonary support (PCPS). The mean interval from onset to surgery was 11.7 (range 3 to 40) hours. In 20 cases, a complete revascularization was performed. The mean number of bypasses was 2.3 and OPCAB was carried out in 14 patients. In 2 cases, OPCAB was converted to on-pump beating CABG for complete revascularization. Fourteen patients (67%), each maintained with preoperative left ventricular ejection fraction (EF), were discharged with an elective bypass. Four patients died after on-pump beating CABG, in whom EF was lower than 10%. In addition, 3 died of low cardiac output syndrome (LOS) under PCPS and 1 of ventricular fibrillation. Based on our results, we considered that complete revascularization using OPCAB was effective for cases of AMI with PCI difficulty. However, in shock cases requiring PCPS, cardiac function was not improved even after revascularization. Therefore, it is necessary to study new procedures for shock cases during the period from onset to surgery.     

The effects of therapeutic sulfide on myocardial apoptosis in response to ischemia–reperfusion injury

Objective: Ischemia–reperfusion (I/R) injury, often encountered clinically, results in myocardial apoptosis and necrosis. Hydrogen sulfide (H₂S) is produced endogenously in response to ischemia and thought to be cardioprotective, although its mechanism of action is not fully known. This study investigates cardioprotection provided by exogenous H₂S, generated as sodium sulfide on apoptosis following myocardial I/R injury. Methods: The mid-LAD coronary artery in Yorkshire swine (n = 12) was occluded for 60 min, followed by reperfusion for 120 min. Controls (n = 6) received placebo, and treatment animals (n = 6) received sulfide 10 min prior to and throughout reperfusion. Hemodynamic, global, and regional functional measurements were obtained. Evans blue/TTC staining identified the area-at-risk (AAR) and infarction. Serum CK-MB, troponin I, and FABP were assayed. Tissue expression of bcl-2, bad, apoptosis-inducing-factor (AIF), total and cleaved caspase-3, and total and cleaved PARP were assessed. PAR and TUNEL staining were performed to assess apoptotic cell counts and poly-ADP ribosylation, respectively. Results: Pre-I/R hemodynamics were similar between groups. Post-I/R, mean arterial pressure (mmHg) was reduced by 30.2 ± 4.3 in controls vs 8.2 ± 6.9 in treatment animals (p = 0.01). +LV dP/dt (mmHg/s) was reduced by 1308 ± 435 in controls vs 403 ± 283 in treatment animals (p = 0.001). Infarct size (% of AAR) in controls was 47.4 ± 6.2% vs 20.1 ± 3.3% in the treated group (p = 0.003). In treated animals, CK-MB and FABP were lower by 47.0% (p = 0.10) and 45.1% (p = 0.01), respectively. AIF, caspase-3, and PARP expression was similar between groups, whereas cleaved caspase-3 and cleaved PARP was lower in treated animals (p = 0.04). PAR staining was significantly reduced in sulfide treated groups (p = 0.04). TUNEL staining demonstrated significantly fewer apoptotic cells in sulfide treated animals (p = 0.02). Conclusions: Sodium sulfide is efficacious in reducing apoptosis in response to I/R injury. Along with its known effects on reducing necrosis, sulfide's effects on apoptosis may partially contribute to providing myocardial protection. Exogenous sulfide may have therapeutic utility in clinical settings in which I/R injury is encountered.     

Cardiovascular function during the first 24 hours after off pump coronary artery bypass grafting--a prospective, randomized study

We hypothesized that cardiovascular performance during the first 24 postoperative hours would be better in patients after off pump coronary artery bypass grafting compared to conventional on pump surgery. Fifty-nine patients were randomized to on or off pump coronary artery bypass grafting. Hemodynamic parameters, including cardiac index and systemic vascular resistance index were measured before and at 1, 4, and 20 h after surgery. Troponin T and creatine kinase-MB (CK-MB) were measured before and at 1, 6, and 20 h after surgery. There was no difference in age, sex, ejection fraction or number of grafts between groups. Cardiac index was higher (p=0.05) and systemic vascular resistance index was lower (p=0.007) in the off pump group 1 h after arrival in the intensive care unit. CK-MB and troponin T were significantly lower in the off pump group after 1 h (CK-MB p<0.001, troponin T p<0.001) and after 6 h (CK-MB p=0.02, troponin T p<0.001). After 24 h there was no difference between the two groups. In conclusion, immediately after surgery there was better cardiovascular performance and less release of markers of myocardial damage after off pump coronary surgery. After 24 h all differences were eliminated.     

Intraaortic balloon pump therapy facilitates posterior vessel off-pump coronary artery bypass grafting in high-risk patients

Background. Displacement of the heart to expose posterior vessels during coronary artery bypass grafting (CABG) without cardiopulmonary bypass (off-pump CABG, or OPCAB) may impair cardiac function. We used the intraaortic balloon pump (IABP) preoperatively to reduce operative risk and to facilitate posterior vessel OPCAB in high-risk patients with left main coronary artery disease (> 75% stenosis), intractable resting angina, postinfarction angina, left ventricular dysfunction (ejection fraction < 35%), or unstable angina.

Methods. One hundred and forty-two consecutive patients who underwent multivessel OPCAB including posterior vessel revascularization were studied prospectively. The patients were divided into group I (n = 57), which received preoperative or intraoperative IABP, and group II (n = 85), which did not receive IABP. In group I, there were 34 patients with left main coronary artery disease, 24 patients with intractable resting angina, 8 patients with left ventricular dysfunction, 5 patients with postinfarction angina, and 40 patients with unstable angina. Seven patients received intraoperative IABP support owing to hemodynamic instability during OPCAB.

Results. There was no operative mortality in group I and 1 death in group II. The average number of distal anastomoses was not different between group I and group II (3.4 ± 0.9 versus 3.5 ± 0.9, p = not significant). There were no significant differences in the number of posterior vessel anastomoses per patient. There were no differences in ventilator support time, length of stay in the intensive care unit, hospital stay, and morbidity between the two groups. There was one IABP-related complication in group I.

Conclusions. IABP therapy facilitates posterior vessel OPCAB in high-risk patients, and surgical results are comparable with those in lower-risk patients.