SYNCOPE ECG CASES. Dr Herman Chua Emergency Medicine Consultant Lyell McEwin Hospital

Transcription

1 SYNCOPE ECG CASES Dr Herman Chua Emergency Medicine Consultant Lyell McEwin Hospital

2 Case 1 92 year old female resident of nursing home found slumped on the chair watching TV

3 CASE 1

4 Case 1 Sinus pause (with junctional escape rhythm)

5 CASE 1

6 Conduction system of the heart

7 Sinus node dysfunction SA node fails to function as pacemaker of heart = BRADYCARDIC RHYTHM

8 Sinus node dysfunction How does it manifest? Inappropriate sinus bradycardia

9 Sinus node dysfunction How does it manifest? Sinus arrest

10 Sinus node dysfunction How does it manifest? Escape rhythm

11 Sinus node dysfunction Causes Intrinsic (irreversible) sick sinus syndrome Extrinsic (reversible) drugs (CCB, β-blocker, digoxin, amiodarone) metabolic (hyperkalaemia) enhanced vagal tone hypoxia, hypercapnia hypothermia hypothyroidism CNS

12 Sick sinus syndrome Important to exclude extrinsic reversible causes first Treatment : permanent pacemaker

13

14 Case 2 86 year old female who collapsed at the shopping mall. Sustained large scalp laceration

15 CASE 2

16 Case 2 Complete heart block with ventricular escape rhythm

17 CASE 2

18 Conduction system of the heart

19 AV Block 1 - delay in conduction 2 - intermittent failure in conduction 3 - total interruption of conduction

20 Complete heart block Complete failure of atrial impulses reaching ventricles = P waves fail to conduct

21 Complete heart block Usually escape rhythm comes to the rescue

22 Complete heart block Escape complexes completely independent from P waves (AV dissociation) Origin of escape rhythm depends on location of AV block

23 Localizing the AV Block AV nodal Infranodal

24 Localizing the AV Block AV nodal junctional escape rhythm (40-60 bpm) good prognosis Infranodal ventricular escape rhythm (20-40 bpm) bad prognosis

25 Complete heart block ECG features P waves and QRS complexes completely dissociated Escape rhythm can be narrow or wide Ventricular rate slower than atrial rate

26 MI Drugs (CCB, β-blocker, digoxin) Metabolic (hyperkalaemia) Congenital Degenerative (Lev, Lenegre) Infiltrative (sarcoid, amyloid) Infective (Lyme) Hypothyroidism Neuromuscular disease Complete heart block Causes

27 CHB with junctional escape

28 Inferoposterior MI with CHB

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30 Case 3 74 year old female presents after an episode of collapse. Has been lethargic and unwell for the last few days. PMH x : AF

31 CASE 3

32 Case 3 Slow AF with multifocal PVCs = DIGOXIN TOXICITY

33 CASE 3

34 Digoxin Toxicity Inhibits Na + -K + -ATPase increase intracellular calcium increase in myocardial contractility (positive ionotropic effect) increase RMP, lowers firing threshold increase in automaticity Enhances vagal tone decrease SA & AV nodal conduction velocity

35 Digoxin toxicity ECG effects Increased AUTOMATICITY Ectopic beats Tachyarrhythmias Decreased CONDUCTION Bradyarrhythmias

36 Digoxin toxicity ECG manifestations Almost any dysrhythmia Classic : atrial tachycardia with block bidirectional VT Common : frequent PVCs AV blocks sinus bradycardia / slow AF AF with CHB ( regular AF )

37 Digoxin toxicity Level = 4.2

38 Digoxin toxicity Level = 27!!

39 Digoxin effect

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41 Case 4 24 year old male with recurrent palpitations, who presents with palpitations, dyspnoea and pre-syncope while waiting for bus

42 CASE 4

43 Case 4 Wolff-Parkinson-White syndrome

44 CASE 4

45 Pre-excitation Syndrome Wolff-Parkinson-White Accessory pathway(s) bypass normal AV conduction Result in ventricular preexcitation Predispose to tachyarrhythmias

46 Accessory pathway

47 Pre-excitation Syndrome ECG features Short PR < 0.12s Wide QRS > 0.12s Initial slurring of QRS complex (delta wave) Secondary ST-T changes

48 WPW

49 Pre-excitation Syndrome ECG features Can resemble pseudoinfarction pattern negative delta waves secondary ST-T changes (repolarization abnormalities)

50 Pre-excitation Syndrome Clinical Significance Tachyarrhythmias requiring accessory pathway for initiation & maintenance (re-entry) AVRT Tachyarrhythmias in which accessory pathway acts as bypass route for conduction AF / flutter

51 Atrio-ventricular reciprocating tachycardia

52 Orthodromic AVRT

53 AF in WPW

54 Post reversion

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56 Case 5 43 year old female presents with unexplained episode of collapse while playing netball

57 CASE 5

58 Case 5 Prolonged QT (Congenital LQT1 variant)

59 CASE 5

60 Long QT Important cause of SCD Cause of death : torsade de pointes

61 Long QT QT interval determination measured from beginning of Q wave to end of T wave Corrected QT interval (Bazett formula) QTc = QT / [RR] 0.5 QT c > 450ms abnormal

62 Measuring QT interval

63 Long QT Risk of torsades greatest when QT c > 500ms

64 Long QT Causes Congenital (channelopathy involving mutations in genes encoding K + channel proteins) LQT1, LQT2, LQT3 most common LQT4-7 Acquired electrolytes (hypokalaemia, hypomagnesaemia, hypocalcaemia) drugs (class Ia, Ic, III antiarrhythmics, antipsychotics, macrolides, antifungals) hypothermia ACS CNS event

65 Torsades de pointes

66 Torsades in sotalol overdose

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