On line ST-segment analysis for detection of myocardial ischaemia during and after coronary revascularization

Purpose

A paucity of information exists to validate the accuracy and reliability of ECG monitoring in the operating room or ICU. The purpose of this study was to determine the accuracy, sensitivity, specificity, and predictive values of the Marquette ECG monitor for detection of perioperative myocardial ischaemia (PMI) as measured by ST segment changes in a high risk population.

Methods

Monitoring for PMI in 28 patients scheduled for aortocoronary bypass surgery was done with the Cardiodata PR® ambulatory continuous electrocardiography (ACECG) monitor lead V₅, and compared with lead V₅ of the Marquette® Series 7000 ECG/ Surgical operating room monitor, and ECG/Resp ICU monitor. The Marquette lead V₅ was evaluated using current criteria for the assessment of diagnostic tests including concordance, sensitivity, specificity, positive and negative predictive values, false positive and false negative rates and compared with the ACECG monitor which served as the reference or “gold standard.” Agreement beyond chance between the two methods was assessed using the Kappa statistic.

Results

Of the 53 observation data points, 27 were defined as ischaemic episodes by ACECG. Concordance between lead V₅ in each system was 83% (44/53 episodes). Discordance was 17% (9/53 episodes), predominantly in the postbypass interval (77%, 7/9; P = 0.0184). The incidences of false negatives and false positives for Marquette lead V₅ was 26% (7/27) and 7.7% ( 2/26), respectively. The sensitivity and specificity of the Marquette was 0.74 and 0.92. Positive predictive value was 0.91, negative predictive value was 0.77, and Kappa statistic was 66%.

Conclusion

Automated ST segment analysis with the Marquette® Series 7000 monitoring system demonstrates good diagnostic accuracy, moderate sensitivity, and high specificity. However, clinically significant false negative and false positive rates of ischaemia detection are associated with its use, especially in the postoperative period.     

Intravenous nifedipine to treat hypertension after coronary artery revascularization surgery. A comparison with sodium nitroprusside.

We administered sodium nitroprusside (SNP) or nifedipine intravenously to patients who became hypertensive after elective coronary revascularization and compared their effects on hemodynamics and the electrocardiogram in a parallel, randomized, open-label study. Four of 21 patients treated with nifedipine required the addition of SNP to maintain mean arterial pressure less than 90 mm Hg, compared with 4 of 28 patients in the SNP group who required the addition of nifedipine. The success rates of nifedipine (81%) and SNP (86%) were not significantly different. There was no difference in the incidence of adverse ST-segment changes during drug infusion (4% versus 5%) or perioperative myocardial infarction (9.5% versus 10.7%) in the nifedipine versus SNP groups, respectively. The plasma nifedipine concentration (mean value +/- SD) at steady state for 21 patients receiving nifedipine was 119 +/- 42.5 ng/mL. The pharmacokinetic variables for nifedipine were as follows (mean values +/- SD): systemic clearance, 0.525 +/- 0.228 L.h-1.kg-1; apparent volume of distribution, 0.738 +/- 0.446 L/kg; and elimination half-life, 1.02 +/- 0.51 h. These values are similar to those reported previously in healthy volunteers. We conclude that intravenous nifedipine can be used safely to control hypertension after coronary revascularization but were unable to demonstrate an advantage of nifedipine compared with SNP in preventing postoperative ischemia or infarction in this group of patients who had good left ventricular function.     

Surveillance after distal revascularization for critical limb ischaemia

Patients with critical limb ischaemia (CLI) are usually elderly and suffer from several co-morbidities. The goal of surveillance after both endovascular and surgical revascularization for CLI is not only the protection of re-established distal perfusion and sustained ambulation but also the reduction of systemic atherothrombotic risk and mortality by ensuring continued best medical care. However, preferred format and rhythm of structured follow-up programs have remained controversial, mainly because of lack of compelling evidence. This review aims to summarize and to appraise available information critically. Thereby, it underlines the importance of systematic surveillance after both surgical and endovascular revascularization for CLI. Recent European guidelines are considered and areas of uncertainty are highlighted and discussed. According to currently available literature and recent guidelines, the early duplex scan is justified in all patients undergoing endovascular or surgical distal revascularization for CLI. There is no best level evidence supporting continued long term duplex surveillance of revascularizations with normal findings at early duplex scan, whereas those patients with abnormal early duplex scan or high risk revacularization are likely to benefit from continued duplex surveillance. Regular clinical follow-up is suggested and clinical deterioration should trigger duplex scanning to ensure revascularization patency.     

Intravenous amiodarone for prevention of atrial fibrillation after coronary artery bypass grafting

BACKGROUND: Atrial fibrillation occurs in 10% to 40% of patients who undergo coronary artery bypass grafting. This prospective study assesses the safety and efficacy of low-dose intravenous amiodarone in the prevention of atrial fibrillation after coronary artery bypass grafting. METHODS: One hundred forty patients were randomly divided into two groups: an amiodarone group (n = 74) receiving intravenous amiadarone in a loading dose of 150 mg and maintenance dose of 0.4 mg x kg(-1) x h(-1) for 3 days before and 5 days after operation and a control group (n = 76) receiving matching infusions of 5% glucose solution. RESULTS: Atrial fibrillation occurred in 9 (12%) of the amiodarone group patients and in 26 (34%) of the control group patients during hospitalization (p < 0.01). The maximum ventricular rate during atrial fibrillation was significantly slower in the amiodarone group (107 +/- 21) than in the control group (138 +/- 24 beats per minute, p < 0.01). The duration of atrial fibrillation in the amiodarone group (1.1 +/- 1.2 hours) was significantly shorter than that in the control group (3.2 +/- 1.3 hours, p = 0.01). The two groups had no significant differences in incidence of major morbidity (8 of 74 versus 8 of 76 in amiodarone and control groups, respectively) or mortality (4 of 74 versus 5 of 76). However, the control group had significantly longer intensive care unit stays (132 +/- 24 versus 111 +/- 19 hours, p < 0.01). CONCLUSIONS: Perioperative low-dose intravenous amiodarone significantly reduces the incidence, ventricular rate, and duration of atrial fibrillation after coronary artery bypass grafting. Furthermore, low-dose intravenous amiodarone is well tolerated and does not increase the risk of intraoperative or postoperative complications.     

Off-pump coronary artery bypass attenuates transient hepatocellular damage after myocardial revascularization

OBJECTIVE: Cardiopulmonary bypass (CPB) affects hepatocellular integrity and occasionally results in liver dysfunction after cardiac surgery. Performing coronary artery bypass graft surgery without CPB may help to reduce the risk of this complication and better preserve perioperative liver function. This study compared perioperative hepatocellular damage in patients undergoing on-pump and off-pump bypass surgery. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Patients scheduled for elective on-pump (n = 21) and off-pump (n = 17) coronary artery bypass surgery. MEASUREMENTS AND MAIN RESULTS: Liver function was assessed by serum levels of alcohol dehydrogenase (AD) and alpha-glutathione S-transferase (alpha-GST), which serve as more sensitive indices of hepatocellular injury than do conventional transaminases. Arterial blood was sampled at 6 stages: after induction of anesthesia (baseline); at the end of CPB in the on-pump group or on completion of the last distal anastomosis in the off-pump group; at the end of surgery; and 6 hours, 12 hours, and 24 hours after the end of anesthesia. The off-pump patients showed significantly lower increases in serum AD and alpha-GST levels than did the on-pump group. AD and alpha-GST values increased in the on-pump patients after the initiation of CPB and peaked at the end of surgery, with a return to baseline at 12 hours and 24 hours after the end of anesthesia. No clinically relevant liver dysfunction was observed in either group. CONCLUSIONS: CPB induced transient subclinical hepatocellular damage, whereas off-pump revascularization attenuated this damage.     

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。     

Occurrence of myocardial ischemia immediately after coronary revascularization using radial arterial conduits

OBJECTIVE: To assess the incidence of myocardial ischemia in patients receiving radial arterial and left internal thoracic arterial conduits (RA+LITA) during the postrevascularization period. DESIGN: Nonrandomized observational sequential cohort. SETTING: University hospital. PARTICIPANTS: Thirty adult patients, scheduled for elective coronary artery bypass graft surgery with RA+LITA, compared with 30 patients who received saphenous vein graft and left internal thoracic arterial conduits. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Myocardial ischemic episodes were defined as reversible ST-segment depressions or elevations >or=1 mm and >or=2 mm at J +60 msec and lasting >or=1 minute using 2-channel Holter monitoring. During the post-cardiopulmonary bypass period, a significantly higher number of patients with >or=2 mm ischemic episodes (21.7%; p = 0.015) and higher number of >or=2 mm ischemic episodes per hour (0.19 +/- 0.4 episodes/hr; p = 0.03) were observed in the radial artery group versus the comparison group (0% of patients and 0 episodes/hr). During the postoperative period (24 hours), a significantly longer duration of >or=2 mm ischemic episodes was observed in the radial artery group (24 +/- 33 minutes v 8.4 +/- 21 minutes; p = 0.046). Radial artery graft, preoperative calcium antagonists, and pulmonary arterial mean pressure were independent predictors of the duration and area under the ST-segment curve of >or=2 mm ischemic episodes during the postoperative period. CONCLUSION: There is an association between the use of the radial artery graft and the incidence and severity of >or=2 mm postrevascularization ischemic episodes.     

Ventricular function and the native coronary circulation five years after myocardial revascularization.

Of 531 patients who underwent coronary artery bypass grafting during 1970 to 1973, 181 were restudied by ventriculography and by graft and coronary angiography at least 5 years following operation. Five patterns of postoperative ventricular function were identified: improved ventricular function resulting in normal left ventricular (LV) function; normal ventricular function that was unchanged; abnormal ventricular function that improved but did not reach normal; abnormal ventricular function that remained unchanged; and deterioration of LV function. Patients who regained (40) and those who retained normal ventricular function (49) comprise 49% of the series and patients with deterioration of ventricular function, only 20%. Graft patency and angina relief were significantly better in those with normal LV function than in those with LV deterioration. Progression of disease in grafted coronary arteries was similar in all groups, but was significantly higher in ungrafted coronary arteries (61.3%) in the patients showing deterioration than in either the improved patients or those with an unchanged normal LV (33.3% each) (p less than 0.05). The high incidence of progression of disease in ungrafted coronary arteries in the group with deterioration suggests that low graft patency and deterioration of ventricular function in this group might both be related to intrinsic acceleration of coronary atherosclerosis unrelated to operative intervention.     

术中多巴酚丁胺负荷经食道超声心动图预测冠状动脉旁路移植术后心肌存活的评价

目的 评价术中多巴酚丁胺负荷经食道超声心动图(DSE)预测冠状动脉旁路移植术后心肌存活情况.方法 择期拟行冠状动脉旁路移植术病人24例,性别不限,年龄50～75岁,体重55～90 kg,NYHA分级Ⅱ或Ⅲ级,左室射血分数30%～55%.麻醉诱导后,采用食道超声按16节段法,观察左室节段室壁运动情况,行半定量评分.静脉输注多巴酚丁胺,初始速率5μg·kg~(-1)min~(-1),然后以1μg·kg~(-1)min~(-1)的速率递增,每一速率持续输注3 min.将舒张末室壁厚度>0.5 cm的节段、室壁运动异常评分较给药前降低≥1分的心肌定义为存活心肌.计算DSE预测心肌运动恢复的敏感度、特异度、准确率、阳性预测率和阴性预测率.结果 DSE预测心肌存活率(36.3%)低于术后心肌运动改善率(43.2%)(P<0.05).DSE预测心肌存活的敏感度、特异度、准确率、阳性预测率和阴性预测率分别为75.3%、92.7%、85.3%、88.4%和83.5%.结论 术中DSE可有效地预测冠状动脉旁路移植术后存活心肌及功能恢复.     

Renal dysfunction after myocardial revascularization.

OBJECTIVES: In this study, we evaluate the incidence of and analyse the pre and intraoperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on perioperative mortality and on hospital length of stay. In addition, we sought to investigate the influence of a mildly increased serum creatinine (1.3-2.0 mg/dl) on perioperative mortality and morbidity. METHODS: The study included 2445 consecutive patients who had no pre-existing renal disease (creatinine or=2.1 mg/dl with a preoperative-to-postoperative increase >or=0.9 mg/dl. Univariate and multivariate analyses were performed where appropriate. RESULTS: Global 30-day mortality was 0.7%. The incidence of PRD was 5.6% (136 patients). Mortality for patients who experienced PRD was 8.8 vs. 0.1% for patients who did not (P<0.001). PRD increased the length of hospital stay by 3.4 days (7.6 vs. 11.0 days; P<0.001), and patients who needed haemodialysis (11%) had a perioperative mortality of 33.3% and a mean hospital length of stay of 16 days. Multivariable logistic regression identified the following variables as independent predictors of PRD: age (P=0.017; odds ratio (OR) 1.3 per 10 years), angina class III/IV (P=0.003; OR 1.7); cardiopulmonary bypass time (P=0.007; OR 1.01 per minute); preoperative serum creatinine levels: group 1 (1.3-1.6 mg/dl (P<0.001; OR 5.5)) and group 2 (1.7-2.0 mg/dl (P<0.001; OR 14.2)). Finally, a mild elevation of the preoperative creatinine level (1.3-2.0 mg/dl) increased significantly the probability of perioperative mortality, low cardiac output, haemodialysis and prolonged hospital stay. CONCLUSIONS: Although the likelihood of PRD in patients without pre-existing renal dysfunction is relatively low, it dramatically increases mortality, morbidity and length of stay after CABG. Mildly elevated (>1.2 mg/dl) preoperative serum creatinine level significantly increases the perioperative mortality and morbidity.     

Improved efficacy of intra-aortic balloon pumping by pharmacological myocardial protection for postoperative pump failure after coronary revascularization

Fifty patients took part in a randomized and prospective study to define the effect of pharmacological myocardial protection when using IABP in patients with postoperative pump failure, following coronary revascularization under cardiopulmonary bypass employing moderate hypothermia and cardioplegia. Pharmacological protection was given to 23 patients, administering coenzyme Q, 5 mg/kg, and aprotinin, 10,000 KIU/kg, intravenously, every 12 hours, following surgery. A single dose of each drug was also given intraoperatively. The postoperative haemodynamics, serum enzyme levels and success of weaning from IABP, were compared between the group of patients who received pharmacological protection (the treated group) and the control group which comprised 27 patients who were treated only with IABP. Among the surviving patients, no significant differences were seen in the hemodynamics or cardiac enzyme levels between the two groups. The rate of successful weaning from IABP however, was 95 per cent in the treated group as compared with only 74 per cent in the control group, p = 0.02. These results suggest that pharmacological myocardial protection, using coenzyme Q and aprotinin in both the intra- and post-operative periods, improves the efficacy of IABP in the treatment of post-operative pump failure following coronary revascularization.     

Prevention of ventricular fibrillation after myocardial revascularization

Ventricular fibrillation during reperfusion after aortic cross-clamping for coronary artery bypass grafting may cause subendocardial injury. We investigated the use of lidocaine to prevent ventricular fibrillation during this period. In a blind, prospective, randomized trial, 91 consecutive patients undergoing elective coronary artery bypass graft procedures were given lidocaine (2 mg/kg) or normal saline immediately before removal of the aortic cross-clamp. The groups were similar with respect to demographic, clinical, and intraoperative variables. Myocardial preservation techniques were similar in both groups. Of 47 patients receiving lidocaine, 38 recovered a supraventricular rhythm without ventricular fibrillation, compared with only 5 of 44 patients in the control group (p less than .001). When ventricular fibrillation occurred, patients in the control group required a greater number of direct-current countershocks (2.31 versus 1.86) to convert to sinus rhythm. Transient heart block, requiring temporary pacing, developed in 3 patients in the lidocaine group, compared with 1 patient in the control group. There was no significant difference between the groups in the requirement for perioperative inotropic support (6 of 47 versus 6 of 44) or the number of myocardial infarctions (2 of 47 versus 1 of 44), and there were no deaths in either group. Lidocaine infusion immediately before removal of the aortic cross-clamp significantly reduces the incidence of ventricular fibrillation during the reperfusion period after cardiopulmonary bypass.     

Improved efficacy of intra-aortic balloon pumping by pharmacological myocardial protection for postoperative pump failure after coronary revascularization

Fifty patients took part in a randomized and prospective study to define the effect of pharmacological myocardial protection when using IABP in patients with postoperative pump failure, following coronary revascularization under cardiopulmonary bypass employing moderate hypothermia and cardioplegia. Pharmacological protection was given to 23 patients, administering coenzyme Q, 5 mg/kg, and aprotinin, 10,000 KIU/kg, intravenously, every 12 hours, following surgery. A single dose of each drug was also given intraoperatively. The postoperative haemodynamics, serum enzyme levels and success of weaning from IABP, were compared between the group of patients who received pharmacological protection (the treated group) and the control group which comprised 27 patients who were treated only with IABP. Among the surviving patients, no significant differences were seen in the hemodynamics or cardiac enzyme levels between the two groups. The rate of successful weaning from IABP however, was 95 per cent in the treated group as compared with only 74 per cent in the control group, p=0.02. These results suggest that pharmacological myocardial protection, using coenzyme Q and aprotinin in both the intra- and post-operative periods, improves the efficacy of IABP in the treatment of post-operative pump failure following coronary revascularization. This paper was presented at the Xth World Congress of Cardiology at Washington, DC in 1986.