Atrioventricular Block

Characterized by an interrupted or delayed conduction between the atria and the ventricles

1st Degree Heart Block

• PR interval greater than 0.2 seconds (5 small squares)

• Can be a sign of CAD, acute rheumatic carditis, digoxin toxicity or electrolyte disturbance, but does not usually require treatment

• Long term follow-up recommended

2nd Degree Heart Block

• Intermittent absence of QRS complexes - indicates there is a blockage between the AV node and the ventricles

Mobitz type 1

• Progressive lengthening of the PR interval, eventually resulting in a dropped beat (P wave with no QRS)

• Often a normal variant and seen in individuals with a high vagal tone without evidence of structural heart disease

Mobitz type 2

• Each P wave is associated with a QRS complex until there is one atrial conduction or P wave that is not followed by a QRS

• Often progresses to 3rd degree AV block

3rd Degree Heart Block

• Complete atrial block - atrial contraction is normal, but no beats are conducted to the ventricles

• No relation between P wave and QRS complexes, but both are present

• Abnormally shaped QRS due to abnormal spread of conduction throughout ventricles

• Always indicates underlying disease

Management

• Hypotension

• Decreased Conciousness

• Shock

• Chest Pain

• Rales → Heart Failure