Protective effect of nisoldipine on myocardial ischemia during coronary bypass surgery.

BACKGROUND: Nisoldipine, a calcium antagonist, was assessed for myocardial protection and the prevention of reperfusion injury in patients undergoing CABG. METHODS: Of the 34 subjects undergoing CABG in this study, 20 were given nisoldipine orally at 10 mg/day for 2 weeks before surgery (N group) and the other 14 untreated controls (C group). Myocardial protection was conducted via ante-grade cold blood cardioplegia at 20-minute intervals. RESULTS: Myocardial blood flow was significantly higher in the N group (67.8 +/- 21.8 ml/100 g vs. 47.2 +/- 14.4 ml/100 g, p < 0.05) after cardiopulmonary bypass. Serum interleukin-6 levels were significantly lower in the N group 1 hour after reperfusion (116 +/- 58 vs. 409 +/- 362 pg/ml, p < 0.05), as were serum lactate dehydrogenase levels immediately after surgery (888 +/- 268 vs. 1350 +/- 486 IU/L, p < 0.05). The N Group showed a better left ventricle stroke work index 6 hours after surgery (43 +/- 8 vs. 36 +/- 9 g.m/m2). Dopamine dosage in the N group on postoperative day 1 was lower than in controls (5.3 +/- 1.9 vs. 3.0 +/- 2.4 micrograms/kg/min). CONCLUSIONS: Preoperative nisoldipine treatment increased blood flow in the postischemic myocardium and prevented myocardial damage and reperfusion injury to some extent.     

Vacuum-assisted apical suction devices induce passive electrical changes consistent with myocardial ischemia during off-pump coronary artery bypass graft surgery

Objective: Off-pump coronary artery bypass graft surgery is common therapy to completely revascularize diseased hearts. In order to graft posterior arteries in this procedure, the heart must be lifted from the chest cavity and manipulated to expose the surgical field using an apical suction device. This suction device may cause unwanted myocardial ischemia. Methods: In this observational study, we measured myocardial electrical impedance, a parameter that responds to myocardial ischemia, as well as ST-segment changes during off-pump coronary artery bypass graft surgery in 12 patients with two-vessel coronary artery disease undergoing revascularisation of the left anterior descending and the posterior descending coronary arteries. During the posterior descending artery revascularisation phase of the procedure the apical suction device was oriented over the electrodes used to measure myocardial electrical impedance, thus allowing us the opportunity to assess myocardial ischemia in this region of the heart. Results: In these 12 patients, myocardial electrical impedance progressively increased under the suction device during posterior coronary artery revascularisation, suggesting that myocardial ischemia developed in this region of the myocardium. ST-segment changes were negligible while the heart was vertically displaced (and the suction device attached), but increased immediately when the heart was returned to the neutral anatomical position. Conclusion: Our data suggest that the apical suction device may cause ischemia while the heart is vertically displaced and electrically disconnected from the body. Under these conditions, ST-segment changes may not detect myocardial ischemia. Myocardial electrical impedance has the potential to reliably detect intraoperative myocardial ischemia under these circumstances.     

Free arterial graft in coronary artery bypass surgery

Free arterial graft of the internal mammary artery (IMA) and the gastroepiploic artery (GEA) has been utilized for coronary artery bypass grafting in 10 patients during 44 months period. There were 6 males and 4 females and age ranged 42 to 73 year old with the mean of 60.8 year old. Eight IMA and 2 GEA were used as a free graft. Sites of distal anastomosis of the free graft were 3 at anterior descending arteries, 3 at diagonal branches and 4 at circumflex arteries. Sites of proximal anastomosis of those grafts were ascending aorta in one, concomitantly utilized saphenous vein graft in 5 and in situ IMA graft in 4 patients. Mean number of grafts was 2.9 (2-5) and mean aortic cross clamp time was 56.2 minutes (16-90 minutes). There was neither operative death, nor perioperative myocardial infarction and intra-aortic balloon pumping was not required. Postoperative angiography was made in 9 patients within 3 postoperative months. Eight (89%) free arterial grafts were patent. Relief of angina was obtained in all patients. We concluded that the complete revascularization with only arterial graft can be achieved more widely by utilizing the free arterial graft with an acceptable patency.     

Protective effect of nisoldipine on myocardial ischemia during coronary bypass surgery

Background: Nisoldipine, a calcium antagonist, was assessed for myocardial protection and the prevention of reperfusion injury in patients undergoing CABG.Methods: Of the 34 subjects undergoing CABG in this study, 20 were given nisoldipine orally at 10 mg/day for 2 weeks before surgery (N group) and the other 14 untreated controls (C group). Myocardial protection was conducted via antegrade cold blood cardioplegia at 20-minute intervals.Results: Myocardial blood flow was significantly higher in the N group (67.8±21.8 ml/100 g vs. 47.2±14.4 ml/100 g, p < 0.05) after cardiopulmonary bypass. Serum interleukin-6 levels were significantly lower in the N group 1 hour after reperfusion (116±58 vs. 409±362 pg/ml, p < 0.05), as were serum lactate dehydrogenase levels immediately after surgery (888±268 vs. 1350±486 IU/L, p < 0.05). The N Group showed a better left ventricle stroke work index 6 hours after surgery (43±8 vs. 36±9 g·m/m²). Dopamine dosage in the N group on postoperative day 1 was lower than in controls (5.3±1.9 vs. 3.0±2.4 μg/kg/min). Conclusions: Preoperative nisoldipine treatment increased blood flow in the postischemic myocardium and prevented myocardial damage and reperfusion injury to some extent.     

Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery

PURPOSE: To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG). SOURCE: Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included. PRINCIPAL FINDING: Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90 degrees anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed. CONCLUSIONS: In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during off-bypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure.     

Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery.

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.     

Propofol attenuates myocardial lipid peroxidation during coronary artery bypass grafting surgery

Background. Propofol can scavenge free radicals because it hasa chemical structure similar to antioxidants. Methods. We examined if free radical scavenging occurs withpropofol during CABG operations. We studied 24 patients undergoingCABG surgery for triple vessel disease, randomized into twogroups. After induction of anaesthesia with fentanyl 10 µgkg^–1 and midazolam 0.1 mg kg^–1, patients in thefentanyl group (n=14) received fentanyl infusion 10–30µg kg^–1 h^–1 and patients in the propofol group(n=10) received propofol infusion 3–6 mg kg^–1 h^–1for maintenance of anaesthesia. Atrial tissue biopsies weretaken during cannulation for bypass, 45 min after cross-clampinsertion, 5 min after unclamping, and in the decannulationperiod. Lipid peroxidation was assessed by measurement of thiobarbituricacid reactive substances (TBARS) in the atrial tissue samples. Results. Lipid peroxidation in the propofol group was less thanin the fentanyl group (P<0.05) in all sampling periods. Lipidperoxidation in the fentanyl group increased significantly duringcardiopulmonary bypass (CPB) (P<0.05), but no increase wasfound in the propofol group (P>0.05). Conclusion. In clinical doses, propofol strongly attenuateslipid peroxidation during CABG surgery. Br J Anaesth 2002; 89: 242–6     

Spinal cord ischemia following coronary artery bypass surgery

Coronary artery bypass graft (CABG) surgery is associated with a low risk of paraplegia. Spinal cord ischemia causing paraplegia following off-pump coronary artery bypass (OPCAB) surgery has not been described previously. We now describe a patient who developed paraplegia following OPCAB and review the literature on spinal cord ischemia following CABG surgery.     

The incidence of myocardial ischemia during anesthesia for coronary artery bypass surgery in patients receiving pancuronium or vecuronium

This study was performed to compare the incidence of prebypass myocardial ischemia in patients receiving fentanyl and enflurane for anesthesia along with either pancuronium or vecuronium. Ninety-eight patients with normal left ventricular function were randomly allocated to receive either pancuronium 0.15 mg.kg-1 or vecuronium 0.15 mg.kg-1 in a double-blind manner after fentanyl 40 micrograms.kg-1 for induction of anesthesia for elective coronary artery bypass grafting (CABG). Premedication included diazepam 0.15 mg.kg-1 po, morphine 0.10 mg.kg-1, and scopolamine 0.005 mg.kg-1 im. Two lead Holter monitor recordings (leads V6 and V9) from the time of arrival in the operating suite to institution of cardiopulmonary bypass were analyzed for ischemia by a cardiologist blinded to the choice of muscle relaxant. Intraoperatively, heart rates greater than 90 beats.min-1 and systolic blood pressure +/- 20% of ward values were treated with propranolol, enflurane, or phenylephrine. Nitroglycerin was infused for ECG signs of ischemia or pulmonary hypertension. After induction of anesthesia the heart rate and cardiac index were consistently decreased in patients receiving vecuronium and also lower in these patients compared with those receiving pancuronium. Thirty-two per cent of patients receiving pancuronium received propranolol for heart rates greater than 90 beats.min-1 versus 7% of those who received vecuronium (P approximately 0.01). Eight patients developed 13 episodes of ischemia after administration of the muscle relaxant: four who received pancuronium (n = 44; 9%) and four receiving vecuronium (n = 54; 7%). Four episodes occurred at induction or tracheal intubation, two in each group. There were four perioperative myocardial infarctions as determined by ECG and CPK-MB levels, two in each group.(ABSTRACT TRUNCATED AT 250 WORDS)     

全动脉化冠状动脉搭桥的临床应用

目的 介绍全动脉移植物行冠状动脉搭桥的早期效果和临床经验。方法 采用全动脉移植物87例冠心病患者实施冠状动脉搭桥。其中男性患者82例,女性5例;单支冠状动脉病变14例,2支病变19例,3支病变54例。62例患者术前有心肌梗死,7例合并室壁瘤,1例合并主动脉瓣关闭不全。71例患者在体外循环下行冠状动脉搭桥术,16例在非体外循环下行冠状动脉搭桥术。同时行室壁瘤切除术7例,行主动脉瓣替换1例,行冠状动脉内膜剥脱2例。应用左乳内动脉84例次,右乳内动脉46例次,胃 网膜右动脉37例次,左桡动脉51例次。单个远端吻合14例,2个19例,3个50例,4个4例。结果 围手术期死亡2例（病死率2．3％）,1例为围手术期心肌梗死低心排,1例为顽固性心律失常。3例术后发生胸骨裂开切口感染,再次清创处理后痊愈。本组患者随访1．0－30．0个月（平均13．2个月）,1例患者因突发脑血管意外在术后40d死亡,其余患者术后均恢复良好,无心绞痛症状再发。B超检查乳内动脉移植血管均通畅。结论 全动脉化冠状动脉搭桥具有良好的临床应用效果,尤其适合于年轻的冠心病患者。     

Leukocyte depleting filter attenuates myocardial injury during elective coronary artery bypass surgery

BACKGROUND: Ischemia-reperfusion injury secondary to leukocyte activation has been widely recognized as one of the most relevant mechanism leading to postoperative organ dysfunction occurring after a period of ischemia. The aim of the present study was to evaluate in a prospective, randomized study, the value of leukocyte depleting filter in patients undergoing elective coronary artery bypass surgery. METHODS: Twenty patients scheduled for elective on-pump coronary artery bypass surgery were randomized to undergo cardiopulmonary bypass either with a leukocyte depleting filter incorporated in the extracorporeal circulation arterial line or without a filter. RESULTS: The main finding of this study was the significantly lower postoperative concentrations of cardiac troponin I in the leukocyte filter group (Tests of between-subjects effects: p = 0.024). There were also slightly better cardiac indices in the leukocyte filter group. A larger amount of blood units was infused intra- and postoperatively in patients undergoing cardiopulmonary bypass with leukocyte filtration (median, 600 [IQR, 0-1200] vs. 0 [IQR, 0-600], p = 0.08). Two patients in the leukocyte filter group underwent reoperation for bleeding but none in the control group (p = 0.48). Intra-and postoperative platelet count was lower in the leukocyte filter group (Tests of between-subjects effects: p = 0.08). Despite a significant increased concentration of C-reactive protein on the first postoperative day in the control group (p = 0.029), repeated-measures analysis failed to show any significant increase during the study period (p = 0.33). CONCLUSIONS: The results of this study suggest a myocardial protective effect of leukocyte filter in the setting of elective coronary artery bypass surgery.     

Prophylactic nitroglycerin did not reduce myocardial ischemia during accelerated recovery management of coronary artery bypass graft surgery patients

OBJECTIVE: To evaluate the use of a high dose of nitroglycerin (NTG) for prophylaxis against myocardial ischemia and infarction in patients undergoing coronary artery bypass graft (CABG) surgery with accelerated recovery. DESIGN: Prospective, double-blind, placebo-controlled randomized study. SETTING: A university-based medical center. PARTICIPANTS: Forty adult patients presenting for elective CABG surgery. INTERVENTIONS: Forty patients were divided into 2 blinded study groups. Twenty patients received 2 microg/kg/min of NTG starting before induction of anesthesia and continuing for 6 hours after extubation in the intensive care unit. The placebo group (n = 20) received normal saline during this same interval. MEASUREMENTS AND MAIN RESULTS: Hemodynamics, incidence and severity of myocardial ischemia, and myocardial infarction rates were determined. There were no differences in hemodynamic parameters between groups. The incidence of ischemia was approximately 35% in each group. Myocardial infarction (as determined by elevated creatine kinase-MB fraction, troponin I, and electrocardiogram criteria) was 10% in the placebo group and 5% in the NTG group (p = 0.234). CONCLUSIONS: This study shows a high incidence of myocardial ischemia and infarction in patients presenting for CABG surgery with an accelerated recovery management scheme. NTG was well tolerated clinically; however, it was not found to be protective against myocardial ischemia or infarction in this setting.     

Postoperative myocardial ischemia in patients undergoing coronary artery bypass graft surgery. S.P.I. Research Group

Cardiac morbidity and mortality after coronary artery bypass graft (CABG) surgery continue to be significant problems. To determine the prevalence, characteristics, and prognostic importance of postoperative myocardial ischemia after CABG surgery, the authors monitored 50 patients continuously for 10 perioperative days with the use of two-lead electrocardiography (ECG). ECG changes consistent with ischemia were defined as a reversible ST depression of 1 mm or greater or an elevation of 2 mm or greater from baseline, lasting at least 1 min. Baseline was adjusted for positional changes and temporal drift. All episodes were verified, with the use of the ECG monitor printout (ECG complexes), by two independent blinded investigators. Clinical care was not controlled by study protocol, and clinicians were unaware of the research data collected. Twenty-six of 50 patients (52%) had 207 episodes of perioperative ischemia (3,409 ischemic minutes). Postoperatively, ischemia developed in 48% of patients, compared with 12% preoperatively and 10% intraoperatively before bypass. Postoperative ischemia was most common in the early period (postoperative days [PODs] 0-2; 38% of patients), peaking during the first 2 h after revascularization, and less common during the late postoperative period (PODs 3-7; 24% of patients). Almost all (120 of 122; 98%) postoperative episodes (after tracheal extubation) were asymptomatic: only 9 of 70 (13%) early episodes were detected by clinical ECG monitoring. Postoperative ischemia did not appear to be related to acute changes in myocardial oxygen demand: only 39% of the postoperative episodes were preceded by a greater than 20% increase in heart rate. However, tachycardia persisted throughout the postoperative week (22-33% of all heart rates greater than 100 beats per min), and patients with postoperative ischemia (POD 0) more frequently had tachycardia (median 43% vs. 12% of the time; P less than 0.01). Five adverse cardiac outcomes occurred on the day of surgery; all five were preceded by postoperative ischemia, three by intraoperative ischemia before bypass, and none by preoperative ischemia. Patients with late postoperative ischemia did not have an adverse cardiac outcome. The authors conclude the following: 1) ischemia is more prevalent postoperatively than preoperatively or intraoperatively before bypass; 2) the incidence of postoperative ischemia peaks shortly after revascularization, during which time it is symptomatically silent, difficult to detect, and related to adverse cardiac outcome; 3) late postoperative ischemia also is silent, but it is less prevalent and not associated with in-hospital adverse cardiac outcome; and 4) a relationship between ischemia and persistently elevated postoperative heart rate may exist and warrants additional investigation.     

Haemodynamic changes during minimally invasive coronary artery bypass surgery using high-dose esmolol

We aimed to investigate the effects of high-dose esmolol on haemodynamics and oxygen extraction in minimally invasive direct coronary artery bypass (MIDCAB) surgery patients. METHODS: In 18 patients, heart rate (HR), mean arterial (MAP), central venous (CVP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and mixed venous oxygen saturation (Sv0(2)) were prospectively measured after induction of anaesthesia (T1), start of surgery (T2), during bypass grafting with beta-blockade (T3), and at the end of surgery (T4). RESULTS: Mean esmolol dose at T3 was 0.44+/-0.2mgkg(-1)min(-1). HR was unchanged, whereas significant decreases in mean CO (3.1+/-0. 8 vs 4.8+/-1.0lmin(-1)m(-2), pre-esmolol), MAP (53+/-10 vs 89+/-14mmHg), and SvO(2) (65+/-10 vs 81+/-4%) were observed during esmolol administration. All haemodynamic parameters normalized immediately after termination of esmolol (T4). CONCLUSIONS: Despite unchanged HR esmolol reduced CO and MAP suggesting a favorable reduction of myocardial oxygen consumption. Mean Sv0(2) during esmolol administration reflects an acceptable ratio of whole-body oxygen delivery and consumption. Haemodynamic changes with high-dose esmolol during MIDCAB surgery remain within safety margins.     

Intravenous glucose-insulin-potassium during off-pump coronary artery bypass surgery does not reduce myocardial injury

BACKGROUND: This randomized, double-blind, placebo-controlled study was designed to determine whether an intra-operative, intravenous infusion of glucose-insulin-potassium (GIK) could be helpful in the prevention of myocardial ischemia and in the maintenance of intra-operative cardiac performance in patients undergoing off-pump coronary artery bypass (OP-CAB) surgery. METHODS: Eighty two adults undergoing elective OP-CAB surgery were randomly divided into two groups that received intravenously either 5% dextrose in water or GIK (50% dextrose in 500 ml of water; regular insulin, 125 IU; potassium, 80 mmol) at 0.75 ml/kg/h immediately before the induction of anesthesia to the end of surgery. To evaluate myocardial damage, creatine kinase MB and troponin T were measured before surgery, immediately after arrival in the intensive care unit and on the first post-operative day. To assess cardiac performance, hemodynamic data were obtained before and after the induction of anesthesia, before and after the bypass graft and after sternal closure. Blood glucose was measured at the same time. RESULTS: There was no significant difference in cardiac enzymes, hemodynamic parameters and blood glucose between the two groups. The use of vasoactive, inotropic and/or anti-arrhythmic agents, insulin and supplemental glucose was not significantly different between the groups. CONCLUSION: The results suggest that the intravenous administration of GIK during OP-CAB surgery neither reduces myocardial damage nor improves intra-operative cardiac performance in patients without contractile dysfunction.