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Placement of an automatic implantable cardioverter-defibrillator in a 6-month-old infant: Anesthetic management
Placement of an Automatic Implantable Cardioverter-Defibrillator in a 6-Month-Old Infant: Anesthetic M a n a g e m e n t Caroline Dumont, MD, Lionel Dumont, MD, Chah6 Mardirosoff, MD, and Andr~e De Ville, MD ENTRICULAR FIBRILLATION is an uncommon event in pediatric patients. It may be observed after electrocution, during and after cardiac surgery, or in the presence of certain myocardial diseases.~ Automatic implanted cardioverterdefibrillators (AICD) are an easy-to-perform and efficient therapy in adult and pediatric patients for the prevention of sudden cardiac death resulting from malignant ventricular arrhythmia. 2,3 AICD therapy remains rare in infants younger than 1 year of age, and anesthesia for such a procedure has not yet been described in the pediatric age group. The authors report a case of AICD insertion under caudal epidural and general anesthesia in a 6-month-old infant suffering from ventricular tachyarrhythmia as a result of a large right ventricnlar congenital tumor.
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CASE REPORT A 6~month-old infant suffered from a nouoperable, nonobstructive congenital right ventricular intramyocardial myxofibroma with high electrical excitability. He was born at term, uneventfully, with a cardiac tumor diagnosed antenatally. The infant presented at 6 months with sudden cardiorespiratory arrest from which he was successfully resuscitated. The neurologic evaluation was favorable, with stable hemodynamics and early extubation. The general clinical status was good, with no signs of cardiac failure, and weight, height, and cranial perimeters were 9.9 kg, 78 cm, and 47 cm. Echocardiography demonstrated that this large tumor completely enclosed the interventricular septum with extension near the left ventricular outflow chamber and the right ventricular cavity. There was no functional or anatomic obstruction to the left ventricular outflow or to the venous return. There was a little restriction of the right ventricular filling, and the valves were normal. The electrocardiogram showed a regular sinus rhythm and a complete right bundle-branchblock. Myocardial biopsy and electrophysiologic study were both performed by angiography under local anesthesia (lidocaine, 1%, 1.2 mL at the puncture point of the femoral artery) and general anesthesia (etomidate, 0.2 mg/kg; atracurium, 0.5 mg/kg; nitrous oxide and oxygen, 50 vol%; isoflurane, 0.3 to 0.5 vol%). During these procedures, the contact between the probe and the septum provoked episodes of ventricular fibrillation converted into sinus rhythm by external shocks of 20 J, and amiodarone was then initiated. The patient was extubated at the end of each procedure. These investigations revealed a congenital right ventricular intramyocardial myxofibroma with a high electrical vulnerabilitywithout retrograde conduction. The patient was then scheduled for AICD implantation. Midazolam, 0.4 mg/kg intrarectally, was given 20 minutes before the procedure. Because of poor venous access, smooth isoflurane inhalation anesthesia was induced, followed by cannulation of the femoral vein, administration of atracurium, 0.5 mg/kg, and tracheal intubation. An end-tidal carbon dioxide value between 32 and 35 mmHg was maintained by mechanical ventilation. Caudal anesthesia was performed, and a single dose of morphine, 500 pg in 10 mL of sodium chloride 0.9%, was administered 30 minutes before the sternotomy. A rectal tempera-
ture probe, a femoral arterial catheter, and an urinary catheter were positioned. Anesthesia was maintained with nitrous oxide and oxygen, 50 vol%, and isoflurane, 0.4 to 0.9 vol%, titrated on the basis of clinical indicators of the depth of anesthesia, and no supplement of narcotic was necessary. The surgical procedure consisted of sternotomy; positioning of two epicardial leads (detection and stimulation); positioning of a defibrillation patch; abdominal incision for the CPI Ventak Mini III system (CPI, Minneapolis, MN), defibrillator, and connection among the lead, the patch, and the defibrillator. Surgery lasted 185 minutes, during which six episodes of ventricular fibrillation were induced (total duration, 110 seconds) and a total of 91 J were administered. During each of these testing episodes, the mean arterial pressure decreased to 20 to 30 mmHg and returned to baseline within 5 minutes after each electrical conversion. The hemodynamic parameters were relatively stable and remained in a normal range (mean arterial pressure, 45 to 65 mmHg; heart rate, 110 to 130 beats/min), and no inotropic support was needed. The infant was extubated at the end of the procedure and brought to the intensive care unit. Postoperative analgesia was started 4 hours later with continuous intravenous infusion of morphine, 10 to 40 pg/kg/h. Feeding was begun on the 1st postoperative day, and the evolution was favorable without anesthesiologic or surgical complications. The testing of the device performed 3 days later was normal. The infant was discharged from the hospital the following day, and amiodarone was continued as further medication.
DISCUSSION The usual transvenous access for the lead with the battery placed in the adipose tissue is not possible in children because of a size incompatibility. The placement of the CPI Mini III device requires a sternotomy, resulting in a major, stressful, and painful operation. Good analgesia is necessary to minimize the stress response to the operation for different reasons. High plasma levels of stress hormones (ie, catecholamines) may induce malignant arrhythmia in a highly excitable myocardium and may also modify the electrophysiologic testing. 4,s Good analgesia and hemodynamic stability prevent an increase in myocardial oxygen consumption6 and decrease the hypertensive rebound after the shock and the myocardial work. 6 The consequences of a decreased myocardial oxygen delivery caused by ventricular fibrillation could be of minor importance.
From the Department of Anesthesiology, Brugmann Unive•rsity Hospital, Brussels, Belgium. Address reprint requests to Lionel Dumont, MD,"Division of Anesthesiology, HOpital Cantonal de Genkve, Rue MicheIi du Crest, 24, CH-1211 Geneva 14, Switzerland• Copyright © 2000 by W.B. Saunders Company 1053-0770/00/1401-0015510.00/0 Key words: anesthesia, automatic implantable cardioverter-defibrillator, pediatric anesthesia, ventricular fibrillation
Journal of Cardiothoracic and Vascular Anesthesia, Vo114,No 1 (February),2000: pp 63-65
63
64
DUMONT ET AL
The goal of this anesthetic management was to provide good perioperative analgesia and adequate hemodynamic stability without interfering with the electrophysiologic testing and measurements. Several anesthetic techniques have been described for AICD insertion in adults (ie, high opioid general anesthesia, balanced general anesthesia, thoracic epidural anesthesia, conscious sedation), but none has been described in children. 7-9 A high opioid general anesthesia could have been used for this infant, but there was no reason to keep him intubated in the postoperative period. Early extubation after cardiac surgery in children seems to result in fewer pulmonary complications and in shorter intensive care unit and hospital stays.l° Balanced general anesthesia was well tolerated previously by the infant. The context, however, was completely different because angiography and electrophysiologic studies usually do not require anesthesia (in adults), which was performed in this case only for the well-being of the infant. There are some theoretic limits to the use of halogenated agents because they may modify the defibrillation threshold and disturb the electrophysiologic testing.11 Halothane and enflurane have been recognized to modify the electrophysiologic properties of the heart in animal studies at 1.1 to 1,8 minimum alveolar concentration. 1L12Isoflurane and sevoflurane seem to have minor effects on cardiac electrophysiology.13,14 Induction and maintenance by inhalation anesthesia allowed the authors to gain venous access and to perform the caudal anesthesia. Isoflurane in this case probably did not interact with the electrophysiologic testing because it was reduced to 0.5 vo1% to 0.9 vol% after intubation and the regional anesthetic and to 0.3 vol% to 0.5 vol% during the testing. 12,14 Propofol may be an alternative for this type of anesthesia but was not approved at the time of this report for children younger than 3 years old in Belgium. Propofol is usually used in adults for these procedures and does not seem to interfere with the testing of the AICD device. 14,15 Remifentanil can also be considered for these kinds of procedures. Because of its short duration of action, it is mandatory to control postoperative pain by other means, such as morphine. 16 Caudal epidural opioid has been shown to be effective for the postoperative period and has been used during the intraoperative period in cardiac surgery. 1°,17 A single dose of morphine was used in this case to provide good antinociception during
and early after the operation, to minimize the interference between anesthesia and electrophysiologic measurements, and to allow early extubation. 17This anesthesia was satisfactory, but the postoperative analgesia was not sufficient after the first 4 hours. This technique is probably not always as successful as it was in this patient; for instance, analgesia may be insufficient, early extubation is not always possible after cardiac surgery, I7 and the risk of postextubation respiratory depression must be taken into account. I8 This patient, however, scheduled for a stemotomy without cardiopulmonary bypass and cardiac surgical correction, was probably a good candidate for this anesthesia. Epidural local anesthetics were not used because their absorption from the epidural space into the plasma may affect the determination of the defibrillation threshold, 19 although their use was previously reported without significant problems. 8 To use local anesthetics in this kind of procedure, it is necessary to place a caudal catheter to continue anesthesia if needed. In the future for such cases, it would be more appropriate to have a caudal catheter, whatever the anesthetic technique (local anesthetics, opioid, or both), for postoperative analgesia. No myocardial stunning, 2° no cardiac failure, 21,22 and no need for inotropic support were observed in this infant. Different hypotheses may explain this small effect on cardiac function: First, the duration of ventricular fibrillation episodes during the testing was short; second, the fibrillation was not a direct consequence of myocardial suffering; third, the defibrillations were of low intensity (2 J/kg)4; and fourth, the heart of neonates and young children seems to exhibit greater functional recovery than the adult heart after a short period of ischemia. 23 In conclusion, there are probably several different anesthetic techniques for AICD implantation in young children with respect to good intraoperative analgesia and hemodynamic stability without interference with electrophysiologic testing. In the authors' experience, the AICD implantation under caudal morphine and light general anesthesia appears to be easy, safe, and adequate for AICD implantation in young infants. The authors have reported the case of an AICD insertion in a 6-month-old infant presenting with ventricular tachyarrhythmia as a result of a large congenital fight ventricular intramyocardial myxofibroma. The possible interactions between anesthesia and A1CD device implantation have been reviewed, with their particularities in children.
REFERENCES
1. Walsh CK, Krongrad E: Terminal cardiac electrical activity in pediatric patients. Am J Cardio151:557-561, 1983 2. Silka MJ, Kron J, Dunnigan A, Dick M: Sudden cardiac death and the use of implantable cardioverter-defihrillators in pediatric patients: The pediatric electrophysiology society. Circulation 87:800-807, 1993 3. AVID Trial: A comparison of antiarrhythmic-drugs therapy with implantable defibrillators in patients resuscitated from non fatal ventricular arrhythmias. N Engl J Med 337:1576-1583, 1997 4. Bossaert LL: Fibrillation and defibrillation of the heart. Br J Anaesth 79:203-213, 1997 5. Babbs CF: Effects of drugs on defibrillation threshold, in Tacker WA (ed): Defibrillation of the Heart. St Louis, MO, Mosby, 1994, pp 224-258
6. Nathan HJ: Coronary physiology, in Kaplan JA (ed): Cardiac Anesthesia (3rd ed). Philadelphia, PA, Saunders, 1993, pp 254-255 7. Cashman JN, Garcia-Rodriguez C, Lamond C: Anaesthesia for transvenous insertion of an automatic implantable cardioverter defibrillator. Anaesthesia 47:720-721, 1992 8. Gilbert TB, Kent JL, Foster AH, Gold MR: Implantable cardioverter/defibrillator placement in a patient with amiodarone pulmonary toxicity under thoracic epidural anesthesia. Anesthesiology 79:608-611, 1993 9. Pacifico A, Wheelan KR, Nasir N, et al: Long term follow-up of cardioverter-defibrillator implanted under conscious sedation in prepectoral subfascial position. Circulation 95:946-950, 1997 10. Heinle JS, Diaz LK, Fox LS: Early extubation after cardiac
AICD PLACEMENT IN AN INFANT
operations in neonates and young infants. J Thorac Cardiovasc Surg 114:413-418, 1997 11. Deutsch N, Hantler CB, Tait A, et al: Suppression of ventricular arrhythmias by volatile anesthetics in a canine model of chronic myocardial infarction. Anesthesiology 72:1012-1021, 1990 12. Atlee JL: Cardiac pacing and electroversion, in Kaplan JA (ed): Cardiac Anesthesia (3rd ed). Philadelphia, PA, Saunders, 1993, pp 877-904 13. Tanaka K, Nakamura M, Umeda T, et al: Effects of sevoflurane and halothane on reperfusion-induced arrhythmia in the isolated rat heart. Clin Ther 15:1085-1093, 1993 14. Moerman A, Herregods, Tavernier R, et al: Influence of anaesthesia on defibrillation threshold. Anaesthesia 53:1156-1159, 1998 15. Lehmann A, Boldt J, Zeitler C, et al: Total intravenous anesthesia with remifentanil and propofol for implantation of cardioverterdefibrillators in patients with severely reduced left ventricular function. J Cardiothorac Vasc Anesth 13:15-19, 1999 16. Btirkle H, Dunbar S, Van Haken H: Remifentanil: A novel, short-acting, p-opioid. Anesth Analg 83:646-651, 1996
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17. Rosen KR, Rosen RA: Caudal epidural morphine for control of pain following open heart surgery in children. Anesthesiology 70:418421, 1989 18. Karl HW, Tyler DC, Krane EJ: Respiratory depression after low-dose caudal morphine. Can J Anaesth 43:1065-1067, 1996 19. Natale A, Jones DL, Kim Y-H, Klein GJ: Effects of lidocaine on defibrillation threshold in the pig: Evidence of anesthesia related increase. Pacing Clin Electrophysiol 14:1239-1244, 1991 20. Brannwald E, Kloner RA: The stunned myocardium: Prolonged, post ischemic ventricular dysfunction. Circulation 66:1146-1149, 1982 21. Steinbeck G, Dorwath U, Mahler S, et al: Hemodynamic deterioration during ICD implant: Predictors of high-risk patients. Am Heart J 127:1064-1067, 1994 22. Keyl C, Tassany R Kemkes B, et al: Hemodynamic changes due to intraoperative testing of the automatic implantable cardioverterdefibrillator: Implications for anesthesia management. J Cardiothorac Vasc Anesth 7:442-447, 1993 23. Booker PD: Myocardial stunning in the neonate. Br J Anaesth 80:371-383, 1998
V
CASE REPORT A 6~month-old infant suffered from a nouoperable, nonobstructive congenital right ventricular intramyocardial myxofibroma with high electrical excitability. He was born at term, uneventfully, with a cardiac tumor diagnosed antenatally. The infant presented at 6 months with sudden cardiorespiratory arrest from which he was successfully resuscitated. The neurologic evaluation was favorable, with stable hemodynamics and early extubation. The general clinical status was good, with no signs of cardiac failure, and weight, height, and cranial perimeters were 9.9 kg, 78 cm, and 47 cm. Echocardiography demonstrated that this large tumor completely enclosed the interventricular septum with extension near the left ventricular outflow chamber and the right ventricular cavity. There was no functional or anatomic obstruction to the left ventricular outflow or to the venous return. There was a little restriction of the right ventricular filling, and the valves were normal. The electrocardiogram showed a regular sinus rhythm and a complete right bundle-branchblock. Myocardial biopsy and electrophysiologic study were both performed by angiography under local anesthesia (lidocaine, 1%, 1.2 mL at the puncture point of the femoral artery) and general anesthesia (etomidate, 0.2 mg/kg; atracurium, 0.5 mg/kg; nitrous oxide and oxygen, 50 vol%; isoflurane, 0.3 to 0.5 vol%). During these procedures, the contact between the probe and the septum provoked episodes of ventricular fibrillation converted into sinus rhythm by external shocks of 20 J, and amiodarone was then initiated. The patient was extubated at the end of each procedure. These investigations revealed a congenital right ventricular intramyocardial myxofibroma with a high electrical vulnerabilitywithout retrograde conduction. The patient was then scheduled for AICD implantation. Midazolam, 0.4 mg/kg intrarectally, was given 20 minutes before the procedure. Because of poor venous access, smooth isoflurane inhalation anesthesia was induced, followed by cannulation of the femoral vein, administration of atracurium, 0.5 mg/kg, and tracheal intubation. An end-tidal carbon dioxide value between 32 and 35 mmHg was maintained by mechanical ventilation. Caudal anesthesia was performed, and a single dose of morphine, 500 pg in 10 mL of sodium chloride 0.9%, was administered 30 minutes before the sternotomy. A rectal tempera-
ture probe, a femoral arterial catheter, and an urinary catheter were positioned. Anesthesia was maintained with nitrous oxide and oxygen, 50 vol%, and isoflurane, 0.4 to 0.9 vol%, titrated on the basis of clinical indicators of the depth of anesthesia, and no supplement of narcotic was necessary. The surgical procedure consisted of sternotomy; positioning of two epicardial leads (detection and stimulation); positioning of a defibrillation patch; abdominal incision for the CPI Ventak Mini III system (CPI, Minneapolis, MN), defibrillator, and connection among the lead, the patch, and the defibrillator. Surgery lasted 185 minutes, during which six episodes of ventricular fibrillation were induced (total duration, 110 seconds) and a total of 91 J were administered. During each of these testing episodes, the mean arterial pressure decreased to 20 to 30 mmHg and returned to baseline within 5 minutes after each electrical conversion. The hemodynamic parameters were relatively stable and remained in a normal range (mean arterial pressure, 45 to 65 mmHg; heart rate, 110 to 130 beats/min), and no inotropic support was needed. The infant was extubated at the end of the procedure and brought to the intensive care unit. Postoperative analgesia was started 4 hours later with continuous intravenous infusion of morphine, 10 to 40 pg/kg/h. Feeding was begun on the 1st postoperative day, and the evolution was favorable without anesthesiologic or surgical complications. The testing of the device performed 3 days later was normal. The infant was discharged from the hospital the following day, and amiodarone was continued as further medication.
DISCUSSION The usual transvenous access for the lead with the battery placed in the adipose tissue is not possible in children because of a size incompatibility. The placement of the CPI Mini III device requires a sternotomy, resulting in a major, stressful, and painful operation. Good analgesia is necessary to minimize the stress response to the operation for different reasons. High plasma levels of stress hormones (ie, catecholamines) may induce malignant arrhythmia in a highly excitable myocardium and may also modify the electrophysiologic testing. 4,s Good analgesia and hemodynamic stability prevent an increase in myocardial oxygen consumption6 and decrease the hypertensive rebound after the shock and the myocardial work. 6 The consequences of a decreased myocardial oxygen delivery caused by ventricular fibrillation could be of minor importance.
From the Department of Anesthesiology, Brugmann Unive•rsity Hospital, Brussels, Belgium. Address reprint requests to Lionel Dumont, MD,"Division of Anesthesiology, HOpital Cantonal de Genkve, Rue MicheIi du Crest, 24, CH-1211 Geneva 14, Switzerland• Copyright © 2000 by W.B. Saunders Company 1053-0770/00/1401-0015510.00/0 Key words: anesthesia, automatic implantable cardioverter-defibrillator, pediatric anesthesia, ventricular fibrillation
Journal of Cardiothoracic and Vascular Anesthesia, Vo114,No 1 (February),2000: pp 63-65
63
64
DUMONT ET AL
The goal of this anesthetic management was to provide good perioperative analgesia and adequate hemodynamic stability without interfering with the electrophysiologic testing and measurements. Several anesthetic techniques have been described for AICD insertion in adults (ie, high opioid general anesthesia, balanced general anesthesia, thoracic epidural anesthesia, conscious sedation), but none has been described in children. 7-9 A high opioid general anesthesia could have been used for this infant, but there was no reason to keep him intubated in the postoperative period. Early extubation after cardiac surgery in children seems to result in fewer pulmonary complications and in shorter intensive care unit and hospital stays.l° Balanced general anesthesia was well tolerated previously by the infant. The context, however, was completely different because angiography and electrophysiologic studies usually do not require anesthesia (in adults), which was performed in this case only for the well-being of the infant. There are some theoretic limits to the use of halogenated agents because they may modify the defibrillation threshold and disturb the electrophysiologic testing.11 Halothane and enflurane have been recognized to modify the electrophysiologic properties of the heart in animal studies at 1.1 to 1,8 minimum alveolar concentration. 1L12Isoflurane and sevoflurane seem to have minor effects on cardiac electrophysiology.13,14 Induction and maintenance by inhalation anesthesia allowed the authors to gain venous access and to perform the caudal anesthesia. Isoflurane in this case probably did not interact with the electrophysiologic testing because it was reduced to 0.5 vo1% to 0.9 vol% after intubation and the regional anesthetic and to 0.3 vol% to 0.5 vol% during the testing. 12,14 Propofol may be an alternative for this type of anesthesia but was not approved at the time of this report for children younger than 3 years old in Belgium. Propofol is usually used in adults for these procedures and does not seem to interfere with the testing of the AICD device. 14,15 Remifentanil can also be considered for these kinds of procedures. Because of its short duration of action, it is mandatory to control postoperative pain by other means, such as morphine. 16 Caudal epidural opioid has been shown to be effective for the postoperative period and has been used during the intraoperative period in cardiac surgery. 1°,17 A single dose of morphine was used in this case to provide good antinociception during
and early after the operation, to minimize the interference between anesthesia and electrophysiologic measurements, and to allow early extubation. 17This anesthesia was satisfactory, but the postoperative analgesia was not sufficient after the first 4 hours. This technique is probably not always as successful as it was in this patient; for instance, analgesia may be insufficient, early extubation is not always possible after cardiac surgery, I7 and the risk of postextubation respiratory depression must be taken into account. I8 This patient, however, scheduled for a stemotomy without cardiopulmonary bypass and cardiac surgical correction, was probably a good candidate for this anesthesia. Epidural local anesthetics were not used because their absorption from the epidural space into the plasma may affect the determination of the defibrillation threshold, 19 although their use was previously reported without significant problems. 8 To use local anesthetics in this kind of procedure, it is necessary to place a caudal catheter to continue anesthesia if needed. In the future for such cases, it would be more appropriate to have a caudal catheter, whatever the anesthetic technique (local anesthetics, opioid, or both), for postoperative analgesia. No myocardial stunning, 2° no cardiac failure, 21,22 and no need for inotropic support were observed in this infant. Different hypotheses may explain this small effect on cardiac function: First, the duration of ventricular fibrillation episodes during the testing was short; second, the fibrillation was not a direct consequence of myocardial suffering; third, the defibrillations were of low intensity (2 J/kg)4; and fourth, the heart of neonates and young children seems to exhibit greater functional recovery than the adult heart after a short period of ischemia. 23 In conclusion, there are probably several different anesthetic techniques for AICD implantation in young children with respect to good intraoperative analgesia and hemodynamic stability without interference with electrophysiologic testing. In the authors' experience, the AICD implantation under caudal morphine and light general anesthesia appears to be easy, safe, and adequate for AICD implantation in young infants. The authors have reported the case of an AICD insertion in a 6-month-old infant presenting with ventricular tachyarrhythmia as a result of a large congenital fight ventricular intramyocardial myxofibroma. The possible interactions between anesthesia and A1CD device implantation have been reviewed, with their particularities in children.
REFERENCES
1. Walsh CK, Krongrad E: Terminal cardiac electrical activity in pediatric patients. Am J Cardio151:557-561, 1983 2. Silka MJ, Kron J, Dunnigan A, Dick M: Sudden cardiac death and the use of implantable cardioverter-defihrillators in pediatric patients: The pediatric electrophysiology society. Circulation 87:800-807, 1993 3. AVID Trial: A comparison of antiarrhythmic-drugs therapy with implantable defibrillators in patients resuscitated from non fatal ventricular arrhythmias. N Engl J Med 337:1576-1583, 1997 4. Bossaert LL: Fibrillation and defibrillation of the heart. Br J Anaesth 79:203-213, 1997 5. Babbs CF: Effects of drugs on defibrillation threshold, in Tacker WA (ed): Defibrillation of the Heart. St Louis, MO, Mosby, 1994, pp 224-258
6. Nathan HJ: Coronary physiology, in Kaplan JA (ed): Cardiac Anesthesia (3rd ed). Philadelphia, PA, Saunders, 1993, pp 254-255 7. Cashman JN, Garcia-Rodriguez C, Lamond C: Anaesthesia for transvenous insertion of an automatic implantable cardioverter defibrillator. Anaesthesia 47:720-721, 1992 8. Gilbert TB, Kent JL, Foster AH, Gold MR: Implantable cardioverter/defibrillator placement in a patient with amiodarone pulmonary toxicity under thoracic epidural anesthesia. Anesthesiology 79:608-611, 1993 9. Pacifico A, Wheelan KR, Nasir N, et al: Long term follow-up of cardioverter-defibrillator implanted under conscious sedation in prepectoral subfascial position. Circulation 95:946-950, 1997 10. Heinle JS, Diaz LK, Fox LS: Early extubation after cardiac
AICD PLACEMENT IN AN INFANT
operations in neonates and young infants. J Thorac Cardiovasc Surg 114:413-418, 1997 11. Deutsch N, Hantler CB, Tait A, et al: Suppression of ventricular arrhythmias by volatile anesthetics in a canine model of chronic myocardial infarction. Anesthesiology 72:1012-1021, 1990 12. Atlee JL: Cardiac pacing and electroversion, in Kaplan JA (ed): Cardiac Anesthesia (3rd ed). Philadelphia, PA, Saunders, 1993, pp 877-904 13. Tanaka K, Nakamura M, Umeda T, et al: Effects of sevoflurane and halothane on reperfusion-induced arrhythmia in the isolated rat heart. Clin Ther 15:1085-1093, 1993 14. Moerman A, Herregods, Tavernier R, et al: Influence of anaesthesia on defibrillation threshold. Anaesthesia 53:1156-1159, 1998 15. Lehmann A, Boldt J, Zeitler C, et al: Total intravenous anesthesia with remifentanil and propofol for implantation of cardioverterdefibrillators in patients with severely reduced left ventricular function. J Cardiothorac Vasc Anesth 13:15-19, 1999 16. Btirkle H, Dunbar S, Van Haken H: Remifentanil: A novel, short-acting, p-opioid. Anesth Analg 83:646-651, 1996
65
17. Rosen KR, Rosen RA: Caudal epidural morphine for control of pain following open heart surgery in children. Anesthesiology 70:418421, 1989 18. Karl HW, Tyler DC, Krane EJ: Respiratory depression after low-dose caudal morphine. Can J Anaesth 43:1065-1067, 1996 19. Natale A, Jones DL, Kim Y-H, Klein GJ: Effects of lidocaine on defibrillation threshold in the pig: Evidence of anesthesia related increase. Pacing Clin Electrophysiol 14:1239-1244, 1991 20. Brannwald E, Kloner RA: The stunned myocardium: Prolonged, post ischemic ventricular dysfunction. Circulation 66:1146-1149, 1982 21. Steinbeck G, Dorwath U, Mahler S, et al: Hemodynamic deterioration during ICD implant: Predictors of high-risk patients. Am Heart J 127:1064-1067, 1994 22. Keyl C, Tassany R Kemkes B, et al: Hemodynamic changes due to intraoperative testing of the automatic implantable cardioverterdefibrillator: Implications for anesthesia management. J Cardiothorac Vasc Anesth 7:442-447, 1993 23. Booker PD: Myocardial stunning in the neonate. Br J Anaesth 80:371-383, 1998