Incidence Of Myocardial Ischemia Research Articles

Myocardial Ischemia in Sedated Patients Undergoing Fiberoptic Bronchoscopy

To study the incidence of myocardial ischemia and related hemodynamic alterations in sedated patients undergoing fiberoptic bronchoscopy (FOB). Prospective study. Tertiary care, university hospital. Twenty-nine patients, age 50 years or older, undergoing elective FOB. Myocardial ischemia was assessed by continuous ECG monitoring beginning 30 min before, and until 2 h after FOB. During FOB, there was a significant rise in heart rate (89+/-3 [mean+/-SE] to 120+/-4 beats/min) and fall in oxygen saturation (95+/-1 to 90+/-1%). There was no significant rise in systolic or diastolic BP. Five patients (17%) had myocardial ischemia during FOB that lasted 20+/-8 min. Their demographic and pre-FOB characteristics were not different from the other patients. Compared to baseline values, a significant rise in heart rate, a fall in oxygen saturation, and no significant change in BP were observed during FOB in patients, both with or without ischemia. Although not statistically significant, ischemia was associated with more protracted procedures. Myocardial ischemia may develop in elderly patients undergoing FOB. This observation encourages the routine use of ECG and oximetry during FOB, allowing for early intervention to prevent the dangerous combination of hypoxia, tachycardia, and myocardial ischemia. Moreover, this study suggests that methods to ensure oxygenation during FOB should be adhered to, and that the routine administration of atropine should be reconsidered.

Myocardial Ischemia and Adverse Cardiac Outcomes in Cardiac Patients Undergoing Noncardiac Surgery with Sevoflurane and Isoflurane

Sevoflurane is associated with less tachycardia and coronary vasodilation than isoflurane and thus might be associated with less myocardial ischemia.This multicenter study examined the incidence of myocardial ischemia and adverse cardiac outcomes in adults (40-87 yr) with cardiac disease having elective noncardiac surgery. Patients were randomized to receive either sevoflurane (S) (n = 106) or isoflurane (I) (n = 108) in conjunction with sodium thiopental, vecuronium, fentanyl, and 50%-70% N2 O. Intraoperative hemodynamics were maintained within 20% of awake baseline with standard drugs. A Holter monitor was applied 3-24 h before surgery and maintained until 48 h after surgery. Electrocardiograms and blood samples for analysis of the MB isoenzyme fraction of creatine phosphokinase were obtained preoperatively and daily for 48 h postoperatively. Anesthetic exposure (1.79 +/- 0.15 [mean +/- SE] minimum alveolar concentration-hour) and duration of surgery (219 +/- 13 min) did not differ between groups. The incidence of ischemia in the pre-, intra- and post-operative periods, adverse cardiac outcomes (18% occurrence), intraoperative hemodynamic variations (+/- 20% change from ward baseline), and administration of adjunct cardiovascular medications were similar between groups. In cardiac patients having noncardiac surgery, sevoflurane was comparable to isoflurane with respect to the incidence of intra- and postoperative myocardial ischemia and in the frequency of adverse cardiac outcomes. Implications: Surgical patients with heart disease are at risk of heart complications, some of which could be induced by an anesthetic. We compared the incidence of cardiac complications between patients receiving sevoflurane and isoflurane. We found that the frequency of additional heart problems in cardiac patients receiving sevoflurane was not different from that associated with isoflurane. (Anesth Analg 1997;85:993-9)

Thoracic Epidural Anesthesia and the Patient with Heart Disease

Thoracic Epidural Anesthesia and the Patient with Heart Disease

Effects of intrathecal opioid on extubation time, analgesia, and intensive care unit stay following coronary artery bypass grafting

Study Objective: To determine if intrathecal opioid decreases time to extubation after coronary artery bypass surgery without compromising postoperative analgesia. Design: Prospective randomized trial. Setting: Veterans Affairs Hospital. Patients: 21 ASA physical status III and IV men scheduled for elective coronary bypass surgery, who had not received medications that would impair anticoagulation at the time of surgery. Interventions: Patients were randomized to receive 10 μg/kg morphine and 25 μg fentanyl intrathecally preoperatively (n = 12) or no intrathecal opioid (n = 9). The latter group received 25 to 50 μg/kg fentanyl and 0.05 to 0.1 mg/kg midazolam intraoperatively, whereas the intrathecal opioid group received intravenous (IV) fentanyl and midazolam only as needed. Both groups were administered IV morphine and midazolam postoperatively as needed by intensive care unit (ICU) personnel who were blinded to the treatment group. Measurements and Main Results: For the first 24 hours postoperatively, pain levels (0 = none, to 10 = most severe) and sedation levels (1 = none, to 5 = unconscious) were measured hourly. The time to extubation and discharge from the ICU was recorded. ECG evidence of myocardial ischemia was noted. Pain scores were low for both groups (1.5), but the intrathecal opioid subjects exhibited less sedation than the high-dose fentanyl subjects [means ± standard deviation (SD) of 2.3 ± 0.4 vs. 2.8 ± 0.5, p = 0.03]. Extubation time was 12 hours shorter in the intrathecal opioid group (2.9 ± 5.3 vs. 14.7 ± 6.8, p = 0.001). The five subjects with a one day ICU stay were all in the intrathecal opioid group ( p = 0.04). The incidence of myocardial ischemia did not differ between the two groups. Conclusions: Intrathecal opioid can facilitate early extubation and discharge from the ICU without compromising analgesia or increasing myocardial ischemia.

Perioperative Sympatholysis

Perioperative Sympatholysis

Incidence of perioperative myocardial ischemia in TURP patients

Study Objective: To determine the incidence of new episodes of myocardial ischemia in patients undergoing transurethral resection of the prostate (TURP). Design: Prospective, nonrandomized study. Setting: Veterans Administration medical center. Patients: 39 patients undergoing elective TURP Interventions: None. Measurements and Main Results: Myocardial ischemia was detected with a 3-channel ambulatory ECG recorded. The ambulatory ECG recorder was applied preoperatively and removed when the patient left the recovery room. New myocardial ischemia was defined as a 1 mm or greater ST depression or a 2 mm or greater ST elevation from baseline, lasting for 1 minute or longer in at least one lead at the J point plus 60 msec unless this point fell within the T wave, in which case the J point 40 msec or greater was used. ST changes consistent with myocardial ischemia were confirmed by a cardiologist blinded to the patient's clinical course. Seven of 39 TURP patients (18%) had ST segment changes indicative of new myocardial ischemia. These seven patients had more prostate tissue resected and more blood loss than the 32 patients who did not have any myocardial ischemia (p < 0.05). Conclusions: Patients undergoing TURP have an 18% incidence of myocardial ischemia. Patients undergoing TURP with more prostate tissue resected and greater blood loss are at increased risk for perioperative myocardial ischemia.

Cardiovascular Responses during Sedation after Coronary Revascularization

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. 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/I). 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. 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.

SILENT MYOCARDIAL ISCHEMIA IN HEMODIALYSIS PATIENTS — FACTOR FICTION?

Thirty eight patients underwent Holter ECG monitoring for a 48 hour period covering dialysis and intermediate period to detect incidence of myocardial ischemia manifesting as ST segment changes. Seventeen patients (44.7%) had 165 episodes of dynamic ST segment changes lasting from 1 to 177 minutes, with maximum ST depression of 4 mm. The mean age of patients was 45 ± 14 years and 14 (82.6%) of them were males. Ten (58.8%) patients had hypertension, and 5 (29.4%) patients each had diabetes mellitus and pre-existing coronary artery disease. Six (35.3%) patients with dynamic ST segment changes had ventricular ectopics ranging from isolated ventricular premature contractions to episodes of ventricular tachycardia. No significant hypotension or angina was documented during these episodes of ST segment deviation. We concluded that hemodialysis plays an important role in the genesis of the above ECG changes.

Cardiovascular responses to sevoflurane: a review.

In conclusion, sevoflurane appears to be similar to isoflurane and desflurane with a few exceptions. Sevoflurane was not associated with increases in heart rate in adult patients and volunteers, whereas higher MACs of isoflurane and desflurane and rapid increases in the inspired concentrations of these two anesthetics have been associated with tachycardia. Increasing concentrations of sevoflurane progressively decrease blood pressure in a manner similar to the other volatile anesthetics, and in unstimulated volunteers this decrease may be slightly less than with isoflurane at a higher MAC. Sevoflurane appears similar to isoflurane in its effect on regional blood flows, including the hepatic, renal, and cerebral circulation. In animals, sevoflurane appears to be a slightly less potent coronary vasodilator than isoflurane, and in a dog model, sevoflurane has not been associated with coronary flow redistribution ("steal"). Sevoflurane decreases myocardial contractility in a manner similar to equianesthetic concentrations of isoflurane and desflurane, and does not potentiate epinephrine-induced cardiac arrhythmias. Sevoflurane reduces baroreflex function in a manner similar to other volatile anesthetics. In several multicenter studies where patients with CAD or patients at high risk for CAD were randomized to receive either sevoflurane or isoflurane for cardiac or noncardiac surgery, the incidence of myocardial ischemia, infarction, and cardiac outcomes did not differ between treatment groups. Thus, sevoflurane has not been associated with untoward cardiovascular changes in volunteers and patients undergoing elective surgery compared with other volatile anesthetics, and it appears to offer a more stable heart rate profile than either isoflurane or desflurane.

Oxygen Therapy in the Postanesthesia Care Unit

In Response: Pulse oximetry became the standard of care in the postanesthesia care unit (PACU) with the expectation that it would be used to guide patient care decisions related to oxygenation. While health care providers have traditionally placed a great deal of confidence in the use of supplemental oxygen, it is not an adequate safeguard against hypoxemia. Kavanagh et al. [1] noted that although it reduces the incidence of desaturation it does not affect the degree or duration. It also does not affect patient outcomes such as the incidence of myocardial ischemia. Our recommendation to use the objective data supplied by the pulse oximeter as a guide for oxygen use is in line with what others, such as DiBenedetto et al. [2], have recommended. The difference in the recommendations was that we chose a pulse oximeter reading of 92% to indicate those at risk for hypoxemia, while DiBenedetto and colleagues recommended a pulse oxymetry reading below 94%. Their use of a more stringent criterion may be due to the difference in populations. DiBenedetto and colleagues studied all patients admitted to the PACU, which would likely include patients having had thoracic and upper abdominal surgery, a group not included in our study. Unfortunately, there is no description in their research report of the type of surgery performed with their sample. Another difference between the two studies is that their patients were breathing room air while being transported to the PACU, whereas ours received supplemental oxygen during transport. As a result of our study, the policy for oxygen administration in the PACU where the study was done has been changed. Now when patients are admitted to the PACU only those whose preoperative workup would indicate them to be at high risk for hypoxemia are given supplemental oxygen. For most patients, the pulse oximeter reading is used along with other clinical variables, such as vital signs, wakefulness, and the like, to determine the need for oxygen. Oxygen is therefore administered only to those who require it. Over a 9-month period there have not been any untoward incidents attributable to this change in policy. Oxygen has, however, continued to be provided during transport. Prior to the start of our study we noted that many patients objected to the application of the high-flow, high-humidity face tent which at that time was routinely used in the unit. Many of the patients were observed removing the face tent immediately after it was applied, which we considered wasteful. Changing the PACU oxygen administration policy has reserved the use of these high-cost oxygen administration devices to only those patients who require increased humidification, reducing hospital waste and costs. Audrey G. Gift, PhD, RN, FAAN University of Pennsylvania School of Nursing, Philadelphia, PA 19104-6096 Kaye Whitmore, RN University of Maryland Medical System, Baltimore, MD 21201

Left Ventricular Ejection Time and End-Systolic Pressure Revisited

Left Ventricular Ejection Time and End-Systolic Pressure Revisited

Myocardial protection with calcium-channel blockers during ischaemia and reperfusion by PTCA.

The effects of calcium channel blockers on acute myocardial ischaemia have been evaluated over the past two decades. A number of experimental studies have demonstrated that calcium antagonists protect the myocardium when administered before or during PTCA. Intracoronary verapamil prior to the second inflation attenuates the severity of ischaemic ST-segment changes and anginal pain. Heart rate and blood pressure are not influenced by verapamil or placebo. Similarly, there are multiple clinical and biological data suggesting that intracoronary nifedipine, diltiazem or bepridil, and intracoronary or intravenous nicardipine might result in a reduced incidence of myocardial ischaemia during PTCA. The beneficial effect of these drugs can be explained by a direct cardioprotective effect or by an enhanced collateral flow and haemodynamic improvement. During early reperfusion in acute myocardial infarction (AMI) administration of calcium channel blockers or agents that inhibit calcium release from the sarcoplasmic reticulum can protect hearts from stunning and can decrease the no-reflow phenomenon. The most recent explanation relates this observation to decreased sensitivity of the myofibrils to calcium. Further clinical and experimental studies are necessary to clarify the protective role in reperfusion injury. To summarize, therefore, administration of calcium channel blockers can decrease ischaemia during elective PTCA and can reduce reperfusion injury during early PTCA in AMI.

Does Hemoglobin Concentration Affect Perioperative Myocardial Lactate Flux in Patients Undergoing Coronary Artery Bypass Surgery?

Increasing concern over complications related to blood transfusions has prompted a reevaluation of what constitutes an "adequate" perioperative hemoglobin concentration, particularly in patients undergoing coronary artery bypass graft (CABG) surgery. Data from 224 patients with preserved ventricular function (ejection fraction > 50%), undergoing CABG surgery, previously studied under a variety of anesthetic protocols, were reexamined to determine the effect of hemoglobin (HGB) concentration on myocardial lactate flux (MLF) (as an index of ischemia). The interaction of MLF and HGB concentration, anesthetic technique (ANES), and hemodynamic variables (including systemic and pulmonary arterial pressures (SAP and PAP), cardiac output (CO), and myocardial oxygen consumption (MVO2) was determined from a pool of 1598 data sets obtained from 224 patients. Data were collected from just prior to induction of anesthesia until 24 h postoperatively. Univariate analysis revealed a statistically significant relationship between MLF and HGB concentration (P < 0.001) but the correlation coefficient was only 0.09. Multiple regression analysis did not determine HGB concentration to be a significant independent term affecting MLF in either the overall group or in a subgroup of 22 patients having an adverse outcome (myocardial infarction, stroke, or death). For patients undergoing CABG surgery, HGB concentrations within the range of 58-172 g/L were not a significant variable in production of global myocardial ischemia as evidenced by MLF. This suggests that HGB concentrations as low as 60-70 g/L in the perioperative period are well tolerated and are not associated with an increased incidence of myocardial ischemia.

Randomised comparison of subcutaneous heparin, intravenous heparin, and aspirin in unstable angina

Intravenous heparin has been used in the control of myocardial ischaemia in patients with unstable angina. We set out to assess the efficacy of subcutaneous heparin in reducing myocardial ischaemia in patients with unstable angina. 343 of 399 patients with unstable angina were monitored for 24 h and 108 were refractory to conventional antianginal treatment and were entered into a randomised multicentre trial. 37 patients were assigned to heparin infusion (partial thromboplastin time 1·5-2 times baseline), 35 to subcutaneous heparin (adjusted dose with partial thromboplastin time 1·5-2 times baseline), and 36 to aspirin (325 mg daily). All had additional conventional antianginal therapy. After the run-in patients were monitored for 3 days. The primary endpoint was reduced myocardial ischaemia assessed by the number of anginal attacks, silent ischaemic episodes, and duration of ischaemia per day. At 1 week and 1 month we accounted for anginal attacks and other clinical events (myocardial infarction, revascularisation procedures, and death). Aspirin did not significantly affect the incidence of myocardial ischaemia. On the first 3 days, infused and subcutaneous heparin significantly decreased the frequency of angina (on average by 91% and 86%, respectively), episodes of silent ischaemia (by 56% and 46%), and the overall duration of ischaemia (66% and 61%) versus run-in day and aspirin (p<0·001 for all variables). The favourable effects of heparin therapy remained evident during follow-up. Only minor bleeding complications occurred. Subcutaneous heparin is effective in the control of myocardial ischaemia in patients with unstable angina.

Perioperative myocardial ischaemia in patients undergoing transurethral surgery: a pilot study comparing general with spinal anaesthesia

We have studied the incidence and duration of perioperative myocardial ischaemia using ambulatory ECG monitoring in 100 patients undergoing transurethral surgery, who were allocated randomly to receive either general or spinal anaesthesia. The overall incidence of myocardial ischaemia increased from 18% to 26% between the preoperative and postoperative periods. Patients with ischaemic heart disease had a significantly greater incidence of myocardial ischaemia after operation than patients without known ischaemic heart disease (P < 0.05). There was an increase in both the incidence and duration of myocardial ischaemia after operation with both anaesthetic techniques, but no significant difference between the two.

Low risk of myocardial ischemia in the elderly visiting moderate altitude

Objective: Ascent to high altitude may be associated with changes in heart rate and systolic blood pressure, resulting in greater cardiac work. In elderly individuals with coronary artery disease, these changes may lead to myocardial ischemia. We studied an elderly population to assess the incidence of myocardial ischemia and the effect on the electrocardiogram (ECG) during a visit to moderate altitude. Design: Inception cohort study. Setting: Vail, Colorado (2500 m). Participants: Members and spouses of the Tenth Mountain Division reunion. Interventions: Resting 12-lead ECGs and blood pressures were obtained daily for 4 days. Results: Ninety-seven subjects participated (77 men and 20 women) with a mean age of 69.8 ± 4.4 years. Twenty-one percent of our subjects had some manifestation of coronary artery disease. On arrival, 59 (61%) of the ECGs were normal, 1 (1%) borderline, and 37 (38%) abnormal. No new ST-T-wave abnormalities clearly indicative of myocardial ischemia during the altitude stay were found. When compared to baseline ECGs recorded previously in 56 of our subjects, 8 (14%) had P-wave vector changes probably related to pulmonary hypertension. Cardiac work as estimated by the heart rate-blood pressure double product was increased by 13% at rest. Conclusions: Despite an increase in cardiac work, no new ST-T-wave abnormalities clearly indicative of myocardial ischemia were present on arrival or during the next 4 days at altitude. Despite a high prevalence of ECG abnormalities and probable coronary artery disease in these elderly subjects, ascent to moderate altitude did not appear to precipitate myocardial ischemia in subjects with asymptomatic coronary artery disease (New York Heart Association Class I).

Anaesthesia for abdominal aortic surgery in patients with coronary artery disease, part II: effects of nitrous oxide on systemic and coronary haemodynamics, regional ventricular function and incidence of myocardial ischaemia

This study examines the effects of nitrous oxide on haemodynamics, anterior left ventricular (LV) function and incidence of myocardial ischaemia in abdominal vascular surgical patients with coronary artery disease. Forty-seven patients were randomly assigned to isoflurane-fentanyl anaesthesia with nitrous oxide-oxygen vs air-oxygen (control). Systemic and coronary haemodynamics, 12-lead ECG, LV anterior wall motion by cardiokymography (CKG) and myocardial lactate balance were recorded at four intervals: before and during anaesthesia and 10 and 30 minutes into surgery. Systemic haemodynamics were controlled by anaesthetic dose, and, when insufficient, by i.v. nitroglycerine (NG) in case of LV failure (PCWP > 18 mmHg) and by phenylephrine during hypotension. We found that nitrous oxide was associated with greater need for i.v. nitroglycerin (patients: P = 0.031, episodes P = 0.005) and more myocardial ischaemia (patients P = 0.012, episodes P = 0.001) despite systemic and coronary haemodynamics comparable to the control group. We conclude that nitrous oxide, known to have both sympathomimetic and cardiodepressive actions, produced cardiodepression in the face of sympathetic stimulation. Our study design did not allow to conclude if myocardial ischaemia was the consequence of increased wall stress or a reason for the observed LV dysfunction. The higher incidence of introperative myocardial ischaemia and need for NG did not cause increased cardiac morbidity.

Anaesthesia for abdominal vascular surgery in patients with coronary artery disease (CAD), part I: isoflurane produces dose-dependent coronary vasodilation

The effects of anaesthesia for major abdominal vascular surgery on coronary flow regulation and mechanisms of myocardial ischaemia were studied in 56 patients with CAD, using a randomized, partly double-blinded protocol. After induction with fentanyl (3 micrograms.kg-1) and thiopentone (2-4 mg.kg-1) and tracheal intubation, principal anaesthetics were nitrous oxide/oxygen (60/40) with isoflurane (n = 20), halothane (n = 19) or fentanyl (15-20 micrograms.kg-1) (n = 17). Conventional invasive techniques and coronary venous retrograde thermodilution were used to assess systemic and coronary haemodynamics. Coronary vascular resistance was estimated from myocardial oxygen extraction. Myocardial ischaemia was diagnosed by 12-lead ECG and/or anterior wall motion abnormalities by cardiokymography and/or myocardial lactate production. When adjustment of anaesthetic dose was insufficient for haemodynamic control, i.v. phenylephrine and nitroglycerine were administered to treat hypotension and hypertension or cardiac failure respectively. Measurements were performed at four specific intervals; awake, before surgery and 10 and 30 min after abdominal incision. Comparable changes of systemic haemodynamics and myocardial oxygen consumption were observed in the three groups. Coronary vasodilation was evidenced in isoflurane patients only and was linearly dose-dependent (P < 0.001). Partial Least Squares Projections to Latent Structures modelling with cross validation confirmed this dose-dependency and ruled out a clinically measurable influence by intervention drugs or simultaneous systemic haemodynamic abnormalities. The incidence of myocardial ischaemia during anaesthesia and surgery was comparable in the three groups (35, 37 and 24%, respectively) and there was an association with systemic haemodynamic aberrations in 19 of the 27 ischaemic episodes. In contrast to ischaemic halothane and fentanyl patients, isoflurane patients with ischaemia had significantly lower myocardial oxygen extraction (P = 0.008 and P = 0.001, respectively), indicating that the oxygen extraction reserve was not utilized in a normal way during ischaemia.

Myocardial ischaemia during tracheal intubation and extubation

The incidence of myocardial ischaemia during tracheal intubation and extubation was compared using ambulatory ECG monitoring in 60 patients undergoing a variety of different surgical operations. Seven patients had myocardial ischaemia after tracheal intubation and seven patients during tracheal extubation. The patients who developed myocardial ischaemia during tracheal extubation had significantly greater rate-pressure products immediately before tracheal extubation (P < 0.05) and 1 min after tracheal extubation (P < 0.01) compared with those patients who did not develop myocardial ischaemia during extubation.

Esmolol and intraoperative myocardial ischemia: A double-blind study

Forty patients scheduled to undergo elective myocardial revescularization were included in a randomized, double-blind, placebo-controlled study to evaluate any influence of esmolol on the incidence of myocardial ischemia. Calibrated recordings of ECG leads II and V 5 were continuously monitored with the QMED Monitor One TC (Qmed Inc, Clark, NJ) from the time of arrival in the operating room holding area through the induction of anesthesia, using a high-dose opioid technique, and until the initiation of cardiopulmonary bypass. One group received a bolus of esmolol, 1.0 mg/kg, followed by a continuous infusion of 100 μg/kg/min. The other group received a bolus and infusion of saline placebo of equal volume. The incidence of myocardial ischemia was not significantly different between the groups on arrival in the holding area, or at any study point. Heart rate, mean arterial pressure, and the number of patients developing myocardial ischemia during the course of the study also did not differ significantly between the groups. There were significant decreases in heart rate and mean arterial pressure compared with the awake baseline values in both groups during multiple study points. It is concluded that esmolol was ineffective at treating preexisting or new-onset myocardial ischemia at this dosage in this clinical setting.