ORIGINAL ARTICLES
Effect of Warm Heart Surgery Undergoing
on Perioperative Urgent Cardiac
Management Surgery
of Patients
Brian P. Kavanagh, MB, BCh, BSc, MRCPI, C. David Mazer, MD, FRCPC, Anthony Panos, MD, MSc, FRCSC, and Samuel V. Lichtenstein, MD, PhD, FRCSC The anesthetic management and outcome data were examined in a retrospective case-controlled study that compared a conventional hypothermic cardioplegic technique with the recently described method of warm heart surgery, in patients undergoing urgent cardiac surgery. Hypothermic continuous oxygenated blood crystalloid cardioplegia with systemic hypothermia was used for 37 patients who underwent cardiac surgery by the same surgeon over a 16-month period from July 1988 (group 1). whereas normothermic continuous oxygenated blood crystalloid cardioplegia with systemic normothermia was used on 56 patients over the following 16.month period until March 1990 (group 2). The groups were similar in terms of age, sex, ASA status, NYHA classification, and preoperative left ventricular function. Defibrillation following cardiopulmonary bypass was required in only 3.8% of the warm heart surgery patients (group 2) compared with 83.8% in group 1 (P < 0.0001). and use of warm heart surgery (group 2) eliminated the need for rewarming. There was a
C vide
ARDIOPLEGIA WAS originally developed to proa still operating field, to allow intracardiac procedures under direct vision, and to protect the myocardium during periods of arrest and cessation of coronary blood flow.’ Whether continuous or intermittent blood or crystalloid cardioplegia is superior is a matter of controversy.2-5Although there are several conventionally accepted components to a successful cardioplegic technique, including the presence of potassium and magnesium, the single most important component is thought to be hypothermia.6-‘0 Lichtenstein et al developed the concept of continuous normothermic blood cardioplegia on the basis that the metabolic demands of the normothermic arrested heart are exceedingly low, and are only minimally further decreased with profound hypothermia.“~” These demands could easily be supplied by continuous perfusion of a normothermic blood-crystalloid solution rather than a cold perfusate, particularly in terms of oxygen delivery to the myocardium.“,” Previously published data point to several advantages of continuous normothermic, compared with continuous hypothermic, blood-crystalloid cardioplegia.” The data were derived from a prospective analysis of consecutive patients who underwent a coronary artery bypass graft (CABG), and suggested that there were beneficial effects in terms of reduction in perioperative myocardial infarction, low output syndrome, increased cardiac output (CO) following cardiopulmonary bypass (CPB), and reduced reperfusion
Journal of Cardiothoracic and VascularAnesthesia,
trend towards a reduced incidence of myocardial infarction (19% in group 1 vs 9% in group 2). low cardiac output syndrome (40% vs 29%). and use of the intraaotiic balloon pump (16% vs 9%) in warm heart surgery patients, but these differences did not reach statistical significance. There were no differences between the two groups in terms of anesthetic drug usage, total heparin or protamine doses, blood loss, transfusion requirements, or duration of ICU stay. These results suggest that: (1) hypothermia is not an absolute requirement for myocardial protection; (2) warm cardioplegia is a useful and safe technique in high-risk patients undergoing urgent cardiac surgery; (3) warm cardioplegia is associated with a reduced requirement for postbypass defibrillation; and (4) introduction into clinical practice of warm heart surgery resulted in no significant changes in perioperative management of patients undergoing urgent cardiac surgery. Copyright o 1992 by W.B. Saunders Company
time following aortic cross-clamp removal. A major advantage of the method may be that greatly prolonged crossclamp times are possible, thus allowing for more complex or longer surgical procedures.‘3 Although these initial reports suggest improved surgical outcome, the anesthetic implications of normothermic blood cardioplegia have not been studied. To determine the effect of the introduction into clinical practice of warm heart surgery on perioperative anesthetic management, patients undergoing urgent CPB using continuous normothermic blood-crystalloid cardioplegia with systemic normothermia were compared with a similar group receiving cold blood-crystalloid cardioplegia and systemic hypothermia.
This article is accompanied by an editorial. Please see: Ix11 WA: Hot or Cold, Continuous or Intermittent? What Goes Around Comes Around. J Cardiothorac Vast Anesth 6:125-126,1992
From the Departments of Anesthesia and Surgery, Universi~ of Toronto, St Michael’s Hospital, Toronto, Ontario, Canada. Address reprint requests to C. David Mazer, MD, FRCPC, Department of Anesthesia, University of Toronto, St Michael’s Hospital, 30 Bond St, Toronto, Ontario, MSB I W8 Canada. Copyright 0 1992 by W.B. Saunders Company X053-0770192/0602-0002$0.00/0
Vol6, No 2 (April), 1992: pp 127-131
127
KAVANAtiH
128
MATERIALS
AND METHODS
The perioperativc records of 93 patients who underwent urgent or emergency cardiac surgery by the same surgeon over a 3-year period were reviewed. Group 1 consisted of 37 patients from July I986 to November 19X7, all of whom received continuous hypothermic blood-crystalloid cardioplegia. All the patients in group 2 (n = 56) were operated on between November 1987 and March 1990, and all received continuous normothermic blood-crystalloid cardioplegia. All patients were ASA class IV or V, and were seen in preanesthetic consultation by a staff anesthesiologist. Patients were premeditated with narcotics and benzodiazepines as appropriate. Intraoperative monitoring consisted of a two-lead (II and V,) electrocardiogram (ECG), pulse oximeter, capnograph, and transduced intra-arterial and pulmonary artery pressure (PAP). Anesthesia was induced with high-dose fentanyl and pancuronium at dosage regimens determined by the attending anesthesiologist, and supplemented with narcotics, benzodiazepines, and/or low concentrations of isoflurane or enflurane. CO was measured at regular intervals using the thermodilution technique with rapid injection of room temperature normal saline. All hemodynamic data were recorded immediately pre-CPB and post-CPB. Patients were anticoagulated with heparin, 390 IUikg, before CPB plus supplemental doses as required to maintain the activated clotting time (ACT) of more than 400 seconds during CPB. In addition, the bypass circuit prime contained 5,000 IU of heparin in both groups. During CPB isoflurane, nitroglycerin, sodium nitroprusside, and/or phenylephrine were used to maintain the mean arterial pressure in the range of 50 to 90 mmHg. The following data were also recorded: serial ACT. blood loss, transfusion requirements, fluid balance, urinary output, aortic cross-clamp time, bypass time, core temperature. and dosages of inotropes, heparin. and protamine sulphate. In all cases, cardiac arrest was induced by infusion of a high potassium (K = 20.0 mmol/L) oxygenated blood-crystalloid (4:l) solution into the aortic root, proximal to the aortic cross-clamp. The cardioplegic solution was infused in all cases at a rate of 300 mL/min for a period of 5 minutes. In group I, the cardioplegia temperature was 10°C; iced saline was inserted into the pericardial well to maintain the myocardial temperature at approximately 15”C, with systemic hypothermia to 27°C to 32°C. In group 2, the cardioplegia temperature was 37°C; body temperature was maintained at 33°C to 37°C. Cardiac arrest was invariably achieved in less than I minute. Following perfusion with the high potassium solution for 5 minutes, the perfusate was switched to a low potassium (K = 6.0 mmol/L) oxygenated blood-crystalloid solution, which was identical in all other respects to the solutions previously described. These cardioplegic solutions, hypothermic in group 1 and normothermic in group 2, were continued at an infusion rate of 50 to 150 mL/min. If electrical activity was detected on the ECG, the high potassium solution was temporarily infused until asystole was again achieved. Following discontinuation of CPB, circulatory support with either inotropic drugs or intra-aortic balloon pump (IABP) counterpulsation was provided if necessary, and patients were transferred to the cardiovascular intensive care unit (ICU). Immediately following admission to the ICU, hemoglobin and serum potassium were measured, and hemodynamic evaluation (arterial blood pressure, central venous pressure, PAP, pulmonary capillary wedge pressure [PCWP], CO) was undertaken. Temperature was recorded, as was the time taken to reach the ICU following discontinuation of CPB. The chest tube drainage. fluid balance, and requirement for blood products were recorded for 12 hours following ICU admission. The low CO syndrome (LCOS) was defined as the need for cardiovascular support with either ino-
t’ ~1.
tropeh or lAHP to mainlain ay\tolic blood pl-esaure abo\c Yll mm Hg, in association with a cardiac index less than 2 L:min/ m head I rale greater than 80 beats/min. and PCWP greater than I8 mmfly. Perioperalive myocardial infarction was defined as the appearance of new Q waves on the ECG and CK-MB greater than 30. Duration of mechanical ventilation and ICI1 stay was recorded. as w
Effect of Warm Heart Surgery Undergoing
on Perioperative Urgent Cardiac
Management Surgery
of Patients
Brian P. Kavanagh, MB, BCh, BSc, MRCPI, C. David Mazer, MD, FRCPC, Anthony Panos, MD, MSc, FRCSC, and Samuel V. Lichtenstein, MD, PhD, FRCSC The anesthetic management and outcome data were examined in a retrospective case-controlled study that compared a conventional hypothermic cardioplegic technique with the recently described method of warm heart surgery, in patients undergoing urgent cardiac surgery. Hypothermic continuous oxygenated blood crystalloid cardioplegia with systemic hypothermia was used for 37 patients who underwent cardiac surgery by the same surgeon over a 16-month period from July 1988 (group 1). whereas normothermic continuous oxygenated blood crystalloid cardioplegia with systemic normothermia was used on 56 patients over the following 16.month period until March 1990 (group 2). The groups were similar in terms of age, sex, ASA status, NYHA classification, and preoperative left ventricular function. Defibrillation following cardiopulmonary bypass was required in only 3.8% of the warm heart surgery patients (group 2) compared with 83.8% in group 1 (P < 0.0001). and use of warm heart surgery (group 2) eliminated the need for rewarming. There was a
C vide
ARDIOPLEGIA WAS originally developed to proa still operating field, to allow intracardiac procedures under direct vision, and to protect the myocardium during periods of arrest and cessation of coronary blood flow.’ Whether continuous or intermittent blood or crystalloid cardioplegia is superior is a matter of controversy.2-5Although there are several conventionally accepted components to a successful cardioplegic technique, including the presence of potassium and magnesium, the single most important component is thought to be hypothermia.6-‘0 Lichtenstein et al developed the concept of continuous normothermic blood cardioplegia on the basis that the metabolic demands of the normothermic arrested heart are exceedingly low, and are only minimally further decreased with profound hypothermia.“~” These demands could easily be supplied by continuous perfusion of a normothermic blood-crystalloid solution rather than a cold perfusate, particularly in terms of oxygen delivery to the myocardium.“,” Previously published data point to several advantages of continuous normothermic, compared with continuous hypothermic, blood-crystalloid cardioplegia.” The data were derived from a prospective analysis of consecutive patients who underwent a coronary artery bypass graft (CABG), and suggested that there were beneficial effects in terms of reduction in perioperative myocardial infarction, low output syndrome, increased cardiac output (CO) following cardiopulmonary bypass (CPB), and reduced reperfusion
Journal of Cardiothoracic and VascularAnesthesia,
trend towards a reduced incidence of myocardial infarction (19% in group 1 vs 9% in group 2). low cardiac output syndrome (40% vs 29%). and use of the intraaotiic balloon pump (16% vs 9%) in warm heart surgery patients, but these differences did not reach statistical significance. There were no differences between the two groups in terms of anesthetic drug usage, total heparin or protamine doses, blood loss, transfusion requirements, or duration of ICU stay. These results suggest that: (1) hypothermia is not an absolute requirement for myocardial protection; (2) warm cardioplegia is a useful and safe technique in high-risk patients undergoing urgent cardiac surgery; (3) warm cardioplegia is associated with a reduced requirement for postbypass defibrillation; and (4) introduction into clinical practice of warm heart surgery resulted in no significant changes in perioperative management of patients undergoing urgent cardiac surgery. Copyright o 1992 by W.B. Saunders Company
time following aortic cross-clamp removal. A major advantage of the method may be that greatly prolonged crossclamp times are possible, thus allowing for more complex or longer surgical procedures.‘3 Although these initial reports suggest improved surgical outcome, the anesthetic implications of normothermic blood cardioplegia have not been studied. To determine the effect of the introduction into clinical practice of warm heart surgery on perioperative anesthetic management, patients undergoing urgent CPB using continuous normothermic blood-crystalloid cardioplegia with systemic normothermia were compared with a similar group receiving cold blood-crystalloid cardioplegia and systemic hypothermia.
This article is accompanied by an editorial. Please see: Ix11 WA: Hot or Cold, Continuous or Intermittent? What Goes Around Comes Around. J Cardiothorac Vast Anesth 6:125-126,1992
From the Departments of Anesthesia and Surgery, Universi~ of Toronto, St Michael’s Hospital, Toronto, Ontario, Canada. Address reprint requests to C. David Mazer, MD, FRCPC, Department of Anesthesia, University of Toronto, St Michael’s Hospital, 30 Bond St, Toronto, Ontario, MSB I W8 Canada. Copyright 0 1992 by W.B. Saunders Company X053-0770192/0602-0002$0.00/0
Vol6, No 2 (April), 1992: pp 127-131
127
KAVANAtiH
128
MATERIALS
AND METHODS
The perioperativc records of 93 patients who underwent urgent or emergency cardiac surgery by the same surgeon over a 3-year period were reviewed. Group 1 consisted of 37 patients from July I986 to November 19X7, all of whom received continuous hypothermic blood-crystalloid cardioplegia. All the patients in group 2 (n = 56) were operated on between November 1987 and March 1990, and all received continuous normothermic blood-crystalloid cardioplegia. All patients were ASA class IV or V, and were seen in preanesthetic consultation by a staff anesthesiologist. Patients were premeditated with narcotics and benzodiazepines as appropriate. Intraoperative monitoring consisted of a two-lead (II and V,) electrocardiogram (ECG), pulse oximeter, capnograph, and transduced intra-arterial and pulmonary artery pressure (PAP). Anesthesia was induced with high-dose fentanyl and pancuronium at dosage regimens determined by the attending anesthesiologist, and supplemented with narcotics, benzodiazepines, and/or low concentrations of isoflurane or enflurane. CO was measured at regular intervals using the thermodilution technique with rapid injection of room temperature normal saline. All hemodynamic data were recorded immediately pre-CPB and post-CPB. Patients were anticoagulated with heparin, 390 IUikg, before CPB plus supplemental doses as required to maintain the activated clotting time (ACT) of more than 400 seconds during CPB. In addition, the bypass circuit prime contained 5,000 IU of heparin in both groups. During CPB isoflurane, nitroglycerin, sodium nitroprusside, and/or phenylephrine were used to maintain the mean arterial pressure in the range of 50 to 90 mmHg. The following data were also recorded: serial ACT. blood loss, transfusion requirements, fluid balance, urinary output, aortic cross-clamp time, bypass time, core temperature. and dosages of inotropes, heparin. and protamine sulphate. In all cases, cardiac arrest was induced by infusion of a high potassium (K = 20.0 mmol/L) oxygenated blood-crystalloid (4:l) solution into the aortic root, proximal to the aortic cross-clamp. The cardioplegic solution was infused in all cases at a rate of 300 mL/min for a period of 5 minutes. In group I, the cardioplegia temperature was 10°C; iced saline was inserted into the pericardial well to maintain the myocardial temperature at approximately 15”C, with systemic hypothermia to 27°C to 32°C. In group 2, the cardioplegia temperature was 37°C; body temperature was maintained at 33°C to 37°C. Cardiac arrest was invariably achieved in less than I minute. Following perfusion with the high potassium solution for 5 minutes, the perfusate was switched to a low potassium (K = 6.0 mmol/L) oxygenated blood-crystalloid solution, which was identical in all other respects to the solutions previously described. These cardioplegic solutions, hypothermic in group 1 and normothermic in group 2, were continued at an infusion rate of 50 to 150 mL/min. If electrical activity was detected on the ECG, the high potassium solution was temporarily infused until asystole was again achieved. Following discontinuation of CPB, circulatory support with either inotropic drugs or intra-aortic balloon pump (IABP) counterpulsation was provided if necessary, and patients were transferred to the cardiovascular intensive care unit (ICU). Immediately following admission to the ICU, hemoglobin and serum potassium were measured, and hemodynamic evaluation (arterial blood pressure, central venous pressure, PAP, pulmonary capillary wedge pressure [PCWP], CO) was undertaken. Temperature was recorded, as was the time taken to reach the ICU following discontinuation of CPB. The chest tube drainage. fluid balance, and requirement for blood products were recorded for 12 hours following ICU admission. The low CO syndrome (LCOS) was defined as the need for cardiovascular support with either ino-
t’ ~1.
tropeh or lAHP to mainlain ay\tolic blood pl-esaure abo\c Yll mm Hg, in association with a cardiac index less than 2 L:min/ m head I rale greater than 80 beats/min. and PCWP greater than I8 mmfly. Perioperalive myocardial infarction was defined as the appearance of new Q waves on the ECG and CK-MB greater than 30. Duration of mechanical ventilation and ICI1 stay was recorded. as w
