Uday Jain

Electrocardiographic and hemodynamic changes and their association with myocardial infarction during coronary artery bypass surgery : A multicenter study

Background Electrocardiographic (ECG) changes during coronary artery bypass graft surgery have not been described in detail in a large multicenter population. The authors describe these ECG changes and evaluate them, along with demographic and clinical characteristics and intraoperative hemodynamic alterations, as predictors of myocardial infarction (MI) as defined by two sets of criteria. Methods Data from 566 patients at 20 clinical sites, collected as part of a clinical trial to evaluate the efficacy of acadesine for reducing MI, were analyzed at core laboratories. Perioperative ECG changes were identified using continuous three‐lead Holter ECG. Systolic blood pressure, diastolic blood pressure, and heart rate were recorded each minute during operation. The occurrence of MI by Q wave or myocardial fraction of creatine kinase (CK‐MB) or autopsy criteria, and by (Q wave and CK‐MB) or autopsy criteria was determined. Results During perioperative Holter monitoring, episodes of ST segment deviation, major cardiac conduction changes greater or equal to 30 min, or use of ventricular pacing greater or equal to 30 min occurred in 58% patients, primarily in the first 8 h after release of aortic occlusion. Of the 25% patients who met the Q wave or CK‐MB or autopsy criteria for MI, 19% had increased CK‐MB as well as ECG changes. (Q wave and CK‐MB) or autopsy criteria for MI were met by 4% of patients. The CK‐MB concentration generally peaked by 16 h after release of aortic occlusion. In patients with (n = 187) and without a perioperative episode of ST segment deviation, the incidence of MI was 36% and 19%, respectively (P < 0.01), by Q wave or CK‐MB or autopsy criteria, and 6% and 3%, respectively (P = 0.055), by (Q wave and CK‐MB) or autopsy criteria. Multiple logistic regression analysis showed that intraoperative ST segment deviation, intraventricular conduction defect, left bundle branch block, duration of hypotension (systolic blood pressure < 90 mmHg) after cardiopulmonary bypass, and duration of cardiopulmonary bypass are independent predictors of Q wave or CK‐MB or autopsy MI. The independent predictors of (Q wave and CK‐MB) or autopsy MI are intraoperative ST segment deviation and duration of aortic occlusion. Conclusions Major ECG changes occurred in 58% of patients during coronary artery bypass graft surgery, primarily within 8 h after release of aortic occlusion. Multicenter data collection revealed a substantial variation in the incidence of MI and an overall incidence of up to 25%, with most MI occurring within 16 h after release of aortic occlusion. Intraoperative monitoring of ECG and hemodynamics has incremental value for predicting MI.

Myocardial infarction during coronary artery bypass surgery

P ERIOPERATIVE myocardial infarction (PMI) is one of the major problems during coronary artery bypass grafting surgery (CABG). Its incidence is reported to be between 2% and 82%.lJ This wide variation can be attributed to different tests and criteria for the detection of PMI, the patient population,3-s and the quality of care.” Some previous reviews of the literature in this area exist. l”-ih This review concentrates on significant new information. The literature on PM1 during noncardiac surgery has been extensively reviewed.r4 Literature on PM1 during cardiac surgery other than CABG is limited, and is not reviewed.

Cardiovascular responses during sedation after coronary revascularization: Incidence of myocardial ischemia and hemodynamic episodes with propofol versus midazolam

Background Propofol sedation offers advantages for titration and rapid emergence in the critically ill patient, but concern for adverse hemodynamic effects potentially limits its use in these patients. The current study compares the cardiovascular effects of sedation with propofol versus midazolam during the first 12 h after coronary revascularization. Methods Three hundred fifty‐one patients undergoing coronary revascularization were anesthetized using a standardized sufentanil/midazolam regimen, and assigned randomly to 12 h of sedation with either propofol or midazolam while tracheally intubated. The incidence and characteristics of hemodynamic episodes, defined as heart rate less than 60 or greater than 100 beats/min or systolic blood pressure greater than 140 or less than 90 mmHg, were determined using data electronically recorded at 1‐min intervals. The presence of myocardial ischemia was determined using continuous three‐channel Holter electrocardiography (ECG) and of myocardial infarctions (MI) using 12‐lead ECG (Q wave MI, Minnesota Code) or creatine kinase isoenzymes (CK‐MB) analysis (non‐Q wave MI, peak CK‐MB > 70 ng/ml, or CK‐MB > 70 IU/l). Results Ninety‐three percent of patients in both treatment groups had at least one hemodynamic episode during the period of postoperative sedation. Propofol sedation resulted in a 17% lower incidence of tachycardia (58% vs. 70%, propofol vs. midazolam; P = 0.04), a 28% lower incidence of hypertension (39% vs. 54%; P = 0.02), and a greater incidence of hypotension (68% vs. 51%; P = 0.01). Despite these hemodynamic effects, the incidence of myocardial ischemia did not differ between treatment groups (12% propofol vs. 13% midazolam; P = 0.66), nor did its severity, as measured by ischemic minutes per hour monitored (8.7+/‐5.8 vs. 6.2+/‐4.6 min/h, propofol vs. midazolam; P = 0.19) or ischemic area under the curve (6.8+/‐4.0 vs. 5.3+/‐4.2; P = 0.37). The incidence of cardiac death (one per group), Q wave MI (propofol, n = 7; midazolam, n = 3; P = 0.27), or non Q wave MI (propofol, n = 16; midazolam, n = 18; P = 0.81) did not differ between treatment groups. Conclusions Hemodynamic episodes occur frequently in the first 12 h after coronary revascularization. Compared with a standard sedation regimen (midazolam), propofol sedation appears to modulate postoperative hemodynamic responses by reducing the incidence and severity of tachycardia and hypertension and increasing the incidence of hypotension. Both sedation regimens appear similarly safe with respect to myocardial ischemia. These findings indicate that propofol infusion provides effective sedation without deleterious hemodynamic effects in patients recovering from cardiac surgery.

Multicenter Study of Target-Controlled Infusion of Propofol-Sufentanil or Sufentanil-Midazolam for Coronary Artery Bypass Graft Surgery

Background The use of target-controlled infusions of anesthetics for coronary artery bypass graft surgery has not been studied in detail. The effects of target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were evaluated and compared. Methods At 14 clinical sites, 329 patients were given a target-controlled infusion of propofol (n = 165) to produce effect-site concentration (Ce) of greater or equal to 3-micro gram/ml or a target-controlled infusion of sufentanil (n = 164). Sufentanil or midazolam, respectively, also were infused. Systolic hypertension, hypotension, tachycardia, and bradycardia were assessed by measuring heart rate and blood pressure every minute during operation. Myocardial ischemia was assessed perioperatively by monitoring ST segment deviation via continuous three-lead Holter electrocardiography, and it was evaluated during operation by monitoring left ventricular wall motion abnormality via transesophageal echocardiography. Results The measured cardiovascular parameters were satisfactory and usually similar for the patients receiving propofol-sufentanil or sufentanil-midazolam. The primary endpoint of the percentage of patients with intraoperative ST segment deviation (23 plus/minus 6% vs. 24 plus/minus 6%, P = 0.86) did not differ significantly between the two groups. The incidence of left ventricular wall motion abnormality shown on transesophageal echocardiography before (19 plus/minus 4% vs. 26 plus/minus 4%, P = 0.25) and after (23 plus/minus 4% vs. 31 plus/minus 5%, P = 0.32) cardiopulmonary bypass also did not differ significantly for the two groups. Changes in intraoperative target concentration were more frequent with propofol-sufentanil anesthetic than with sufentanil-midazolam (11.7 plus/minus 7.1 vs. 7.3 plus/minus 3.6, P <0.001). The incidence of intraoperative hypotension (77% vs. 55%, P <0.001), the use of inotropic/vasopressor medications (93% vs. 84%, P = 0.01), and the administration of crystalloids (2.8 plus/minus 1.4 L vs. 2.4 plus/minus 1.2 L, P < 0.001) were significantly greater in the propofol-sufentanil group. Conversely, the incidence of intraoperative hypertension (43% vs. 54%, P = 0.05) and the use of antihypertensive/vasodilator medications (70% vs. 90%, P < 0.001) were significantly less in the propofol-sufentanil group. Conclusions Target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were suitable to provide anesthesia for coronary artery bypass graft surgery. Continuous monitoring revealed a high prevalence of hemodynamic abnormalities. Despite greater hypotension in the propofol-sufentanil group and greater hypertension in the sufentanil-midazolam group, episodes of myocardial ischemia were similar for both groups and were not temporally related to episodes of hemodynamic abnormalities.

Myocardial Ischemia After Cardiopulmonary Bypass

Intraoperatively, myocardial ischemia is more common after cardiopulmonary bypass (CPB) than before CPB. Ischemia associated with coronary vasospasm and thrombosis may be much more common toward the end of surgery and early in the postoperative period than previously appreciated. This may be because the coagulation system is altered during CPB, and the coronary endothelium is damaged significantly as a result of cardioplegic arrest followed by reperfusion. In this milieu, vasospasm and thrombosis may be caused by the administration of protamine. Some of the ischemia observed in this period actually is not reversible and is associated with myocardial injury and infarction. It may be ameliorated by the administration of calcium channel blockers, aspirin, and anticoagulants. Electrocardiography may be the most suitable modality for the detection of ischemia after CPB and postoperatively. During this period, many episodes of ST deviation are of a nonischemic etiology, and the ECG needs careful interpretation. Transesophageal echocardiography is suitable for use intraoperatively and early on in the intensive care unit.

Myocardial injury during reoperation for coronary artery bypass surgery

Objectives: To determine the incidence, triggers, and timing of myocardial injury during reoperation for coronary artery bypass surgery. Design: Prospective observational. Setting: One tertiary care university hospital. Participants: 15 patients undergoing reoperation. Interventions: Multilead electrocardiographic monitoring approximately every 3 minutes during surgery. Measurements and Main Results: The occurrence of a new ischemic ST elevation or depression on the electrocardiogram (ECG) was determined. A major deterioration in ventricular function after cardiopulmonary bypass (CPB) also was determined. Peak creatine kinase myocardial band (CK-MB) ≥ 25 IU/L was considered to be the marker of myocardial injury. Seven patients demonstrated myocardial injury, all intraoperatively. Five of these patients had new ST elevation episodes before CPB. Three of the episodes were temporally associated with an abrupt increase in the heart rate. The other two episodes were temporally associated with surgical manipulation of the heart and the old grafts. The sixth patient had a significant deterioration of ventricular function during CPB. One of the patients who had ST elevation before CPB and the seventh patient developed ST elevation towards the end of protamine administration. Conclusions: In patients undergoing reoperation, the intraoperative incidence of myocardial injury, especially before CPB, was found to be substantially higher than that previously reported.

Perioperative use of propofol for cardiac surgery.

Worldwide, approximately 750,000 cardiac surgeries are being performed annually. No fundamental differences have been demonstrated between anesthesia for cardiac versus noncardiac surgery.* If used appropriately, virtually all available anesthetics are suitable for cardiac surgery. To achieve adequate general anesthesia, a minimum of two different classes of anesthetic drugs is usually required.* In patients with cardiac disease, the maintenance of hemodynamic stability is considered important for reducing the incidence of adverse cardiovascular outcomes. Because opioids are associated with relative hemodynamic stability, they are the most commonly used primary anesthetics during cardiac surgery. Supplementation with potent inhalational anesthetics, benzodiazepines, or other anesthetics is required. Opioid anesthesia is associated with a small incidence of hypotension, especially on induction of anesthesia. Intraoperative hypertension also may occur. Potent inhalational anesthetics and intravenous (IV) sedative-hypnotics such as benzodiazepines are also used as the prirnary anesthetics for cardiac surgery. Other sedative-hypnotics such as propofol are being used during cardiac surgery. Compared with most anesthetics, propofol allows easier titratability and more rapid emergence.s-5 Su pplementation of propofol with an opioid leads to a synergistic interaction.* Propofol can be used for preoperative sedation as an anesthetic and for postoperative sedation. Propofol has certain disadvantages. It may contribute to hypotension and bradycardia.3-6 This may be especially true for cardiac surgery patients who are often given antihypertensive, antiischemic, and vasodilator medications such as beta-blockers and calcium-channel blockers. Anesthetics including propofol and opioids cause hypotension because of loss of sympathetic tone. In addition, propofol also has a dose-dependent hypotensive effect. This leads to lesser hemoclynamic stability and greater need for titration when propofol is used. Propofol infusion may have 70 be titrated frequently and skillfully to avoid hypotension on one hand and light anesthesia on the other. The bradycardiac effects *Assistant Professor of Anesthesia

An electrocardiographic lead system for coronary artery bypass surgery

STUDY OBJECTIVES To identify the optimal subset of two electrocardiographic (ECG) leads for monitoring of ischemic ST depression and elevation during coronary artery bypass grafting (CABG) surgery. DESIGN Prospective observational clinical study. SETTING University hospital cardiac surgery operating room. PATIENTS 120 patients undergoing primary surgery or reoperation for CABG. INTERVENTIONS All six ECG limb leads and a precordial matrix of four leads were recorded intraoperatively approximately every 3 minutes. The limb leads were placed on the torso in modified Mason-Likar positions. The precordial leads were placed at V4, V5, and one interspace below them. MEASUREMENTS AND MAIN RESULTS New ischemic 1 mm ST depression and elevation episodes were determined. New ST deviation episodes attributed to nonischemic causes such as cooling at the onset of cardiopulmonary bypass (CPB), defibrillation at the end of CPB, new cardiac conduction changes after CPB, and postoperative pericarditis were excluded. Fixed ST deviation that did not change by 1 mm in the perioperative period was also excluded. Leads V5 and III constituted the best two-lead set. These leads recorded 15 of the 16 ischemic ST elevation episodes and all 8 ischemic ST depression episodes. One ST elevation episode was not recorded intraoperatively but was recorded in lead V1 in the immediate postoperative ECG. Leads V5 and II recorded 13 of the 16 ischemic ST elevation episodes and all 8 ischemic ST depression episodes. Lead V5 alone missed 8 episodes of ischemic ST elevation and one episode of ischemic ST depression. CONCLUSIONS For monitoring of ischemia during CABG, leads V5 and III are preferable to other two-lead sets, including the commonly used V5 and II. No single lead is adequate. Lead V5 alone missed approximately one half the episodes of ST elevation that were recorded by lead III or another inferior lead.

Electrocardiographic Determination of Perioperative Myocardial lschemia and Stunning

Many modalities are available for monitoring for ischemia. Electrocardiography (ECG) is the most suitable modality for monitoring for perioperative ischemia. The detection and monitoring of myocardial stunning is more difficult. T wave inversion or peaking may be caused by ischemia. However, numerous nonischemic causes may lead to perioperative T wave changes. Inverted T waves may also indicate myocardial stunning. ST deviation is the most commonly used feature of ischemia. ST depression may be indicative of subendocardial ischemia while ST elevation may be associated with transmural ischemia or injury. Perioperatively, ST deviation may be caused by many nonischemic causes. Fixed ST deviation may be caused by left ventricular hypertrophy (LVH), cardiac conduction changes, old MI, coronary artery disease, and other causes such as drugs, including digitalis. New ST deviation may be caused by changes in body position. During cardiopulmonary bypass, ST deviation may be caused by hypothermia and defibrillation. ST deviation may be caused by new cardiac conduction changes and pericarditis. Ischemia may cause changes in other features of the ECG including the R wave, Q wave, U wave, QRS axis, and the angle between QRS axis and T wave axis. However, the specificity of these features for ischemia is even lower than that of the ST segment.

Wave recognition and use of the intraoperative unipolar esophageal electrocardiogram

STUDY OBJECTIVES To evaluate the automated determination of onset and offset times and amplitudes of all the PQRST waves from simultaneously recorded surface electrocardiogram (SECG) and unipolar esophageal ECG (EsECG). The occurrence of ST segment deviation is also examined. DESIGN Prospective, observational study. SETTING University hospital. PATIENTS 30 patients undergoing coronary artery bypass graft (CABG) surgery. INTERVENTIONS SECG and two-lead unipolar EsECG were recorded after induction of anesthesia and before cardiopulmonary bypass (CPB). MEASUREMENTS AND MAIN RESULTS The amplitudes of the P and T waves and the ST segment deviation were measured. EsECG had more noise than SECG. Slight movement of the esophageal electrodes occasionally caused substantial changes in the wave amplitudes and ST segment deviation in the unipolar EsECG. The maximum P wave amplitude in EsECG was, on average, 97% greater than the maximum P wave amplitude in SECG, ST segment deviation in EsECG was observed in the absence of ST segment deviation in SECG and vice versa. CONCLUSIONS The recognition and measurement of all the PQRST waves can be improved and automated by simultaneous use of EsECG and SECG. The P wave amplitude is greater in EsECG than in SECG, which may faciliate the identification of supraventricular versus ventricular arrhythmias. ST segment deviation in the unipolar EsECG may not be suitable for the routine detection of ischemia.