The 'pause' equals two or more times the PP-interval of the normal rhythm. One or more QRS-complex are not present during the 'pause', except when escape beats are present. This arrhythmia is characterized by the fact that the depolarization's of the sinus-node are not conducted. The SA conduction is disturbed. Escape rhythm of atrial or AV-junctional origin.
Frequency is dependent on the normal rhythm.
The first grade AV-block can be accompanied by a sinusbradycardia or a sinustachycardia. Normal QRS-complex, except with an intraventricular conduction disturbance. PQ-time is longer then normal. In adults normal PQ-time is not more then 0,20 sec., in children not more then 0,17 sec. Rhythm dependent on the basic rhythm.