ARRHYTHMIA Cardiological Department Li Hongbo

1. ARRHYTHMIACardiological Department Li Hongbo

2. Anatomy of the conducting system

3. ELECTROPHYSIOLOGIC PRINCIPLES • Automaticity: • the property of a cardiac cell has depolarization spontaneous during phase 4 of the action potential. normally observed in the sinus node; the specialized fibers of the His-Purkinje system; some specialized atrial fibers .

4. ELECTROPHYSIOLOGIC PRINCIPLES • Excitability • Refractoriness-the period of recovery that cells can be reexcited by a stimulus after being discharged. • Absolute refractory period • Effective refractory period • Relative refractory period

5. ELECTROPHYSIOLOGIC PRINCIPLES • Conductivity • the cardiac conducting system included sinus node; interatria; atrioventricular node; right and left bundle branch; purkinje system. • The conduction speed is fastest through purkinje system and is slowest through the atrioventricular node.

6. Classification of arrhythmia • Pathogenesis of arrhythmia • Disturbances of impulse formation • Sinus nodal disturbance • Ectopic rhythm • Disturbances of impulse conduction • physiological • pathological

7. Classification of arrhythmia • Heart rate of arrhythmia • Bradyarrhythmias • Tachyarrhythmias

8. Sinus Nodal disturbance

9. Normal sinus rhythm • The normal sinus rhythm is defined as sinus rhythm with a heart rate between 60 and 100 beats/min. • The P wave is negative in lead aVR and positive in lead II

11. Sinus tachycardia • With a heart rate exceeding 100 beats/min , Generally is between 100 and 180 beats/min • Sinus tachycardia is an arrhythmia, but not necessarily an abnormal rhythm. • The following conditions can develop sinus tachycardia: Such as exercise, anxiety, fever, hyperthyroidism, anemia, myocarditis and some drugs.

13. SinusBradycardia • ECG characteristics: sinus rhythm is present and the heart rate is less than 60 beats/min • As a normal variant many normal and older people have sinus bradycardia • Sinus bradycardia commonly occurs in the following conditions: trained athletes, during sleep, Hypothyriodism, drugs or sick sinus syndrome • Most people with sinus bradycardia have no symptoms. If the patient has chronic sinus bradycardia cause symptoms, an electronic pacemaker may be needed.

15. Sinus Arrhythmia • The definition of sinus arrhythmia is sinus rhythm with an irregular rate. • The maximum sinus cycle length minus the minimum sinus cycle length exceeds 0.12 sec • The most common cause of sinus arrhythmia is respiration • This arrhythmia is a normal finding in children and teenagers.

17. Sinus Arrest or Sinus Pause • Sinus arrest or pause is recognized by a pause in the sinus rhythm. • The P-P interval of the pause does not equal a multiple of the basic P-P interval. • Sinus arrest or pause will lead to cardiac arrest with asystole unless the sinus node regains function or some other pacemaker (escape pacemaker) takes over.

18. Sinus Arrest or Sinus Pause • Sinus arrest can be caused by hypoxia, myocardial ischemia, hyperkalemia, digitalis toxicity, and some drugs. • In elderly people the sinus node may undergo degenerative changes and fail to function effectively.

20. Sick Sinus Syndrome(1) • Sick sinus syndrome is a term that is applied to a syndrome encompassing a number of sinus nodal abnormalities • SSS encompasses both disordered SA node automaticity and SA conduction. • With marked sinus bradycardia, sinus arrest, sinus exit block or junctional escape rhythms • Bradycardia-tachycardia syndrome

21. Sick Sinus Syndrome (2) • EKG Recognition: • Inappropriate sinus bradycardia; sinus arrest • Bradycardia -tachycardia syndrome (sinus bradyarrhythmia and nonsinus tachyarrhythmia). • AF or Afi with a slow ventricular rate response in the absences of drugs • Escape rhythm in the setting of persistent sinus arrest or exit block

24. Premature beat Extrasystole

25. The term “ectopy” , “ectopic pacemaker”, “ectopic beat” are used to describe non sinus beats. • Ectopic beats can be premature: premature atrial contractions (PACs) premature AV junctional contractions (PJCs) premature ventricular contractions (PVCs)

26. Some definition about the premature beats • Coupling interval: refers to the interval between the premature beat and the preceding normal beat. • Compensatory pause: Compensatory pause indicates that the interval between the normal QRS complexes immediately before and immediately after the premature beat. A fully compensatory pause is exactly twice the basic R-R interval.

28. Premature atrial contractions (PACs) • Premature beats arising from somewhere in either the left or the right atrium but not in the sinus node. • The atria are depolarized from an ectopic site. • The ventricular depolarization is generally not affected by PACs.

29. Premature atrial contractions (PACs) • PACs have the following major features: 1. The beat is premature 2. The PAC is often preceded by a visible P wave. Occasionally the P wave may be “buried” in the T wave of the preceding beat. This P wave has different shape and/or different PR interval from the P wave seen with the normal sinus beats. . 3. With noncompensatory pause. 4. The QRS complex is normal. Occasionally, PACs will result in aberrant ventricular conduction so the QRS is wider than normal.

30. B: a blocked PAC

31. Premature junctional contractions (PJCs) • Premature beats arising from AV junction • The direction of atrial depolarization is from bottom to top, just opposite to direction of normal sinus rhythm. • The P wave is upright in lead aVR and downward in lead II • QRS complex is normal. • Fully compensatory pause

32. P wave is upright in lead aVR and downward in lead II P wave will before, after, or buried in the QRS complex. P-R interval is less than 0.12’, R-P interval is less than 0.20’

33. Premature ventricular contractions (PVCs) • Premature beats arising in either the right or the left ventricle • The EKG characteristics of PVCs: • Aberrant in appearance. QRS complex is abnormally wide, usually 0.12 sec or more. T wave and the QRS complex usually point in opposite directions. 2. Have fully compensatory pause. 3. Interpolated PVC: A PVC falls between two normal beats

35. Different forms of PVCs in different leads

36. Difference between PVC and PAC

37. Interpolated PVC

39. Ectopic Tachycardia • A run of three or more consecutive premature beats • paroxysmal atrial tachycardia • paroxysmal AV junctional tachycardia • Both of them are called supraventricular tachycardia 3. paroxysmal ventricular tachycardia

40. Paroxysmal supraventricular tachycardia (PSVT) • Including paroxysmal atrial and AV junctional tachycardia • Mechanism: • Reentrant • Automatic

41. Paroxysmal supraventricular tachycardia (PSVT) • EKG characteristics • The heart rate is between 150 and 240 beats/min • Extremely regular • P waves may or may not be visible. When seen, they are different from the P waves with normal sinus rhythm. • The QRS complexes are normal A wide QRS complex will be seen if the patient has an underlying bundle branch block or if the PSVT induces a “rate -related” bundle branch block.

46. Paroxysmal ventricular tachycardia (PVT) • A run of three or more consecutive PVCs • May occur as a single isolated burst, recurrent, or may persist for a long run

47. Paroxysmal ventricular tachycardia (PVT) • EKG characteristics • The heart rate is generally between 140-200 beats/min • The QRS complex is abnormally wide, usually 0.12 sec or more. • AV dissociation • Fusion beats, Sinus capture beats