LQT Syndrome and
Other Inherited
Disorders
Eugene H Chung, MD, FACC, FHRS
Associate Professor of Medicine
UNC@Chapel Hill
...
SCD - structurally normal heart
• Wolff-Parkinson-White Syndrome
• Catecholamine induced polymorphic VT
• Idiopathic VF
• ...
Catecholaminergic Polymorphic VT
(CPVT)
• Exertion induced (catecholamine) syncope or SCD
• Higher prevalence in school-ag...
CPVT
A: Torsades de pointes
B: Bidirectional VT
Idiopathic VF
• Young adults presenting with syncope or
cardiac arrest due to polymorphic
tachyarrhythmias in the absence ...
Idiopathic VF
Idiopathic VF
Short QT syndrome
SQTS
Gollob et al, JACC 2010
Figure 1 Cellular Mechanism of Short QT Interval A gain-of-function potassium channel mutation results in an increased eff...
A, Twelve-lead ECG showing characteristic ECG features of SQTS. B, Twelve-lead ECG
showing characteristic ECG features of ...
Self-terminating episode of polymorphic Vt in a patient with SQTS: Lead V3.
Patel C et al. Circ Arrhythm Electrophysiol 20...
Arrhythmogenic Right
Ventricular Dysplasia
• Inherited disorder
characterized by fibro-fatty
replacement of the right
vent...
ARVD/C
•Arrhythmias from RV
•LBBB morphology VT,
frequent RV ectopy
•EKG changes in right
precordial leads
•↓T waves V1-3
...
ARVD
ARVDARVD
Puffer, J.C.
Long QT Syndrome (LQTs)
• 1:3000-5000
• broad spectrum presentations:
– asymptomatic
– syncope
– palpitations
– aborted ca...
LQTs
• QTc > 460 ms (F), 440 ms (M)
• Autosomal dominant
– Romano-Ward Syndrome
• Autosomal recessive
– Jervell-Lange-Niel...
LQTs- Risk stratification
• history of syncope or arrest
• QTc > 500 ms
• family history of SCD
• T wave alternans
• JNL s...
LQTs
LQTs
LQTs- beta blocker therapyLQTs- beta blocker therapy
Holter ECG Recording in LQTS Patient with Syncope
(representative strips of ECG recording, part 1 of 2)
Holter ECG Recording in LQTS Patient with Syncope
(representative strips of ECG recording, part 2 of 2)
Link et al Curr Opinion Cardiol 2001 16 30
Brugada Syndrome
Brugada Syndrome
Loss of INa causes:
Endocardial
Epicardial
“notch”
(Ito)
Baseline
Epicardial
Endocardial
INa reduced
“unbalanced”
Ito
•Inc...
SCD - structurally normal heart
• Wolff-Parkinson-White Syndrome
• Catecholamine induced polymorphic VT
• Idiopathic VF
• ...
Thank you
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
SCD 2014: Long QT and Other Inherited Ion Channel Disorders
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SCD 2014: Long QT and Other Inherited Ion Channel Disorders

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Eugene H. Chung, MD

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  • Team cardiologist at UNC, walked in, started ECG screening, ACC section, program committee, cases
  • Concealed LQT: genotype positive but phenotype negative
  • More often male
    Shorter QT intervals
  • Haissaguerre et al reported that 1 in 3 pts with idiopathic VF has ECG with J waves and ST seg elevation in interolateral leads in a “early repolarization” pattern.
    J waves common in healthy individuals, males, athletes, and AA- challenge
  • Higher amplitude J waves confer higher risk of arrhythmic storm, and transiet augmentation of the J wave amplitude precedes the onset of VF
    Quinidine is effective, presumably due to Ito blockade and normalizes the short VRP.
  • A, Twelve-lead ECG showing characteristic ECG features of SQTS. B, Twelve-lead ECG showing characteristic ECG features of new clinical entity with combined ECG phenotype of Brugada syndrome in addition to SQTS. The ECG shows Brugada-type ST elevation in V1 and V2 after administration of ajmaline in addition to short QT interval. Modified from References 4 and 6 with permission.4,6
  • Self-terminating episode of polymorphic Vt in a patient with SQTS: Lead V3. The episode is precipitated by an extrasystole with a very short coupling interval.
  • Prevalence underestimated, can involve RV
    Subtle morphological and histological changes
    TTE and EKG aren’t reliable
    Best available noninvasive test is MRI
  • MRI, echo
    Endonyocardial biopsy
  • especially unexplained syncope;
    Mexilitine can shorten the QT but not shown to be effective
  • LQT 1,2: decreased function of 2 potassium channels, prolong QT
    LQT 3: gain of functon in NA channel, prolongs ST segment and thereby prolongs QT
  • LQT1- exercise, swimming; tall wide based T waves
    LQT2- stress and auditory stimuli; T wave alternatns, low ampl ro nothced T waves
    LQT3- sleep; tall wide based waves (BEDPPOST)
  • The cardiac transient outward potassium current (Ito1) is the main contributing current to the repolarizing phase 1 of the cardiac action potential, and results from movement of potassium (K+) ions from the intracellular to the extracellular space. It is complemented with Ito2 resulting from Cl- ions.: when have loss of function in the Na channel get unopposed Ito
    [edit]
  • RV AP
  • SCD 2014: Long QT and Other Inherited Ion Channel Disorders

    1. 1. LQT Syndrome and Other Inherited Disorders Eugene H Chung, MD, FACC, FHRS Associate Professor of Medicine UNC@Chapel Hill 1st Annual Duke SCD in Athletes Symposium April 12, 2014
    2. 2. SCD - structurally normal heart • Wolff-Parkinson-White Syndrome • Catecholamine induced polymorphic VT • Idiopathic VF • Short QT syndrome • Congenital long QT syndrome • Brugada Syndrome
    3. 3. Catecholaminergic Polymorphic VT (CPVT) • Exertion induced (catecholamine) syncope or SCD • Higher prevalence in school-age children • No structural heart disease • Phenotypically mimics (concealed) LQT 1 – EKG normal, QTc normal – ETT may provoke VT • DADs from calcium induced calcium release – Ryanodine receptor, calsequestrin, ankyrin B proteins • Hallmark arrhythmia: bidirectional VT • Treat wth beta blockers +/- ICD
    4. 4. CPVT A: Torsades de pointes B: Bidirectional VT
    5. 5. Idiopathic VF • Young adults presenting with syncope or cardiac arrest due to polymorphic tachyarrhythmias in the absence of SHD or identifiable channelopathies • Spontaneous arrhythmias are not related to stress and are triggered by shortly- coupled PVCs Viskin et al AHJ 1990, Viskin JACC 2009, Haissaguerre et al NEJM 2008
    6. 6. Idiopathic VF
    7. 7. Idiopathic VF
    8. 8. Short QT syndrome
    9. 9. SQTS Gollob et al, JACC 2010
    10. 10. Figure 1 Cellular Mechanism of Short QT Interval A gain-of-function potassium channel mutation results in an increased efflux of potassium current from the cell resulting in an acceleration of cardiomyocyte repolarization and a shortened action potential ... Michael H. Gollob , Calum J. Redpath , Jason D. Roberts The Short QT Syndrome : Proposed Diagnostic Criteria Journal of the American College of Cardiology, Volume 57, Issue 7, 2011, 802 - 812 http://dx.doi.org/10.1016/j.jacc.2010.09.048
    11. 11. A, Twelve-lead ECG showing characteristic ECG features of SQTS. B, Twelve-lead ECG showing characteristic ECG features of new clinical entity with combined ECG phenotype of Brugada syndrome in addition to SQTS. The ECG shows Brugada-type ST elevation in V1 and V2 after administration of ajmaline in addition to short QT interval. Patel C et al. Circ Arrhythm Electrophysiol 2010;3:401-408 Copyright © American Heart Association, Inc. All rights reserved.
    12. 12. Self-terminating episode of polymorphic Vt in a patient with SQTS: Lead V3. Patel C et al. Circ Arrhythm Electrophysiol 2010;3:401-408 Copyright © American Heart Association, Inc. All rights reserved.
    13. 13. Arrhythmogenic Right Ventricular Dysplasia • Inherited disorder characterized by fibro-fatty replacement of the right ventricular myocardium • No single diagnostic test • Best noninvasive test is MRI (Ricci et al., AJC 1991) • Global and/or regional dysfunction and structural alteration of the RV
    14. 14. ARVD/C •Arrhythmias from RV •LBBB morphology VT, frequent RV ectopy •EKG changes in right precordial leads •↓T waves V1-3 •Epsilon waves V1-3 •RV functional and structural alterations Dilatation, ↓RV EF, aneurysms
    15. 15. ARVD
    16. 16. ARVDARVD Puffer, J.C.
    17. 17. Long QT Syndrome (LQTs) • 1:3000-5000 • broad spectrum presentations: – asymptomatic – syncope – palpitations – aborted cardiac arrest – family history
    18. 18. LQTs • QTc > 460 ms (F), 440 ms (M) • Autosomal dominant – Romano-Ward Syndrome • Autosomal recessive – Jervell-Lange-Nielsen Syndrome • Sporadic
    19. 19. LQTs- Risk stratification • history of syncope or arrest • QTc > 500 ms • family history of SCD • T wave alternans • JNL syndrome (deafness) • 2:1 AV block
    20. 20. LQTs
    21. 21. LQTs
    22. 22. LQTs- beta blocker therapyLQTs- beta blocker therapy
    23. 23. Holter ECG Recording in LQTS Patient with Syncope (representative strips of ECG recording, part 1 of 2)
    24. 24. Holter ECG Recording in LQTS Patient with Syncope (representative strips of ECG recording, part 2 of 2)
    25. 25. Link et al Curr Opinion Cardiol 2001 16 30 Brugada Syndrome
    26. 26. Brugada Syndrome
    27. 27. Loss of INa causes: Endocardial Epicardial “notch” (Ito) Baseline Epicardial Endocardial INa reduced “unbalanced” Ito •Incomplete depolarization in phases 0 and 1, and a deep notch during phase 2 induces a transmural current between endocardium and epicardium. •Heterogeneity within RV epicardium leads to reentry during phase 2.
    28. 28. SCD - structurally normal heart • Wolff-Parkinson-White Syndrome • Catecholamine induced polymorphic VT • Idiopathic VF • Short QT syndrome • Congenital long QT syndrome • Brugada Syndrome
    29. 29. Thank you

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