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J-Wave Syndromes

J-Wave Syndromes. Brian Foo B.Sc. Life Sciences Student Queen’s University Canada. Road-Map. Background Repolarization of heart tissue Physiology of J-wave syndromes Cellular Basis Arrhythmogenesis Classification Acquired Inherited. Background Information. Overview.

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J-Wave Syndromes

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  1. J-Wave Syndromes Brian Foo B.Sc. Life Sciences Student Queen’s University Canada

  2. Road-Map • Background • Repolarization of heart tissue • Physiology of J-wave syndromes • Cellular Basis • Arrhythmogenesis • Classification • Acquired • Inherited

  3. Background Information

  4. Overview • Repolarization of cardiac tissue • Different repolarization patterns within the heart • ECG

  5. Cardiac Repolarization Ito: “transient outwards” r repolarizing K+ Ica: Depolarizing inwards Ca+2 Ik : Repolarizing inwards K+ Ito Ica IK Reviewed in Keating and Sanguinetti, 2001

  6. Layers of the Heart Exterior Epicardium Myocardium vascularconcepts.net Endocardium Interior Litovski and Antzelevitch, 1988

  7. Differences in repolarization Endocardium Epicardium Reviewed in Yan et al,. 2003

  8. Differences in Repolarization Reviewed in Yan et al,. 2003

  9. ECG of Repolarization • ECG deflection reflects voltage differences between layers of the heart Mod. From Antzelvitch and Yan, 2003 Reviewed in Yan et al,. 2003

  10. J-Wave Physiology

  11. Overview • Cellular Basis of J-wave syndromes • ECG manifestations: • J-wave • ST elevation • Arrhythmogenesis • Re-enterant fibrilation

  12. Cellular Basis • Low Vm during repolarization phase of action potential • Excessive phase 1 repolarization • Insufficient phase 2 depolarization

  13. J-Wave • Excessive phase 1 hyperpolarization Yan et al., 2003 Reviewed in Yan et al., 2003

  14. ST Elevation • Excessive phase 1 repolarization • Insufficient phase 2 depolarization ST Elevation Reviewed in Yan et al., 2003

  15. Potential Consequences • If cell repolarizes too quickly, Ica will not occur. • Leads to loss of phase 2 plateau and shortening of action potential duration Antzelevitch and Yan, 2010

  16. Potential Consequences Shortened AP Antzelevitch and Yan, 2010

  17. Arrhythmogenesis • Re-entrant ventricular fibrillation Area 1 Area 2 Antzlevitch and Yan, 2010

  18. Classifications

  19. Overview • Inherited • Brugada Syndrome (BS) • Early Repolarization Syndrome (ERS) • Acquired • Myocardial Infarction • Hypothermia

  20. Inherited J-wave Syndromes • Ion Channel Mutations Gain of Function Loss of Function Antzelevitch and Yan, 2010

  21. Brugada vs. ERS Gussak and Antzelevitch 2000

  22. Brugada Syndrome • Increased Phase 1 repolarization • Shortened action potential  re-entry Brugada.org Potential for loss of Phase 2 Ca+2 current Heterogeneous Repolarization and risk of re-entry Gussak and Antzelevitch 2000

  23. Early Repol. Syndrome • Decreased phase 2 Vm • Creates transmural voltage gradient without heterogeneous repolarization Transmural voltage gradient Brugada.org Gussak and Antzelevitch 2000

  24. Aquired J-Wave Syndromes • Myocardial Infarction • Hypothermia

  25. Myocardial Injury • Different epi and endo response to ischemia Yan et al. 2004 Gilmour and Zipes, 1980; Yan et al. 2004

  26. Hypothermia • Etiology unknown • Ion movement kinetics altered by temperature? • Injury associated? (similar to MI) Patel et al. 1994; Yan and Antzelevitch, 1996

  27. Hypothermia Yan, 1996 Patel et al. 1994; Antzelvitch and Yan, 1996

  28. Summary Cardiac Injury (MI, Hypothermia) Channel Defects (Brugada, ERS) Excessive Epicardial/ Myocardial Repolarization Transmural Voltage gradient Heterogeneous loss of Ica ECG Signs: -J-Wave -ST elevation Re-entry and fibrillation

  29. References • Antzelevitch C and Yan GX. Heart Rhythm 7: 549-558, 2010. • Gilmour RF, Jr. and Zipes DP. Circ Res 46: 814-825, 1980. • Gussak I, Antzelevitch C. J. Electrophysio 33(4): 299, 2000. • Hu D, Viskin S, Oliva A, Carrier T, Cordeiro JM, Barajas-Martinez H, Wu Y, Burashnikov E, Sicouri S, Brugada R, Rosso R, Guerchicoff A, Pollevick GD and Antzelevitch C. Heart Rhythm 4: 1072-1080, 2007. 5. Keating MT and Sanguinetti MC. Cell 104: 569-580, 2001. • Litovsky SH and Antzelevitch C. Circ Res 62: 116-126, 1988. 7. Patel A, Getsos JP, Moussa G and Damato AN. Clin Cardiol 17: 273-276, 1994. 8. Yan GX and Antzelevitch C. Circulation 93: 372-379, 1996. 9. Yan GX, Joshi A, Guo D, Hlaing T, Martin J, Xu X and Kowey PR. Circulation 110: 1036-1041, 2004. 10. Yan GX, Lankipalli RS, Burke JF, Musco S and Kowey PR. J Am Coll Cardiol 42: 401-409, 2003.

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