Tachydysrrhythmias

1. Tachydysrrhythmias Lisa Campfens MD, FRCPC, FACEP

2. Generation of Dysrrhythmias Two fundamental causes Disturbances of automaticity Disturbances of conduction AV block Reentry

3. Presentation • Multiple symptoms: Fatigue Chest pain Dyspnea Dizziness Presyncope Palpitations • Patients can be symptomatic even with single premature beats or non-sustained atrial arrhythmias

4. Complications • SVTs common but persistent • Rarely life-threatening but present sig problems in patient management • A fib/A flutter: Stroke 2°to embolization • Persistence of tachycardia : • Dilated cardiomyopathy • CHF

5. Referral • All patients with wide complex tachycardia of unknown origin • Resistant/intolerant to pharmacological therapy • WPW Syndrome

6. Classification ofAntidysrrhythmic Drugs Vaughan Williams classification Class I: Na channel blockers Class II: B blockers Class III: K channel blockers Class IV: Ca channel blockers Other: adenosine, digoxin, and ibutilide

7. Class I: Na Channel Blockers Class IA Quinidine, Procainamide Class IB Lidocaine, Phenytoin, Mexilitine Class IC Flecainide, Propafenone

8. Procainamide • Therapeutic use • Ventricular tachycardia • SVT with aberrancy • Pre-excitation Syndromes

9. Class II: Beta Blockers Metoprolol, Atenolol, Esmolol Therapeutic use Slow ventricular rate (A fib/ A flutter) Terminate SVT caused by an AV nodal reentrant circuit

10. Class II: Beta Blockers (cont’d) Adverse effects Heart block Heart failure AV block Sinus arrest Hypotension Bronchospasm (asthma/COPD)

11. Class III: K Channel Blockers Amiodarone Therapeutic use Life-threatening ventricular dysrrhythmias SVT with aberrancy Pre-excitation Syndromes

12. Class IV: Ca Channel Blockers Verapamil, Diltiazem Therapeutic use Slow ventricular rate (A fib/ A flutter) Terminate SVT caused by an AV nodal reentrant circuit .

13. Other Antidysrhythmic Drugs Adenosine Half-life few seconds Intense but transient AV block thereby terminating tachycardia Safe in patients with heart disease Contraindications: asthma/COPD Therapeutic use termination of PSVT

14. PSVTs • A Fibrillation • A Flutter • AVNRT • AVRT (ORT)

15. Reentry Most common mechanism Requires two separate paths of conduction Requires an area of slow conduction Requires unidirectional block

16. Regular SVT in Adults 90% reentrant 60% AVNRT 30% AVRT (ORT) 10% Atrial tachycardia 2 to 5% involve WPW syndrome

17. AV Nodal Reentrant Tachycardia Re-entrant circuit is small and is in or closely related to the AV node Slow pathway Fast pathway

18. AV Nodal Reentrant Tachycardia 3o % respond to vagal maneuvers Very responsive to AVN blocking agents: B blockers, CA channel blockers, adenosine. Recurrences are the norm on medical therapy Catheter ablation 95% successful with 1% major complication rate

19. Orthodromic Reciprocating Tachycardia Anterograde over AV node and retrograde conduction of an accessory pathway. Frequently presents in patients with WPW as narrow complex tachycardia Conduction down AVnode Up accessory pathway

20. ORT Amenable to AV nodal blocking agents in absence of WPW syndrome (anterograde conduction of pathway) Amenable to catheter ablation with 95% success and 1% rate major complication Conduction down AVnode Up accessory pathway

21. Atrial Tachycardia Atrial rate 150-250 bpm Does not require AVN or infranodal conduction P wave morphology different PR interval > 120 ms differentiating from junctional tachycardia

22. Atrial Tachycardia Left atrial focus- P wave upright V1/negative in aVL Right atrial focus-P wave negative V1/upright in aVL Adenosine may help with diagnosis 70-80% will also terminate with Adenosine.

23. Atrial Tachycardia Most are due to abn automaticity and have right atrial focus May be reentry in patients with prev atriotomy scar, such as CABG or congenital repair patients

24. Atrial Tachycardia Therapy Antiarrhythmics Class 1 : procainamide, quinidine, flecainide Patients without structural heart disease. Class III : sotalol, amiodarone, dofetilide AVN blocking agents for rate control Catheter ablation effective in 70-80%

25. Atrial Flutter Rate 250 to 350 bpm Rotates counter-clockwise around right atrium using a protected isthmus Negative saw-tooth pattern leads II , III, AVF and positive in lead V1 Treatment similar to atrial tachycardia but rate control more difficult

26. Atrial Flutter and Risk of Stroke Although risk of stroke historically thought to be low, multiple instances of stroke with cardioversion lead to similar indication for anticoagulation as AF

27. 42 year old smoker presents to the ED with palpitations. BP 100/60. A. Emergent cardioversion for polymorphic VT B. IV procainamide C. IV lidocaine D. IV diltiazem to obtain rate control.

29. Answer WPW with AF and a rapid ventricular response. He is stable, thus IV procainamide indicated to slow conduction down the accessory pathway Diltiazem contraindicated Lidocaine will have no effect, as is not VT

30. Epidemiology of AF Affects 2-4% of population Increases to 5-10 % >80 yrs 2-fold increased risk of death 15-25% of all strokes in US attributed to AF Risk of thromboembolism approx 5%/yr but may be as high as 20% in high risk groups not anticoagulated

31. Management of Atrial Fibrillation Symptom relief by rate and rhythm control Reduce risk of thromboembolism by anticoagulation Prevent tachycardia-mediated cardiomyopathy

32. Acute Management of AF Focus on rate control DC cardioversion or pharmacologic conversion if <48 hrs or following TEE on Heparin without evidence of left atrial thrombus Following cardioversion anticoagulate for 4 wks with goal INR of 2-3 until atrial fx normalizes**

33. Acute Management of AF 50% spontaneously convert <24 hours Digoxin used heavily in past for prevention/ conversion, ineffective at either May be profibrillatory as decreases atrial refractory period

34. Acute Management of Atrial Fibrillation Rate control: Ca channel blockers or B blockers in patients with normal LV fx Cautious use of Ca channel blockers if depressed LV fx. Associated with increased mortality in long term. Avoid Beta blockers in acutely decompensated CHF patients with AF

35. AF and Depressed LV Fx Digoxin and amiodarone may be effective if LV dysfx and decompensated CHF to slow ventricular response. Digoxin alone rarely effective when patient sympathetically driven Avoid high dose digoxin with amiodarone as digoxin levels increase 2-fold with amiodarone

36. Chronic Management of AF • Maintenance of sinus similar with class I and class III drugs-50% recurrence at 1 year • Recurrence of AF 80% at 1 year without treatment

37. Chronic Management of AF Recent large trials reveal no benefit of rhythm vs rate control Trend of increased mortality in rhythm arm Patients unable to tolerate AF due to symptoms were not enrolled in these studies and are increasingly undergoing ablation , catheter and surgical procedures.

38. Wide ComplexTachycardias Ventricular Tachycardia SVT with aberrancy (functional bundle branch block) SVT with underlying bundle branch block SVT with pre-excitation

39. Additional Mimimics of Wide Complex Tachycardias SVT with severe hyperkalemia SVT with use of antiarrhythmic agents particularly 1C agents SVT with acute MI

40. Wide-Complex Tachycardia Majority are SVT with BBB In higher risk population VT until proven otherwise

41. Differentiating VT from SVT with Aberrancy Leads to correct initial therapy Verapamil may ppt hemodynamic collapse Hemodynamic status or rate not a clue to mechanism In higher risk population VT until proven otherwise ECG criteria for diagnosis

42. The Brugada Criteria

43. Morphology Criteria for VT

44. Therapy for VT Stable-chemical or DC cardioversion Unstable-DC cardioversion Amiodarone 150 mg IV over 10 mins, max 2.2 gm/24 hrs class IIA recommendation

45. New ACLS Algorithm

46. VT with Depressed LV Fx Amiodarone drug of choice mortality neutral or beneficial Initial dose 150 mg IV. over 10 mins effective in VF using 300 mg bolus with improved arrival to hospital. DC cardioversion always acceptable option Procainamide contraindicated

47. VT with Preserved LV Fx DC cardioversion Amiodarone 1st line RX according to ACLS Procainamide Lidocaine Avoid use of combination antiarrhythmic agents

48. AVRT Extranodal Accessory Pathways and WPW Syndrome • Extremely symptomatic but rarely observed • In the presence of AF, VF can occur if the refractory period of the accessory pathway is <250 msec

49. WPW • Not an arrhythmia but a clinical syndrome • ECG: PR<.12 sec, QRS>.10 sec, delta wave • Many types of arrhythmias • ‘Is AVN an integral part or an innocent bystander?’

50. WPW AV Node Integral • AVRT-Orthodromic AV blocking diagnostic and therapeutic • AVRT-Antidromic Regular AV blocking diagnostic and therapeutic