Heart block

heart block

1. HEART BLOCK RATHEESH R.L

2. Normal conduction pathway: SA node -> atrial muscle -> AV node -> bundle of His -> Left and Right Bundle Branches -> Ventricular muscle

3. DEFINITION Heart block  is an abnormal  heart  rhythm where the  heart  beats too slowly ( bradycardia ). In this condition, the electrical signals that tell the  heart  to contract are partially or totally blocked between the upper chambers (atria) and the lower chambers (ventricles).

4. TYPES They are  further classified   as, First degree heart block ( first degree AV block)   second degree heart block (second degree AV block)   third degree heart block (third degree AV block)

5. FIRST DEGREE HEART BLOCK First - degree atrio -ventricular block  ( AV block ), or PR prolongation, is a disease of the electrical conduction system of the  heart  in which the PR interval is lengthened beyond 0.20 seconds.

6. The following are the most common causes of first-degree AV block: Intrinsic AVN disease Acute   myocardial infarction  (MI), particularly acute inferior wall MI Myocarditis Electrolyte disturbances ( eg ,  hypokalemia , hypomagnesemia ) Drugs (especially those drugs that increase the refractory time of the AVN, thereby slowing conduction)

7. First Degree Heart Block (1 º) SA Node – normal Normal P wave AV Node conducts more slowly than normal Prolonged PR Interval Rest of conduction is normal Normal QRS

8. Significance Clinical significance None Treatment None Note – this can progress to 2 º or 3º heart block

9. Second Degree Heart Block (2 º) Mobitz Type I ( Wenkebach ) Mobitz Type II

10. Second Degree Heart Block (2 º) Mobitz Type I (Wenkebach) Conduction through the AV Node – progressively delayed until a drop beat is seen

11. Second-degree atrio -ventricular (AV) block, or second-degree heart block, is characterized by disturbance, delay, or interruption of atrial impulse conduction through the AV node to the ventricles.

12. CAUSES Drugs (beta-blockers, calcium channel blockers, amiodarone ) Cardiomyopathy rheumatic fever, myocarditis varicella-zoster virus infection Rheumatic diseases Hypoxia Hyperkalemia Hypothyroidism  inferior wall myocardial infarction  

13. Second Degree Heart Block (2 º) Mobitz Type I (Wenkebach) PR Interval prolongs with each beat until a dropped beat is seen The PR Interval is NOT constant After each dropped beat, the PR interval is normal and the cycle starts again

14. Second Degree Heart Block (2 º) Mobitz Type I (Wenkebach) PR PR PR DROPPED BEAT

15. Significance Clinical Significance Slight symptoms e.g.. Lethargy, Confusion Treatment Pacemaker if during day &/or symptoms No treatment if at night Note – this can progress to 3 º Heart Block

16. Second Degree Heart Block (2 º) Mobitz Type II Conduction through the AV node is constant. PR interval is normal and constant Occasionally a dropped beat is seen

17. Second Degree Heart Block (2 º) Mobitz Type II PR PR DROPPED BEAT PR

18. Significance Clinical significance – this is more significant disease Treatment – pacemaker Note – this can progress to 3 º Heart Block

19. Third Degree Heart Block (3 º) (Complete) Complete failure of the AV Node No impulses from Sinus Node will pass through to the ventricles Some part if the conducting system will take over as pacemaker of the heart (even a myocardial cell 10-15 bpm)

20. Third-degree atrioventricular (AV) block, also referred to as third-degree heart block or  complete heart block , is a disorder of the cardiac conduction system where there is no conduction through the atrioventricular node.

21. Third Degree Heart Block (3 º) (Complete) P wave rate – normal Ventricular rate – slow Ventricular complex may be broad Idioventricular rhythm Complete dissociation between P waves & QRS

22. Third Degree Heart Block (3 º) (Complete) P P P P P QRS QRS

23. Significance clinical significance Symptoms LOC, Confusion, Dizziness, Low BP Can lead to standstill, VT or VF (stokes Adams) Treatment - pacemaker

24. NURSING MANAGEMENT Assess the high risk patients Monitor ECG of the patient Assess the family history of heart disease Assess the history of smoking and alcoholism Monitor lab values frequently especially serum cholesterol levels. Assess for CAD Monitor vital signs Instruct to avoid high fat and oil rich diet