Transcript 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 • Repolarization of cardiac tissue • Different repolarization patterns within the heart • ECG
Cardiac Repolarization I to : “transient outwards” r repolarizing K + I ca : Depolarizing inwards Ca +2 I k : Repolarizing inwards K + I to I ca I K Reviewed in Keating and Sanguinetti, 2001
Layers of the Heart Exterior Epicardium vascularconcepts.net
Litovski and Antzelevitch, 1988 Interior Myocardium Endocardium
Differences in repolarization Endocardium Epicardium Reviewed in Yan
et al,.
2003
Differences in Repolarization Reviewed in Yan
et al,.
2003
ECG of Repolarization • ECG deflection reflects voltage differences between layers of the heart Reviewed in Yan
et al,.
2003 Mod. From Antzelvitch and Yan, 2003
J-Wave Physiology
Overview • Cellular Basis of J-wave syndromes • ECG manifestations: •J-wave •ST elevation • Arrhythmogenesis •Re-enterant fibrilation
Cellular Basis • Low V m during repolarization phase of action potential •Excessive phase 1 repolarization •Insufficient phase 2 depolarization
J-Wave • Excessive phase 1 hyperpolarization Reviewed in Yan
et
al., 2003 Yan
et
al., 2003
ST Elevation • Excessive phase 1 repolarization • Insufficient phase 2 depolarization ST Elevation Reviewed in Yan
et
al., 2003
Potential Consequences • If cell repolarizes too quickly, I ca occur.
will not • Leads to loss of phase 2 plateau and shortening of action potential duration Antzelevitch and Yan, 2010
Potential Consequences Shortened AP Antzelevitch and Yan, 2010
Arrhythmogenesis • Re-entrant ventricular fibrillation Area 1 Area 2 Antzlevitch and Yan, 2010
Classifications
Overview • Inherited •Brugada Syndrome (BS) •Early Repolarization Syndrome (ERS) • Acquired •Myocardial Infarction •Hypothermia
Inherited J-wave Syndromes • Ion Channel Mutations Gain of Function Loss of Function Antzelevitch and Yan, 2010
Brugada vs. ERS Location of J-wave Prognosis Proposed Mechanism Brugada Right precordial leads (V1-V3) High risk of fibrillation Increased phase 1 repol.
ERS Mid - left precordial leads (V4-V6) Lower risk of fibrillation Phase 2 depression Gussak and Antzelevitch 2000
Brugada Syndrome • Increased Phase 1 repolarization • Shortened action potential re-entry Gussak and Antzelevitch 2000 Potential for loss of Phase 2 Ca +2 current Brugada.org
Heterogeneous Repolarization and risk of re-entry
Early Repol. Syndrome • Decreased phase 2 V m • Creates transmural voltage gradient without heterogeneous repolarization Transmural voltage gradient Gussak and Antzelevitch 2000 Brugada.org
Aquired J-Wave Syndromes • Myocardial Infarction • Hypothermia
Myocardial Injury • Different epi and endo response to ischemia Gilmour and Zipes, 1980; Yan
et al.
2004 Yan
et al.
2004
Hypothermia • Etiology unknown •Ion movement kinetics altered by temperature?
•Injury associated? (similar to MI) Patel
et al.
1994; Yan and Antzelevitch, 1996
Hypothermia Patel
et al.
1994; Antzelvitch and Yan, 1996 Yan, 1996
Summary Cardiac Injury (MI, Hypothermia) Excessive Epicardial/ Myocardial Repolarization Transmural Voltage gradient Heterogeneous loss of I ca Re-entry and fibrillation Channel Defects (Brugada, ERS) ECG Signs: -J-Wave -ST elevation
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References Antzelevitch C and Yan GX. Heart Rhythm 7: 549-558, 2010. 2.
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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. Keating MT and Sanguinetti MC. Cell 104: 569-580, 2001.
Litovsky SH and Antzelevitch C. Circ Res 62: 116-126, 1988. Patel A, Getsos JP, Moussa G and Damato AN. Clin Cardiol 17: 273-276, 1994. Yan GX and Antzelevitch C. Circulation 93: 372-379, 1996.
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Yan GX, Joshi A, Guo D, Hlaing T, Martin J, Xu X and Kowey PR. Circulation 110: 1036-1041, 2004.
Yan GX, Lankipalli RS, Burke JF, Musco S and Kowey PR. J Am Coll Cardiol 42: 401-409, 2003.