Recurrent resemblance in potential topography at different instants during ventricular depolarization and repolarization. Normal conduction contrasted with left bundle branch block and paced beats.
During ventricular activation and recovery, potential distribution may be exquisitely reproduced on instantaneous maps separated in time by many milliseconds. The timing and duration of these periods of strong resemblance (absolute r = 0.80 over 142 thoracic reference sites) may provide useful insight into the underlying patterns of the spread of activation and resumption of the repolarized state. This study examined 80 normal volunteers, 35 patients with left bundle branch block (LBBB), and 41 patients with permanent pacemakers. Normal subjects showed three basic patterns of recurrent surface map resemblance: (1) positive correlation between maps in early QRS and those throughout ST-T, but with greatest focus in late ST-T; (2) negative correlation between maps in early QRS and late QRS; and (3) negative correlation between maps in late QRS and early ST-T. These findings may be hypothetically attributed to the retention or recreation of similar relationships between the anatomic distributions of resting versus active or plateau versus repolarizing cells on the endocardial and epicardial surfaces, respectively. On the other hand, patients with LBBB and pacemakers were distinctly different in the timing and frequency of sustained resemblances. In these two states, there was sustained or continuing resemblance (positive correlation) between successive maps throughout QRS and again between successive maps through ST-T. In addition, the surface map pattern found throughout ST-T consistently appeared as the negative correlate of the preceding pattern that had dominated QRS.
Sridharan
M R
MR
Veterans Administration Medical Center, Augusta, GA 30910.
Flowers
N C
NC
Wilson
J A
JA
Horan
L G
LG
D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology*; D004562:Electrocardiography; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D010138:Pacemaker, Artificial