Major types of heart block

2.  Introduction .
 Definition Of Atrio-ventricular Heart Block .
 Etiology .
 Types of Heart Block :
 First degree heart block .
 Second degree heart block.
 Third Degree ( Complete ) heart block .
 Clinical Manifestation .
 Management .
 Nursing Diagnosis.

3.  Cardiac Conduction system and Normal ECG:

4.  It is a partial or complete interruption of
impulses transmission from Atrium to
Ventricle .

5.  Acute myocardial Infarction:
specially Inferior MI .
 Medications : Beta Blockers ,
calcium channel blockers or
Digoxin .
 Inflammation : myocarditis ,
Rheumatic fever or Lupus .
 Infections :Toxoplasmosis .
Causes of permanent block
 Acute myocardial infarction :
specially Anterior MI .
 Degeneration of Conduction
system due to : advanced age or
cardiac calcification of mitral or
aortic valve .
 Latrogenic damage : due to
arrhythmia Ablation at the site of
AV Junction or Valve surgery
(Tricuspid valve replacement) .

6.  According to relation between Atrium andVentricle ,
we can detect three degrees of AV heart block :
▪ First Degree Heart Block :
slowing of Conduction .
▪ Second Degree Heart Block :
intermittent interruption of conduction
subtype into :
▪ Mobitz Type I .
▪ Mobitz Type II .
▪ Third Degree ( Complete ) Heart Block :
Complete interruption of conduction .

7.  It is not consider complete block ,it is just slow
down of impulses that come from SA node
more than the normal .

8.  ECG Manifestation :
 Prolongation of PR interval more than 0.2 second or
more than 5 small squares .
 Constant PR interval from beat to another .
 Regular Rhythm .
 Normal Rate or slightly slow .

9.  This problem occur at the level of AV node itself .
 It also is not considered a complete block .

10.  ECG Manifestations :
 It is characterized by progressive prolongation of PR
interval until dropped QRS , then the cycle start again .
 Constant PP interval .
 Irregular Rhythm .
 Normal or slightly slow Rate .

11.  This type of block occur below AV node at the level of Hiss
Bundle.
 Also is considered incomplete but high risk to be
complete.
 Some of electrical impulses are unable to reach ventricles .

12.  ECG Manifestation :
 Recurrent appearance of non-conducted P waves which
is blocked and not followed by QRS complex ( indicate
to block of impulses to reach ventricle ) .
 PR interval and PP interval are constant .
 QRS usually normal but sometimes become Wide .

13.  Characterized by Atrio-ventricular dissociation .
 This blockage level is infra-nodal ( Bilateral Bundle
Branches ) .
 Atrial and ventricular activities are unrelated due to
complete block of electrical impulses to reach the
ventricle.
 Another pacemaker distal to
the block takes over in order to
activate the ventricles or
ventricular standstill will occur.

14.  ECG manifestation :
 Dissociation between P wave and QRS
 P wave may overlap on T wave or QRS complex .
 PR interval is not constant
 Rate usually less than 40 .
 QRS complex usually wide and sometimes normal .

15.  Usually first degree and sometimes second degree
are asymptomatic .
 The most common signs and symptoms :
 Sever Bradycardia .
 Hypotension .
 Syncope ( fainting ) .
 Chest pain .
 Dyspnea .
 Dizziness .

16.  General Management :
 Cardiac monitoring : for close observation .
 Oxygen supply : to Manage de-saturated patients .
 IV Line :To support blood pressure with fluids .
 Atropine standby : to treat bradycardia specially
incomplete degrees .

17. Management of heart block depend on symptoms
 First degree heart block :
this type usually is asymptomatic and not indicated for treatment :
 Close observation of Hemodynamic status .
 Discontinue of some medication that cause bradycardia such as :
▪ Beta-blockers : Concor
▪ Digoxins : Lanoxine
▪ calcium channel blockers : Diltiazem .
Just for

18.  Second Degree and Complete heart block :
 Usually these degrees are associated with sever bradycardia which can be
treated by atropine .
 Associated conditions should be treated correctly such as :
▪ Myocardial infarction.
▪ Electrolyte disturbance (hyperkalemia).
▪ Digitals intoxication.
 Transvenous temporary pacemaker is indicated for pt with sever
bradycardia who has no effect of Atropine administration (For 24 hours : 48
hours .)
 Transcutanous permanent pace-maker is indicated for
chronic AV block .

19.  Nursing priorities :
 Decrease cardiac output related to failure of the heart to pump
enough blood to meet metabolic needs of the body as manifested by
hypotension .
 Acute chest Pain related to decrease blood flow to myocardium
through coronary arteries .
 Ineffective Tissue perfusion related to decrease cardiac output as
manifested by pt syncope .
 Fatigue related to increase hypoxic tissue and slowed removal of
metabolic wastes.