Tachydysrhythmias

1. Tachydysrhythmias TABAN MD. Internist & cardiologist Tabriz medical faculty

2. 3 types of tachydysrhythmias • Re-entrant • Respond well to electricity • Atrial fib and flutter • PSVT • Ventricular tachycardia • Monomorphic, Polymorphic (non-torsade) • Some atrial tachycardias • Automatic • Sinus, junctional, most atrial tach, MAT, AIVR • Triggered automaticity • Some atrial tach, Torsades

3. Re-entry • Requires 2 functional pathways that differ in their refractory periods. • Triggered by early beat (e.g., PAC) Atrium LA AV node Sinus node LV Ventricle

4. Mechanism of Reentry

5. Mechanism of Reentry

6. Enhanced Automaticity--Pacemaker cell • Pacemaker has spontaneous depolarization • Fires when reaches threshold • 1) Enhanced Normal automaticity (normal pacer cells): • Steepening of depolarization, usually by adrenergic stimulation • Some Atrial and Junctional tachycardia • 2) Abnormal automaticity • Happening in tissues that are not normally pacemakers • Myocardial ischemia or recent cardiac surgery • Accelerated idioventricular rhythm • Atrial tachycardia, MAT • Diagnosis • Accelerates and decelerates gradually • Beat to beat variability • Treatment • Do not respond well to standard interventions • May respond to overdrive pacing

7. Cardiac Action Potential Automaticity depends on the slope of phase 4

8. Triggered Automaticity/Dysrhythmias Afterdepolarizations • Early or Late afterdepolarizations • “R on T” phenomenon • Long preceding R-R interval • Conditions that prolong QT • Occur in salvos • More likely to occur when sinus rate is slow • Torsades de Pointes • Digoxin toxicity

9. Ventricular Tachycardia, wide (>120 ms)the origin of the arrhythmia is within the ventricles • Re-entrant • Classic VT • Monomorphic • Polymorphic • Triggered • Torsade de pointe • Polymorphic • long QT on baseline EKG • Automatic • Accelerated Idioventricular

10. WQRST تشخیصتاکی کاردی

11. Wide Complex Tachycardia--Sinus tach with aberrancy vs.--SVT (PSVT, AF, flutter) with aberrancy vs.--Ventricular tachycardia • Pretest probability: • Majority of wide complex tachycardia is ventricular tachycardia REMEMBER: VT does not invariably cause hemodynamic collapse; patients may be conscious and stable

12. Clinical Clues to Basis for Regular Wide QRS Tachycardia • History of heart disease, especially priormyocardial infarction, suggests VT • Occurrence in a young patient with no known heart disease suggests SVT • 12-lead EKG (if patient stable) should be obtained

13. 5 Questions in tachyarrhythmia • 1- QRS: Wide or Narrow? Axis? Shap? • 2- Regularity? • Regular • Regularly irregular • Irregularly irregular • 3- P-waves? • 4- Rate? HR? • 5- Rate change sudden or gradual?

17. 1- QRS: Wide or Narrow • Narrow • Sinus, PSVT, A flutter, A fib • (All without aberrancy) • Wide • SVT with aberrancy • Ventricular tachycardia

18. Aberrancy - SVT with wide complex • Abnormal ventricular conduction • RBBB • LBBB • Nonspecific intraventricular conduction defect • Rate-related BBB • Antidromic Reciprocating • Goes down through bypass tract

19. Suggest VT • In RBBB pattern > 140 ms • In LBBB pattern > 160 ms

20. 1- QRS: Shape? Typical or atypical LBBB/RBBB • Look for a true bundle branch block pattern • Right or left (sinus or SVT with aberrancy) • absence of RS complex in all leads V1-V6(negative Concordance)

22. Morphology criteria for VT RBBB V1 V6 LBBB V6 V1

24. 1-QRS: Axis • >45 degree R in aVR

25. 1- QRS : Fusion beats / capture beats • Fusion beats (occasional narrow complex fused with wideone) • Capture beats

28. Accelerated Idioventricular Rhythm ( Ventricular Escape Rate, but  100 bpm) Fusion beat Sinus acceleration Ectopic ventricular activation Normal ventricular activation

29. Ventricular tachycardia in the arrhythmogenic right ventricular dysplasia

30. 2- P waves • If p waves, and associated with QRS, then sinus (or, rarely, atrial tachycardia) • PSVT: generally no p wave visible • PR short • P wave hidden in QRS, inverted • A fib and flutter: • No p waves, but flutter may fool you • V tach • May rarely see P waves, but with no association (AV dissociation) or retrograde

31. MoreR-Waves Than P-Waves Implies VT! II

32. P-waves in front of QRS?

34. AV Dissociation ATRIA AND VENTRICLES ACT INDEPENDENTLY SA Node Ventricular Focus

35. Ventricular Tachycardia (VT) V1 • Rates range from 100-250 beats/min • Non-sustained or sustained • P waves often dissociated (as seen here)

36. 3- Regularity in tachycardia • Regular • VT, Sinus, PSVT, flutter, • Regularly irregular • Atrial flutter • Irregularly irregular • AF, MAT

38. 4- rate • Rate: the faster, the less likely it is sinus (260 beats/min)

39. 5- Sudden vs. Gradual change(Re-entry vs. automaticity) • Sinus: gradual • PSVT: sudden • Atrial flutter: sudden • AF: always changing, but sudden onset • Ventricular tachycardia: Sudden

40. Rate gradually changes or always the same? • Gradual: sinus • Unchanging: flutter vs. PSVT vs. v tach

41. Very Fast and Irregular think :WPW and AF • Never give AV nodal blocker • Never give Dig or Calcium channel blocker (IV). Even adenosine associated with VF • Electrical or chemical conversion • procainamide, amiodarone, ibutilide • WPW with regular rhythm (orthodromic/antidromic), not atrial fib: • AV nodal blockers are OK

42. Atrial Fibrillation with Rapid Conduction Via Accessory Pathway: Degeneration to VF

44. چند تمرین: Regular Wide QRS Tachycardia: VT or SVT with Aberrant Conduction?

45. V1

46. Identify ventricular tachycardia Regular and wide • Step 1: Is there absence of RS complex in all leads V1-V6? (Concordance) • If yes, then rhythm is VT • Step 2: Is interval from onset of R wave to nadir of the S > 100 msec (0.10 sec) in any precordial leads? • If yes, then rhythm is VT. • Step 3: Is there AV dissociation? • If yes, then rhythm is VT. • Step 4: Are morphology criteria for VT present (not typical BBB)? • If yes, then VT > 0.10 sec?

48. Ventricular Tachycardia Concordance Step 1: Absence of RS in all precordial leads

50. Ventricular Tachycardia Step 1: there is no absence of RS in all precordial leads (no concordance) (V5, V6) Step 2: RS in V5 > 0.10 ms, therefore v tach Step 3: No AV dissociation Step 4: RBBB pattern (tall R in V1). Notching of this monophasic R indicates VT