Beat number 1, 4 and 7 in leads V1 and V2 are ventricular premature complexes. They are identified as bizarre complexes without a preceding P wave and premature occurrence. Beat 1 is followed by a pause while beat 4 is not. Hence beat 4 is an interpolated ventricular premature complex. The PR interval of the basic rhythm is 200 msec, but the PR interval in the sinus beat after the interpolated premature complex is prolonged. Beat 5 has a PR interval of 280 msec. Similar lengthening of PR interval is seen for beat 4 in leads V3 and V4. This is an indication of concealed retrograde conduction of the ventricular premature complex which causes a prolongation of the anterograde conduction of the subsequent sinus beat.