Atrioventricular (AV) block and Sinus Pause
PR interval gets progressively prolonged, suggesting second degree type I AV block. But the pause is not containing a P wave, suggesting a sinus pause in addition to AV block. The pause helps the AV junction to recover and the next cycle starts with a lesser PR interval. Such combination of dual nodal disease is seen in structural nodal disease or sick sinus syndrome as well as in the acute phase of inferior wall myocardial infarction.