Heart block is a condition where the heart beats more slowly or irregularly due to a disruption in the electrical signals controlling the heartbeat. There are three main types of heart block - first, second, and third degree - which differ based on the level and extent of disruption in electrical signal conduction. Diagnosis involves ECG, echocardiogram, and cardiac monitoring. Treatment ranges from medication and pacemaker implantation depending on symptoms and severity of block. Temporary pacemakers are used initially, while permanent pacemakers provide long-term treatment for persistent blocks.

1. HEART BLOCK
Presented By:
Mr. Nandish.S
Asso. Professor
Mandya Institute of Nursing Sciences

6. DEFINITION :
 It is a condition where the heart beats more slowly or with an
abnormal rhythm.
 It is a disorder in the heart’s rhythm due to fault in the natural
pacemaker.
 Atrioventricular block is a disruption in the electrical signals that
control heartbeat.
 It is a disturbance of impulse conduction that can be permanent or
transient contributing to anatomical or functional impairment.

7. ETIOLOGY & RISK FACTORS :
 Medications like digitalis, calcium channel blockers, beta blockers ….
 Lyme disease
 Myocardial Infarction & Ischemia
 Valvular disorders
 Cardiomyopathy
 Endocarditis & Myocarditis
 Increased Vagal Tone.
 Rheumatic Heart Disease
 Hyperthyroidism

8. TYPES OF HEART BLOCK :
1. First degree AV Block
2. Second Degree AV Block
- Mobitz type I or Wenckebach phenomena
- Mobitz type II AV Block
3. Third Degree AV Block

9. FIRST DEGREE AV BLOCK :
 It occurs when all the impulses are conducted through AV Node into
the ventricles at a rate slower than normal.
 It is a disease of electrical conduct system in which PR interval is
lengthened than 0.20 seconds.

10. Causes for First Degree Heart Block :
- Intrinsic AVN Disease
- Acute Myocardial Infarction
- Myocarditis
- Hypokalemia
- Medications (that increase refractory time of AVN)

11. SECOND DEGREE HEART / AV BLOCK
Type I or Mobitz Type I or Wenckebach phenomena
 It is characterized by disturbance, delay or interruption of atrial
impulse conduction through the AV Node to ventricles.
 PR interval prolongs with each beat until a dropped beat is seen. After
each dropped beat, new cycle begins which is normal.

12. Causes for Mobitz type I AV Block :
 Cardiomyopathy
 Rheumatic Fever
 Varicella zoster infection
 Hyperkalemia
 Hypothyroidism
 Hypoxia
 Inferior wall MI
 Medications like Beta blockers, calcium channel blockers,
Amiodarone…

13. Type II or Mobitz type II AV Block :
 It occurs when only some of the atrial impulses are conducted
through AV Node into ventricles.
 PR interval is usually regular & constant, but may be irregular.
 Occasionally a dropped beat is seen.
 It is more significant disease.

14. Third Degree AV Block :
 It is also called as complete heart block, it is a serious disorder of
conductive system, where there is no conduction through the Atrio-
Ventricular node.
 Complete failure of AV Node.
 No impulses from sinus node will pass through to the ventricles.
 Complete dissociation between P wave & QRS Complex, where
more P waves are seen before one QRS complex.

17. Types of Infra – Hisian Block :
- Left Bundle Branch Block
a. Left Anterior Fascicular Block
b. Left Posterior Fascicular Block
- Right Bundle Branch Block

18. Left Bundle Branch Block :
 In this condition, activation of Left ventricle is delayed which results
in the left ventricle contracting later than right ventricle.
 It is caused due to Aortic stenosis, Cardiomyopathy, Acute MI,
Coronary Artery Disease, Aortic Regurgitation.
 It is manifested by prolongation of QRS complex, duration is more
than 120 ms in ECG.

19. Right Bundle Branch Block :
 In is the right ventricle is not directly activated by impulses travelling
through right bundle branch block.
 Heart beat is originated above the ventricle.
 It is manifested by QRS complex less than 100 ms in ECG.

20. CLINICAL FEATURES :
 Decreased heart rate or Bradycardia
 Irregular Heart beat
 Shortness of breath
 Syncope or Fainting
 Fatigue
 Chest pain
 Light headedness
 Seizures
 In severe cases : breathlessness
 Breathlessness on exertion

21. DIAGNOSTIC STUDIES :
- History collection & physical examination
- ECG
- Echocardiography
- Holter monitor
- Stress Test
- Continuous cardiac monitoring
- Blood examination (cardiac markers)

22. Management :
- For asymptomatic patients, decreasing or eliminating the cause is
planned by holding the medications.
- For symptomatic patients, medications such as Atropine, Epinephrine,
Isoproterenol, Dopamine are given to increase BP and Heart rate.
- Temporary Pacing can be initiated for advanced AV Block, acute MI.
- Permanent Pacemaker is planned if the block persists.

23. PACE MAKER THERAPY
Definition :
o It is an electric instrument that provides electrical stimuli to the heart
muscle.
o They are usually used when a patient has a slower than normal
impulse formation or a conduction disturbances that cause symptoms.
Types :
 Temporary
 Permanent

24. Temporary Pacemaker :
It is used until long term therapy can be initiated.
Indications :
• Cardiac catheterization
• Coronary Angioplasty
• Before implantation of permanent Pace maker
• After open heart surgery
• Acute Anterior MI with 2nd or 3rd Degree block
• Acute Inferior MI
• Ventricular Tachycardia
• Atrial Flutter
• Brady or Tachy Arrhythmias

25. Types of Temporary Pacemaker
- Transcutaneous pacing (External)
- Transvenous pacing
- Transthoracic pacing
- Transesophageal pacing

26. Transcutaneous Cardiac Pacing :
• It is a non invasive & delivers electricity from the external power
source.
• This causes the depolarization of excitable myocardial tissue by
pulsed electrical current conducted through the chest wall, between
electrodes adherent to the skin.

27. Transvenous Pacing :
An intravenous catheter electrode is positioned endocardially through
subclavian or external Jugular venous route and this is then connected to
an external Generator by a lead connector.
Types :
 Bipolar Electrodes – both anode & cathode are intra thoracic.
 Unipolar – anode is extra thoracic.
Insertion Site :
- Right External Jugular vein - Left Subclavian vein
- Femoral vein - Brachial vein.

30. Transthoracic Cardiac Pacing :
 It is a technique of pacing the heart with an electrode introduced
percutaneously into the ventricular cavity using a needle Trocar
introducer.
 It was used in patients with acute unstable dysrhythmia until
transcutaneous pacing is introduced.

31. Trans esophageal pacing :
Trans esophageal pacing & recording is done by using specialized or
simple catheters.
There are 2 types.
- The pill electrode, connected to flexible wire that patient swallows
with water, which needs patient's collaboration.
- A flexible catheter that can be used in unconscious or intubated
patients.
Bipolar flexible catheter is introduced into esophagus through nose after
local anaesthesia / throat anaesthesia. Lead is introduced with guide
wires. It is positioned into esophagus in order to record posterior
paraseptal atrial electro gram.

32. Complications :
 Haemo or Pneumothorax
 Rupture of major blood vessels
 Perforation of right ventricle
 VT or VF
 Cardiac Arrest
 Heart Failure