Anesthesia for children with long QT syndrome

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Anesthesia for children with long QT syndrome

  1. 1. Anaesthesia for children with long QT syndrome Samia I. Sharaf , M.D Ain Shams University
  2. 2. Long QT Syndrome In Children ( LQS) <ul><li>Arrhythmogenic cardiovascular disorder resulting from mutation cardiac ion channels characterized by prolonged ventricular repolarization and manifest itself as QT prolongation on ECG. It predisposes to ventricular tachycarrhythmia ( Torsade de points ) which may lead to sudden death. </li></ul>
  3. 3. What Is QT Interval ? How It Is Measured ? <ul><li>QT interval is measured from the beginning of Q wave to the end of T wave on the surface ECG. </li></ul><ul><li>It represent time taken for ventricular depolarization and repolarization . </li></ul><ul><li>To control for heart rate is calculated using Bazett s equation </li></ul><ul><li>QtC=QT/√RR </li></ul><ul><li>QTC is prolonged if >440 ms </li></ul>
  4. 4. Classification Of LQTS <ul><li>Congenital ( c-LQTS ) </li></ul><ul><li>Caused by mutation in genes coding for myocardial K+ or Na + channels </li></ul><ul><li>Acquired ( a-LQTS ) </li></ul><ul><li>Caused by drugs , electrolyte abnormalities or metabolic conditions </li></ul>
  5. 5. How QT Interval Is Prolonged ? <ul><li>Congenital type: </li></ul><ul><li>Mutation in genes coding for myocardial K+ or Na+ channels which allow a surplus of intracellular positive ions to prolong ventricular repolarization. </li></ul><ul><li>Acquired type: </li></ul><ul><li>Causes usually reduce outward K+currents increasing repolarization as well . </li></ul>
  6. 6. Congenital Long QT Syndrome <ul><li>There are two clinical phenotypes of c-LQTS: </li></ul><ul><li>Romano-ward syndrome </li></ul><ul><li>Autosomal dominant with variable penetrance </li></ul><ul><li>More common </li></ul><ul><li>Only has cardiac manifestations </li></ul><ul><li>Jervell and lange-nielsen syndrome </li></ul><ul><li>Autosomal recessive </li></ul><ul><li>Cardiac manifestations with congenital deafness </li></ul><ul><li>Generally runs a more malignant course </li></ul>
  7. 7. Congenital Long QT Syndrome <ul><li>Genotypic variations </li></ul><ul><li>There are seven genotypes associated with C-LQTS </li></ul><ul><li>LQT-1 and LQT-5 are associated with JLN </li></ul><ul><li>RW is associated with defects in LQT 1-6 </li></ul><ul><li>LQT1, LQT2, and LQT3 account for over 90 percent of cases of congenital LQTS </li></ul>
  8. 8. Genotypes Of Long QT Syndrome Ion channel affected Chromosome/gene Frequency Phenotype Genotype K+(1K S ) 11-KVLQT1 +++ LQT1 LQT1 K+(1K R ) 7-HERG ++ LQT2 LQT2 NA+ 3-SCN5A + LQT3 LQT3 UNKNOWN UNKNOWN - LQT4 K+(1K S ) 21-KCNE1 - LQT1 LQT5 K+(1K R ) 21-KCNE2 - LQT2 LQT6
  9. 9. Clinical Picture Of c-LQTS <ul><li>Symptoms : </li></ul><ul><li>Palpitations </li></ul><ul><li>Syncope </li></ul><ul><li>Seizures </li></ul><ul><li>Cardiac arrest </li></ul>
  10. 10. Clinical Picture Of c-LQTS <ul><li>Precipitating factors of arrhythmias </li></ul><ul><li>* Genotype dependent </li></ul><ul><li>* LQT1 patients are at highest risk with adrenergic stimuli: emotional stress, exercise (particularly swimming) </li></ul><ul><li>* LQT2 patients are especially susceptible to auditory stimuli but not exercise </li></ul><ul><li>* LQT3 patients do not trigger by adrenergic stimuli and are at highest risk of TDP at rest as their QT is prolonged by bradycardia </li></ul>
  11. 11. Clinical Outcome Of c-LQTS <ul><li>The median ages for first cardiac event in LQT1, 2 and 3 are 9, 12 and 16 years respectively </li></ul><ul><li>If untreated, mortality is 20% in year after initial event and 50% within ten years </li></ul><ul><li>Patients with JLN generally have their first cardiac event at a younger age, and are more likely to experience SCD </li></ul>
  12. 12. C-LQTS: Diagnosis, Schwartz Score <ul><li>ECG findings Points </li></ul><ul><li>- QTc </li></ul><ul><li>Greater than or equal 480 msec: 3 </li></ul><ul><li>460 to 470 msec: 2 </li></ul><ul><li>450 msec (males): 1 </li></ul><ul><li>- Torsade de pointes: 2 </li></ul><ul><li>- T-wave alternans: 1 </li></ul><ul><li>- Notched T wave in 3 leads: 1 </li></ul><ul><li>- Low heart rate for age: 0.5 </li></ul>
  13. 13. c-LQTS: Diagnosis, Schwartz Score <ul><li>History of Points </li></ul><ul><li>- Fainting with stress 2 </li></ul><ul><li>- Fainting without stress: 1 </li></ul><ul><li>- Congenital Deafness: 0.5 </li></ul><ul><li>Family History </li></ul><ul><li>Family member diagnosed with LQTS 1 </li></ul><ul><li>- Unexplained SCD in family member under 30 0.5 </li></ul><ul><li>A score equal to or greater than 4 is considered diagnostic of c-LQTS </li></ul><ul><li>A score of 2- 3 implies an intermediate risk </li></ul><ul><li>A score of less than 1 is low risk </li></ul>
  14. 14. Acquired LQTS Quinidine,procainamide,disopyramide,sotalol,amiodarone Antidysrhythmic drugs Terfenadine,astemizole Histamine receptor antagonists Erythromycin,clindamycin,imidazole,ampicillin Antibiotics Ketanserin,flouxetine Drugs acting on serotonin receptors Tetra-and tricyclic antidepressant , haloperidol,phenothiazine,lithium,risperidone Antipsychotic drugs indapamide Diuretics Massive blood transfusion Citrate Cisapride Gastrointestinal drugs Hypokalemia , hypomagnesemia, hypocalcaemia Metabolic abnormalities Complete atrioventricular block Bradydysrhythmias Myocardial ischemis,acute carditis,acute cor pulmonale, mitral valve prolapse Cardiac Anorexia nervosa,gastroplasty,liquid protein diet Starvation Subarachinoid hge. Head injury,right-sided radial neck surgery Nervous system injury Hypothermia, pituitary insufficiency Others
  15. 15. Treatment OF c-LQTS <ul><li>First line treatment for LQT1 and 2 consists of β -blockers </li></ul><ul><li>For LQT3 flecanide and mexilitine are used </li></ul><ul><li>Patients who remain symptomatic on pharmacotherapy are candidates for dual chamber pacemakers and/ or ICDs to prevent SCD </li></ul><ul><li>Patients whose disease triggers an ICD frequently may be candidates for Left Cardiac Sympathetic Denervation </li></ul><ul><li>Genotype directed therapy </li></ul>
  16. 16. Treatment Of Torsade De Pointes Mechanism Of Torsade De Pointes <ul><li>The prolongation of the QT interval in c-LQTS makes membranes susceptible to Early After-Depolarizations (EAD) </li></ul><ul><li>EADs are single or multiple oscillations of the membrane potential that can occur during phases 2 and 3 of the action potential </li></ul><ul><li>EADs that reach threshold potential result in action potentials which may propagate </li></ul><ul><li>Propagation of these EADs may initiate polymorphic VT (TdP) in susceptible subjects </li></ul>
  17. 18. Treatment <ul><li>Torsades can be self-limiting causing palpitations or syncope </li></ul><ul><li>It can also degenerate into ventricular fibrillation and sudden cardiac death </li></ul><ul><li>Intravenous magnesium is the treatment of choice. Bolus 30mg/kg, then infusion of 2-4 mg/min </li></ul><ul><li>Magnesium stabilizes membrane potentials without shortening the QT interval </li></ul>
  18. 19. Drugs Well Documented To Prolong QT Interval Relevant To Anesthetic Practice <ul><li>Amiodarone </li></ul><ul><li>Sotalol </li></ul><ul><li>Procainamide </li></ul><ul><li>Haloperidol </li></ul><ul><li>Droperidol </li></ul><ul><li>Methadone </li></ul>
  19. 20. Drugs That Prolong QT Interval In Documented Case Reports <ul><li>Nicardipine </li></ul><ul><li>Chloral Hydrate </li></ul><ul><li>Fosphenytoin </li></ul><ul><li>Ondansetron </li></ul><ul><li>Granisetron </li></ul><ul><li>Salmeterol </li></ul>
  20. 21. Drugs To Be Avoided In Patients With c-LQTS <ul><li>Dobutamine </li></ul><ul><li>Dopamine </li></ul><ul><li>Ephedrine </li></ul><ul><li>Epinephrine </li></ul><ul><li>Isoprotenerol </li></ul><ul><li>Norepinephrine </li></ul><ul><li>Phenylephrine </li></ul><ul><li>Albuterol </li></ul><ul><li>Levalbuterol </li></ul><ul><li>Metoprotenerol </li></ul><ul><li>Terbutaline </li></ul>
  21. 22. Anesthesia For Patients With c-LQTS General considerations <ul><li>Avoiding triggers of TDP, prolongation of QT </li></ul><ul><li>Perioperative Beta-Blockade </li></ul><ul><li>Adequate anxiolysis pre-operatively </li></ul><ul><li>Adequate pain control intra-operatively and post-operatively </li></ul><ul><li>Cardiopulmonary stabilization </li></ul>
  22. 23. General Considerations For Conduct Of Anesthesia In Patients With c-LQTS <ul><li>Being prepared for the possibility of a perioperative arrhythmia: </li></ul><ul><li>If patient has ICD, ensure the device is functioning properly </li></ul><ul><li>Have pacemaker and defibrillator available throughout the perioperative period </li></ul><ul><li>Have appropriate personnel and consultant services available </li></ul>
  23. 24. General Considerations For Conduct Of Anesthesia In Patients With c-LQTS <ul><li>Correct electrolyte abnormalities: </li></ul><ul><li>Hypokalemia, hypomagnesemia and hypocalcemia predispose to delayed myocyte repolarization </li></ul><ul><li>Its is possible that prophylactic magnesium infusion is beneficial, even in patients with normal serum magnesium </li></ul>
  24. 25. Although information of the effect of some anaesthetic drugs on QT were available before significance of TDR of M cells yet the clinical significance is often unclear & it is difficult to advise with authority on which the safest anaesthetic agent for LQTS Anaesthetic Drugs & Ventricular Repolarization
  25. 26. Premedication <ul><li>The effects of midazolam followed by administration of either vecuronium or atracurium on the QT interval in humans </li></ul><ul><li>Michaloudis DG, Kanakoudis FS, Xatzkraniotis A, Bischiniotis TS </li></ul><ul><li>Midazolam does not produce significant changes in the QTc during IM premedication </li></ul><ul><li>Midazolam does not produce significant changes in the QTc as an induction agent when used with either vecuronium or atracurium. The QTc increases after intubation likely due to midazolam’s inability to blunt hemodynamic response </li></ul><ul><li>Eur J Anaesthesiol. 1995 Nov;12(6):577-83 . </li></ul>
  26. 27. Intravenous Agents <ul><li>Thiopentone: </li></ul><ul><li>Prolongs QT interval in healthy premedicated children & adult ( Eur Heart J 2001 ) </li></ul><ul><li>Despite using it in patients with c-LQTS </li></ul><ul><li>It reduces the transmural dispertion of repolarization ( Basic Res Cardiol , 2001 ) </li></ul>
  27. 28. Effects Of Sevoflurane Versus Propofol On QT interval Paventi S, Santevecchi A, Ranieri R. <ul><li>Propofol when used as induction agent and in total intravenous anesthesia significantly shortens the QT interval but not the QTc in ASA I-III patients undergoing elective non cardiac surgery </li></ul><ul><li>Minerva Anestesiologica 2001 Sep;67(9):637-40 . </li></ul>
  28. 29. Methohexital : prolongs QTC in healthy adults but not in children ( despite atropine premedication ) Act. Anaesthesiol Scand, 1993 ketamine : unreported effect , better avoided Etomidate : has no significant effect Act. Anaesthesiol Scand 1994
  29. 30. Volatile Anesthetics Effects of Sevoflurane versus Propofol on QT interval . Paventi S, Santevecchi A, Ranieri R. <ul><li>Sevoflurane significantly lengthens the QT interval and the QTc in ASA I-III patients undergoing elective non cardiac surgery </li></ul><ul><li>Minerva Anestesiologica 2001 Sep;67(9):637-40 . </li></ul>
  30. 31. Volatile Anesthetics The effects of sevoflurane, isoflurane and desflurane on QT interval of the ECG. Yildirim H, Adanir T, Aday A, Katircioglu K. Savaci S . <ul><li>Sevoflurane, Isoflurane and Desflurane at 1 MAC all significantly lengthened the QTc in ASA I patients undergoing elective non cardiac surgery. There was no significant intergroup difference </li></ul><ul><li>Eur J Anaesthesiolgy. 2004 Jul;21(7):566-70 . </li></ul>
  31. 32. Volatile Anesthetics Anaesthesia and the QT interval in humans. The effects of isoflurane and halothane. Michaloudis D, Fraidakis O, Lefaki T, Dede I, Kanakoudes F, Askitopoulou H, Pollard BJ. <ul><li>Isoflurane significantly lengthened the QTc, whereas halothane significantly shortened the QTc in ASA I and II patients during induction of anesthesia after premedication with midazolam administered IM </li></ul><ul><li>Anaesthesia. 1996 Mar;51(3):219-24 . </li></ul>
  32. 33. Volatile Anesthetics Anaesthesia and the QT interval. Effects of isoflurane and halothane in unpremedicated children. Michaloudis D, Fraidakis O, Petrou A. Gigourtsi C, Parthenakis F. <ul><li>Isoflurane significantly lengthened the QTc, whereas halothane significantly shortened the QTc in un- premedicated ASA I children during induction of anesthesia, after vecuronium administration and after intubation. </li></ul><ul><li>Anaesthesia. 1998 May;53(5):435-9 </li></ul>
  33. 34. <ul><li>All 4 volatile agents prolong QT interval , but uneventful anaesthesia has been reported in Beta blocked patients with LQTS </li></ul>
  34. 35. Muscle Relaxants The effects of midazolam followed by administration of either vecuronium or atracurium on the QT interval in humans. Michaloudis DG, Kanakoudis FS, Xatzkraniotis A, Bischiniotis TS <ul><li>Vecuronium and atracurium have been shown to have no effect on the QT interval </li></ul><ul><li>Eur J Anaesthesiol. 1995 Nov;12(6):577-83 . </li></ul>
  35. 36. Muscle Relaxants The effects of midazolam or propofol followed by suxamethonium on the QT interval in humans. Michaloudis DG, Kanakoudis FS, Petrou AM, Konstantinidou AS, Pollard BJ. <ul><li>Succinylcholine significantly prolonged the QTc in ASA I and II patients induced with either propofol or midazolam. Prolongation was seen both after administration and after intubation </li></ul><ul><li>Eur J Anesthesiology. 1996 Jul;13(4):364-8 </li></ul>
  36. 37. Muscle Relaxants <ul><li>Pancuronium : </li></ul><ul><li>Ventricular fibrillation in one case report </li></ul><ul><li>Avoided if there is an alternative drug </li></ul>
  37. 38. Neuromuscular Reversal Effects of four anticholinesterse-anticholinergic combinations and tracheal extubation on QTc interval of the ECG, heart rate and arterial pressure. Saarnivaara L, Simola M. <ul><li>Combinations of anticholinergic agents and anticholinesterases : neostigmine-glycopyrrolate, neostigmine-atropine, edrophonium-atropine were found to increase QTc both 1 minute after administration and after extubation. </li></ul><ul><li>Eur J Anaesthesiology. 1995 Nov;12(6):577-8 3. </li></ul>
  38. 39. Antiemetics Prolongation of QTc interval after postoperative nausea and vomiting treatment by droperidol or ondansetron . Charbit B, Albaladerjo P, Funck-Brentano C, Legrand M, Samain E, Marty J <ul><li>Droperidol 0.75 mg IV and Ondansteron 4 mg IV both produced similar and statistically significant QTc prolongation when administered to patients with postoperative nausea and vomiting </li></ul><ul><li>Anesthesiology. 2005 Jun;102(6):1094-1100 . </li></ul>
  39. 40. Antiemetics Effect of low-dose droperidol on the QT interval during and after general anesthesia: a placebo controlled study White PF, Song D, Abrao J, Klein KW, Navarette B. <ul><li>Droperidol 0.625 mg IV and 1.25 mg IV produced an increase in QTc that was not significantly different from the increase produced by a saline placebo when given after anesthetic induction in outpatients undergoing otolaryngologic procedures. </li></ul><ul><li>Anesthesiology. 2005 Jun;102(6):1101-1105 . </li></ul>
  40. 41. Narcotics <ul><li>Fentanyl & morphine .. No adverse effect on c-QTS </li></ul><ul><li>Su fentanil prolong QT in one case report </li></ul><ul><li>Alfentanil was better than Esmolol in preventing QT increase following succinyl choline & intubation </li></ul><ul><li>Methadone was associated with Torsade de pointes in large doses </li></ul>
  41. 42. Conclusion <ul><li>Anaesthestist can reduce the risk of the dangerous tachydysrhythmias in children by awareness & understanding of pathophysiological and biological bases of this disorder </li></ul>

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