Determination of troponin I release after CABG surgery

BACKGROUND: Troponin I is used to diagnose myocardial infarction (MI). Its use and pattern of elevation is not well defined in coronary artery bypass graft (CABG) surgery. This study assessed the timing of troponin I elevation in patients undergoing urgent CABG. METHOD: Patients undergoing urgent isolated-CABG with cardiopulmonary bypass were studied prospectively. Blood samples were taken to measure CK, CK-MB, and troponin I: preoperatively, 7 hours postoperatively, 14 to 18 hours postoperatively, 30 to 48 hours postoperatively, and on postoperative day 4. Electrocardiograms and in-hospital course were recorded. Perioperative MI (PMI) was defined by either (i) ECG criteria of new Q-waves in the presence of CK-MB elevation >50 microg/L or (ii) CK-MB > 100 microg/L. RESULTS: Of the 50 patients studied, 6 met the criteria for PMI (12%); 2 by criteria (i) and 4 by criteria (ii). In patients not meeting the criteria for MI the troponin I level peaked at 7 hour post-op with a mean of 20.97 microg/L (95% CI, 17.11 to 24.83). At this time, patients who met the criteria for MI had a mean troponin I level of 46.85 microg/L (95% CI, 36.40 to 57.30). Of variables investigated for the 44 patients who did not meet MI criteria, only preoperative troponin I level impacted peak postoperative troponin I. CONCLUSIONS: CABG elevates troponin I far beyond current diagnostic benchmarks without the clinical occurrence of a MI and appears to peak during the second postoperative day. An elevated preoperative troponin I may predict an elevated peak postoperative troponin I in patients who do not have a PMI.     

Elective minimally invasive coronary artery bypass: Shunt or tournique occlusion? Assessment of a protective role of perioperative left anterior descending shunting on myocardial damage. A prospective randomized study

ABSTRACT: BACKGROUND: To determine impact of intraluminal-left anterior descending shunt to prevent myocardial damage in minimally invasive coronary artery bypass. METHODS: 38 patients were randomly assigned to external tournique occlusion (n = 19) or intraluminal-left anterior descending shunt group (n = 19). Blood samples for cardiac troponin T were collected at 30 minutes prior to, 6 and 24 hours after surgery. RESULTS: One patient in external tournique occlusion and two patients in intraluminal-left anterior descending shunt group were excluded from futher analysis due to preoperative cardiac troponin T level above the 99th-percentile. Postoperatively, each six patients in external tournique occlusion (33.3%) and intraluminal-left anterior descending shunt (35.3 %) group were above the 99th-percentile. Two patients from each group (external tournique occlusion group 11.1 % vs. intraluminal-left anterior descending shunt group 11.8 %) had peak values above 10-% coeficient of variation cutoff (p = 1). There were no significant differences in between both groups at all studied timepoints. CONCLUSION: There was no protective effect of intraluminal shunting on myocardial damage compared to tournique occlusion. It is upon the surgeon's discretion which method may preferrably be used to achieve a bloodless field in grafting of the non-occluded left anterior descending in minimally invasive coronary artery bypass.     

Strict thermoregulation attenuates myocardial injury during coronary artery bypass graft surgery as reflected by reduced levels of cardiac-specific troponin I

We assessed the cardioprotective effects of perioperative maintenance of normothermia by determining the perioperative profile of troponin I, a highly cardiac-specific protein important in risk stratification of patients with acute ischemic events. Candidates for their primary coronary artery bypass grafting (CABG) were randomized into a new thermoregulation system group, Allon( thermoregulation (AT; n = 30), and a routine thermal care (RTC; n = 30) group. Anesthetic and operative techniques were similar in both groups. Intraoperative warming was applied before and after cardiopulmonary bypass (CPB) and up to 4 h after surgery. Perioperative temperature and hemodynamic data were recorded. Blood samples for creatine kinase (CK) and its isoform, MB (CK-MB), and for cardiac-specific troponin I (cTnI) were obtained at predetermined intervals throughout the entire operation. Core and skin temperatures were higher in the AT group at all time points. The systemic vascular resistance was lower and the cardiac index higher in the AT group at all intra- and postoperative time points. Increases in CK, CK-MB, and cTnI levels indicated intraoperative ischemic insult in all patients. The respective CK levels for the AT and RTC groups were 53.3 +/- 22.7 IU/L and 47.9 +/- 17.86 IU/L at the time of anesthesia and 64.7 +/- 45.6 IU/L and 47.8 +/- 19.4 IU/L 30 min after the onset of surgery, demonstrating thereafter a steep increase before the discontinuation of CPB. CK-MB mass concentrations in both groups behaved almost identically. Pre-CPB cTnI levels at anesthesia induction were 0.3 +/- 0 ng/mL in both groups, followed by a distinctive profile observed after separation from CPB: 28.1 +/- 11.4 ng/mL, 26.05 +/- 9.20 ng/mL, and 22.3 +/- 8.9 ng/mL at discontinuation from CPB, chest closure, and 2 h after surgery, respectively, in the RTC group, versus 0.6 +/- 4.6 ng/mL, 6.6 +/- 5.5 ng/mL, and 7.9 +/- 4.76 ng/mL at these three time points, respectively, in the AT group (P < 0.01 between groups at the specified time points). Contrary to conventional thinking about the benefits of hypothermia, maintenance of normothermia throughout the non-CPB phases during CABG was demonstrated to be important in attenuating myocardial ischemic injury. Insofar as troponin I was more sensitive than other tested markers, it may provide important data on possible protection from myocardial insult and on other cardioprotective measures.     

Intracoronary shunts reduce transient intraoperative myocardial dysfunction during off-pump coronary operations

BACKGROUND: This study investigated the hemodynamic changes in patients undergoing multiple vessel beating heart coronary revascularization in the presence or absence of an intracoronary shunt. METHODS: Forty patients were randomized to off-pump with a shunt (n = 20) or with the proximal coronary artery occluded by a soft snare (n = 20). Hemodynamic measurements were recorded at base line, during construction, and after completion of each distal anastomosis. RESULTS: Grafting of the left anterior descending coronary artery anastomosis was associated with a significant decrease in stroke volume, cardiac index, and mean arterial pressure, and an increase in pulmonary capillary wedge pressure and systemic vascular resistance in the snare but not in the shunt group. During grafting of the posterior descending coronary artery there was a marked decrease in stroke volume and cardiac index, and an increase in central venous pressure in both groups, and an increase in heart rate, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, and systemic vascular resistance only in the snare group. The most extensive changes were observed during the circumflex coronary artery anastomosis with a reduction in stroke volume, cardiac index, and mean arterial pressure, and an increase in central venous pressure, pulmonary capillary wedge pressure, pulmonary arterial pressure, and systemic vascular resistance in both groups. In all settings, these changes were transient and recovered after the heart was returned to its anatomical position in the shunt group, whereas stroke volume and cardiac index remained reduced, and systemic vascular resistance was elevated in all settings in the snare group. CONCLUSIONS: Stabilization of the left anterior descending coronary artery to perform the anastomosis resulted in temporary hemodynamic changes, which are prevented by the use of an intracoronary shunt. The hemodynamic deterioration during the construction of the posterior descending coronary artery and circumflex coronary artery anastomoses is transient in the shunt group, whereas the snaring technique is associated with an impairment of early functional recovery.     

Cardiac biomarker release after CABG with different surgical techniques

OBJECTIVE: To investigate the release of cardiac biomarkers (troponin I and CK-MB) in patients undergoing coronary artery bypass graft (CABG) with or without cardiopulmonary bypass (CPB). DESIGN: Prospective study. SETTING: University tertiary hospital. PARTICIPANTS: Sixty-five consecutive patients undergoing coronary artery bypass grafting (>or=2 vessel disease, ejection fraction >or=0.35%, elective procedure). INTERVENTIONS: Cardiac biomarkers were measured before surgery, at intensive care unit arrival, 4 and 18 hours after the end of the procedure. MEASUREMENTS AND MAIN RESULTS: Cardiac biomarker release was higher in on-pump than in off-pump patients at every time point. On multivariate analysis, CPB (p < 0.0001), number of distal grafts (p = 0.005), and hypertension treatment (p = 0.03) were the only independent predictors of peak cardiac troponin release. CONCLUSIONS: Cardiac troponin I release after multivessel CABG is associated with the technique. Different values for the normal range should be considered. OPCABG is minimally invasive for the heart as far as myocardial marker release is concerned.     

Biochemical markers of myocardial injury in the pericardial fluid of patients undergoing heart surgery

The purpose of this study was to compare cardiac markers in the pericardial fluid and serum in order to evaluate preoperative myocardial injury. Thirty patients were divided into three groups. The first group (AVR; n=10) received an aortic valve replacement. The second group (SA; n=10) included patients with stable angina who underwent elective coronary artery bypass grafting (CABG). The third group (ACS; n=10) included patients with acute coronary syndrome who underwent urgent CABG. Pericardial fluid and venous samples were taken after opening the pericardium and 24 h postoperatively. Serum and pericardial concentration of troponin I (cTnI), creatine kinase (CK), its MB isoenzyme (CK-MB) and myoglobin were determined. Preoperative pericardial cTnI was significantly (P<0.01) higher than in serum in all groups. Preoperative pericardial CK, CK-MB and myoglobin were significantly (P<0.01) lower than in serum in groups AVR and SA. Preoperative pericardial and serum cTnI were significantly higher in the ACS than in AVR and SA groups (P<0.01). Postoperative pericardial concentration of all markers was significantly higher (P<0.01) than in serum in all groups. We conclude that preoperative pericardial accumulation of cTnI may reflect subclinical injury which may not be demonstrated by the usual laboratory tests.     

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.     

异氟醚和七氟醚对非体外循环冠状动脉旁路移植术患者心肌保护作用的比较

目的 比较异氟醚和七氟醚对非体外循环冠状动脉旁路移植术患者的心肌保护作用.方法 择期行非体外循环冠状动脉旁路移植术患者40例,性别不限,年龄40～55岁,体重55～94 kg,ASA分级Ⅱ或Ⅲ级,NYHA分级Ⅱ或Ⅲ级.采用随机数字表法,将患者随机分为2组(n=20):异氟醚组(Ⅰ组)和七氟醚组(S组).麻醉诱导:静脉注射咪达唑仑0.08 mg/kg、舒芬太尼2μg/kg和维库溴铵0.1 mg/kg,气管插管后行机械通气.麻醉维持:Ⅰ组吸入异氟醚,初始呼气末浓度1.2%;S组吸入七氟醚,初始呼气末浓度1.7%;两组静脉输注舒芬太尼0.04μg·kg-1·min-1和维库溴铵0.8μg·kg-1·min-1.通过调节异氟醚或七氟醚的呼气末浓度,维持BIS值40～50.分别于切皮前即刻、术毕、术后2和4 h时,采集中心静脉血样,测定血浆MB型肌酸激酶同工酶(CK-MB)的活性和心肌肌钙蛋白Ⅰ(cTnI)的浓度.记录术中心血管不良事件的发生情况.结果 与Ⅰ组比较,S组术中室性早搏、心动过速、心动过缓、室颤和S-T段抬高＞0.1 mV的发生率升高,术后血浆CK-MB活性和cTnI浓度升高(P＜0.05).结论 非体外循环冠状动脉旁路移植术患者异氟醚的心肌保护作用优于七氟醚.

Abstract：

Objective To compare the myocardial protective effects of isoflurane versus sevoflurane in patients undergoing off-pump coronary artery bypass grafting (OPCABG). Methods Forty ASA Ⅱ or Ⅲ patients (NYHA Ⅱ or Ⅲ ) of both sexes, aged 40-55 yr, weighing 55-94 kg, scheduled for elective OPCABG, were randomly divided into 2 groups ( n = 20 each): isoflurane group ( group Ⅰ) and sevoflurane group ( group S). Anesthesia was induced with midazolam, sufentanil and vecuronium. Patients were tracheal intubated and mechanically ventilated. Anesthesia was maintained with inhalation of isoflurane or sevoflurane and infusion of sufentanil and vecuronium. In group Ⅰ, the initial end-tidal concentration of isoflurane was 1.2%. In group S, the initial end-tidal concentration of sevoflurane was 1.7 %. BIS value was maintained at 40-50 by adjusting the end-tidal concentration of isoflurane or sevoflurane. The central venous blood samples were collected immediately before skin incision, at the end of surgery, 2 and 24 h after surgery for determination of plasma creatine kinase-MB (CK-MB) activity and cardiac troponin Ⅰ (cTnI) concentration. The adverse cardiovascular events were recorded. Results The incidences of ventricular premature beat, tachycardia, bradycardia, ventricular fibrillation and S-T segment elevation ( ＞0.1 mV) during surgery and the plasma CK-MB activity and cTnI concentration after surgery were significantly higher in group S than in group Ⅰ ( P ＜ 0.05). Conclusion Isoflurane has better myocardial protective effect than sevoflurane in patients undergoing OPCABG.     

Role of troponin I, myoglobin, and creatine kinase for the detection of early graft failure following coronary artery bypass grafting.

OBJECTIVE: The detection of early graft failure following coronary artery bypass grafting (CABG) enables immediate reintervention and may significantly limit myocardial damage, thus potentially improving outcome. To date, non-invasive indicators of early graft failure following coronary surgery are still of uncertain diagnostic value. METHODS: In a prospective study, patients following isolated CABG with a postoperative serum cardiac troponin I (cTnI) above 20 ng/ml or significant ECG-changes underwent acute repeat angiography. cTnI, myoglobin (Myo), and creatine kinase (CK) were measured preoperatively and at 1, 6, 12, and 24 h after aortic unclamping. Peak values of cTnI, Myo, CK and isoenzyme CK-MB were determined postoperatively. Receiver operating curves (ROC) for cTnI, Myo and CK/CK-MB were constructed at 6, 12, and 24 h after aortic unclamping to differentiate between patients with and without early graft failure. Based on these curves, the area under curve+/-standard deviation (AUC+/-SD), the sensitivity and specificity were calculated. RESULTS: Out of 2078 consecutive patients having undergone isolated CABG from January 2001 to April 2003, 55 fulfilled the inclusion criteria and underwent acute repeat angiography. Early graft failure was found in 35 patients (group 1), whereas 20 patients did not show graft failure (group 2). CTnI and Myo, but not CK and CK-MB levels were significantly increased in group 1 compared to group 2 at 12 and 24 h after aortic unclamping. ROC analysis of cTnI, Myo and CK/CK-MB indicated cTnI as the best discriminator between the groups with 21.5 ng/ml at 12 h (AUC, 0.82+/-0.06; sensitivity, 82%; specificity, 66%) and 33.4 ng/ml at 24 h (AUC, 0.95+/-0.03; sensitivity, 98%; specificity, 82%) and Myo with 887 microg/ml at 12 h (AUC, 0.72+/-0.07; sensitivity, 73%; specificity, 57%) after aortic unclamping. In contrast, CK/CK-MB as well as the appearance of ECG-changes could not separate between the groups. CONCLUSIONS: cTnI, but not Myo and CK served as a reliable marker for the identification of patients with early graft failure following CABG.     

Risk factors of postoperative nephropathy in patients undergoing innovative CABG and intraoperative graft angiography.

INTRODUCTION: Intraoperative graft angiography is considered gold standard in quality control of innovative CABG techniques. Iodixanol, an iso-osmolar, non-ionic contrast agent has been safely applied in patients with impaired renal function. We aimed to quantify postoperative nephropathy in CABG patients undergoing intraoperative angiography and to define associated risk factors. METHODS: One hundred and thirty-five patients, aged 61 years (range: 43-83), underwent intraoperative angiography following CABG (36 robotically assisted CABG via sternotomy, 41 OPCAB and MIDCAB, 51 AHTECAB, 7 BHTECAB). In all patients iodixanol (Visipaque) was used, median amount: 150 ml (range: 20-500). Nephropathy was defined as an increase in serum creatinine concentration >or= 0.5 mg/dl compared with preoperative values. RESULTS: Nephropathy occured in 19/135 (14%) patients, and was correlated with the following variables: preoperative serum creatinine (p = 0.015, r = 0.208), age (p = 0.008, r = 0.229), postoperative peak troponin T levels (p < 0.001, r = 0.545), postoperative CK-MB peak levels (p = 0.028, r = 0.189), and presence of peripheral vascular disease (p = 0.011). No correlation was found for the contrast agent amount, diabetes mellitus, hypertension, preoperative urea level, cardiopulmonary bypass time, aortic cross clamp time, postoperative CK peak levels. Multivariate analysis showed that postoperative peak troponin T levels (p < 0.001), preoperative serum creatinine (p = 0.031), and patient age (p = 0.043) were independently associated with a postoperative increase of serum creatinine. In all 19 patients with postoperative nephropathy serum creatinine levels returned to preoperative levels. CONCLUSION: Patients with older age and elevated serum creatinine levels undergoing innovative CABG and intraoperative angiography were at increased risk of postoperative nephropathy. However, no correlation was found between the amount of contrast agent (iodixanol) applied and the nephropathy rate and none of the nephropathy cases persisted.     

Intracoronary shunt prevents left ventricular function impairment during beating heart coronary revascularization.

OBJECTIVE: Beating heart coronary revascularization is becoming increasingly popular world-wide. Temporary occlusion of the coronary artery is often required in order to perform the anastomosis. An alternative method to maintain perfusion is to use an intracoronary shunt. In this study, we monitored global left ventricular function and regional wall motion in the presence or absence of a shunt using transesophageal echocardiography (TEE). METHOD: Left ventricular wall motion score index (WMSI), wall motion score (WMS) in the left anterior descending (LAD) coronary artery territory, and ejection fraction (EF%) were measured by multiplane TEE during construction of the left internal mammary artery (LIMA)-LAD coronary artery anastomosis in 40 patients undergoing revascularization with or without the use of a shunt. WMSI was assessed preoperatively, 1, 3 and 6 min during the construction of the anastomosis and after 5 min of reperfusion. WMS was assessed at 6 min during anastomosis and after 5 min of reperfusion. EF% was calculated preoperatively, 5 min into the construction of the anastomosis, and 5 min after reperfusion. RESULTS: During construction of the anastomosis, when the shunt was used, there were no changes in WMSI, WMS in the LAD territory or EF%. A significant decline in these parameters was seen in the group in which the shunt was not used, although on reperfusion all the values returned to baseline control. CONCLUSION: (i) occlusion of the LAD to perform the anastomosis results in temporary impairment in left ventricular function with complete recovery on reperfusion; (ii) the use of an intracoronary shunt presumably by maintaining myocardial perfusion prevents deterioration in ventricular function; (iii) from this data it seems therefore advisable to use an intracoronary shunt in patients with unstable angina, poor left ventricular function, or in cases in which a longer time to perform the anastomosis is anticipated.     

Pre-operative balloon counterpulsation and off-pump coronary surgery for high-risk patients

Coronary artery bypass surgery (CABG) can be performed less invasively without cardiopulmonary bypass (CPB). Multivessel off-pump CABG (OPCAB) is challenging in patients with critical left main stenosis (> 70%) and/or severe ventricular dysfunction (ejection fraction < 0.35) Our objective was the evaluation of efficiency of intra aortic balloon pump (IABP) preoperatively in this high-risk group in order to perform OPCABG safely. MATERIAL AND METHOD: In a consecutive 10-month period (out of 88 OPCABG patients) 23 high-risk patients were treated and were compared with 15 on-pump patients (out of 69) with the same criteria. RESULTS: Preoperative implantation of IABP was significantly higher in the OPCABG group (70% vs 46%, p < 0.05). No conversion to CPB was required in the OPCABG group. Post-operative angiography was systematically performed and demonstrated 97.5% patency of anastomosis. No device-related complications occurred. No difference was found concerning age, risk factors, emergency surgery, ejection fraction, mean number of grafts per patient (2.64 versus 2.75) and average operating time. In contrast, OPCABG demonstrated a trend toward reduced morbidity in terms of atrial fibrillation, reexploration for bleeding and prolonged ventilator requirement > 12 h. Mortality was less in the OPCABG group (p < 0.05). CONCLUSION: More randomized controlled trials are needed to evaluate the true efficacy of elective IABP in OPCABG high-risk patients. Until such studies are evaluated, and therefore because older and sicker patients now constitute a greater percentage of candidates for OPCABG, the timing of application of the IABP is warranted. These results may further justify preoperative use of the IABP in a large proportion of this group of patients.     

The effect of preoperative clopidogrel on bleeding after coronary artery bypass surgery

INTRODUCTION: Clopidogrel treatment is associated with a reduction in thrombotic complications in coronary stent placement, improved outcome after acute coronary syndromes, and decreased mortality in patients with coronary artery disease. The purpose of this study was to analyze the effect of preoperative clopidogrel exposure on bleeding complications, blood transfusions requirements, and reoperations in patients undergoing coronary artery bypass grafting (CABG). PATIENTS AND METHODS: This study included 320 patients from a single institution that underwent an isolated CABG who were discharged between July 2003 and June 2004. The cohort of 320 patients was classified into 3 groups. The control group consisted of 255 patients that did not receive clopidogrel or stopped clopidogrel 7 days before surgery but were treated with aspirin instead. Clopidogrel I consisted of 25 patients that were taking clopidogrel within 3 days of surgery, and Clopidogrel II consisted of 40 patients that were taking clopidogrel 4 to 7 days before surgery. Patients were compared based on preoperative data (age, gender, use of clopidogrel, preoperative hemoglobin, and ejection fraction), intraoperative data (cross-clamp time), postoperative data (chest tube output, rate of reoperation, units of transfused blood, length of stay in the intensive care unit, and length of intubation). RESULT: There were no significant differences among the 3 groups concerning age, sex, ejection fraction, or preoperative hemoglobin. There were no differences in length of intensive care unit stay and length of intubation among the 3 groups of patients. Patients in the clopidogrel I group had more units of blood transfused than either the control or the Clopidogrel II group (p=0.027). There is also a trend toward more chest tube output in clopidogrel I group compared with the control group. Fifteen patients (4.6%) of the total group required reoperation secondary to bleeding: 2 (8.0%) in the Clopidogrel I group, 2 (5%) in the clopidogrel II group, and 11 (4.3%) in the control group (p=0.41). CONCLUSION: This study demonstrated that clopidogrel within 3 days preoperatively increases the requirement for blood transfusion in patients undergoing CABG. Waiting more than 3 days after the last dose of clopidogrel decreases blood transfusion requirements. There is also a trend toward more postoperative bleeding for those patients that took clopidogrel within 3 days before their CABG. The reoperation rate of patients that took clopidogrel within 3 days of their procedure required almost twice as many reoperations as the patients that did not take clopidogrel.     

Cardiac surgery with cardiopulmonary bypass in patients with chronic renal failure.

OBJECTIVE: Renal failure is known to increase the morbidity and mortality in patients undergoing cardiac surgery. The results of heart surgery in patients with non-dialysis-dependent, mild renal insufficiency are not clear. METHODS: One hundred nineteen adult patients with chronic renal failure underwent cardiac surgery. Group I consisted of 93 patients who had creatinine levels between 1.6 and 2.5 mg/dL but who were not supported by dialysis. Group II consisted of 18 patients with creatinine levels higher than 2.5 mg/dL who were not supported by dialysis. Group III consisted of 8 patients with end-stage renal disease who were receiving hemodialysis. RESULTS: The hospital mortality rates were 11.8%, 33.0%, and 12.5%, respectively. Morbidity was 21.5%, 44.4%, and 75.0%, respectively, in groups I, II, and III. Postoperative hemodialysis was needed in 2 (2.15%) patients from group I and 6 (33%) patients from group II. On multivariable logistic regression analysis, risk factors for mortality were preoperative creatinine level more than 2.5 mg/dL, angina class III-IV, emergency operation, excessive mediastinal hemorrhage, postoperative pulmonary insufficiency, low cardiac output, and rhythm disturbances. Risk factors for morbidity were preoperative creatinine level more than 2.5 mg/dL and postoperative dialysis. CONCLUSIONS: Chronic renal failure increases the mortality and morbidity in patients undergoing cardiac surgery. Renal insufficiency with creatinine levels higher than 2.5 mg/dL increases the risk of postoperative dialysis and prolongs the length of hospital stay. Careful preoperative management and intraoperative techniques, such as avoiding low perfusion pressure and using low-dose dopamine, may be useful for a good operative outcome.     

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.     

Pulmonary abnormalities after coronary arterial bypass grafting operation: cardiopulmonary bypass versus mechanical stabilization

BACKGROUND: Cardiopulmonary bypass has been implicated in causing poor pulmonary gas exchange postoperatively in patients undergoing coronary artery bypass grafting procedures. This randomized prospective study was conducted to determine whether patients undergoing coronary artery bypass grafting operations using cardiac stabilization and thereby avoiding cardiopulmonary bypass will have improved pulmonary function postoperatively. METHODS: Fifty-eight patients were randomized to one of two groups: coronary artery bypass grafting operation with stabilization or coronary artery bypass grafting operation with cardiopulmonary bypass. Preoperative and postoperative pulmonary gas exchange measurements were performed on intubated patients, including the arterial partial pressure of oxygen on 100% inspired oxygen, the alveolar-arterial oxygen gradient, and pulmonary shunt. Static and dynamic lung compliance measurements were performed postoperatively. Hemodynamic variables (including creatine kinase-MB and troponin levels), intubation time, postoperative bleeding, and blood transfusions were compared. RESULTS: Both study groups had a large decrease in arterial partial pressure of oxygen on 100% inspired oxygen (p < 0.0001) and a significant postoperative increase in the alveolar-arterial oxygen gradient (p < 0.0001). There was no statistical difference in the postoperative gas exchange between the two groups; however, the postoperative pulmonary shunt was significantly better in the stabilization group (24% versus 31%, p = 0.03). The patients were extubated in the intensive care unit earlier in the stabilization group (8.2 hours versus 9.2 hours, not significant). The mean static and dynamic lung compliance postoperatively was lower in the stabilization group, although not statistically significant (p = 0.06). CONCLUSIONS: Coronary artery bypass grafting operation using cardiac stabilization technique is safe and avoids the risk of cardiopulmonary bypass. The pulmonary gas exchange postoperatively is comparable to standard cardiopulmonary bypass procedures, but a reduced postoperative pulmonary shunt was seen in the stabilization group.     

The effect and role of the intraaortic balloon pumping in off-pump coronary artery bypass

Eighty consecutive patients who underwent off-pump coronary artery bypass (OPCAB) were studied. They were divided into group I (n = 10) which received preoperative intraaortic balloon pumping (IABP), and group II (n = 70) which did not receive IABP. The indications for preoperative IABP were severe left main coronary artery disease in 7 patients, severe 3 vessel disease in 3 patients, unstable angina in 5 patients, acute myocardial infarction in 3 patients. There was no operative mortality in both groups. The average number of distal anastomosis 2.7/patients in group I and 3.3/patients in group II. There was no differences in ventilator support time, length of stay in the intensive care unit and morbidity between 2 groups. The average postoperative IABP support time was 5.4 hours. There was no IABP-related complication in group I. IABP was very effective to perform OPCAB surgery safety. Preoperative IABP may be effective modality to support OPCAB surgery not only in emergent case but also in elective case.     

Minimally invasive direct coronary artery bypass grafting: changes in anesthetic management and surgical procedure.

OBJECTIVE: The authors hypothesized that changes in surgical procedures for minimally invasive direct coronary artery bypass grafting (MIDCAB) have led to changes in anesthetic management with a resultant decrease in the complexity of care. DESIGN: Retrospective observational study. SETTING: University teaching hospital. PARTICIPANTS: Review of the records of 60 patients who underwent MIDCAB surgery. MEASUREMENTS AND MAIN RESULTS: Data included preoperative demographics, perioperative anesthetic management, and postoperative cardiac and noncardiac issues and complications. Two groups were formed: in group I, a coronary stabilizer (CS) was not used, and in group II, it was. With the exception of a greater incidence of those with no preoperative comorbidities in group II (CS), there were no differences between the two groups with respect to demographics or preoperative variables. A surgical design called H-graft was used in a greater number of group II (CS) patients, whereas a direct anastomosis was performed in the majority of group I patients. Use of pharmacologically induced bradycardia/asystole has not been performed after the introduction of the CS. The use of central venous catheters (instead of pulmonary artery catheters) and single-lumen (v double-lumen) endotracheal tubes was greater in group II (CS) patients. Despite changes in intraoperative management, there was no significant change in the incidence of postoperative complications, intensive care unit stay, and hospital stay between groups I and II. New-onset atrial fibrillation was the most common postoperative complication (13 of 56 patients; 23%). Three of 24 patients (12.5%) who received intraoperative magnesium experienced atrial fibrillation compared with 10 of 32 patients (31%) who did not receive magnesium. CONCLUSIONS: The complexity of anesthetic technique has decreased since the onset of MIDCAB surgery. The decrease in complexity may be related to changes in surgical design and technology.     

Nicardipine or nitroglycerin in patients with failed percutaneous coronary angioplasty: effect on myocardial diastolic function

OBJECTIVE: To evaluate whether intracoronary vasodilators can improve diastolic function in 32 patients with failed percutaneous transluminal coronary angioplasty (PTCA). DESIGN: Clinical trial. SETTING: Single-institution, academic hospital. PARTICIPANTS: Failed PTCA patients undergoing emergency coronary artery bypass grafting surgery. INTERVENTIONS: Patients were divided into 2 groups: group A received 0.1 mg of intracoronary nicardipine, and group B received 20 microg of intracoronary nitroglycerin. Both drugs were administrated via a coronary dilatation perfusion catheter inserted in the catheterization laboratory by the cardiologist. Subsequently, they were continuously infused via the side port of the introducer of the pulmonary artery catheter and titrated to keep systolic blood pressure at about two thirds of the control value. Transesophageal echocardiography (Power Vision/6000, 9-mm 5MHZ Probe; Toshiba, Elmsford, NY) was used in this study. MEASUREMENTS AND MAIN RESULTS: Left ventricular ejection fraction, cardiac index, tissue Doppler imaging velocity of the left ventricle and mitral annulus, and troponin levels were measured before and after administration of the 2 vasodilators and after cardiopulmonary bypass. Diastolic dysfunction was found preoperatively in all the patients and responded only to intracoronary nicardipine. Ea of mitral annulus velocity significantly increased in group A patients from 7.5 +/- 0.02 to 11.8 +/- 0.01 (p < 0.005) and decreased in group B patients from 8.0 +/- 0.03 to 7.5 +/- 0.02 after nicardipine or nitroglycerin administration. Left ventricular ejection fraction and cardiac index increased significantly (p < 0.005) only after nicardipine administration. Troponin levels were significantly lower in group A than in group B patients (p < 0.005). CONCLUSION: Intracoronary nicardipine improves diastolic function and myocardial flow velocity in patients with failed PTCA undergoing emergency coronary artery bypass graft surgery.     

Myocardial protective effect of lidocaine during experimental off-pump coronary artery bypass grafting.

Off-pump coronary artery bypass grafting (OPCABG) has recently gained popularity. During OPCABG, patients remain vulnerable to ischemic-reperfusion injury due to a temporary coronary occlusion without any active cardioprotection. Some strategies such as ischemic preconditioning (IP) and an intracoronary shunt have been applied with a view to minimizing the effects of ischemia, but the effects of these strategies remain controversial. This study was carried out to investigate the protective effect of lidocaine against myocardial ischemic-reperfusion injury. Twenty-one pigs were assigned to three groups, each consisting of seven pigs. In the control group, using a left internal thoracic artery (LITA) bypass circuit, the left anterior descending coronary artery (LAD) was occluded for 45 min followed by two hours of reperfusion. In the IP group, five min of occlusion followed by 15 min of reperfusion was performed. In the lidocaine group, 2 mg/kg of lidocaine was administered directly into the LAD just before the LAD occlusion. Infarct size expressed as a percentage of the area at risk was significantly smaller in the lidocaine group (2.7+/-4.2%) than in the control group (79.9+/-6.0%, p<0.001) or the IP group (57.0+/-25.9%, p<0.001). Lidocaine exhibited a potent myocardial protective effect in the present OPCABG model.