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Anesthetic management of neonates with congenital complete atrioventricular heart block undergoing pacemaker implantation
Anesthetic Management of Neonates With Congenital Complete Atrioventricular Heart Block Undergoing Pacemaker Implantation Jan Ammann, MD,* Joachim Winter, MD, PhD,† Ulrich Sunderdiek, MD, PhD,† and Stephan A. Loer, MD, PhD*
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ARDIAC OUTPUT OF infants depends on a high heart rate (140-160 beats/min), and decreases in heart rate can only partially be compensated for by increases in stroke volume of the stiff neonatal ventricles. Children with congenital complete heart block, however, have a low heart rate (often ⬍60 beats/min) and are therefore at increased risk of cardiac failure. This applies particularly to the perioperative period when pharmacologically and surgically induced changes in contractility, preload, and afterload occur. Thus, a thorough understanding of the cardiovascular pathophysiology and treatment options of infants with complete heart block is necessary for adequate perioperative care of these children. The incidence of congenital complete heart block is estimated to range between 0.5 and 1 in 10,000 births.1,2 Heart block may exist alone or in combination with other congenital malformations.1,2 It is associated with maternal anti-SS-A/Ro and anti-SS-B/La antibodies, which are transferred via the placenta and which induce an inflammatory tissue injury within the fetal heart.3 This inflammatory reaction can result in a fibrosis of the atrioventricular node with subsequent conduction abnormalities as well as a progressive endocardial fibrosis.2-4 In some infants, not only the atrioventricular node but also the sinoatrial node are involved.5 Mothers of these children often suffer from diseases like lupus erythematosus or Sjögren’s syndrome but may also be asymptomatic.1,2,4,6,7 Prenatal echocardiography allows diagnosis within the 24th to 26th week of gestation so that therapy can be started in utero.4 Treatment options include corticosteroids to prevent further inflammatory tissue injury, -sympathomimetics to increase fetal heart rate, plasmapheresis to reduce or eliminate circulating maternal antibodies, and in utero pacing.1,2,7-9 Often, however, the heart block is irreversible and the affected children require lifelong pacemakers, which are implanted within the first weeks of their lives.10-12 Because these children are at an increased perioperative risk for cardiac decompensation, 2 cases of neonates requiring pacemaker implantation are reported and possible implications for the perioperative management are discussed. CASE REPORTS
Patient 1 The female neonate was delivered by cesarean section in the 36th week of gestation. The complete heart block had been diagnosed in the
From the Departments of *Anesthesiology and †Thoracic and Cardiovascular Surgery, University Hospital Düsseldorf, Düsseldorf, Germany. Address reprint requests to Stephan Alexander Loer, MD, PhD, Klinik für Anaesthesiologie, Universitätsklinikum Düsseldorf, Moorenstr 5, 40225 Düsseldorf, Germany. E-mail: [email protected] © 2005 Elsevier Inc. All rights reserved. 1053-0770/05/1902-0016$30.00/0 doi:10.1053/j.jvca.2005.01.018 Key words: congenital heart block, atrioventricular heart block, pacemaker, neonate 212
16th week of gestation, and her ventricular rate during pregnancy, birth, and the time until pacemaker implantation ranged between 54 to 68 beats/min. Her mother suffered from Sjögren’s syndrome and had a history of another infant with complete congenital heart block in a previous pregnancy who died after birth. During pregnancy, she received a corticosteroid medication to prevent further inflammatory tissue injury of the fetal heart as well as -sympathomimetics to increase fetal heart rate during the last weeks of the pregnancy. After cesarean section, the neonate developed respiratory distress syndrome requiring tracheal intubation and mechanical ventilation. On arrival at the pediatric intensive care unit, her skin color was pale, systolic blood pressure was 60 mmHg, and all 4 extremities were cold. Attempts to increase her heart rate by the administration of atropine (0.04 mg) were not successful, and an infusion of isoproterenol (0.17 and 0.36 g/kg/ min) increased her heart rate only by 5 to 10 beats/min without improvement of clinical signs. An echocardiogram and chest x-ray showed an enlarged heart. On the second day of her life, urinary output ceased and she developed a metabolic acidosis (pH 7.23, BE 12.7 mmol/L, HCO3 concentration 14.2 mmol/L), indicating pending cardiopulmonary decompensation. Her skin color was still pale, and her extremities were still cold. Therefore, she was scheduled for urgent pacemaker implantation. On arrival in the anesthetic department, her heart rate was 68 beats/min and her blood pressure 60/30 mmHg. Her body weight was 2.3 kg, hemoglobin concentration was 14.3 g/dL, and her metabolic status and electrolytes had been corrected. In addition to a cannula that had been placed before arrival in the operating room in a cephalic vein, a 24-G cannula was placed in a vein of the back of her right hand and isoproterenol was infused at a rate of 0.36 g/kg/min. An external pacemaker (Oyspka Pace 500 D; Dr Osypka GmbH, RheinfeldenHerten, Germany) was prepared in case additional external emergency pacing would become necessary before implantation of a permanent pacemaker. During the perioperative period, electrocardiogram, pulse oximetry (probe placed at an earlobe and at a hand), and esophageal body temperature were monitored continuously, and noninvasive arterial blood pressure was monitored intermittently every 3 minutes. To maintain normothermia, the room temperature was increased to 24°C, and the girl was placed on a warm air bed (Bair Hugger; Arizant Healthcare, Eden Prairie, MN). Anesthesia was induced and maintained with sevoflurane (endtidal concentration 2.0-2.5 vol%). The lungs were mechanically ventilated with oxygen in air (FIO2 0.5) with a tidal volume of 10 mL/kg of body weight at a frequency of 30 to 40 breaths/min. End-tidal CO2 concentration was maintained between 36 and 40 mmHg. Peripheral oxygen saturation measured at the left hand was above 95% throughout the procedure. She received an infusion of one third glucose 5% and two thirds Ringer’s solution (9 mL/kg/h). Intraoperative electrocardiogram showed a third-degree atrioventricular block with an atrial rate of 140 beats/min and a ventricular rate of 68 beats/min. Systolic blood pressure during the course of anesthesia ranged between 60 to 66 mmHg. After implantation of a permanent VVI pacemaker via the right subclavian vein (St. Jude Medical, Sylmar, CA; bipolar screwing lead Medtronic 5076, Minneapolis, MN), her heart was paced with a rate of 100 beats/min (Figs 1 and 2), and she was transferred to a pediatric intensive care unit (ICU). She was extubated 1 day after the implantation without any complications. The child was discharged from the pediatric ICU on day 3 after pacemaker implantation.
Journal of Cardiothoracic and Vascular Anesthesia, Vol 19, No 2 (April), 2005: pp 212-216
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Fig 1. (A) Intraoperative electrocardiogram of a 2-day-old anesthetized girl with congenital complete heart block showing an atrial rate of 140 beats/min and a ventricular rate of 68 beats/min before lead implantation. (B) After pacemaker implantation, the girl was paced with a rate of 100 beats/min by the implanted VVI pacemaker.
Patient 2 The second neonate was also delivered by cesarean section with a complete heart block but no other heart malformation in the 38th week of gestation. The heart block had been diagnosed in the 24th week of gestation, and the heart rate during pregnancy, birth, and the time until pacemaker implantation ranged between 48 to 54 beats/min. Her mother suffered from an autoimmune disease without any clinical manifestations. In a previous pregnancy, she had also delivered an infant with a complete congenital heart block who died within the first weeks of his life. To prevent further inflammatory tissue injury of the fetal heart, she had received a corticosteroid medication during the last weeks of the pregnancy. After the cesarean section, the girl showed no signs of congestive heart failure; however, attempts to increase her heart rate pharmacologically failed so she was scheduled for elective pacemaker implantation. At the age of 26 days and with a body weight of 3 kg, she arrived in the operating room without any signs of heart failure. Her heart rate was 50 beats/min, and her blood pressure was 60/28 mmHg. Hemoglobin concentration (17.5 g/dL) and other values were within the normal range. Before induction of general anesthesia, a 24-G cannula was placed in a vein of her right foot and an external pacemaker (Oyspka Pace 500 D) was prepared in case external pacing became necessary. Electrocardiogram, pulse oximetry, and body temperature were monitored continuously, and arterial blood pressure was monitored intermittently every 3 minutes. After preoxygenation, anesthesia was induced with 4 mg/kg of thiopental and maintained with sevoflurane (end-tidal concentration 2.5-2.8 vol%). Thereafter, her trachea was intubated with a cuffed endotracheal tube (internal diameter 3.0 mm), and the lungs were mechanically ventilated with a tidal volume of 10 mL/kg body weight at a frequency of 30 to 40 breaths/min maintaining end-tidal CO2 between 38 and 43 mmHg. Peripheral oxygen saturation was above 94% during mechanical ventilation with 50% oxygen in air. A 20-G catheter of 8-cm length was introduced into the inferior vena cava via the right femoral vein using a guidewire. This catheter was placed to allow infusion of vasoactive drugs and to attempt transvenous emergency pacing if required. During the operation, she received an infusion of one third glucose 5% and two thirds Ringer’s solution (7 mL/kg/h). Before skin incision, 1 g/kg of fentanyl was administered intravenously. Intraoperative electrocardiogram recording showed a third-degree atrioventricular block with an atrial rate of 120 beats/min,
a ventricular rate of 50 beats/min, and a long QT-interval (above 600 milliseconds) (Fig 3). Systolic blood pressure during the implantation of a pacemaker lead ranged between 60 to 70 mmHg. After implantation of the pacemaker lead, her heart was paced with a rate of 70 beats/min and she was transferred to a pediatric ICU. In the ICU, her heart rate was increased stepwise to 100 beats/min. This procedure was chosen to allow adaptation of her cardiovascular system to the increased heart rate. She was extubated in the afternoon of the same day without any complications. DISCUSSION
Neonates with complete congenital heart block undergoing general anesthesia may have an increased risk of cardiac complications. Their heart rate is fixed at low rates (often below 60 beats/min) so that any changes in volume loading, contractility, or systemic vascular resistance may predispose to cardiac failure. Although neonates with complete congenital heart block show some degree of compensatory adaptation to the persisting slow ventricular rate in the form of an increase in fractional shortening and ventricular size already in utero,13,14 anesthetics and the operative procedure may predispose to cardiac decompensation. Because the incidence of this abnormality is low, recommendations on the perioperative management of these infants are mainly based on case reports.15-18 Neonates in general have an increased sensitivity to volume loading and a poor tolerance to changes in systemic vascular resistance. This applies particularly to neonates with a low and fixed heart rate because of congenital heart block. Thus, in addition to the principles applying to all neonates requiring general anesthesia (strict control and maintenance of body temperature, normovolemia, normocapnia, and normoxia), specific effects of the administered anesthetics on the cardiovascular system should be considered and pharmacologic as well as electrical measures to increase heart rate should be prepared before induction of general anesthesia. Most volatile and intravenous anesthetics influence myocardial contractility, heart rate, and systemic flow resistance so
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Fig 2. Anterior-posterior chest x-ray of a 2-day-old girl with congenital complete heart block (A) before and (B) after pacemaker implantation.
that the doses should be carefully titrated to response. The authors decided to use sevoflurane for induction and maintenance of anesthesia in the first neonate and for maintenance of anesthesia in the second case. The cardiovascular effects of sevoflurane have been well studied in normal infants19-21; however, scant data are available in infants with heart disease,22 and no study addresses the cardiovascular effects in neonates with complete heart block. Sevoflurane exerts direct myocardial depressant effects; however, the magnitude is smaller than those of other volatile anesthetics.19-22 While halothane causes significant decreases in mean arterial pressure, ejection frac-
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tion, and cardiac index, sevoflurane maintained cardiac output with only little change in heart rate and contractility.19-21 Isoflurane was observed to increase heart rate and lower systemic vascular resistance.22 It remains unclear, however, whether this increase in heart rate can also be observed in neonates with congenital complete heart block. A decrease in systemic vascular resistance appears undesirable because this would result in a decrease in systemic blood pressure. In the present 2 cases, the authors noted no clinically relevant cardiovascular depression during anesthesia with sevoflurane (2.0-2.8 vol%) when compared with the preoperative state. Neither ventricular heart rate nor systolic or diastolic arterial blood pressure were altered during the administration of sevoflurane. In the second neonate, the authors induced anesthesia with thiopental (4 mg/kg) and maintained anesthesia subsequently with sevoflurane (end-tidal concentration 2.5%-2.8%). The authors observed no relevant effects on heart rate or systolic or diastolic blood pressure during induction of anesthesia with this dose. A reduced dose of thiopental has also been used as an induction agent in older children between the ages of 8 and 16 years with complete heart block.15-17 Nevertheless, it has to be considered that thiopental and propofol may depress contractility and decrease systemic vascular resistance.23,24 An alternative intravenous drug might be ketamine, which exerts fewer depressant effects on systolic and mean arterial blood pressure of neonates than isoflurane, halothane, or fentanyl.25,26 Other alternatives may be the administration of opioids (eg, fentanyl) in combination with benzodiazepines (eg, midazolam) for induction and maintenance of anesthesia, which have modest hemodynamic effects even in patients with significantly limited cardiac reserve. In the authors’ opinion, the relative merits of 1 anesthetic technique over another in infants with congenital heart block are not clear. Whichever anesthetic technique is used, its cardiovascular effects should be observed carefully and measures to increase heart rate should be prepared. Pharmacologic attempts to increase heart rate in children with complete heart block include prenatal and postnatal administration of sympathomimetics, catecholamines, and atropine. Ritodrine and terbutaline have been reported to increase fetal heart rate in utero.9 In this case report, heart rate increased from 54 to 65 beats/min with a dose of 66 g/min of ritodrine administered to the mother. There are no reports on the use of ritodrine in neonates; however, it might be a pharmacologic treatment option for a low heart rate after delivery. After birth, some neonates with congenital heart block respond to catecholamines with an increase of both ventricular and atrial rates.16,17 Many neonates, however, do not respond to an adequate degree. The underlying reason is unknown, and these patients often need pacemaker treatment.27-31 In contrast to neonates with acquired heart block, atropine has been reported to increase atrial as well as ventricular rate in some children with congenital heart block. The reported increase in heart rate ranged between 5 to 20 beats/min.15,17 The mechanism of this chronotropic response to atropine in congenital blocks is unclear. It has been speculated that atropine exerts vagolytic effects on fibers in the ventricular myocardium.15 The administration of atropine, however, has also induced ventricular arrhythmias in children with complete heart block.16 All in all, the pharma-
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Fig 3. Intraoperative electrocardiogram of a 26-day-old anesthetized girl undergoing pacemaker implantation showing a third-degree atrioventricular block with an atrial rate of 120 beats/min and a ventricular rate of 50 beats/min (A) before and (B) after pacemaker implantation. The girl was paced with a rate of 70 beats/min by the implanted VVI pacemaker after lead implantation. Pacing rate was increased stepwise after implantation to a rate of 100 beats/min.
cologic response is unpredictable and often inadequate in children with congenital complete heart block. For all patients with complete congenital heart block undergoing general anesthesia, the equipment for temporary pacing should be available. In neonates, various modes of temporary pacing have been described.10 Although transesophageal stimulation preferentially paces the atria and is therefore of limited use in infants with complete heart block, transcutaneous stimulation has been used successfully even in premature infants.10 In 1 case report, a premature newborn (body weight 832 g) was successfully stimulated with 115 to 120 beats/min (impulse of 35 mA).27 To avoid muscle activation, this infant was sedated and paralyzed. Of importance is an appropriate patch size to minimize the risk of skin burns. In the present 2 cases, the authors attached, before the induction of general anesthesia,
patches for external stimulation (Osypka X2-pads for children; 94 cm2 surface area). Especially in infants with congestive heart failure because of bradycardia, transcutaneous pacing with an increased heart rate may be indicated before surgery. An alternative mode of stimulation uses the transvenous access.10,28,29,31 In premature infants and neonates, the umbilical vein can be used; more common routes are via a femoral or saphenous vein.10,28,30,31 In conclusion, the authors report on 2 neonates with congenital complete heart block undergoing general anesthesia. Induction and maintenance with sevoflurane was a safe practice. Because of the limited effects of sympathomimetic and vagolytic drugs, the authors recommend taking precautions for emergency pacing with an external pacemaker.
REFERENCES 1. Friedman RA, Fenrich AL, Kertesz NJ: Congenital complete atrioventricular block. Pacing Clin Electrophysiol 24:1681-1688, 2001 2. Udink ten Cate FE, Breur JM, van Woerkom JM, et al: Congenital complete atrioventricular block in children: Pathogenesis and clinical outcomes. Ned Tijdschr Geneeskd 21:1777-1781, 2002 3. Boutjdir M: Molecular and ionic basis of congenital complete heart block. Trends Cardiovasc Med 10:114-122, 2000 4. Nield LE, Silverman ED, Taylor GP, et al: Maternal anti-Ro and anti-La antibody-associated endocardial fibroelastosis. Circulation 19: 843-848, 2002 5. Menon A, Silverman ED, Gow RM, et al: Chronotropic competence of the sinus node in congenital complete heart block. Am J Cardiol 82:1119-1121, 1998 6. Askanase AD, Friedman DM, Copel J, et al: Spectrum and progression of conduction abnormalities in infants born to mothers with anti-SSA/Ro-SSB/La antibodies. Lupus 11:145-151, 2002 7. Zemlin M, Bauer K, Dorner T, et al: Intrauterine therapy and outcome in four pregnancies of one mother with anti-Ro-autoantibody positive Sjoegren’s syndrome Z Geburtshilfe Neonatol 206:22-25, 2002 8. Assad RS, Zielinsky P, Kalil R, et al: New lead for in utero pacing for fetal congenital heart block. J Thorac Cardiovasc Surg 126:300302, 2003
9. Matsushita H, Higashino M, Sekizuka N, et al: Successful prenatal treatment of congenital heart block with ritodrine administered transplacentally. Arch Gynecol Obstet 267:51-53, 2002 10. Sliz NB Jr, Johns JA: Cardiac pacing in infants and children. Cardiol Rev 8:223-239, 2000 11. Breur JM, Udink Ten Cate FE, Kapusta L, et al: Pacemaker therapy in isolated congenital complete atrioventricular block. Pacing Clin Electrophysiol 25:1685-1691, 2002 12. Gillette PC, Zeigler VL, Winslow AT, et al: Cardiac pacing in neonates, infants, and preschool children. Pacing Clin Electrophysiol 15:2046-1049, 1992 13. Kertesz NJ, Friedman RA, Colan SD, et al: Left ventricular mechanics and geometry in patients with congenital complete atrioventricular block. Circulation 18:3430-3435, 1997 14. Eronen M, Heikkila P, Teramo K: Congenital complete heart block in the fetus: Hemodynamic features, antenatal treatment, and outcome in six cases. Pediatr Cardiol 22:385-392, 2001 15. Linton DM, Human DG: Perioperative management and administration of anaesthesia in children with congenital complete heart block. A case report and review. S Afr Med J 8:875-876, 1984 16. O’Gara JP, Edelman JD: Anesthesia and the patient with complete congenital heart block. Anesth Analg 60:906-908, 1981
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17. Diaz JH, Friesen RH: Anesthetic management of congenital complete heart block in childhood. Anesth Analg 58:334-336, 1979 18. Duffy BL: Congenital complete heart block. General anaesthesia for appendectomy in an adolescent. Anaesthesia 36:956-957, 1981 19. Constant I, Dubois MC, Piat V, et al: Changes in electroencephalogram and autonomic cardiovascular activity during induction of anesthesia with sevoflurane compared with halothane in children. Anesthesiology 91:1604-1615, 1999 20. Wodey E, Pladys P, Copin C, et al: Comparative hemodynamic depression of sevoflurane versus halothane in infants: An echocardiographic study. Anesthesiology 87:795-800, 1997 21. Holzman RS, van der Velde ME, Kaus SJ, et al: Sevoflurane depresses myocardial contractility less than halothane during induction of anesthesia in children. Anesthesiology 85:1260-1267, 1996 22. Rivenes SM, Lewin MB, Stayer SA, et al: Cardiovascular effects of sevoflurane, isoflurane, halothane, and fentanyl-midazolam in children with congenital heart disease: An echocardiographic study of myocardial contractility and hemodynamics. Anesthesiology 94:223229, 2001 23. Wodey E, Chonow L, Beneux X, et al: Haemodynamic effects of propofol vs thiopental in infants: An echocardiographic study. Br J Anaesth 82:516-520, 1999
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24. Aun CS, Sung RY, O’Meara ME, et al: Cardiovascular effects of IV induction in children: comparison between propofol and thiopentone. Br J Anaesth 70:647-653, 1993 25. Friesen RH, Henry DB: Cardiovascular changes in preterm neonates receiving isoflurane, halothane, fentanyl, and ketamine. Anesthesiology 64:238-242, 1986 26. Radnay PA, Hollinger I, Santi A, et al: Ketamine for pediatric cardiac anesthesia. Anaesthesist 25:259-265, 1976 27. Nurnberg JH, Weng Y, Lange PE, et al: Transthoracic pacing in a very low birth weight infant with congenital complete atrioventricular block—Case report. Klin Padiatr 214:89-92, 2002 28. Hanseus K, Sandstrom S, Schuller H, et al: Emergency pacing and subsequent permanent pacemaker implantation in a premature infant of 1770 g with a follow-up of 6 years. Pediatr Cardiol 21:470473, 2000 29. von Schnakenburg C, Fink C, Peuster M, et al: Permanent pacemaker implantation in a 1,445 g preterm neonate on the first day of life. Thorac Cardiovasc Surg 50:363-365, 2002 30. Villain E, Martelli H, Bonnet D, et al: Characteristics and results of epicardial pacing in neonates and infants. Pacing Clin Electrophysiol 23:2052-2056, 2000 31. Nowak B, Kampmann C, Schmid FX, et al: Pacemaker therapy in premature children with high-degree AV block. Pacing Clin Electrophysiol 21:2695-2698, 1998
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ARDIAC OUTPUT OF infants depends on a high heart rate (140-160 beats/min), and decreases in heart rate can only partially be compensated for by increases in stroke volume of the stiff neonatal ventricles. Children with congenital complete heart block, however, have a low heart rate (often ⬍60 beats/min) and are therefore at increased risk of cardiac failure. This applies particularly to the perioperative period when pharmacologically and surgically induced changes in contractility, preload, and afterload occur. Thus, a thorough understanding of the cardiovascular pathophysiology and treatment options of infants with complete heart block is necessary for adequate perioperative care of these children. The incidence of congenital complete heart block is estimated to range between 0.5 and 1 in 10,000 births.1,2 Heart block may exist alone or in combination with other congenital malformations.1,2 It is associated with maternal anti-SS-A/Ro and anti-SS-B/La antibodies, which are transferred via the placenta and which induce an inflammatory tissue injury within the fetal heart.3 This inflammatory reaction can result in a fibrosis of the atrioventricular node with subsequent conduction abnormalities as well as a progressive endocardial fibrosis.2-4 In some infants, not only the atrioventricular node but also the sinoatrial node are involved.5 Mothers of these children often suffer from diseases like lupus erythematosus or Sjögren’s syndrome but may also be asymptomatic.1,2,4,6,7 Prenatal echocardiography allows diagnosis within the 24th to 26th week of gestation so that therapy can be started in utero.4 Treatment options include corticosteroids to prevent further inflammatory tissue injury, -sympathomimetics to increase fetal heart rate, plasmapheresis to reduce or eliminate circulating maternal antibodies, and in utero pacing.1,2,7-9 Often, however, the heart block is irreversible and the affected children require lifelong pacemakers, which are implanted within the first weeks of their lives.10-12 Because these children are at an increased perioperative risk for cardiac decompensation, 2 cases of neonates requiring pacemaker implantation are reported and possible implications for the perioperative management are discussed. CASE REPORTS
Patient 1 The female neonate was delivered by cesarean section in the 36th week of gestation. The complete heart block had been diagnosed in the
From the Departments of *Anesthesiology and †Thoracic and Cardiovascular Surgery, University Hospital Düsseldorf, Düsseldorf, Germany. Address reprint requests to Stephan Alexander Loer, MD, PhD, Klinik für Anaesthesiologie, Universitätsklinikum Düsseldorf, Moorenstr 5, 40225 Düsseldorf, Germany. E-mail: [email protected] © 2005 Elsevier Inc. All rights reserved. 1053-0770/05/1902-0016$30.00/0 doi:10.1053/j.jvca.2005.01.018 Key words: congenital heart block, atrioventricular heart block, pacemaker, neonate 212
16th week of gestation, and her ventricular rate during pregnancy, birth, and the time until pacemaker implantation ranged between 54 to 68 beats/min. Her mother suffered from Sjögren’s syndrome and had a history of another infant with complete congenital heart block in a previous pregnancy who died after birth. During pregnancy, she received a corticosteroid medication to prevent further inflammatory tissue injury of the fetal heart as well as -sympathomimetics to increase fetal heart rate during the last weeks of the pregnancy. After cesarean section, the neonate developed respiratory distress syndrome requiring tracheal intubation and mechanical ventilation. On arrival at the pediatric intensive care unit, her skin color was pale, systolic blood pressure was 60 mmHg, and all 4 extremities were cold. Attempts to increase her heart rate by the administration of atropine (0.04 mg) were not successful, and an infusion of isoproterenol (0.17 and 0.36 g/kg/ min) increased her heart rate only by 5 to 10 beats/min without improvement of clinical signs. An echocardiogram and chest x-ray showed an enlarged heart. On the second day of her life, urinary output ceased and she developed a metabolic acidosis (pH 7.23, BE 12.7 mmol/L, HCO3 concentration 14.2 mmol/L), indicating pending cardiopulmonary decompensation. Her skin color was still pale, and her extremities were still cold. Therefore, she was scheduled for urgent pacemaker implantation. On arrival in the anesthetic department, her heart rate was 68 beats/min and her blood pressure 60/30 mmHg. Her body weight was 2.3 kg, hemoglobin concentration was 14.3 g/dL, and her metabolic status and electrolytes had been corrected. In addition to a cannula that had been placed before arrival in the operating room in a cephalic vein, a 24-G cannula was placed in a vein of the back of her right hand and isoproterenol was infused at a rate of 0.36 g/kg/min. An external pacemaker (Oyspka Pace 500 D; Dr Osypka GmbH, RheinfeldenHerten, Germany) was prepared in case additional external emergency pacing would become necessary before implantation of a permanent pacemaker. During the perioperative period, electrocardiogram, pulse oximetry (probe placed at an earlobe and at a hand), and esophageal body temperature were monitored continuously, and noninvasive arterial blood pressure was monitored intermittently every 3 minutes. To maintain normothermia, the room temperature was increased to 24°C, and the girl was placed on a warm air bed (Bair Hugger; Arizant Healthcare, Eden Prairie, MN). Anesthesia was induced and maintained with sevoflurane (endtidal concentration 2.0-2.5 vol%). The lungs were mechanically ventilated with oxygen in air (FIO2 0.5) with a tidal volume of 10 mL/kg of body weight at a frequency of 30 to 40 breaths/min. End-tidal CO2 concentration was maintained between 36 and 40 mmHg. Peripheral oxygen saturation measured at the left hand was above 95% throughout the procedure. She received an infusion of one third glucose 5% and two thirds Ringer’s solution (9 mL/kg/h). Intraoperative electrocardiogram showed a third-degree atrioventricular block with an atrial rate of 140 beats/min and a ventricular rate of 68 beats/min. Systolic blood pressure during the course of anesthesia ranged between 60 to 66 mmHg. After implantation of a permanent VVI pacemaker via the right subclavian vein (St. Jude Medical, Sylmar, CA; bipolar screwing lead Medtronic 5076, Minneapolis, MN), her heart was paced with a rate of 100 beats/min (Figs 1 and 2), and she was transferred to a pediatric intensive care unit (ICU). She was extubated 1 day after the implantation without any complications. The child was discharged from the pediatric ICU on day 3 after pacemaker implantation.
Journal of Cardiothoracic and Vascular Anesthesia, Vol 19, No 2 (April), 2005: pp 212-216
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Fig 1. (A) Intraoperative electrocardiogram of a 2-day-old anesthetized girl with congenital complete heart block showing an atrial rate of 140 beats/min and a ventricular rate of 68 beats/min before lead implantation. (B) After pacemaker implantation, the girl was paced with a rate of 100 beats/min by the implanted VVI pacemaker.
Patient 2 The second neonate was also delivered by cesarean section with a complete heart block but no other heart malformation in the 38th week of gestation. The heart block had been diagnosed in the 24th week of gestation, and the heart rate during pregnancy, birth, and the time until pacemaker implantation ranged between 48 to 54 beats/min. Her mother suffered from an autoimmune disease without any clinical manifestations. In a previous pregnancy, she had also delivered an infant with a complete congenital heart block who died within the first weeks of his life. To prevent further inflammatory tissue injury of the fetal heart, she had received a corticosteroid medication during the last weeks of the pregnancy. After the cesarean section, the girl showed no signs of congestive heart failure; however, attempts to increase her heart rate pharmacologically failed so she was scheduled for elective pacemaker implantation. At the age of 26 days and with a body weight of 3 kg, she arrived in the operating room without any signs of heart failure. Her heart rate was 50 beats/min, and her blood pressure was 60/28 mmHg. Hemoglobin concentration (17.5 g/dL) and other values were within the normal range. Before induction of general anesthesia, a 24-G cannula was placed in a vein of her right foot and an external pacemaker (Oyspka Pace 500 D) was prepared in case external pacing became necessary. Electrocardiogram, pulse oximetry, and body temperature were monitored continuously, and arterial blood pressure was monitored intermittently every 3 minutes. After preoxygenation, anesthesia was induced with 4 mg/kg of thiopental and maintained with sevoflurane (end-tidal concentration 2.5-2.8 vol%). Thereafter, her trachea was intubated with a cuffed endotracheal tube (internal diameter 3.0 mm), and the lungs were mechanically ventilated with a tidal volume of 10 mL/kg body weight at a frequency of 30 to 40 breaths/min maintaining end-tidal CO2 between 38 and 43 mmHg. Peripheral oxygen saturation was above 94% during mechanical ventilation with 50% oxygen in air. A 20-G catheter of 8-cm length was introduced into the inferior vena cava via the right femoral vein using a guidewire. This catheter was placed to allow infusion of vasoactive drugs and to attempt transvenous emergency pacing if required. During the operation, she received an infusion of one third glucose 5% and two thirds Ringer’s solution (7 mL/kg/h). Before skin incision, 1 g/kg of fentanyl was administered intravenously. Intraoperative electrocardiogram recording showed a third-degree atrioventricular block with an atrial rate of 120 beats/min,
a ventricular rate of 50 beats/min, and a long QT-interval (above 600 milliseconds) (Fig 3). Systolic blood pressure during the implantation of a pacemaker lead ranged between 60 to 70 mmHg. After implantation of the pacemaker lead, her heart was paced with a rate of 70 beats/min and she was transferred to a pediatric ICU. In the ICU, her heart rate was increased stepwise to 100 beats/min. This procedure was chosen to allow adaptation of her cardiovascular system to the increased heart rate. She was extubated in the afternoon of the same day without any complications. DISCUSSION
Neonates with complete congenital heart block undergoing general anesthesia may have an increased risk of cardiac complications. Their heart rate is fixed at low rates (often below 60 beats/min) so that any changes in volume loading, contractility, or systemic vascular resistance may predispose to cardiac failure. Although neonates with complete congenital heart block show some degree of compensatory adaptation to the persisting slow ventricular rate in the form of an increase in fractional shortening and ventricular size already in utero,13,14 anesthetics and the operative procedure may predispose to cardiac decompensation. Because the incidence of this abnormality is low, recommendations on the perioperative management of these infants are mainly based on case reports.15-18 Neonates in general have an increased sensitivity to volume loading and a poor tolerance to changes in systemic vascular resistance. This applies particularly to neonates with a low and fixed heart rate because of congenital heart block. Thus, in addition to the principles applying to all neonates requiring general anesthesia (strict control and maintenance of body temperature, normovolemia, normocapnia, and normoxia), specific effects of the administered anesthetics on the cardiovascular system should be considered and pharmacologic as well as electrical measures to increase heart rate should be prepared before induction of general anesthesia. Most volatile and intravenous anesthetics influence myocardial contractility, heart rate, and systemic flow resistance so
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Fig 2. Anterior-posterior chest x-ray of a 2-day-old girl with congenital complete heart block (A) before and (B) after pacemaker implantation.
that the doses should be carefully titrated to response. The authors decided to use sevoflurane for induction and maintenance of anesthesia in the first neonate and for maintenance of anesthesia in the second case. The cardiovascular effects of sevoflurane have been well studied in normal infants19-21; however, scant data are available in infants with heart disease,22 and no study addresses the cardiovascular effects in neonates with complete heart block. Sevoflurane exerts direct myocardial depressant effects; however, the magnitude is smaller than those of other volatile anesthetics.19-22 While halothane causes significant decreases in mean arterial pressure, ejection frac-
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tion, and cardiac index, sevoflurane maintained cardiac output with only little change in heart rate and contractility.19-21 Isoflurane was observed to increase heart rate and lower systemic vascular resistance.22 It remains unclear, however, whether this increase in heart rate can also be observed in neonates with congenital complete heart block. A decrease in systemic vascular resistance appears undesirable because this would result in a decrease in systemic blood pressure. In the present 2 cases, the authors noted no clinically relevant cardiovascular depression during anesthesia with sevoflurane (2.0-2.8 vol%) when compared with the preoperative state. Neither ventricular heart rate nor systolic or diastolic arterial blood pressure were altered during the administration of sevoflurane. In the second neonate, the authors induced anesthesia with thiopental (4 mg/kg) and maintained anesthesia subsequently with sevoflurane (end-tidal concentration 2.5%-2.8%). The authors observed no relevant effects on heart rate or systolic or diastolic blood pressure during induction of anesthesia with this dose. A reduced dose of thiopental has also been used as an induction agent in older children between the ages of 8 and 16 years with complete heart block.15-17 Nevertheless, it has to be considered that thiopental and propofol may depress contractility and decrease systemic vascular resistance.23,24 An alternative intravenous drug might be ketamine, which exerts fewer depressant effects on systolic and mean arterial blood pressure of neonates than isoflurane, halothane, or fentanyl.25,26 Other alternatives may be the administration of opioids (eg, fentanyl) in combination with benzodiazepines (eg, midazolam) for induction and maintenance of anesthesia, which have modest hemodynamic effects even in patients with significantly limited cardiac reserve. In the authors’ opinion, the relative merits of 1 anesthetic technique over another in infants with congenital heart block are not clear. Whichever anesthetic technique is used, its cardiovascular effects should be observed carefully and measures to increase heart rate should be prepared. Pharmacologic attempts to increase heart rate in children with complete heart block include prenatal and postnatal administration of sympathomimetics, catecholamines, and atropine. Ritodrine and terbutaline have been reported to increase fetal heart rate in utero.9 In this case report, heart rate increased from 54 to 65 beats/min with a dose of 66 g/min of ritodrine administered to the mother. There are no reports on the use of ritodrine in neonates; however, it might be a pharmacologic treatment option for a low heart rate after delivery. After birth, some neonates with congenital heart block respond to catecholamines with an increase of both ventricular and atrial rates.16,17 Many neonates, however, do not respond to an adequate degree. The underlying reason is unknown, and these patients often need pacemaker treatment.27-31 In contrast to neonates with acquired heart block, atropine has been reported to increase atrial as well as ventricular rate in some children with congenital heart block. The reported increase in heart rate ranged between 5 to 20 beats/min.15,17 The mechanism of this chronotropic response to atropine in congenital blocks is unclear. It has been speculated that atropine exerts vagolytic effects on fibers in the ventricular myocardium.15 The administration of atropine, however, has also induced ventricular arrhythmias in children with complete heart block.16 All in all, the pharma-
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Fig 3. Intraoperative electrocardiogram of a 26-day-old anesthetized girl undergoing pacemaker implantation showing a third-degree atrioventricular block with an atrial rate of 120 beats/min and a ventricular rate of 50 beats/min (A) before and (B) after pacemaker implantation. The girl was paced with a rate of 70 beats/min by the implanted VVI pacemaker after lead implantation. Pacing rate was increased stepwise after implantation to a rate of 100 beats/min.
cologic response is unpredictable and often inadequate in children with congenital complete heart block. For all patients with complete congenital heart block undergoing general anesthesia, the equipment for temporary pacing should be available. In neonates, various modes of temporary pacing have been described.10 Although transesophageal stimulation preferentially paces the atria and is therefore of limited use in infants with complete heart block, transcutaneous stimulation has been used successfully even in premature infants.10 In 1 case report, a premature newborn (body weight 832 g) was successfully stimulated with 115 to 120 beats/min (impulse of 35 mA).27 To avoid muscle activation, this infant was sedated and paralyzed. Of importance is an appropriate patch size to minimize the risk of skin burns. In the present 2 cases, the authors attached, before the induction of general anesthesia,
patches for external stimulation (Osypka X2-pads for children; 94 cm2 surface area). Especially in infants with congestive heart failure because of bradycardia, transcutaneous pacing with an increased heart rate may be indicated before surgery. An alternative mode of stimulation uses the transvenous access.10,28,29,31 In premature infants and neonates, the umbilical vein can be used; more common routes are via a femoral or saphenous vein.10,28,30,31 In conclusion, the authors report on 2 neonates with congenital complete heart block undergoing general anesthesia. Induction and maintenance with sevoflurane was a safe practice. Because of the limited effects of sympathomimetic and vagolytic drugs, the authors recommend taking precautions for emergency pacing with an external pacemaker.
REFERENCES 1. Friedman RA, Fenrich AL, Kertesz NJ: Congenital complete atrioventricular block. Pacing Clin Electrophysiol 24:1681-1688, 2001 2. Udink ten Cate FE, Breur JM, van Woerkom JM, et al: Congenital complete atrioventricular block in children: Pathogenesis and clinical outcomes. Ned Tijdschr Geneeskd 21:1777-1781, 2002 3. Boutjdir M: Molecular and ionic basis of congenital complete heart block. Trends Cardiovasc Med 10:114-122, 2000 4. Nield LE, Silverman ED, Taylor GP, et al: Maternal anti-Ro and anti-La antibody-associated endocardial fibroelastosis. Circulation 19: 843-848, 2002 5. Menon A, Silverman ED, Gow RM, et al: Chronotropic competence of the sinus node in congenital complete heart block. Am J Cardiol 82:1119-1121, 1998 6. Askanase AD, Friedman DM, Copel J, et al: Spectrum and progression of conduction abnormalities in infants born to mothers with anti-SSA/Ro-SSB/La antibodies. Lupus 11:145-151, 2002 7. Zemlin M, Bauer K, Dorner T, et al: Intrauterine therapy and outcome in four pregnancies of one mother with anti-Ro-autoantibody positive Sjoegren’s syndrome Z Geburtshilfe Neonatol 206:22-25, 2002 8. Assad RS, Zielinsky P, Kalil R, et al: New lead for in utero pacing for fetal congenital heart block. J Thorac Cardiovasc Surg 126:300302, 2003
9. Matsushita H, Higashino M, Sekizuka N, et al: Successful prenatal treatment of congenital heart block with ritodrine administered transplacentally. Arch Gynecol Obstet 267:51-53, 2002 10. Sliz NB Jr, Johns JA: Cardiac pacing in infants and children. Cardiol Rev 8:223-239, 2000 11. Breur JM, Udink Ten Cate FE, Kapusta L, et al: Pacemaker therapy in isolated congenital complete atrioventricular block. Pacing Clin Electrophysiol 25:1685-1691, 2002 12. Gillette PC, Zeigler VL, Winslow AT, et al: Cardiac pacing in neonates, infants, and preschool children. Pacing Clin Electrophysiol 15:2046-1049, 1992 13. Kertesz NJ, Friedman RA, Colan SD, et al: Left ventricular mechanics and geometry in patients with congenital complete atrioventricular block. Circulation 18:3430-3435, 1997 14. Eronen M, Heikkila P, Teramo K: Congenital complete heart block in the fetus: Hemodynamic features, antenatal treatment, and outcome in six cases. Pediatr Cardiol 22:385-392, 2001 15. Linton DM, Human DG: Perioperative management and administration of anaesthesia in children with congenital complete heart block. A case report and review. S Afr Med J 8:875-876, 1984 16. O’Gara JP, Edelman JD: Anesthesia and the patient with complete congenital heart block. Anesth Analg 60:906-908, 1981
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17. Diaz JH, Friesen RH: Anesthetic management of congenital complete heart block in childhood. Anesth Analg 58:334-336, 1979 18. Duffy BL: Congenital complete heart block. General anaesthesia for appendectomy in an adolescent. Anaesthesia 36:956-957, 1981 19. Constant I, Dubois MC, Piat V, et al: Changes in electroencephalogram and autonomic cardiovascular activity during induction of anesthesia with sevoflurane compared with halothane in children. Anesthesiology 91:1604-1615, 1999 20. Wodey E, Pladys P, Copin C, et al: Comparative hemodynamic depression of sevoflurane versus halothane in infants: An echocardiographic study. Anesthesiology 87:795-800, 1997 21. Holzman RS, van der Velde ME, Kaus SJ, et al: Sevoflurane depresses myocardial contractility less than halothane during induction of anesthesia in children. Anesthesiology 85:1260-1267, 1996 22. Rivenes SM, Lewin MB, Stayer SA, et al: Cardiovascular effects of sevoflurane, isoflurane, halothane, and fentanyl-midazolam in children with congenital heart disease: An echocardiographic study of myocardial contractility and hemodynamics. Anesthesiology 94:223229, 2001 23. Wodey E, Chonow L, Beneux X, et al: Haemodynamic effects of propofol vs thiopental in infants: An echocardiographic study. Br J Anaesth 82:516-520, 1999
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24. Aun CS, Sung RY, O’Meara ME, et al: Cardiovascular effects of IV induction in children: comparison between propofol and thiopentone. Br J Anaesth 70:647-653, 1993 25. Friesen RH, Henry DB: Cardiovascular changes in preterm neonates receiving isoflurane, halothane, fentanyl, and ketamine. Anesthesiology 64:238-242, 1986 26. Radnay PA, Hollinger I, Santi A, et al: Ketamine for pediatric cardiac anesthesia. Anaesthesist 25:259-265, 1976 27. Nurnberg JH, Weng Y, Lange PE, et al: Transthoracic pacing in a very low birth weight infant with congenital complete atrioventricular block—Case report. Klin Padiatr 214:89-92, 2002 28. Hanseus K, Sandstrom S, Schuller H, et al: Emergency pacing and subsequent permanent pacemaker implantation in a premature infant of 1770 g with a follow-up of 6 years. Pediatr Cardiol 21:470473, 2000 29. von Schnakenburg C, Fink C, Peuster M, et al: Permanent pacemaker implantation in a 1,445 g preterm neonate on the first day of life. Thorac Cardiovasc Surg 50:363-365, 2002 30. Villain E, Martelli H, Bonnet D, et al: Characteristics and results of epicardial pacing in neonates and infants. Pacing Clin Electrophysiol 23:2052-2056, 2000 31. Nowak B, Kampmann C, Schmid FX, et al: Pacemaker therapy in premature children with high-degree AV block. Pacing Clin Electrophysiol 21:2695-2698, 1998