1. Scott E. Ewing DO Lecture #2
EKG Rate and Rhythm I -
Scott E. Ewing DO
Lecture #2

2. Review Electrophysiology Anatomy Depolarization EKG Paper
Lead Placement
Normal EKG
Waves / Intervals / Segments

3. Cardiac Action Potential
SA node, AV, Purkinje cells display pacemaker activity (phase 4 depolarization)
Body surface manifestation of the depolarization and repolarization waves
P wave is generated by atrial depolarization
QRS by ventricular muscle depolarization
T wave by ventricular repolarization
PR interval is a measure of conduction time from atrium to ventricle
QRS duration indicates the time required for all of the ventricular cells to be activated (i.e., the intraventricular conduction time)
QT interval reflects the duration of the ventricular action potential

5. Depolarization

6. EKG Frontal Plane

7. Waveform Review

8. 8-Step Method EKG Interpretation
Rate
Rhythm
Axis
P wave
PR interval
QRS complex
QT interval
ST segment and T wave

9. Rate Determination

11. Rate

12. Rate?

13. Rate?

14. Rate?

15. Rate?

16. Rate?

17. Rhythm
Atrial
Junctional
Ventricular
Pacemaker
Last but not least

18. Normal Sinus Rhythm

19. Normal Sinus Rhythm

20. Sinus Bradycardia

21. Sinus Bradycardia Pathophysiology Increased vagal tone in athletes
Inferior wall myocardial infarction
Digitalis glycosides, β-blockers, CCB agents, class I antiarrhythmic agents, amiodarone
Other drugs, toxins, environmental exposure (lithium, paclitaxel, toluene, dimethyl sulfoxide, topical ophthalmic acetylcholine, fentanyl, reserpine, clonidine)
Electrolyte disorders
Infection (diphtheria, rheumatic fever, viral myocarditis)
Sleep apnea
Hypoglycemia
Hypothyroidism
Hypothermia
Increased intracranial pressure

22. Sinus Bradycardia

23. Sinus Tachycardia

24. Sinus Tachycardia Pathophysiology Hypoxia Hypovolemia / Sepsis Pain
Fever
Anxiety
Hyperthyroidism PE
Exercise
Drugs (nicotine, caffeine, atropine, pseudoephedrine, cocaine, methamphetamines, ecstasy)

25. Sinus Tachycardia

26. Sinus Arrhythmia

27. Sinus Pause

28. Wandering Atrial Pacemaker

29. Atrial Tachycardia

30. PAC’s

31. Nonconducted PAC

32. 1st Degree AV Block

33. 1st Degree AV Block Pathophysiology
PR interval represents time needed for electrical impulse from sinoatrial node to conduct through the atria, AV node, bundle of His, bundle branches, and Purkinje fibers
PR interval prolongation due to conduction delay within the right atrium, the AV node, or the His-Purkinje system
AV nodal dysfunction accounts for the majority of cases
1st degree AV block caused by conduction delay in the His-Purkinje system often is associated with BBB

34. 1st Degree AV Block

35. 2nd Degree AV Block Mobitz Type I (Wenckebach)

36. Karel Frederik Wenckebach (1864 – 1940)
1908 – Doctorate University of Utrecht, Netherlands
– professor of IM Groningen, Netherlands
– professor of IM Strasbourg , France
– professor of IM Vienna, Austria, retired from his chair 1929
Early work concerned embryology, later pathology of heart and circulatory diseases
– first description of the beneficial effects of quinine alkaloids on arrhythmias and mainly in patients with auricular fibrillation of recent onset
– 2nd degree AV block independently discovered by English physician John Hay and Wenckebach

37. 2nd Degree AV Block Mobitz Type I (Wenckebach)
Pathophysiology
Conduction disturbance in the AV node
Rarely secondary to AV nodal structural abnormalities when the QRS complex is narrow in width and no underlying cardiac disease is present
May be vagally mediated (well-trained athletes, digoxin excess, neurally mediated syncopal syndromes)
Vagally mediated AV block improves with exercise and may occur more commonly during sleep when parasympathetic tone dominates
Cardioactive drugs (digoxin, β-blockers, CCBs, certain antiarrhythmic drugs)
Various inflammatory, infiltrative, metabolic, endocrine, collagen vascular disorders

38. 2nd Degree AV Block Mobitz Type I

39. 2nd Degree AV Block Mobitz Type I

40. 2nd Degree AV Block Mobitz Type II (Hay)
Intermittent failure of conduction of P waves
PR interval is constant (may be normal or prolonged)
May include wide QRS
May progress to complete 3rd degree AV block

41. 2nd Degree AV Block Mobitz Type II

42. Woldemar Mobitz (1889 – 1951)
Born May 31, 1889 St. Petersburg, Russia, the son of a prominent surgeon
1908 – gymnasium Meiningen, Saxony
1914 – doctorate University of Munich
Internship, hospital service, and assistant years in the surgical clinics in Berlin and Halle, and medical clinics Munich and Freiburg
1924 – first classified 2nd degree AV block into Type I and II
– professor extraordinary at University of Freiburg in Breisgau
Remained in Magdeburg until it was occupied by the Russian army in 1945
Suffered from laryngeal tuberculosis until his death April 11, 1951
Primary interest in cardiovascular circulation and arrhythmias

43. 3rd Degree Heart Block

44. 3rd Degree Heart Block Pathophysiology
Class Ia antiarrhythmics (quinidine, procainamide)
Class Ic antiarrhythmics (flecainide, propafenone)
Class II antiarrhythmics (β-blockers)
Class III antiarrhythmics (amiodarone, sotalol, dofetilide, ibutilide)
Class IV antiarrhythmics (CCBs)
Digoxin or other cardiac glycosides
Infection
Profound hypervagotonicity
Anterior wall MI
Cardiomyopathy, eg, Lyme carditis and acute rheumatic fever
Metabolic disturbances, eg, severe hyperkalemia

45. 3rd Degree Heart Block

46. Atrial Fibrillation

47. Atrial Fibrillation Pathophysiology Long-standing hypertension
Valvular heart disease (rheumatic)
LVH
CAD DM
AMI
CHF
Pulmonary embolism
Cardiomyopathy
Pericarditis
Hyperthyroidism
ETOH (holiday heart)
Postoperative revascularization
Use of illegal drugs, such as cocaine or amphetamine derivatives
Over-the-counter herbs (ephedra, ginseng)
Idiopathic or “Lone” AF

48. Atrial Fibrillation

49. Atrial Fibrillation

50. Atrial Fibrillation

51. Atrial Fibrillation with WPW

52. Atrial Flutter

53. Atrial Flutter Pathophysiology Long-standing hypertension
Valvular heart disease (rheumatic)
LVH
CAD with or without depressed left ventricular function DM
CHF
Pulmonary embolism
Pericarditis
Hyperthyroidism
Postoperative revascularization
Digitalis toxicity

54. Atrial Flutter

55. Atrial Flutter

56. Rhythm
Atrial
Junctional
Ventricular
Pacemaker
Last but not least

57. Junctional Rhythm

58. Accelerated Junctional Rhythm

61. EKG Frontal Plane

62. Atrial Bigeminy

63. 3rd Degree Heart Block