First Degree Heart Block

FIRST DEGREE HEART BLOCK

First degree atrioventricular (AV) junctional block may be caused by heart disease (Coronary artery disease CAD), acute myocardial infarction (MI), AV node ischemia, and drugs that act at the AV node. The AV delays the progression of the impulse from the sinoatrial (SA) node for an abnormal length of time

Identifying characteristics

The rate is normal: the rhythm is regular: P wave is normal: and the PR interval is prolonged beyond 0.20 s. The QRS complex is normal and conduction is normal except for the prolonged delay at the AV node.

Risk

First-degree block is not a serious dysrhythmia in itself. It may progress to a second-degree type 1 block and less commonly to a second-degree type 2 or third-degree block.

Treatment

If the PR interval is less than 0.25s and it does not increase, no treatment may be required. The length of the PR is not significant as the effect on stroke volume and heart rate. No treatment is indicated unless a bradycardia results.

Nursing intervention

Document the dysrhythmia with a rhythm strip. Monitor the patient closely for progression to a slower heart rate or a worsening block. If progress develops document with a rhythm strip and notify the physician immediately.