The significance of bundle branch block in the immediate postoperative electrocardiograms of patients undergoing coronary artery bypass

Three hundred sixteen consecutive patients undergoing coronary artery bypass were studied for postoperative electrocardiographic conduction disturbances. Fifty-five of these 316 patients had postoperative bundle branch block (Group 1). This group had a higher incidence of left main coronary stenosis, together with previous inferior myocardial infarction, than patients without postoperative conduction disturbances (Group 2). Perioperative myocardial infarction, low cardiac output, and death were significantly more common in Group 1 than in Group 2: 7.3% versus 1.9% for perioperative myocardial infarction, 16.4% versus 2.7% for low cardiac output, and 5.5% versus 0.8% for death. Analysis of the type of conduction disturbances indicates that the presence of a new complete left bundle branch block postoperatively in a patient undergoing coronary artery bypass is a sign of intraoperative myocardial damage. This damage is potentially lethal, especially in a patient with left main coronary stenosis and previous inferior myocardial infarction.     

Cardiac arrhythmias and myocardial ischemia after thoracotomy for lung cancer.

The records of 598 patients undergoing a thoracic surgical procedure for lung cancer from 1975 through 1989 were reviewed for occurrence of cardiac arrhythmias and myocardial ischemic events. Atrial tachycardias occurred in 16% (94/598); atrial fibrillation was preponderant (87%), followed by supraventricular tachycardia and atrial flutter. Patients with recurrent episodes of dysrhythmias had a significantly higher mortality rate than those without episodes or with a single episode only (17% versus 2.4%; p less than 0.01). Transient ischemic electrocardiographic changes were documented in 23 patients (3.8%) and myocardial infarction in 7 (1.2%). An abnormal preoperative exercise test result and intraoperative hypotension were strongly associated with both dysrhythmia and ischemia (p less than 0.01). Pneumonectomy, ischemic changes on the electrocardiogram, and cardiac enlargement were also associated with arrhythmias (p less than 0.01). A weaker association (p less than 0.05) was found between postoperative arrhythmias and old myocardial infarction (greater than 6 months), arterial hypertension, and heart failure. Pulmonary function had no predictive value in this respect. A history of angina or old myocardial infarction was predictive of transient postoperative myocardial ischemia but not myocardial infarction. Despite improved anesthetic and monitoring techniques and more frequent use of the intensive care unit postoperatively in the last decade, the incidence of arrhythmias after thoracotomy has not decreased. More effective prevention is needed, particularly for patients with defined preoperative and perioperative risk factors.     

Changes in serum creatine kinase and lactate dehydrogenase caused by acute perioperative myocardial infarction and by transatrial cardiac surgical procedures

A prospective clinical study was conducted to ascertain if a patient's postoperative elevation in serum creatine kinase MB isoenzyme coupled with determination of the lactate dehydrogenase1/lactate dehydrogenase2 ratio could differentiate whether atrial or ventricular myocardium was the source of these changes. Animal studies have shown that atrial myocardium is as rich a source of creatine kinase MB as is ventricular myocardium. Atrial myocardium has a lactate dehydrogenase1/lactate dehydrogenase2 ratio less than 1.00, whereas in ventricular myocardium the ratio is greater than 1.00. Sixty-four patients were assigned to six groups on the basis of serial electrocardiograms and vectorcardiograms by a cardiologist who was unaware of their clinical courses. The control group (Group 1) consisted of 16 patients admitted to the coronary care unit who had no electrocardiographic changes. Three surgical groups without electrocardiographic or vectorcardiographic evidence of perioperative myocardial infarction were studied: 10 patients undergoing routine coronary artery bypass procedures (Group 2), six adults undergoing repair of secundum atrial septal defect (Group 3), and 13 patients having mitral valve replacement (Group 4). Two groups of surgical patients who had acute perioperative transmural myocardial infarctions confirmed by serial electrocardiograms and vectorcardiograms were studied: 15 patients (Group 5) who had elective coronary artery bypass procedures and four (Group 6) who had mitral valve replacement. This study suggests that serum creatine kinase MB levels in excess of 50 IU/L on the postoperative day 1 and day 2 samples coupled with serum lactate dehydrogenase1/lactate dehydrogenase2 ratios greater than 1.00 on the postoperative day 2 and day 3 samples support the diagnosis of acute myocardial infarction. Patient groups undergoing procedures necessitating atriotomies had average elevations in serum creatine kinase MB and in the lactate dehydrogenase1/lactate dehydrogenase2 ratio, but these were significantly less than those seen when acute perioperative myocardial infarction had occurred.     

Equilibrium radionuclide angiocardiography prior to elective abdominal aortic surgery

Equilibrium radionuclide angiocardiography (ERNA) was employed preoperatively in 183 patients undergoing elective abdominal aortic reconstruction to measure left ventricular ejection fraction (LVEF) and to detect abnormal regional wall movement. Abnormal ejection fractions were virtually confined to the 97 patients who had clinical, electrocardiographic or radiographic evidence of heart disease. An operative mortality of 8.7% was recorded. Major cardiac events (defined as myocardial infarction, cardiac failure or malignant ventricular arrhythmia) occurred in 15 of 86 abdominal aortic aneurysm patients (17.4%) and six of 96 (6.25%) patients with aorto-iliac occlusive disease. Patients with an abdominal aortic aneurysm and abnormal LVEF or regional wall motion abnormality were more likely to suffer a cardiac event (p less than 0.001), the event rate exceeding 60% in patients whose LVEF was less than 35%. An abnormal LVEF failed to predict a cardiac event in patients with aorto-iliac occlusive disease. While not indicated in patients lacking clinical evidence of heart disease, ERNA can refine the assessment of cardiac risk, particularly in patients with previous myocardial infarction and define a high risk group in whom aortic reconstruction should be avoided except for the most compelling of indications.     

Atrial fibrillation after coronary artery bypass grafting without cardiopulmonary bypass.

OBJECTIVE: Atrial fibrillation is the most common complication after heart surgery. It rarely has a fatal outcome but causes patient instability, prolongs hospital stay, or even is the reason for perioperative infarction. Although conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass has excellent short-term and long-term results, the number of coronary operations on a beating heart without cardiopulmonary bypass is still growing. To reduce surgical trauma, off-pump coronary artery bypass grafting via sternotomy (OPCABG) or minimally invasive direct vision coronary artery bypass grafting (MIDCABG) via small thoracotomy are performed. The aim of this study was to estimate the frequency of atrial fibrillation in patients after myocardial revascularization without cardiopulmonary bypass. METHODS: A retrospective analysis of 48 patients undergoing myocardial revascularization without cardiopulmonary bypass was performed. Twenty-four patients underwent OPCABG and 24 were operated using the MIDCABG technique. The incidence of cardiac arrhythmias was analyzed since operation to the fourth postoperative day. Each patient had continuous ECG monitoring with option of arrhythmia analysis during ICU stay. After discharge from ICU 24-h ECG monitor studies were carried out. Surface 12-lead ECG was accomplished once a day, and additionally each time symptoms of cardiac arrhythmia occurred. Risk factors of atrial fibrillation were estimated. RESULTS: Atrial fibrillation occurred in 25% of patients after MIDCABG, in 29% after OPCABG, and in 18% after CABG with cardiopulmonary bypass. This difference has no statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups. CONCLUSIONS: Atrial fibrillation is a common complication after procedures of myocardial revascularization, performed with or without cardiopulmonary bypass. The occurrence is not dependent on the type of operation.     

Angina and other risk factors in patients with cardiac diseases undergoing noncardiac operations

Six hundred eighty-eight consecutive patients with cardiac diseases or who were older than 70 yr of age, all of whom were undergoing noncardiac operations, were studied. Twenty-four preoperative risk factors were analyzed for the outcome of perioperative myocardial infarction (PMI) or cardiac death using stepwise logistic regression. Old age, emergency operation, angina, previous myocardial infarction, electrocardiographic signs of ischemia, type of surgical procedure, and hypokalemia were identified as individual factors useful in predicting outcome. Thirty-two patients (4.65%) developed PMI. Seven of these 32 patients (21.9%) and eight more patients without PMI--a total of 15 patients (2.2%)--died a cardiac death. Nonfatal but serious complications occurred in 23% of the patients. Patients undergoing emergency operations and patients with chronic stable angina, previous myocardial infarction, and electrocardiographic signs of ischemia were found to be at increased risk for PMI and cardiac death.     

Significance of right bundle branch block in the diagnosis of myocardial ischemia in patients undergoing coronary artery bypass grafting.

BACKGROUND: Perioperative diagnosis of myocardial ischemia following cardiac surgical procedures remains a challenging problem. Particularly, the role of new conduction disturbances as markers of postoperative ischemia is still questionable. The goal of this study was to elucidate the diagnostic significance of new postoperative right bundle branch block (RBBB) for the detection of perioperative myocardial ischemia in patients undergoing elective coronary artery bypass grafting (CABG). METHODS: In 169 consecutive patients, three-channel Holter monitoring and serial assessment of serum enzymes were performed for 48 h, and 12-lead ECG repeated for up to 5 days postoperatively. Postoperative events were classified as either myocardial infarction (MI), transient ischemic events (TIE) or various conduction disturbances. RESULTS: Transient (n=9) or permanent (n=4) RBBB occurred in 13 patients (8%); 14 patients (8%) showed signs of perioperative MI and 18 patients (11%) evidence of TIE. Peak activity of creatine-kinase (CK, 561+/-135 vs. 316+/-19, P<0.05) and CK-MB (22.7+/-3.2 vs. 13.4+/-0.8, P<0.01) were higher in patients with RBBB than in patients without perioperative ischemic events. Peak CK-MB levels were significantly higher in patients with MI as compared to those with RBBB (33.4+/-7.6 vs. 22.7+/-3.2, P<0. 05). Patients with TIE had similar perioperative enzyme levels as patients with no events. CONCLUSION: It is concluded that the combined assessment of repeated 12-lead ECG, continuous Holter monitoring and enzyme analysis allows a reliable diagnosis of perioperative myocardial ischemia and conduction disturbances. The occurrence of new RBBB following elective CABG is indicative of perioperative myocardial necrosis and thus serves as a valuable tool for the diagnosis of new, perioperative ischemic events.     

Failure of negative dipyridamole thallium scans to predict perioperative myocardial ischaemia and infarction

Three cases of postoperative myocardial infarction are reported in patients with normal or fixed defects on preoperative dipyridamole thallium scans (interpreted as "negative" for active cardiac ischaemic risk). All patients were monitored with an ambulatory electrocardiographic recorder from the evening before surgery through the first two postoperative days. Two of the patients demonstrated preoperative or early postoperative ischaemia, suggesting that the test was a false negative. The third patient did not demonstrate ischaemia during the period of monitoring, but developed a myocardial infarction during the third postoperative day, suggesting progression of the underlying coronary artery disease. Preoperative dipyridamole thallium imaging may result in false negative scans in selected high-risk populations.     

腹部手术对老年心脑血管病患者的影响

目的探讨老年患者腹部手术后心脑血管意外的发病特点及防治体会。 方法回顾性分析2011年1月至2013年12月本科室诊治的64例腹腔手术后发生心脑血管意外的老年患者临床资料,其中32例伴有心脑血管疾病为A组,同期无心脑血管疾病的32例行腹腔手术的患者为B组,探讨其发病的原因及防治方法。 结果A组术后11例发生了脑梗死,其中6例为脑栓塞,4例发生脑出血,心肌梗死6例,心电图有心肌缺血5例,ST段改变9例,急性心力衰竭2例,心律失常5例; B组术后3例发生了脑梗死,其中1例为脑栓塞,1例发生脑出血,心肌梗死1例,心电图有心肌缺血2例,ST段改变2例,心律失常1例。A组术后心脑血管疾病的发生率明显高于B组,组间差异有统计学意义(P < 0.05)。 结论患有腔隙性脑梗死、陈旧性脑梗死、心肌梗死、心肌缺血、ST段改变等心脑血管疾病的患者手术风险高,易出现猝死及心脑血管意外,必须引起临床医师的注意和重视。     

Myocardial infarction after general anesthesia

During 1967 and 1968, a total of 32,877 patients had general anesthesia at the Mayo Clinic; 422 had previous myocardial infarction. Of these 6.6% experienced another infarction during the first postoperative week. There was no relationship between incidence of postoperative reinfarction and type or duration of anesthesia. However, operations on the thorax and upper abdomen were followed by three times as many reinfarctions as operations at other sites. Patients who were operated on within three months of infarction had a 37% reinfarction rate. This rate decreased to 16% in patients at three to six months after infarction, and remained at 4% to 5% when infarction had occurred more than six months previously. A significantly higher number of myocardial infarctions occurred during the third postoperative day.     

St. Thomas' Hospital cardioplegia for myocardial preservation during prolonged aortic cross-clamping

The effectiveness of St. Thomas' Hospital cardioplegia for myocardial preservation during prolonged aortic cross-clamping was analyzed in a clinical series of 100 consecutive cardiac surgical patients identified as having aortic cross-clamp times greater than 120 minutes. Hospital mortality from all causes was 8%, but only one of these 8 patients succumbed from immediate primary failure of the myocardial preservation protocol. Severe but reversible low cardiac output syndrome occurred in 5 patients, and in 4 of them there had obviously been a primary failure in cardiac protection. Peri-operative, clinically "silent" myocardial infarction could be demonstrated in retrospect by electrocardiographic criteria in 3 other patients. Post-operative complications occurred in 26 patients, many of them having several complications at the same time. Paired left ventricular and right ventricular prebypass and post-bypass biopsies processed for cytochemical and biophysical investigation were available from one third of the patients. Only 2 cases showed a severe deterioration. There was lack of correlation between the duration of aortic occlusion and operative mortality rate, incidence of peri-operative infarction, and occurrence of low cardiac output syndrome post-operatively. The results thus indicate that St. Thomas' Hospital cardioplegia is a very effective means of myocardial protection during prolonged periods of aortic cross-clamping.     

Myocardial ischemia revisited

Does perioperative myocardial ischemia lead to postoperative myocardial infarction? By Stephen Slogoff and Arthur S. Keats. Anesthesiology 1985; 62:107-14. Reprinted with permission. To determine if a relationship exists between perioperative myocardial ischemia (ST segment depression greater than or equal to 0.1 mV) and postoperative myocardial infarction (PMI), nonparticipating observers recorded all electrocardiographic, hemodynamic, and other events between arrival of patients in the operating room and onset of cardiopulmonary bypass during 1,023 elective coronary artery bypass operations (CABG). The roles of preoperative patient characteristics, quality of the operation limited by disease as rated by the surgeon and duration of ischemic cardiac arrest as risk factors for PMI also were quantified. Electrocardiographic ischemia occurred in 36.9% of all patients, with almost half the episodes occurring before induction of anesthesia. PMI was almost three times as frequent in patients with ischemia (6.9% vs. 2.5%) and was independent of when ischemia occurred. Ischemia was related significantly to tachycardia but not hypertension nor hypotension and was frequent in the absence of any hemodynamic abnormalities. The anesthesiologist whose patients had the highest rate of tachycardia and ischemia had the highest rate of PMI. Although neither single nor multiple preoperative patient characteristics related to PMI, suboptimal quality of operation and prolonged ischemic cardiac arrest increased the likelihood of PMI independent of the occurrence of myocardial ischemia. The authors conclude that perioperative myocardial ischemia is common in patients undergoing CABG, occurs randomly as well as in response to hemodynamic abnormalities, and is one of three independent risk factors the authors identified as related to PMI. PMI is unrelated to preoperative patient characteristics such as ejection fraction and left main coronary artery disease, and its frequency will relate primarily to perioperative management rather than patient selection.     

Postoperative junctional ectopic tachycardia in children: incidence,risk factors,and treatment

BACKGROUND: Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET. METHODS: Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET. RESULTS: The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions. CONCLUSIONS: Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.     

Perioperative cardiac complications of surgical repair of infrarenal aortic aneurysms

From 1985 to 1987, 261 patients (241 male, 20 female; mean age 66.5 years, range 38-90 years) were hospitalized for elective repair of infrarenal aortic aneurysms. One-hundred forty seven patients (56%) had coronary artery disease, attested to by past history of myocardial infarction or angina pectoris, electrocardiographic signs at rest, or abnormalities of dipyridamole thallium scintigraphy (performed in 72 patients). Ten patients had coronary arteriography and one patient then underwent aortocoronary bypass. Only two patients were not offered operation. All patients operated on had perioperative monitoring using Swan-Ganz catheters. Forty-five patients (17.5%) had a total of 62 postoperative events related to coronary artery disease. These included 40 cases of myocardial ischemia (15%), 16 cases of left heart failure (6%), and six myocardial infarctions (2%). There were nine (3.4%) postoperative deaths, four of which were due to cardiac causes (1.5%). In spite of the frequency of preexisting coronary artery disease and of intra- or postoperative myocardial ischemia, surgical repair of abdominal aortic aneurysm was not responsible for increased perioperative cardiac morbidity or mortality. In this population of aged patients, abdominal aortic aneurysm repair does not necessitate extending the indications for preoperative coronary arteriography or aortocoronary bypass.     

Magnesium in cardioplegia: Is it necessary?

Objective

To study the effectiveness of magnesium in cardioplegic solution in preventing postoperative arrhythmias and perioperative ischemia.

Design

Randomized, control study.

Setting

The cardiovascular surgery division of a major referral centre for the maritime provinces of Canada.

Patients

Fifty patients scheduled to undergo coronary artery bypass who had a normal ejection fraction, normal preoperative serum magnesium level and no history of atrial or ventricular arrhythmia were randomized into two groups of 25 patients. One group received magnesium sulfate (15 mmol/L) in the cardioplegic solution (group 1), the other (control) group did not receive magnesium sulfate in the cardioplegic solution (group 2).

Intervention

Coronary artery bypass grafting during which myocardial protection was provided by intermittent cold blood cardioplegia.

Outcome Measures

Postoperative serum magnesium levels, cardiac-related death, infarction and arrhythmias.

Results

All group 2 patients had a lower postoperative serum magnesium level than group 1 patients. There were no cardiac-related deaths in either group. More group 2 patients had ischemic electrocardiographic changes than group 1 patients (p < 0.03). Non-Q-wave myocardial infarction occurred in two patients (one in each group). Eight patients in group 2 had atrial fibrillation compared with five patients in group 1. Ventricular ectopia occurred significantly (p < 0.01) more frequently in group 2 than in group 1.

Conclusion

The addition of magnesium to the cardioplegic solution is beneficial in reducing the incidence of perioperative ischemia and ventricular arrhythmia in patients who undergo coronary bypass grafting.     

Factors associated with cardiac rhythm disturbances in the early post-pneumonectomy period: a study on 259 pneumonectomies.

OBJECTIVE: To identify predisposing factors associated with cardiac rhythm disturbances during the early post-pneumonectomy period (first 7 postoperative days). MATERIALS AND METHODS: During the study period (1995-1999), 259 pneumonectomies were performed for malignant (244 cases) or benign disease (15 cases). Postoperative monitoring of patients included continuous arterial pressure - rhythm monitoring and pulse oximetry. Cardiac rhythm disturbances during the intensive care unit stay were detected on the monitor screen and recorded with a 12-lead electrocardiogram. Cardiac rhythm disturbances associated with electrolytes or fluid balance abnormality, mediastinal deviation or surgical postoperative complications were excluded from the study. Age of patients, preexisting cardiac disease, side of pneumonectomy, intrapericardial procedures, stage of the malignant disease, expected postoperative FEV(1)<1200 ml, intraoperative transfusions of packed red cells, elevated right heart pressures, low postoperative serum magnesium levels and long operative times were considered as predisposing factors for the development of post-pneumonectomy cardiac rhythm disturbances. Statistical analysis has been made using logistic regression analysis, Student t-test and chi-square test. RESULTS: Cardiac rhythm disturbances were detected in 49 patients (18.91%). Atrial fibrillation/flutter (31 cases), supraventricular tachycardia (14 cases), and premature ventricular contractions (four cases) were the observed rhythm disturbances. Right pneumonectomy versus left pneumonectomy (P<0.0001) and intrapericardial pneumonectomy versus standard pneumonectomy (P<0.0001) were identified as strong predisposing factors for the establishment of post-pneumonectomy cardiac rhythm disturbances. Patients who established post-pneumonectomy cardiac rhythm disturbances had significantly higher (P=0.024) right ventricular systolic pressure (42.50+/-15.50 mmHg) when compared with patients who had postoperative sinus rhythm (29.07+/-7.71 mmHg) and had also longer operative times than patients who did not develop rhythm disturbances (P=0.015). Mortality rate in patients who developed post-pneumonectomy rhythm disturbances was 20.40%. CONCLUSIONS: Cardiac rhythm disturbances observed early after pneumonectomy are mainly of supraventricular origin, complicating right and intrapericardial pneumonectomies, patients with elevated right heart pressures and long operative times, and are associated with high mortality rates.     

Thoracoabdominal aneurysm repair: a representative experience.

Between May 1966 and June 1991, 129 patients underwent surgical repair of thoracoabdominal aneurysms, with an overall 30-day mortality rate of 35%. In 75 operations (58%) performed electively, 11 deaths (15%) occurred, and in 54 cases (42%) of either symptomatic or ruptured aneurysms 34 deaths (63%; p less than 0.001) occurred. No one survived among six patients with preoperative hypotension (less than 90 mm Hg) or cardiac arrest. In 16 patients (12%) the etiology of aneurysms was a result of chronic aortic dissection, and the mortality rate in this subgroup was 44%. In the remaining 113 patients (88%) where the etiology was atherosclerosis, 38 deaths occurred (34%; p = 0.433). Spinal cord ischemia occurred in 25 cases (21%) among 116 patients who survived operation. Partial ischemia occurred in six cases (25%), and complete paraplegia occurred in the remainder. Complete and partial paraplegia occurred in 16 of 42 cases (38%) when all of the thoracic aorta was replaced (Crawford groups I, II) and in 9 of 74 cases (12%) when only the abdominal or lower thoracic aorta was replaced (Crawford groups III, IV; p = 0.016). Other complications included myocardial infarction (14 cases, 11%), respiratory failure (46 cases, 36%), and renal failure (33 cases, 27%). The major prospect for improved early survival of patients with thoracoabdominal aneurysms seems to be early detection and elective repair before the occurrence of symptoms.     

Effects of myocardial infarction on perioperative cardiac complications

Of 1104 consecutive noncardiac operations on 981 patients using general anesthesia, 63 were performed on 53 patients who had had a previous myocardial infarction. Patients with a previous infarct were compared to those with no prior infarct to determine the influence of a previous infarct on perioperative cardiac complications. Two of the 53 patients with a previous myocardial infarction (3.8%) had perioperative myocardial infarction, compared to 0.4% (4/928) of patients with no prior history of myocardial infarction (P less than 0.05). Ventricular tachycardia (P less than 0.05) and cardiac death (P less than 0.01) were more frequent in patients with a previous myocardial infarction compared to those with no prior infarct. All patients with a previous myocardial infarction who developed cardiac complications underwent vascular procedures (P less than 0.005) and were over 77 years of age. The two patients who reinfarcted experienced intraoperative hypotension (P less than 0.05). Fourteen of the 53 patients with a history of a myocardial infarction (26.4%) had previous coronary artery bypass surgery; no perioperative cardiac complications occurred in these patients.     

The value of silent myocardial ischemia monitoring in the prediction of perioperative myocardial infarction in patients undergoing peripheral vascular surgery

Real-time electrocardiographic monitoring for silent myocardial ischemia was performed on 200 patients undergoing peripheral vascular surgery to try to better define those at high risk of perioperative myocardial infarction. The patients were divided into those undergoing abdominal aortic aneurysm or lower extremity revascularization procedures (group I, n = 120) and those undergoing carotid artery endarterectomy (group II, n = 80). Silent ischemia was detected during the preoperative, intraoperative, or post-operative periods in 60.8% of group I and 67.5% of group II patients. Six group I and three group II patients suffered an acute perioperative myocardial infarction with two cardiac deaths. In both groups I and II a variety of parameters based on monitoring of silent myocardial ischemia were compared between the subgroups of patients who had myocardial infarction and those who did not. The results show that in both groups there was a significantly (p less than or equal to 0.05) greater total duration of perioperative ischemic time, total number of perioperative ischemic episodes, and total duration of perioperative ischemic time as a percent of total monitoring time in patients who suffered a perioperative myocardial infarction compared to those who did not. Multivariate logistic regression analysis of preoperative characteristics in all 200 patients showed the occurrence of preoperative silent myocardial ischemia and angina at rest to be the only significant predictors of perioperative myocardial infarction. Thus perioperative monitoring for silent myocardial ischemia might noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for perioperative myocardial infarction, permitting implementation of timely preventive measures in selected patients.     

Correlation between prior coronary revascularization and perioperative cardiac events in patients for noncardiac surgery

We evaluated the influence of interval between prior coronary revascularization and subsequent noncardiac surgery on perioperative cardiac events. We retrospectively identified 162 consecutive patients with previous revascularization procedures who had undergone noncardiac surgery. Postoperative cardiac complications occurred in 10 (6.2%) patients, cardiac death in 1 patient, and significant arrhythmia in 3 patients. These patients had higher rates of unstable angina, myocardial infarction within 3 months, cerebrovascular disease, peripheral vascular disease, renal dysfunction (Cr > or = 1.9 mg.dl-1) and higher preoperative risk scores as described by the Cleveland Clinic (P < 0.05). Also, the incidence of cardiac complications increased when noncardiac surgery was performed within 1 week of previous percutaneous transluminal coronary angioplasty (PTCA) and in more than 5 years after coronary artery bypass grafting or PTCA (P < 0.05). Although PTCA is widely accepted, especially in Japan, early lesion progression was observed during the first several days and atherosclerotic progression was apparent in more than 5 years after the procedure. Therefore, the time between coronary revascularization and noncardiac surgery, as well as atherosclerotic risk factors, is important in evaluating patients with history of previous revascularization procedures.