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Ventricular tachyarrhythmias

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Publié dans : Formation, Santé & Médecine
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Ventricular tachyarrhythmias

  2. 2. May manifest in following forms: Ventricular extrasystoles  ventricular tachycardia  ventricular flutter  ventricular fibrillation  ventricular parasystole
  3. 3. • PREMATURE VENTRICULAR CONTRACTIONS(extrasystoles) Due to premature discharge of an ectopic ventricular focus Arises in diastolic period of preceding sinus beat  recorded earlier than next anticipated sinus beat
  4. 4. • ECG SHOWS QRS COMPLEX:  bizarre  widened (more than 2 small squares)  slurred/notched  as impulse travels through ordinary muscle tissue which is relatively poor conductor 
  5. 5. • ST SEGMENT AND T WAVE ST segment depressed, T wave inverted when QRS upright ST segment elevated, T wave upright when QRS downward 
  6. 6. Unifocal Multifocal (diff. coupling interval) Multiformed (same coupling interval, but diff. shapes) Coupling interval : interval b/w ectopic beat and preceding sinus beat
  7. 7. PVC’s can be Isolated  Couplets  Triplets  Salvos i.e 4 or 6 PVC’s in a row (brief ventricular tachycardia) 
  8. 8. • COMPENSATORY PAUSE Sum of pre- and post ectopic intervals is exactly equal to two consecutive sinus cycles PVC’s followed by complete pause, PAC’s followed by incomplete
  9. 9. • SIGNIFICANCE OF PVC’s Always significant when associated with myocardial disease Unifocal PVC’s significant if they occur frequently,occur in person over 40 yrs of age or they are precipated by exercise Frequent PVC’s esp. couplets often herald V-tac or V-fib
  10. 10. • VENTRICULAR TACHYCARDIA “Series of three or more consecutive ventricular ectopic beats, recorded in rapid succession” It is due to rapid discharge of an ectopic ventricular pacemaking focus
  11. 11. Bizarre QRS complexes recorded in rapid succession Can be monomorphic or polymorphic  There is AV dissociation , P wave has no relationship to QRS complexes  Retrograde AV conduction, bizarre QRS complexes followed by P` waves
  12. 12. CAPTURE BEAT:  occasionally during relatively slow ventricular tachycardia, a sinus impulse may reach AV node during nonrefractory phase Sinus impulse can then be conducted to ventricles This conducted beat during ectopic ventricular rhythm is called Captured beat
  13. 13. QRS complex of captured beat is recognized because it resembles sinus beat  more reliable diagnostic pointers to ventricular origin of basic tachycardia
  14. 14. FUSION BEAT:  capturing sinus impulse may invade the ventricles concomitantly with ectopic ventricular impulse  QRS complex will have shape in b/w sinus beat and ectopic beat  VFB is most reliable diagnostic pointer of ventricular origin of basic tachycardia 
  15. 15. • VENTICULAR FLUTTER Very rapid and REGULAR ectopic ventricular discharge MECHANISM: mostly caused by re-entry with a frequency of 300 bpm ventricles depolarize in a circular pattern, which prevents good function resulting in minimal CO
  16. 16. • ECG SHOWS: Grossly abnormal intraventricular conduction: QRS and deflexions are very wide and bizarre, one merging with the other  difficult to define QRS complex, ST segment and T wave This results in appearance of a continuous sine-like waveform
  17. 17. Atrial frequency 60-100 bpm Ventricular frequency 150-300 bpm Regularity regular Origin ventricles P-wave AV-dissociation
  18. 18. • TORSADES DE POINTES (twisting of points) QRS bizarre and multiform Have sharply pointed apices  QRS form and axis undulate  sharp points of QRS, for a short period, be directed upwards followed by QRS contours directing downwards for a short period Multiform ventricular flutter
  19. 19. Multiform ventricular flutter  complicate advanced and third degree AV block
  20. 20. • VENTRICULAR FIBRILLATION Expression of chaotic, uncoordinated, ventricular depolarization MECHANISM:  Advanced physiological asymmetry of biventricular chamber such as in MI Premature or rapid stimulation of asymmetrical chamber i.e PVC’s,VT or V.flutter 
  21. 21. • ECG SHOWS Completely irregular, chaotic and deformed deflexions of varying height, width and shape P waves, QRS complexes, ST segments and T waves cant be identified
  22. 22. • SIGNIFICANCE Is a terminal event  associated with IHD, esp. acute MI  quinidine and digitalis intoxication esp. with hypokalemia  hypothemia <28 C
  23. 23. DIFFERENCE B/W V.FLUTTER AND V.FIB:  V.flutter deflexions are uniform , constant, regular and are of relatively large amplitude V.fib deflexions are small,completely chaotic and irregular 
  24. 24. THANK YOU!