七氟醚对冠状动脉旁路移植术患者心肺转流后右心室功能的影响

目的评价七氟醚对冠状动脉旁路移植术(CABG)患者心肺转流(CPB)后右心室收缩功能的影响。方法选择择期CPB下行CABG的冠心病患者18例,男13例,女5例,年龄50~80岁,ASAⅡ或Ⅲ级。麻醉维持采用静脉麻醉,于CPB后15min开始在静脉麻醉基础上持续吸入七氟醚1 MAC 60min。记录麻醉诱导后锯胸骨前(T1)、停CPB后15min开始吸入七氟醚前(T2)、停CPB后吸入七氟醚1 MAC 30min(T3)、60min(T4)时的HR、MAP、CVP、心输出量(CO)、外周血管阻力(SVR)和三尖瓣环收缩期位移(TAPSE)、三尖瓣瓣环收缩期速度(TAPSV)。结果与T1时比较,T2时CO明显升高(P0.05);与T2时比较,T3、T4时CO明显下降(P0.05或P0.01)。与T1时比较,T2时TAPSE、TAPSV明显增大(P0.05或P0.01);与T2时比较,T3、T4时TAPSE、TAPSV明显减小(P0.05)。结论择期CPB下行CABG的患者,停CPB后吸入七氟醚1 MAC可降低右心室收缩功能,但仍在临床正常范围。     

Ischemic preconditioning protects right ventricular function in coronary artery bypass grafting patients experiencing angina within 48-72 hours

BACKGROUND: To test whether ischemic preconditioning (IP) is able to protect the myocardium in recently unstable CABG patients. METHODS: Experimental design: prospective, randomised, controlled clinical study. Setting: University Hospital. Patients: Forty CABG patients with recent unstable angina were randomised into an IP group (n=20) and a control group (n=20). Subgroup was divided based on the time of the most recent ischemia onset before the operation. Intervention: The IP group was preconditioned with 2 cycles of 2-min ischemia followed by 3-min reperfusion before cross clamping. Measures: Hemodynamic data were monitored till the 1st POD. Biochemical markers were measured till the 2nd POD. RESULTS: There were no differences in cardiac index (Cl) and right ventricular ejection fraction (RVEF) in patients experiencing angina within 48 hours prior to operation. The percentage changes in CI and RVEF at 1 hour after declamping were significantly better in the IP group in patients experienced angina within 48-72 hours (106% vs 88% of baseline, p=0.027 and 103% vs 81% of baseline, p=0.023). No difference in postoperative cardiac troponin I (CTnI) and CK-MB was found between the IP and controls in either subgroup. CONCLUSIONS: IP has a beneficial effect on global and right ventricular hemodynamic functional recovery in unstable CABG patients experiencing angina within 48-72 hours prior to the operation. However, IP has no additional protective effects in unstable CABG patients who experience angina within 48 hours.     

Impact of remote ischemic preconditioning preceding coronary artery bypass grafting on inducing neuroprotection

Background

Neurological complications after coronary artery bypass grafting (CABG) reduce quality of life, increase mortality, and inflate resource utilization. The risk of postoperative neurological complications parallels the increasing risk burden of the contemporary patient population. We evaluated the efficacy of remote ischemic preconditioning (RIPC) on inducing neuroprotection.

Bradykinin preconditioning in coronary artery bypass grafting

Background

Experimental studies have shown that activation of bradykinin B₂ receptor is one of the most important triggers of ischemic preconditioning. However, the effect of exogenous administration of bradykinin in cardiac surgery is not yet known. The present prospective randomized study was designed to investigate the effect of bradykinin pretreatment in patients undergoing elective coronary artery bypass surgery.

Methods

Forty-one patients with multiple-vessel coronary artery disease and stable angina, admitted for the first time for elective coronary artery bypass surgery, were randomized into control or bradykinin (BK) groups. Patients in the BK group received bradykinin infusion for 7 minutes (total dose 25 μg) before the initiation of cardiopulmonary bypass. Perioperative cardiac specific troponin I (cTnI) and creatine kinase cardiac isoenzyme (CKMB) release and hemodynamics were recorded.

Results

Bradykinin infusion caused acute decrease of blood pressure in most of the cases and the mean minimum mean blood pressure during bradykinin infusion was 72.7% of the original mean blood pressure (MBP) level (74.7 ± 7.9 vs 54.4 ± 12.1 mm Hg, p < 0.01). There were no differences in baseline levels of cTnI and CKMB between the groups. The postoperative cTnI levels were lower than 10 ng/mL in most patients in both groups (18 in the BK group and 15 in the control group). There was no difference in cTnI between the groups. However, patients who received bradykinin released significantly less CKMB than did the controls postoperatively (6 hours, BK, 22.1 ± 9.5 vs control, 23.6 ± 12.7 U/L; 12 hours, BK, 19.4 ± 12.4 vs control, 28.7 ± 23.8 U/L; 24 hours, BK, 21.5 ± 14.7 vs control, 35.5 ± 28.9 U/L; 48 hours, BK, 14.4 ± 7.5 vs control, 23.5 ± 13.6 U/L; analysis of variance [ANOVA] for repeated measurement, p = 0.036). Maximum CKMB was also lower in the BK group (22.4 ± 14.4 vs 37.7 ± 27.5 U/L, p = 0.044). There was no significant difference between the groups in any of the hemodynamic variables.

Conclusions

Exogenous bradykinin infusion showed weak cardioprotective effect in the low-risk patients undergoing coronary artery bypass surgery but the dose used in the study caused acute decrease of systemic blood pressure.     

Precardiopulmonary bypass right ventricular function is associated with poor outcome after coronary artery bypass grafting in patients with severe left ventricular systolic dysfunction

Patients with severe left ventricular systolic dysfunction (LVSD) undergoing coronary artery bypass grafting (CABG) have an increased risk for morbidity and mortality. The purpose of this study was to assess the association of pre-CABG right ventricular (RV) function with outcome for patients with severe LVSD. We performed a retrospective evaluation of 41 patients with severe LVSD (left ventricular ejection fraction [LVEF] < or =25%) scheduled for nonemergent CABG. Data were obtained from review of medical records, transesophageal echocardiography tapes, and phone interview. The pre- and post-cardiopulmonary bypass (CPB) LVEF and the RV fractional area of contraction (RVFAC) were calculated by using intraoperative transesophageal echocardiography. Group 1 patients had an RVFAC < or =35% (n = 7), whereas Group 2 patients had RVFAC >35% (n = 34). The durations of mechanical ventilation and of intensive care unit and hospital stays are presented as the median. Pre-CABG LVEF was similar between Groups 1 and 2 (15.8% +/- 3.3% versus 17.8% +/- 3.9%). Compared with Group 2, Group 1 patients required greater duration of mechanical ventilation (12 days versus 1 day; P < 0.01), longer intensive care unit (14 versus 2 days; P < 0.01) and hospital (14 versus 7 days; P = 0.02) stays, had a more frequent incidence and severity of LV diastolic dysfunction, and had a smaller change in LVEF immediately after CPB (4.1% +/- 8.3% versus 12.5% +/- 9.2%; P = 0.03). All Group 1 patients died of cardiac causes within 2 yr of surgery; five died during the same hospital admission. Three Group 2 patients died: one of colon cancer at 18 mo after CABG and two of cardiac causes 24 and 48 mo after surgery. A fourth patient was awaiting cardiac transplantation 4 yr after surgery. The remaining Group 2 patients were New York Heart Association Classification I or II. For patients with severe LVSD undergoing CABG, pre-CPB RV dysfunction was associated with poor outcome. Patients with RVFAC >35% had a relatively uneventful perioperative course and good long-term survival, whereas patients with RVFAC < or =35% had a poor early and late outcome. Assessment of RV function is useful to further assess the risk of CABG. IMPLICATIONS: Right ventricular function before cardiopulmonary bypass is associated with poor outcome after coronary artery surgery in patients with poor left ventricular function.     

Cardiopulmonary bypass affects cognitive brain function after coronary artery bypass grafting

Background. The causes for cognitive impairment after coronary artery bypass grafting (CABG) have long been a topic for debate.

Methods. We prospectively followed 308 consecutive, unselected survivors of CABG at our institution. In addition to determination of clinical measurements, cognitive brain function was measured objectively by P300 auditory-evoked potentials before CABG, at 7-day and at 4-month follow-up. Standard psychometric tests (Trail Making Test A, Mini Mental State Examination) were also performed.

Results. At 7-day follow-up cognitive P300 auditory-evoked potentials were significantly impaired compared with preoperative levels (peak latencies: 376 ± 40 ms versus 366 ± 37 ms, p = 0.0001). P300 measurements were almost normalized at 4-month follow-up (peak latencies: 369 ± 33 ms, p = NS versus preoperative). Standard psychometric tests failed to detect this subclinical cognitive impairment. Multiple regression analysis revealed that use of cardiopulmonary bypass was the only independent predictor of impaired cognitive brain function at 7-day (p < 0.0001) and 4-month follow-up (p = 0.0008). The presence of diabetes mellitus (p = 0.0135) or concomitant repair of significant carotid artery stenosis (p = 0.0049) was predictive of late improvement of cognitive brain function at 4-month follow-up.

Conclusions. Objective cognitive P300 auditory-evoked potential measurements demonstrate that the use of cardiopulmonary bypass is the only predictor of short- and long-term cognitive brain dysfunction after CABG. Interestingly, the presence of diabetes mellitus and concomitant repair of a significant carotid artery stenosis were predictive for long-term cognitive benefit.     

Impairment of left ventricular diastolic function during coronary artery bypass grafting

Twelve patients were studied by transoesophageal Doppler echocardiography to determine diastolic function during coronary artery bypass grafting. Haemodynamic and Doppler-derived variables were measured after induction of anaesthesia and after closure of the sternum. Early diastolic filling of the left ventricle decreased from 55% to 35% during surgery. The contribution of atrial contraction to left ventricular filling increased from 41% to 62% (p less than 0.001). We conclude that coronary artery bypass grafting results in impairment of diastolic function during the operation.     

Early versus late extubation after coronary artery bypass grafting: effects on cognitive function

OBJECTIVE: To compare the effects of a short period of mechanical ventilation and sedation and a longer one on cognitive functioning of patients exposed to cardiopulmonary bypass (CPB). DESIGN: A randomized, prospective study. SETTING: Tertiary-care university hospital. PARTICIPANTS: Forty-eight adult patients with surgical coronary artery disease. INTERVENTION: Elective coronary artery bypass surgery. MEASUREMENT AND MAIN RESULTS: Patients (n = 48; mean age, 60.12+/-9.30 years) were randomized to either group I (mean delay, 3.49+/-2.21 hours) or group II (mean delay, 10.32+/-1.75 hours). Cognitive functioning was evaluated before surgery, postoperatively, and at the 8-week follow-up. Tests included measures of central nervous system integrity, attention/concentration and psychomotor performance, verbal fluency, visual scanning speed, mental flexibility, auditory and visual attention, and verbal memory. Covariance analyses were used for group comparisons. Covariates were age, education, and baseline or postoperative performance. No differences in cognitive functioning were found between the two groups. Globally, performance deteriorated for 34.1% of the patients at the posttest evaluation, whereas 2.3% improved and 63.6% remained unchanged. At follow-up, nearly 40.5% of the patients showed an improvement from baseline, 2.4% still had deficits, and 57.1% had no change. None of the cognitive functions appeared to be more affected than others. CONCLUSION: Early extubation and a shortened period of anesthesia/analgesia do not appear to positively or negatively affect cognitive functioning at 3 to 5 days and 8 weeks postoperatively. Early extubation is suggested because it has no deleterious effect (besides the low risk for reintubation) and it may facilitate patients' care in the intensive care unit.     

The right gastroepiploic artery in coronary artery bypass grafting

The right gastroepiploic artery (RGEA) has been used as a conduit in coronary artery bypass grafting. Although some reports presenting good results justify its use in clinical settings, there is still much concern about using the RGEA in bypass surgery. The RGEA demonstrates different behaviors from the internal thoracic artery (ITA) in bypass surgery due to its histological characteristics and anatomical difference, which might contribute to the long-term outcome. Now that left ITA (LITA) to left anterior descending artery (LAD) is the gold standard, other grafts are expected to cover the rest of the coronary arteries. It should be elucidated how we can use other grafts and what we can expect from them. RGEA, as an arterial graft, can be used as an in situ graft or a free graft. The RGEA is mainly used to graft to the right coronary artery (RCA) because of its anatomical position, and its patency is not inferior to that of the saphenous vein (SVG). The RGEA can cover the lateral walls when its length is long enough or by making a composite graft with other grafts. However, when used to graft to the LAD, its mid-term patency is not favorable.     

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。     

Effects of ischemic preconditioning and synchronized coronary venous retroperfusion in an off-pump coronary artery bypass grafting model

Off-pump coronary artery bypass grafting (CABG) has become a popular procedure. However, temporary occlusion of the target vessel is sometimes a threat to the patients. Although ischemic preconditioning (IP) has been proposed to reduce myocardial injury, its effects remain controversial. The coronary veins represent an alternate route for delivery of therapeutic agents and arterial blood to the acutely ischemic myocardium. The aim of this study was to investigate the protective effect against myocardial ischemia and reperfusion injury of combined IP and synchronized coronary venous retroperfusion (SCVR) in an off-pump CABG model. Twenty-one pigs were assigned to 3 groups of 7 animals. In the control group, the left anterior descending coronary artery (LAD) was occluded for 45 min followed by 2 h of reperfusion using a left intrathoracic artery (LITA) bypass circuit. In the IP group, LAD occlusion was done for 5 min with 15 min of reperfusion, followed by 45 min of LAD occlusion. In the SCVR group, pretreatment before LAD occlusion was the same as in the IP group. Then, SCVR was commenced just after the start of LAD occlusion for 45 min. The percent systolic shortening of ischemic myocardium (measured by sonomicrometry) after reperfusion via the LITA was significantly (p < 0.001) greater in the SCVR group (14.6 +/- 3.3%) than in the control group (-1.6 +/- 5.6%, 95%CI: -24.3 - -8.1) or the IP group (0.7 +/- 8.0%, 95%CI: -22.0 - -5.8) after 30 min of reperfusion, and this difference persisted throughout the reperfusion period. Infarct size (expressed as a percentage of the area at risk) was significantly (p < 0.001) smaller in the SCVR group (2.4 +/- 2.7%) than in the control group (83.0 +/- 2.3%, 95%CI: -99.0 - -62.4) or the IP group (42.0 +/- 23.0%, 95%CI: -58.0 - -21.3). Combined SCVR and IP had a potent myocardial protective effect in the present off-pump CABG model. This method may be clinically feasible and may be able to prolong a safe coronary occlusion.     

Tetraplegia after coronary artery bypass grafting

The authors present a rare case of a cervical cord dysfunction after uncomplicated coronary artery bypass grafting. The preoperative neurological examination did not reveal any abnormalities; however, the postoperative magnetic resonance image showed significant spinal canal stenosis at the same levels as high signal lesions. Although the pathophysiological basis of the case was impossible to determine retrospectively, it seems probable that placing the neck in an extended position during surgery might have aggravated a preexisting spinal canal stenosis to produce cervical injury. IMPLICATIONS: The authors present a rare case of tetraplegia after coronary artery bypass grafting. It is suggested that neck extension during surgery might have aggravated an occult preexisting cervical spinal canal stenosis to produce cervical injury.