Cardiology & cardiovascular system heart block deep.pptx

Cardiology & cardiovascular system heart block deep.pptx

1. Heart Blocks Deepshikha Kakoty Dept of Medical Surgical Nursing

2. Heart Blocks Partial delays or complete interruptions in the cardiac conduction pathway between the atria and ventricles . Q I

3. AV Heart Blocks 1st-degree AV heart block 2nd-degree AV heart block, type I (Wenckebach) 2nd-degree AV heart block, type II 3rd-degree AV heart block AV dissociation I

4. Heart Blocks Common causes: Ischemia Myocardial necrosis Degenerative disease of the conduction system Congenital anomalies Drugs ( eg D igitalis) I

5. 1st-Degree AV Heart Block Not a true block. Consistent delay of conduction at the AV node. I Q

6. Causes of 1st-Degree AV Heart Block May occur in healthy persons for no apparent reason (athletes)

7. Effects of 1st-Degree AV Heart Block Often of little or no clinical significance because all impulses are conducted to the ventricles Can progress to higher degree block, especially in the presence of inferior wall myocardial infarction I

8. Treatment of 1 st Degree AV Block As cardiac output is not affected, no specific treatment is indicated, however, efforts may directed toward identifying and treating the cause

9. 2nd-Degree AV Heart Block, Type I Intermittent block at the level of the AV node Also referred to as Wenckebach

10. 2nd-Degree AV Heart Block, Type I More P waves than QRS complexes and the rhythm has patterned irregularity PR interval increases until a QRS complex is dropped After dropped beat the next PR interval is shorter As each subsequent impulse generated there is a progressively longer PR interval until again, a QRS is dropped Cycle repeats I

11. 2nd-Degree AV Heart Block, Type I Often occurs in acute MI or acute myocarditis Other causes include:

12. Effects of 2nd-Degree AV Heart Block, Type I May occur in otherwise healthy persons Usually transient and reversible, mostly resolving when underlying condition is corrected May progress to more serious blocks (particularly if it occurs early in myocardial infarction)

13. Effects of 2nd-Degree AV Heart Block, Type I If dropped ventricular beats occur frequently, patient may show signs and symptoms of decreased cardiac output I

14. Treatment of 2nd-Degree AV Heart Block, Type I Asymptomatic patients require no specific treatment Symptomatic patients (e.g., chest pain, hypotension) should receive oxygen, an IV lifeline, and the administration of atropine and transcutaneous pacing should be considered if the heart rate is slow

15. 2nd-Degree AV Heart Block, Type II Intermittent block at the level of the bundle of His or bundle branches resulting in atrial impulses that are not conducted to the ventricles I

16. Mobitz Type II

17. Mobitz Type II Sudden appearance of a single, non-conducted sinus P wave... ... without ... ...the progressive prolongation of the PR intervals… ...and the shortening of the PR interval in the beat after the nonconducted P wave.

18. 2nd-Degree AV Heart Block, Type II More P waves than QRS complexes Duration of PR interval of the conducted beats remains constant

19. Causes of 2nd-Degree AV Heart Block, Type II U sually associated with anterior-wall MI, degenerative changes in the conduction system, or severe coronary artery disease Common causes include:

20. Effects of 2nd-Degree AV Heart Block, Type II A serious dysrhythmia (usually considered malignant in the emergency setting) Can result in decreased cardiac output and may produce signs and symptoms of hypoperfusion May progress to a more severe heart block and ventricular asystole I

21. Treatment of 2nd-Degree AV Heart Block, Type II Symptomatic patients should receive oxygen, an IV lifeline, and transcutaneous pacing Atropine may be used in type II AV block with new wide QRS complexes while you are setting up the transcutaneous pacemaker

22. 3rd-Degree AV Heart Block Complete block of conduction at or below the AV node Impulses from atria cannot reach ventricles

23. Third-Degree (Complete) AV Block

24. Third-Degree (Complete) AV Block P waves are present, with a regular atrial rate faster than the ventricular rate QRS complexes are present, with a flow (usually fixed) ventricular rate The P wave bears no relation to the QRS complexes, and the PR intervals are completely variable

25. Causes of 3rd-Degree AV Heart Block 3rd-degree AV heart block occurring at the AV node is most commonly caused by a congenital condition It may also occur in older adults because of chronic degenerative changes in the conduction system Other causes are:

26. Effects of 3rd-Degree AV Heart Block Well tolerated as long as the escape rhythm is fast enough to generate a sufficient cardiac output to maintain adequate perfusion Can result in decreased cardiac output because of the asynchronous action of the atria and ventricles and if the ventricular rate is slow I

27. Treatment of 3rd-Degree AV Heart Block Symptomatic patients should receive oxygen, an IV lifeline, and transcutaneous pacing Atropine may be used in 3 rd degree AV block with new wide QRS complexes while you are setting up the transcutaneous pacemaker I

28. Differences Between AV Heart Blocks

29. Ventricular Conduction Disorders. Left Bundle Branch Block. Right Bundle Branch Block. Other related blocks.

30. Left Bundle Branch Block. Block of the left bundle or both fasicles of the left bundle. Electrical potential must travel down RBB. De-polarisation from right to left via cell transmission. Cell transmission longer due to LV mass.

31. Left Bundle Branch Block (LBBB).

32. ECG Criteria for LBBB. QRS Duration >0.12secs. Broad, mono-morphic R wave leads I and V6. Broad mono-morphic S waves in V1 (can also have small 'r' wave).

33. LBBB consequence. Mostly abnormal ECG finding - indicates heart disease. Coronary artery disease (indication for thrombolysis - if associated with chest pain and raised Troponin ). Valvular heart disease. Hypertension. Cardiomegaly . Heart failure. Impacts on prognosis - QRS duration. Use of Bi-Ventricular Pacemakers.

34. Extra note on BVP. Red arrow - coronary sinus lead. Black arrow - right atrium. Dotted arrow - right ventricle. Synchronise ventricular contraction. Only works in selected patients (echocardiography role). Often also defibrillators (note thick RV wire).

35. Right Bundle Branch Block. Impulse transmitted normally by left bundle. Blocked right bundle results in cell depolarisation to spread impulse (slower). Impulse to IV septum and RV delayed.

36. Right Bundle Branch Block (RBBB).

37. ECG Criteria RBBB. QRS duration >0.12 secs. Slurred 'S' wave in leads I and V6. RSR' pattern in V1 - bunny ears!!

38. Additional Info RBBB. Can be normal. Sometimes related to asthma or other airway conditions. Possibly due to RVH in young individuals. Usually due to CAD in older persons. Often related to congenital heart disease (particularly ASD). Often apparent following cardiac surgery.

39. Hemi-blocks. Block of an entire fascicle of the left bundle branch. Anterior fascicle - left anterior hemi-block. Posterior - left posterior hemi-block. Altered vectors and ECG appearance.

40. Hemiblocks The anterior fascicle is longer and thinner and has a more fragile blood supply than the posterior fascicle, so LAHB is far more common than LPHB While LAHB can be seen in both normal and diseased hearts, LPHB is almost always associated with heart disease

41. Left Anterior Hemi-block. LV depolarisation progresses from the IV septum, inferior wall and posterior wall towards anterior and lateral walls. Unopposed vector pointed superiorly and leftward. Produces left axis deviation.

42. Left Anterior Hemi-block.

43. Left Anterior Hemi-block Appearance.

44. ECG Features of Left Anterior Hemi-block. Abnormal left axis deviation (between -30 and -90 ). Either a qR complex or an R wave in lead I. rS complex in lead III (possibly also II and aVF). Extremely common and un-diagnosed ECG feature. NOT ALWAYS ASSOCIATED WITH BBB.

45. Left Posterior Hemi-block. Quite rare - fibres spread over large area of LV tissue ( infero -posterior walls - large lesion needed). Difficult to diagnose. Delayed infero -posterior depolarisation. Results in rightward axis deflection.

46. Left Posterior Hemi-block.

47. Left Posterior Hemi-block.

48. ECG Features Left Posterior Hemi-block. Axis of 90 - 180 o - (right axis). An s wave in lead I and a q wave in lead III. Exclusion of RAE or RVH. REMEMBER - most common cause of right axis is RVH so this must be excluded before you diagnose LPH.

49. Bi-Fascicular Blocks.

50. What are they? Three fascicles innervating the ventricles. RBB LBB - anterior and posterior fascicles. Bi-fascicular block is concurrent RBBB and either LAH or LPH. ** NOTE: LBBB presents the same as LAH and LPH so is disregarded.

51. RBBB and LAH.

52. ECG Features of RBBB and LAH. Slurred S wave in leads I and V6. 'RSR' pattern in V1 - 'bunny ears'. Prolonged QRS complex >0.12 secs. Leftward axis deviation. rS waves in lead III. Common ECG presentation and usually a stable pattern. UNLESS new-onset during an ischemic episode.

53. RBBB and LPH.

54. ECG Features of RBBB and LPH. All features of RBBB. Rightward axis deviation. Small q wave lead III. NB don't forget to exclude RAH or RVH. Not usually stable ECG pattern. Often deteriorates into CHB - especially in setting of AMI.

55. Trifascicular Block I s a conduction disturbance in which there are three features seen on the ECG such as: Prolongation of the PR interval (first degree AV block) RBBB Either LAFB or LPFB I s uncommon

56. AV Dissociation AV dissociation occurs when the atria and the ventricles are under the control of separate pacemakers and beat independently of each other

57. AV Dissociation The key difference between AV dissociation and 3 rd degree AV heart block is the ventricular rate in AV dissociation is nearly the same or faster than the atrial rate whereas in 3 rd degree AV heart block it should be slower

58. Causes of AV Dissociation S lowed or impaired sinus impulse formation or SA nodal conduction Impulse formation in the AV junction or ventricles that is faster than the firing rate of the sinus node Complete AV heart block Anything that interferes with the ability of an atrial impulse to conduct to the ventricles, such as pauses produced by premature beats

59. Effects of AV Dissociation Signs and symptoms vary depending on the underlying cause Signs of decreased cardiac output may be present if the heart rate is reduced

60. Treatment of AV Dissociation No treatment is needed if the condition causing AV dissociation is clinically insignificant If the condition causing the AV dissociation reduces cardiac output, treatment is directed at managing the underlying problem Specific measures include delivering atropine and other rate-accelerating agents and/or pacemaker insertion If drug toxicity caused the original disturbance, the drug should be discontinued

61. Practice Makes Perfect Determine the type of dysrhythmia I

62. Practice Makes Perfect Determine the type of dysrhythmia I

63. Practice Makes Perfect Determine the type of dysrhythmia I

64. Practice Makes Perfect Determine the type of dysrhythmia I

65. Practice Makes Perfect Determine the type of dysrhythmia I

66. Practice Makes Perfect Determine the type of dysrhythmia I

67. Practice Makes Perfect Determine the type of dysrhythmia I

68. Practice Makes Perfect Determine the type of dysrhythmia I

69. Practice Makes Perfect Determine the type of dysrhythmia I

70. Summary Heart blocks are partial delays or complete interruptions in the cardiac conduction pathway between the atria and ventricles 1st-degree AV heart block is a consistent delay of conduction at the level of the AV node which results in a PR interval that is greater than 0.20 seconds in duration 2nd-degree AV heart block, Type I is an intermittent block at the level of the AV node

71. Summary With 2nd-degree AV heart block, type I, the PR interval increases until a QRS complex is dropped. After the dropped beat the next PR interval is shorter. Then as each subsequent impulse is generated and transmitted through the AV junction there is a progressively longer PR interval until again, a QRS is dropped. This cycle can repeat itself With 2nd-degree AV heart block, type I, there are more P waves than QRS complexes and the rhythm is regularly irregular

72. Summary 2nd-degree AV heart block, type II is an intermittent block at the level of the bundle of His or bundle branches resulting in atrial impulses that are not conducted to the ventricles With 2nd-degree AV heart block, type II, there are more P waves than QRS complexes and the duration of PR interval of the conducted beats remains the same (are constant) 3rd-degree AV heart block is a complete block of the conduction at or below the AV node and impulses from the atria cannot reach the ventricles

73. Summary In 3rd-degree AV heart block the pacemaker for the atria arises from the SA node while the pacemaker for the ventricles arises as an escape rhythm from the AV junction or from the ventricles With 3rd-degree AV heart block the upright and round P waves seem to “march right through the QRS complexes" revealing that there is no relationship between the P waves and QRS complexes 2nd- and 3rd-degree AV heart block can lead to decreased cardiac output