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Table of Contents
CASE REPORT  
Year : 2011  |  Volume : 14  |  Issue : 2  |  Page : 122-126
Placement of an implantable cardioverter-defibrillator in an infant with congenital long QT syndrome: Anesthetic considerations


1 Department of Anesthesiology and Critical Care, Escorts Heart Institute and Research Center Ltd., Okhla Road, New Delhi, India
2 Department of Cardiothoracic Surgery, Escorts Heart Institute and Research Center Ltd., Okhla Road, New Delhi, India
3 Department of Electrophysiology, Escorts Heart Institute and Research Center Ltd., Okhla Road, New Delhi, India

Click here for correspondence address and email

Date of Submission06-Dec-2010
Date of Acceptance26-Feb-2011
Date of Web Publication25-May-2011
 

   Abstract 

Sudden cardiac arrest (SCA) in children is a rare, but catastrophic event. Children with cardiac pathology at particular risk include those with congenital long QT syndrome (CLQTS) and hypertrophic cardiomyopathy. CLQTS is a genetic disorder of the cardiac ion channels and is associated with significant risk of malignant ventricular arrhythmias and SCA. For symptomatic, untreated patients, the mortality rate is approximately 20% for the first year and 50% at ten years. Use of an implantable cardioverter-defibrillator (ICD) is recommended for the prevention of SCA in this patient population. We report a case of CLQTS, who after successful resuscitation from SCA, underwent ICD placement at our center.

Keywords: Congenital long QT syndrome, implantable cardioverter-defibrillator, anesthesia

How to cite this article:
Kansara B, Singh A, Kaushal S, Saxena A. Placement of an implantable cardioverter-defibrillator in an infant with congenital long QT syndrome: Anesthetic considerations. Ann Card Anaesth 2011;14:122-6

How to cite this URL:
Kansara B, Singh A, Kaushal S, Saxena A. Placement of an implantable cardioverter-defibrillator in an infant with congenital long QT syndrome: Anesthetic considerations. Ann Card Anaesth [serial online] 2011 [cited 2020 Oct 1];14:122-6. Available from: http://www.annals.in/text.asp?2011/14/2/122/81568



   Introduction Top


Sudden cardiac arrest (SCA) in most children results from potentially treatable cardiomyopathies, conduction system abnormalities, and primary ventricular arrhythmias. Identification of children at risk and termination of life-threatening arrhythmias should improve the outcomes. Children with cardiac pathology at particular risk include those with congenital long QT syndrome (CLQTS) and hypertrophic cardiomyopathy. CLQTS is an arrhythmogenic cardiovascular disorder resulting from mutations in the cardiac ion channels. It is characterized by prolonged ventricular repolarization and frequently manifests as prolonged QT interval and abnormal T wave morphology on the electrocardiogram (ECG). CLQTS is associated with significant risk of malignant ventricular arrhythmias and SCA, and 9% of the patients present with cardiac arrest as their sentinel event. [1],[2] Following an out-of-hospital arrest that has occurred, only 8 - 9% patients survive to hospital discharge. Even those who survive, suffer from significant neurological morbidity. [3],[4]

Use of an implantable cardioverter-defibrillator (ICD) is recommended for the prevention of SCA in this patient population, and advances in the development of ICDs during the past decade have significantly altered both the approach to and prognosis for patients resuscitated from SCA. [5] We report a case of CLQTS, who after successful resuscitation from SCA, underwent ICD placement at our centre.


   Case Report Top


A ten-month-old boy, weighing 10 kg, was diagnosed with having long QT syndrome (QT corrected or QTc 550 msecs). He had an episode of SCA, from which he was successfully resuscitated. He had a family history of sudden death in two siblings. A day before admission, he had an episode of syncope associated with generalized seizures lasting for a few seconds, and aborted on its own. The ECG showed prolonged QTc [(550 msecs)[Figure 1]. Echocardiography revealed no structural or functional abnormality of the heart. Twenty-four hours ambulatory arrhythmia monitoring (Holter) showed prolonged QTc, but no arrhythmia. The child was started on β blocker therapy (tablet propranolol 5 mg, six hourly). A neurologist's opinion was sought and he was started on phenobarbitone. Magnetic resonance imaging (MRI) of the brain and electroencephalogram (EEG) were normal. The brainstem evoked response audiometry (BERA) revealed cochlear microphonics at alteration polarities suggestive of auditory dyssynchrony, but clinically there was no deafness. All biochemical parameters were normal. In view of a prolonged QTc, strong family history, an episode of SCA, and syncope, ICD placement under general anesthesia was planned. A written, informed consent was taken from the parents.
Figure 1: Electrocardiogram showing prolonged QTc (550 m second), marked as a thick arrow, whereas, the thin arrow shows reduced QTc as a result of slow heart rate

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Syrup midazolam 10 mg, orally, was given 30 minutes before the scheduled procedure. Initial intraoperative monitoring consisted of ECG (lead II and V 5 ), pulse oximetry, capnography and noninvasive blood pressure. Pacemaker / defibrillator pads were applied on the chest, prior to induction of anesthesia. Anesthesia was induced by facemask using nitrous oxide in oxygen (50 : 50) and sevoflurane (5 - 8%), followed by administration of fentanyl 3 μg/kg, vecuronium 0.1 mg/kg, and endotracheal intubation. Normocarbia was maintained by mechanical ventilation. During mechanical ventilation, high intrathoracic pressures were avoided. The radial artery was cannulated for invasive arterial pressure monitoring. A rectal temperature probe was inserted and core temperature was maintained at 36 - 37°C with the help of a blanket warmer and Bair hugger. After induction of anesthesia, the patient was placed in the left lateral position, and a caudal block was performed. Under sterile conditions, a 22G cannula was inserted through the sacrococcygeal ligament into the caudal space. After negative aspiration of blood and cerebrospinal fluid, morphine 500 μg and ropivacaine 20 mg, diluted in 10 ml of 0.9% normal saline were injected. Sterile dressing was applied to the site and patient was repositioned to the supine position. Magnesium sulfate 300 mg was infused intravenously over 10 minutes. Anesthesia was maintained with nitrous oxide in oxygen (50 : 50), sevoflurane (1.5 - 2%) and intermittent doses of fentanyl.

The surgical procedure consisted of lower mini-sternotomy and pericardiotomy through the subxiphoid approach, placement of a bipolar epicardial lead (4968 / 35 cm; Medtronic Inc., Minneapolis, MN) on the right ventricular surface, and placement of an ICD lead (6935 / 58 cm; Medtronic Inc.) intrapericardially, encircling the heart at the basal portion. An abdominal pocket was created for placement of a single chamber ICD generator (Maxima II VR D284VRC [Medtronic Inc.]) behind the rectus sheath, but in front of the rectus muscle. Leads were passed across a subcutaneous tunnel to the device placed in the abdomen [Figure 2]. Testing of the device revealed excellent ventricular sensing and pacing. Ventricular fibrillation (VF) was induced by giving a shock on the T wave at 280 beats / minute, and was successfully terminated at 15 joules. After the electronic status was confirmed, the pericardium and sternum were closed. The hemodynamic parameters were stable and no inotropic support was required. The infant was then shifted to the post surgical Intensive Care Unit, where he was ventilated for four hours and then extubated. For postoperative pain relief, intravenous morphine infusion, 10 - 30 μg/kg/hour, was started and continued for 24 hours, followed by syrup paracetamol 150 mg, eight hourly. b blocker therapy (tablet propranolol 5 mg, six hourly) was restarted immediately after surgery through the nasogastric tube. The patient did not have any postoperative complications. The testing of the device, done on the third postoperative day, was normal and no episode of VF was noted. The infant was discharged from the hospital on the fourth postoperative day. Telephonic communication with the parents revealed an uneventful postoperative course at the end of three months.
Figure 2: Chest and abdominal X-ray showing bipolar lead (thick arrow), implantable cardioverter-defibrillator (ICD) lead (thin arrow), and ICD generator (broken arrow)

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   Discussion Top


Congenital long QT syndrome, first described by Jervell and Lange-Nielsen, [6] is an autosomal recessive cardioauditory syndrome, characterized by a prolonged QT interval and congenital deafness. The age at presentation of patients with CLQTS varies from in utero to adulthood. The prevalence of CLQTS in developed countries is estimated to be approximately one in 5000 persons. [7] With effective therapy, the 10-year mortality risk can be reduced from 50 to 3 - 4%. Children, adolescents, and young adults presenting with a history of abrupt syncope during exertion or auditory stimulation, epilepsy, or family history of SCA should raise suspicion for CLQTS. SCA is a potentially fatal consequence of CLQTS in children. Schwartz et al.[8] have published a list of diagnostic criteria (the 'Schwartz score') for CLQTS including, electrophysiological findings (QTc >470 m second in males and >480 m second in females) and family and clinical history. As the QT interval varies with the heart rate (lengthening with bradycardia and shortening with an increase in heart rate), the QT interval is corrected (QTc) for heart rate using the Bazett's formula: QTc = measured QT / √R to R interval (second).

A majority of symptomatic events are triggered by situations of increased sympathetic nervous system output, such as physical activity, emotional stress, anxiety, or fear. Although the use of β-blockers helps reduce the incidence of cardiac events, it is not entirely effective in preventing SCA in patients with CLQTS. Moss et al.[9] have reported limitations of β-blocker therapy in patients with CLQTS, and have found that 32% of the patients on β-blockers have had another cardiac event within five years. For patients who continue to have symptomatic cardiac events despite β-blockade, placement of an ICD is the most reliable method to prevent death from arrhythmia. [10]

Retrospective data on patients with CLQTS (55% children) revealed no death during 31 months of follow-up after prophylactic ICD placement. [11] The current practice, to insert an ICD in pediatric patients with aborted sudden death due to ventricular tachycardia or fibrillation, or syncope in patients with sustained ventricular tachycardia or inducible tachycardia unresponsive to antiarrhythmic medication, has been described by other authors as well. [5],[12],[13]

Patients with CLQTS may be at increased risk of development of malignant Torsade de pointes (TdP) in the perioperative period. [7] Intraoperative management of such patients should focus on the prevention of excessive sympathetic activity and avoidance of factors that can prolong the QT interval. Sympathetic stimulation including abrupt and loud noises can trigger TdP. If a patient is being treated with β blockers for CLQTS, they should continue to receive it perioperatively. Magnesium sulfate is the treatment of choice for prevention of TdP, even in patients with normal magnesium concentrations. TdP may occur at any time during the perioperative period and may be self-terminating. However, prolonged episodes can cause severe hemodynamic compromise and can degenerate into VF. Such episodes should be treated immediately, with asynchronous defibrillation and cardiac massage.

Premedication must ensure sufficient anxiolysis, because anxiety and emotional stress before surgery can trigger TdP. Use of midazolam for premedication has been described by other authors as well, [14] and it does not seem to adversely affect the QT interval. Ketamine is best avoided in patients with CLQTS because it stimulates the sympathetic nervous system activity. Chloral hydrate is reported to be moderately associated with the prolongation of QT interval. [7] Thiopentone prolongs the QT interval, whereas, propofol has been found to have little or no effect on it. [7] All volatile anesthetics (halothane, enflurane, isoflurane, and sevoflurane) prolong the QT interval, but isoflurane and sevoflurane seem to have minor effects on the cardiac electrophysiology. [15] Nitrous oxide has been used in conjunction with the inhalational agents without any adverse effects. In addition, it helps reduce the minimum alveolar concentration of volatile anesthetics. Use of sevoflurane allowed the authors to gain a quick and smooth induction of anesthesia. Vecuronium was used as a muscle relaxant, because of its lack of autonomic effects. The use of anticholinergic agents and anticholinesterases has been shown to prolong the QT interval, [16] hence it was avoided, and the effect of vecuronium was allowed to wear off. Among narcotics, fentanyl and morphine have been used without adverse effects on patients with CLQTS, whereas, sufentanil has been shown to prolong the QT interval. [17] Hypothermia prolongs the QT interval, through a prolonged recovery of inactivated sodium channels, so core temperature must be monitored and maintained. Adequate analgesia is essential to avoid any stress responses, hence caudal ropivacaine and morphine have been used. The use of a neuraxial technique can be beneficial in an attempt to minimize the use of intravenous opioid administration. The use of single shot intrathecal or caudal morphine, with or without local anesthetics, has been shown to provide superior analgesia, improved pulmonary function, and less stress response to surgery. [18] However, the use of epinephrine as an adjunct to local anesthetics should be avoided, because epinephrine can paradoxically prolong the QT interval in individuals with CLQTS. In small children, a single shot caudal technique with a small bore needle provides adequate pain relief for several hours following surgery. Intravenous morphine infusions of between 10 and 30 μg / kg / hour provide adequate postoperative analgesia with an acceptable level of side-effects, when administered with an appropriate level of monitoring. [19] No matter what anesthetic technique is used, factors such as light anesthesia, hypertension, bradycardia / tachycardia, hypoxia, hypocarbia, and hypercarbia must be avoided, as they can all potentially affect repolarization of the cardiac myocyte and augment the sympathetic tone. Positive pressure ventilation strategies should ensure that sustained high intrathoracic pressures are avoided, as these mimic a Valsalva maneuvre, which can prolong the QT interval in patients who are not completely β-blocked. One should avoid high peak and end-expiratory pressures, end-inspiratory pauses, and prolonged inspiratory times, with low or reversed I : E ratios. [20]

The usual transvenous access for the leads, with the battery placed in the subcutaneous space, is not possible in children because of size incompatibility, however, reduction in ICD size and modification in implantation procedures have permitted their increased use in pediatric patients. In smaller patients, this technique has often been shown to be associated with venous occlusion, lead malfunction, and difficult lead removal. [21]

In conclusion, a balanced anesthetic technique comprising of adequate perioperative analgesia for ICD placement in an infant appears to be a safe technique. Steps to blunt the sympathetic stimulation such as adequate anxiolysis and adequate perioperative analgesia were taken. Drugs with the potential to prolong QT interval were avoided.

 
   References Top

1.Chatrath R, Porter CB, Ackerman MJ. Role of transvenous implantable cardioverter-defibrillators in preventing sudden cardiac death in children, adolescents, and young adults. Mayo Clinic Proc 2002;77:226-31.  Back to cited text no. 1
    
2.Brunn J, Bocker D, Weber M, Castrucci M, Gradaus R, Borggrefe M, et al. Is there a need for routine testing of ICD defibrillation capacity? Results from more than 1000 studies. Eur Heart J 2000;21:162-9.  Back to cited text no. 2
    
3.Schindler MB, Bohn D, Cox PN, McCrindle BW, Jarvis A, Edmonds J, et al. Outcome of out-of-hospital cardiac or respiratory arrest in children. N Engl J Med 1996;335:1473-79.  Back to cited text no. 3
    
4.Kuisma M, Suominen P, Korpela R. Paediatric out-of-hospital cardiac arrests-epidemiology and outcome. Resuscitation 1995;30:141-50.  Back to cited text no. 4
    
5.Silka MJ, Kron J, Dunnigan A, Dick M. Sudden cardiac death and the use of implantable cardioverter-defibrillators in pediatric patients. Circulation 1993;87:800-7.  Back to cited text no. 5
    
6.Jervell A, Lange-Nielsen F . Congenital deaf-mutism, functional heart disease with prolongation of the QT interval and sudden death. Am Heart J 1957;54:59-68.  Back to cited text no. 6
    
7.Kies SJ, Pabelick CM, Hurley HA, White RD, Ackerman MJ. Anesthesia for patients with congenital long QT syndrome. Anesthesiology 2005;102:204-10.  Back to cited text no. 7
    
8.Schwartz PJ, Moss AJ, Vincent GM, Crampton RS. Diagnostic criteria for the long QT syndrome. An update. Circulation 1993;88:782-4.  Back to cited text no. 8
    
9.Moss AJ, Zareba W, Hall WJ, Schwartz PJ, Crampton RS, Benhorin J, et al. b-blocker therapy in congenital long QT syndrome. Circulation 2000;101:616-23.  Back to cited text no. 9
    
10.Arend DG, Harkel T, Witsenburg M, de Jong PL, Jordaens L, Wijman M, et al. Efficacy of an implantable cardioverter-defibrillator in neonate with LQT 3 associated arrhythmias. Europace 2005;7:77-84.  Back to cited text no. 10
    
11.Schwartz PJ. Idiopathic long QT syndrome: progress and questions. Am Heart J 1985;109:399-411.  Back to cited text no. 11
    
12.Hamilton RM, Dorian P, Gow RM, Williams WG. Five year experience with implantable defibrillators in children. Am J Cardiol 1996;77:524-26.  Back to cited text no. 12
    
13.Jons C, Moss AJ, Goldenberg I, Liu J, McNitt S, Zareba W, et al. Risk of fatal arrhythmic events in long QT syndrome patients after syncope. J Am Coll Cardiol 2010;55:783-88.  Back to cited text no. 13
    
14.Michaloudis DG, Kanakoudis FS, Xatzikraniotis A, Bischiniotis TS. The effects of midazolam followed by administration of either vecuronium or atracurium on the QT interval in humans. Eur J Anaesthesiol 1995;12:577-83.  Back to cited text no. 14
    
15.Tanaka K, Nakamura M, Umeda T, Izumi T, Takura M, Tsujimura K, et al. Effects of sevoflurane and halothane on reperfusion induced arrhythmia in the isolated rat heart. Clin Ther 1993;15:1085-93.  Back to cited text no. 15
    
16.Saarnivaara L, Simola M. Effects of four anticholinesterase-anticholinergic combinations and tracheal extubation on QTc interval of the ECG, heart rate, and arterial pressure. Acta Anaesthesiol Scand 1998;42:460-63.  Back to cited text no. 16
    
17.Blair JR, Pruett JK, Crumrine RS, Balser JJ. Prolongation of QT interval in association with the administration of large doses of opiates. Anesthesiology 1987;67:442-3.  Back to cited text no. 17
    
18.Mittnacht AJC, Hollinger I. Fast-tracking in pediatric cardiac surgery: The current standing. Ann Card Anaesth 2010;13:92-101.  Back to cited text no. 18
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19.Lönnqvist PA, Morton NS. Postoperative analgesia in infants and children. Br J Anaesth 2005;95:59-68.  Back to cited text no. 19
    
20.Booker PD, Whyte SD, Ladusans EJ. Long QT syndrome and anaesthesia. Br J Anaesth 2003;90:349-66.  Back to cited text no. 20
    
21.Figa FH, McCrindle BW, Bigras JL, Hamilton RM, Gow RM. Risk factors for venous obstruction in children with transvenous pacing leads. Pacing Clin Electrophysiol 1997;20:1902-09.  Back to cited text no. 21
    

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Correspondence Address:
Bhuvnesh Kansara
Department of Anesthesiology and Critical Care, Escorts Heart Institute and Research Center Ltd, Okhla Road, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-9784.81568

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