472
SECTION III: Abnormal Rhythms
Figure 22.17 presents another example of type II block. Note that the PR intervals re-
main unchanged despite longer and shorter RP intervals (i.e., there is no RP/PR reciproc-
ity). The recording illustrates the two sources of variation in RP intervals: a change in the
AV conduction ratio (from 1:1 to 2:1) and the presence of a ventricular premature beat.
V
1
F I G U R E 2 2 . 1 7 .
A lead V1 rhythm strip from a patient with chronic congestive heart failure.
There is a lack of increase in the PR interval when a decrease occurs in the RP interval.
