Incidence of 'dual A-V nodal pathways' in first- and second-degree type I supra-His A-V block.
The incidence of 'dual A-V nodal pathways', diagnosed on the basis of spontaneous or induced modifications in the PR interval, has been assessed in a group of 168 consecutive patients with first- (77) and second-degree (91) type I supra-His block. 'Dual A-V nodal pathways' were found in 12 cases (16%) with first-degree and in 7 cases (7.7%) with second-degree type I supra-His A-V block. His bundle recording confirmed the hypothesis that PR interval variations observed in these cases are due to modifications in the AH interval and thus to changes in A-V nodal conduction velocity. The electrophysiologic study also showed that the phenomenon was easily reproduced by atrial stimulation. The frequent association between 'dual A-V nodal pathways' and supra-His blocks suggests that the block mechanism should be studied in depth as it could have prognostic and therapeutic implications.
Di Biase
M
M
Division of Cardiology, University of Bari, Italy.
Favale
S
S
Rizzo
U
U
Minafra
F
F
Rizzon
P
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D001283:Atrioventricular Node / Q000503:physiopathology*; D002036:Bundle of His / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged