Attention is drawn to differences of opinion regarding the upper normal limit of P-wave duration and the definition of intra-atrial block. There seems to be good reason for accepting 0.11 sec. as the upper limit of normal and a P-wave duration of 0.12 sec. or more as indicative of intra-atrial block. By this criterion 4,500 consecutive electrocardiograms taken in a general hospital were examined and the findings are reported.
- © 1956 American Heart Association, Inc.