Electrocardiogram (ECG) showing concurrent Mobitz type I (Wenckebach) atrioventricular (AV) block and inferior myocardial infarction (MI)

This rhythm strip shows a Mobitz type I (Wenckebach) atrioventricular block with 4:3 and 3:2 conduction and progressive prolongation of the PR intervals of conducted beats. The marked ST segment elevation suggests acute inferior wall ischemia or infarction that may be responsible for the arrhythmia.

Normal rhythm strip in lead II. The PR interval is 0.15 sec and the QRS duration is 0.08 sec. Both the P and T waves are upright.