Atrio-Ventricular Block

Prepared by Islam Mohamed

Out-lines: 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.

IntroductionCardiac Conduction system and

Normal ECG:

: Definition of AV Block

It is a partial or complete interruption of

impulses transmission from Atrium to Ventricle .

Causes of Atrio-ventricular block

Causes of Temporary block 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) .

: Types of AV Heart block According to relation between Atrium and Ventricle ,

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.

First Degree Heart Block :

It is not consider complete block ,it is just slow down of impulses that come from SA node

more than the normal .

First Degree Heart Block: 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 .

Second Degree heart block Mobitz I

This problem occur at the level of AV node itself .

It also is not considered a complete block .

Second Degree heart block Mobitz I

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 .

Second Degree heart block Mobitz II

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 .

Second Degree heart block Mobitz II

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 .

Third Degree ( Complete )Heart Block 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.

Third Degree (Complete )Heart Block 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 .

Clinical Manifestation: Usually first degree and sometimes

second degree are asymptomatic .

The most common signs and symptoms : Sever Bradycardia . Hypotension . Syncope ( fainting ) . Chest pain . Dyspnea . Dizziness .

Management and Treatment:

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 .

Management and Treatment :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

Management and Treatment:

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.

Nursing Diagnosis: 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.

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