ECG Case 55: Sinus Rhythm with First Degree AV Block

Sinus Rhythm with First Degree AV Block
Sinus Rhythm with First Degree AV Block

ECG Interpretation

  • Sinus rhythm, 55/min
  • Prolonged PR interval of 320 ms
  • Normal axis
  • Normal ST segments and T waves

Clinical Interpretation

Sinus rhythm with prolonged PR interval that indicates a first degree AV Block. First degree AV block does not cause any haemodynamic impairment, and by itself is of little significance. However, when a patient has symptoms (in this case dizziness) which might be due to a bradycardia, there may be episodes of second or third degree block, or possibly Stokes–Adams attacks, associated with a slow ventricular rate.

What to do next ?

The appropriate action is to request an ambulatory ECG, recorded over 24 h, in the hope that the patient will have one of her attacks of dizziness during this time.

It would then be possible to see whether the dizziness was associated with a change in heart rhythm. First degree block itself is not an indication for permanent pacing or for any other intervention.