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Ventricular arrhythmias

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Ventricular arrhythmias

  1. 1. Ventricular Tachyarrhythmias BY DR SHAWANA SAJJAD
  2. 2. Module Objectives – Ventricular Tachyarrhythmias After completion of this module, the participant should be able to: • Differentiate types of ventricular tachycardias using ECG
  3. 3. Module Outline – Ventricular Tachyarrhythmias I. Description II. Characteristics A. Mechanisms B. Sustained vs. nonsustained C. Premature ventricular contractions
  4. 4. Module Outline – Ventricular Tachyarrhythmias III. Classification A. Monomorphic 1. Idiopathic a. b. ECG recognition c. 2. Description Treatment – ablation Bundle branch a. Description b. ECG recognition c. Treatment –ablation
  5. 5. Module Outline – Ventricular Tachyarrhythmias III. Classifications - continued 1. Ventricular flutter a. 4. Ventricular fibrillation a. B. ECG recognition ECG recognition Polymorphic 1. Torsades de pointes a. b. Description ECG recognition
  6. 6. Ventricular Tachycardia (VT) • Originates in the ventricles • Can be life threatening • Most patients have significant heart disease – Coronary artery disease – A previous myocardial infarction – Cardiomyopathy
  7. 7. Mechanisms of VT • Reentrant – Reentry circuit (fast and slow pathway) is confined to the ventricles and/or bundle branches • Automatic – Automatic focus occurs within the ventricles • Triggered activity – Early afterdepolarizations (phase 3) – Delayed afterdepolarizations (phase 4)
  8. 8. Reentrant • Reentrant ventricular arrhythmias – Premature ventricular complexes – Idiopathic left ventricular tachycardia – Bundle branch reentry – Ventricular tachycardia and fibrillation when associated with chronic heart disease: • Previous myocardial infarction • Cardiomyopathy
  9. 9. Automatic • Automatic ventricular arrhythmias – Premature ventricular complexes – Ischemic ventricular tachycardia – Ventricular tachycardia and fibrillation when associated with acute medical conditions: • Acute myocardial infarction or ischemia • Electrolyte and acid-base disturbances, hypoxemia • Increased sympathetic tone
  10. 10. Automaticity Abnormal Acceleration of Phase 4 Fogoros: Electrophysiologic Testing. 3rd ed. Blackwell Scientific 1999; 16.
  11. 11. Triggered Fogoros: Electrophysiologic Testing. 3rd ed. Blackwell Scientific 1999; 158.
  12. 12. Sustained vs. Nonsustained • Sustained VT – Episodes last at least 30 seconds – Commonly seen in adults with prior: • Myocardial infarction • Chronic coronary artery disease • Dilated cardiomyopathy • Non-sustained VT – Episodes last at least 6 beats but < 30 seconds
  13. 13. Premature Ventricular Contraction • PVC – Ectopic beat in the ventricle that can occur singly or in clusters – Caused by electrical irritability • Factors influencing electrical irritability – Ischemia – Electrolyte imbalances – Drug intoxication
  14. 14. Classification • Ventricular Tachycardia – Monomorphic • • Bundle branch reentry tachycardia • Ventricular flutter • – Idiopathic VT Ventricular fibrillation Polymorphic • Torsades de pointes (TdP)
  15. 15. Monomorphic VTs
  16. 16. Monomorphic VT • Heart rate: 100 bpm or greater • Rhythm: Regular • Mechanism – Reentry – Abnormal automaticity – Triggered activity • Recognition – Broad QRS – Stable and uniform beat-to-beat appearance
  17. 17. ECG Recognition ECG used with permission of Dr. Brian Olshansky.
  18. 18. Distinguishing wide complex SVT from ventricular tachycardia In VENTRICULAR TACHYCARDIA • H/O coronary disease or infarction • QRS width >0.14 sec • AV dissociation showing capture or fusion beats • Extreme right axis deviation • Q wave in V6
  19. 19. The Brugada Criteria Table I. Diagnosis Of Wide QRS Complex Tachycardia With A Regular Rhythm Step 1. Is there absence of an RS complex in all precordial leads V1 – V6? If yes, then the rhythm is VT. • Sens 0.21 Spec 1.0 Step 2. Is the interval from the onset of the R wave to the nadir of the S wave greater than 100 msec in any precordial leads? If yes, then the rhythm is VT. • Sens 0.66 Spec 0.98 Step 3. Is there AV dissociation? If yes, then the rhythm is VT. • Sens 0.82 Spec 0.98 Step 4. Are morphology criteria for VT present? See Table II. If yes, then the rhythm is VT. • Sens 0.99 Spec 0.97
  20. 20. Morphology Criteria for VT Table II. Morphology Criteria for VT Right bundle type requires waveform from both V1 and V6. V1 V6 Monophasic R wave QR or QS RS or QR R/S <1 Left bundle type requires any of the below morphologies. V1or V2 V6 R wave > 30 msec QR or QS Notched downstroke S wave. Greater than 60msec nadir S wave. Adapted from Brugada et al. A new approach to the differential diagnosis of regular tachycardia with a wide QRS complex. Circulation 1991; 83:1649-59.
  21. 21. Idiopathic Right Ventricular Tachycardia • Right ventricular idiopathic VT – Focus originates within the right ventricular outflow tract – Ventricular function is usually normal – Usually LBBB, inferior axis • Treatment options: – Pharmacologic therapy (beta blockers, verapamil) – RF ablation
  22. 22. ECG Recognition Kay NG. Am J Med 1996; 100: 344-356.
  23. 23. Case History: Idiopathic VT 39 y.o. female with no prior cardiac history • First episode – 9 hours of palpitations – In ER, found to be in wide-complex tachycardia of LBBB, inferior axis, at 205 bpm – Converted with IV lidocaine; placed on tenormin • Second episode – While on tenormin, patient had onset of palpitations at airport – In ER, converted with IV lidocaine • Patient underwent EP study
  24. 24. Case History: Idiopathic VT • At EP study, tachycardia focus was mapped and localized to right ventricular outflow tract • The focus was successfully ablated using radiofrequency energy, with no subsequent inducible or clinical VT
  25. 25. Idiopathic Left Ventricular Tachycardia • RBBB – Involves the Purkinje network • Treatment options: – RF ablation – Pharmacologic therapy (verapamil, beta blockers)
  26. 26. ECG Recognition ECG used with permission of Kay NG.
  27. 27. Bundle Branch Reentry • Reentry circuit is confined to the left and right bundle branches • Usually LBBB, during sinus rhythm • Presents with: – Syncope – Palpitations – Sudden cardiac death • Treatment: RF ablation of right bundle
  28. 28. VT Due to Bundle Branch Reentry
  29. 29. Ventricular Flutter • Heart rate: 300 bpm • Rhythm: Regular and uniform • Mechanism: Reentry • Recognition: – No isoelectric interval – No visible T wave – Degenerates to ventricular fibrillation • Treatment: Cardioversion
  30. 30. Ventricular Fibrillation • Heart rate: Chaotic, random and asynchronous • Rhythm: Irregular • Mechanism: Multiple wavelets of reentry • Recognition: – No discrete QRS complexes • Treatment: – Defibrillation
  31. 31. ECG Recognition • P waves and QRS complexes not present • Heart rhythm highly irregular • Heart rate not defined
  32. 32. Polymorphic VT
  33. 33. Polymorphic VT • Heart rate: Variable • Rhythm: Irregular • Mechanism: – Reentry – Triggered activity • Recognition: – Wide QRS with phasic variation – Torsades de pointes
  34. 34. ECG Recognition EGM used with permission of Texas Cardiac Arrhythmia, P.A.
  35. 35. Torsades de Pointes (TdP) • Heart rate: 200 - 250 bpm • Rhythm: Irregular • Recognition: – Long QT interval – Wide QRS – Continuously changing QRS morphology
  36. 36. Mechanism • Events leading to TdP are: – Hypokalemia – Prolongation of the action potential duration – Early afterdepolarizations – Critically slow conduction that contributes to reentry
  37. 37. ECG Recognition • QRS morphology continuously changes • Complexes alternates from positive to negative
  38. 38. A 67 year old male with history of previous infarct and reduced LV function presents with palpitations and dizziness. His blood pressure is 80/40. The appropriate next step is ? • A. Synchronized cardioversion for VT • B. I.V. Procainamide for Atrial Fibrillation with WPW syndrome • C. Synchronized cardioversion for unstable SVT with aberrancy. • D. I.V. Amiodarone for SVT with aberrancy in a patient with reduced LV function.
  39. 39. Answer A. • This patient has ventricular tachycardia. An RS interval of greater than 100 msec is clearly visible. In addition, by history this patient is overwhelmingly likely to present with VT with a wide complex rhythm. Also this patient is not stable with relative hypotension requiring immediate cardioversion as opposed to pharmacologic therapy.
  40. 40. A 46 year old female is admitted with dizziness. She is an alcoholic, on methadone, with schizophrenia. She began feeling dizzy after starting a fluoroquinalone for a UTI. Which of the following should be your next step? • A. Administer I.V . Procainamide • B. Consult E.P. for placement of a defibrillator • C. Discontinue antibiotic, treat with I.V. magnesium, discontinue antipsychotic, and consider temporary pacing • D. Administer I.V. amiodarone because it is unlikely Torsades de Pointes. cause
  41. 41. Answer C. • This patient has Torsades de Pointes with classic polymorphic VT and prolonged QT demonstrated in the bottom strip. Antipsychotics, hypomagnesemia, quinolones all may predispose to this arrhythmia. Procainamide or amiodarone would worsen this rhythm. ICD is not indicated .
  42. 42. Thank you!