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Sudden Death Syndromes An Electrical Perspective

Sudden Death Syndromes An Electrical Perspective. Girish V. Nair, M.D. The Care Group, LLC January 13, 2010. Sudden Cardiac Death. Affects 350,000 – 400,000 each year in U.S. alone Only 5% survive Causes Structural heart disease Genetic channelopathies. Congenital heart disease

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Sudden Death Syndromes An Electrical Perspective

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  1. Sudden Death SyndromesAn Electrical Perspective Girish V. Nair, M.D. The Care Group, LLC January 13, 2010

  2. Sudden Cardiac Death • Affects 350,000 – 400,000 each year in U.S. alone • Only 5% survive • Causes • Structural heart disease • Genetic channelopathies Congenital heart disease (+/- surgical correction) Myocarditis Coronary anomalies Hypertrophic CM ARVC and other CM CTD MVP

  3. Syncope Slow Onset Slow Offset Abrupt Onset Slow Offset Hyperventilation Hypoglycemia

  4. ChannelopathiesECG and the Action Potential

  5. Syndromes • Long QT • Short QT • Brugada • Catecholaminergic Polymorphic VT-CPVT • Idiopathic VF • Short coupled TdP • Lev-Lenegre Syndrome

  6. Case 1 • 13 yo girl presents with syncope while swimming • QTc ≥500 msec • ß-blocker initiated with no further events • Presents five years later inquiring about stopping medications • Do you stop ß-blocker? • Is an ICD indicated?

  7. 1957 1963-1964 1958-1970 1971 1979 1991-2007 1st LQTS family reported Romano-Ward Syndrome 25 LQTS cases reported 1st treatment – left stellate ganglionectomy LQTS registry started 10 LQTS genes identified Long QT SyndromeHistory

  8. Long QT SyndromeOverview • Incidence: 1/7,000 • Presentation: mean age 8-14 years • Symptoms: • Syncope, palpitations, seizures, sudden death • Syncope in pediatric population should be considered malignant until proven otherwise • Arrhythmia: Torsades des pointes

  9. LQT 1Broad T waves

  10. LQT 2Bifid T waves

  11. LQT 3Prolonged ST segment

  12. Long QT SyndromeDiagnosis • ECG definition • QTc > 460 females • QTc > 450 males • Challenges • 25 to 50% of LQT 1, 2, & 3 individuals will have QTc ≤ 460 msec • Genetic testing has 3 to 5% false (+) rate • Epinepherine challenge • Useful in evaluating LQT1 (∆QT 30 msec) • Iks response to epinepherine in LQT1 impaired • NPV 93%, PPV 76%, Sens 92%, Spec 86% • Less useful when on beta-blockers

  13. LQTSGene Specific Triggers Lethal and Non-lethal CV Events Schwartz PJ et al. Circulation 103:89-95, 2001

  14. Aborted cardiac arrest Family history (< 50 y) of cardiac arrest or unexplained syncope History of “seizures” or congenital deafness Prolonged QTc ≥500 msec on ECG Positive genetic test Long QT SyndromeHigh Risk Features

  15. LQTSRisk of Cardiac Event (syncope, cardiac arrest, or sudden death) • Risk > 50% • QTc ≥ 500 msec: LQT1, LQT2, Male LQT3 • Risk 30-50% • QTc ≥ 500 msec: Female LQT3 • QTc < 500 msec: Female LQT2/3, Male LQT3 • Risk < 30% • QTc < 500 msec: LQT1, Male LQT2

  16. LQT Subtypes

  17. LQTSManagement Options • Lifestyle modification (IB) • Beta-blockers (IB) • Very effective LQT1, Moderate LQT2 • Minimal effect LQT3 • ICD plus BB • Cardiac arrest (IA) • Syncope / VT (IB) • Prophylactic in LQT2 or LQT3 (IIB) • Left stellate ganglionectomy (IIB)

  18. LQTResources • Cardiac Arrhythmias Research & Education (CARE) • www.longqt.org • Cardiac Arrest Survivors Network (CASN) • www.casn-network.org • International Registry for Drug Induced Arrhythmias • www.qtdrugs.com

  19. Case 1 Review • 13 yo girl with syncope during swimming and QTc ≥500 msec • Asymptomatic for 5 y on BB • Swimming…suggests LQT1 • High risk subgroup based LQT1 and QTc ≥500 msec • Recommendation • Continue BB given very effective in LQT1 • Consider ICD if has arrest, syncope, or VT

  20. Case 2 • 17 yo girl presents with atrial fibrillation • QT 268 msec at HR 69 • Mother, age 51, and brother, age 21 with QT intervals of <300 msec also • History, exam, and cardiovascular workup otherwise negative • First reported family • Cardiology 2000;94:99-102

  21. Short QT Syndrome1999 – Dr. P. Bjerregaard

  22. Short QTECG Characteristics • QT < 300msec • No significant QT change with HR ∆s • Short ST segment with tall, narrow peaked T-waves in V1-V6 • Reentrant arrhythmias • Other clues • Lone AF, VF • Family Hx of SCD

  23. Short QT • EP testing • Short atrial and ventricular refractory periods • Management • Pharmacological (small studies) • Only hydroquinidine effective in increasing QT • Fleicanide, sotalol, ibutilide ineffective • ICD experience (limited) • T wave oversensing/inappropriate shocks • Device selection (St.Jude – delay/decay)

  24. Case 2 Review • 17 yo girl with AF and short QT. Mother and brother with short QT. • Treated with quinidine • For atrial fibrillation suppression • QT prolongation via K+ channel blockade • Long-term follow-up unavailable

  25. Case 3 • 39y man c/o cp, palpitations, and presyncope • PMH: none • SH: married, carpenter, occasional beer • FH: (-) sudden death, arrhythmias, premature CVD • Normal cardiac markers, echo

  26. Brugada SyndromeOverview • Identified 1992 • Age spectrum - 2d to 84y • Mean age sudden death 40 ± 15y • Men > 5x risk of arrhythmic events • Prevalence • 5/10,000 - overall • #2 cause of death SE Asian men <40y • Dynamic but characteristic ECG changes • 1 in 5 have Na channel mutation (SCN5A)

  27. Brugada SyndromeDefinition • Type 1 pattern ECG in V1-V3 plus 1 of following: • Pharm conversion to Type 1 from Type 2/3 ECG • Na channel blocker (procainamide, fleicanide, ajmaline) • Documented VF/polymorphic VT • Family history of SCD < 45y • Inducible VT at EP study • Syncope • Nocturnal agonal respirations • ECG pattern only = Brugada pattern ECG but not Brugada Syndrome • Exclude other heart conditions

  28. Brugada pattern ECGST elevation V1-V3 • Type 1 (DIAGNOSTIC) • Coved ST elevation ≥ 2mm with negative T wave • sensitivity by moving V2/V3 from 4th to 2nd/3rd intercostal space • Type 2 • Saddleback ST elevation ≥ 2mm w/ ST trough ≥ 1mm • Positive/biphasic T wave • Type 3 • Coved/saddle ST elevation ≥ 2mm w/ ST trough < 1mm • Also reported in inferior leads and left precordial leads • Some individuals also had SCN5A mutation

  29. Utility of EP study Controversial 6-9% of healthy individuals of induced VF at EPS Brugada, +EPS associated w/ 8x risk Other conduction abnormalities QT prolongation (R > L precordial) Prolonged action potential duration in RV epicardium P, PR, & QRS PR prolongation associated with His-purkinje delay Brugada Syndrome

  30. Brugada Consensus ConferenceSpontaneous Type 1 ECG

  31. Brugada Consensus ConferenceSodium Channel Blocker Induced Type 1 ECG

  32. Case 3 Review • 39y man c/o cp, palpitations, and presyncope • Spontaneous type 1 ECG • “Asymptomatic” • Negative family hx • EP study (IIA indication) • Sustained VT with DES at 500 from RVA • No supraventricular arrhythmias induced • Normal AV node and His-Purkinje function • ICD was implanted (IIA indication) • Asymptomatic without events at 32 mo f/u • ** Most events occur at night - autonomic role? • Other tx options: ablation, quinidine

  33. Case 4 • 16 yo girl suddenly arrests running into store • History of exertional palpitations and syncope • Successful resuscitation by bystander nurse

  34. Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) • Clinical Features • Direct correlation with adrenergic stimulation (physical/emotional) • Threshold heart rate 120-130 bpm • Abnormal automaticity or triggered activity • Bidirectional VT • Symptom onset in childhood • Genetic mutations – Ryanodine / Calsequestrin

  35. CPVTGenetic Mutations • Calsequestrin (CASQ2) • Autosomal Recessive • Calcium storage protein w/in lumen of sarcoplasmic reticulum • Cardiac Ryanodine Receptor (RyR2) • Autosomal Dominant • Regulates Ca++ from sarcoplasmic reticulum • Delayed after-depolarizations • Associated with ARVC • RYR1 - malignant hyperthermia syndrome

  36. CPVTManagement • Anti-adrenergic treatment • Beta blockers are the mainstay of treatment • ICDs • B-blockers not always effective

  37. Case 4 Review • 16 yo with history of palpitations and syncope who collapses in store • Arrested 3 times en route to hospital • ICD implanted and atenolol started • 3 ICD revision procedures • 2 lead dislodgements resulting in inappropriate ICD therapies

  38. Case 5 • 24 yo man with recurrent syncope • Signs and symptoms • Recent decrease in exercise tolerance • Lower extremity edema • Mild elevation in liver transaminases • Family hx + for sudden death – paternal uncle • Telemetry strip below

  39. Arrhythmogenic Right Ventricular Cardiomyopathy - ARVC

  40. ARVCIndik JH et al. Indian Pacing Electrophys J. 2003:3:148 • Top picture: • Fibro-fatty replacement of the myocardium • Thin and enlarged RV wall. • Bottom picture: • Trichrome stain • Areas of mature fibrosis (F) and adipose tissue (A) within the epicardial (Epi) and mid-myocardial zones

  41. ARVC • Diffuse fibrosis of the RV wall with preservation of normal LV tissue • Fibrous tissue appears white • Normal cardiac tissue appears black • www.geneticheartdisease.org • Ventriculogram demonstrating fibrofatty infiltration • Indik JH et al. Indian Pacing Electrophys J. 2003:3:148

  42. ARVC • Signal-Averaged ECG -SAECG (below left): • Characteristic high-frequency low-amplitude late-potential • SAECG averages multiple QRS complexes that are then digitalized and filtered and further processed with spectral analysis to eliminate noise. • Late-potentials represent areas of delayed activation due to slowed conduction from either regions of scar or fibrosis  electrical substrate that initiates and perpetuates ventricular tachycardia.

  43. ARVC High Risk Features • Younger patients • Recurrent syncope • History of cardiac arrest or sustained VT • Clinical signs of RV failure or LV involvement • Patients with or having a family member with the high risk ARVD gene (ARVD2) • Increase in QRS dispersion ≥ 40 msec • QRS dispersion = max measured QRS minus min measured QRS • Naxos disease

  44. Case 5 Review • Diagnosis • Rhythm strip and ECG notable for epsilon waves and T wave inversion in right precordial leads • Risk • High risk features present – young age, recurrent syncope, signs of RV failure, family history of sudden cardiac arrest • Management • ICD implantation

  45. Idiopathic Ventricular Fibrillation • Sodium channel mutation • Short-coupled Torsades des Pointes • Normal QT interval with coupling interval of 1st ectopic beat < 300 msec • Prognosis poor with unproven tx (BB or CCB); ablation? • Lev-Lenegre Syndrome • Progressive cardiac conduction defect associated with bradyarrhythmias although tachyarrhythmias may also occur • Sodium channel defect

  46. Idiopathic Ventricular Fibrillation

  47. Lev-Lenegre Syndrome • Progressive Cardiac Conduction Defect • Acquired complete heart block • Idiopathic fibrosis and calcification of cardiac conduction system • Very rare • Sodium channel mutations (subtype-SCN 5A) • Often result in bradyarrhythmias although tachyarrhythmias may also result • Lev M. Anatomic basis for atrioventricular block. Am J Med 1964;37:742-8. • Lenegre J. Etiology and pathology of bilateral bundle branch block in relation to complete heart block. Prog Cardiovasc Dis 1964;6:409-444

  48. Hypertrophic Cardiomyopathy • #1 cause of SCA in athletes • > 1/3 of deaths • Often associated with physical activity • 60% high school age • >90% males • Genetic disorder left ventricular hypertrophy • First symptom often sudden death

  49. HCM - ECG

  50. HCM – Echowww.hcmny.org

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