title: Characteristics of ventriculoatrial conduction in patients with enhanced atrioventricular nodal conduction.
abstract: To study the characteristics of the ventriculoatrial conduction system in patients capable of rapid antegrade atrioventricular conduction, electrophysiologic studies were performed in 23 subjects capable of 1:1 atrioventricular conduction at atrial cycle lengths less than or equal to 300 ms (Group I), and in 23 subjects with normal 1:1 atrioventricular conduction (Group II). During ventricular pacing, ventriculoatrial block at all cycle lengths was seen in 5/23 (22%) in Group I and in 7/23 (30%) in Group II patients (p = NS). In the remainder, the minimum ventricular pacing cycle length maintaining 1:1 ventriculoatrial conduction was 359 +/- 85 ms in Group I, compared to 444 +/- 118 ms in Group II (p less than .02). Both flat and exponential VA conduction interval curves, drawn as a function of pacing cycle length, were observed in both groups. Discontinuous ventriculoatrial conduction curves were seen in 5/18 (28%) Group I and 1/16 (6%) Group II patients (p = NS). In conclusion, retrograde ventriculoatrial conduction, when present in patients capable of rapid 1:1 atrioventricular conduction, is maintained at shorter cycle lengths than in patients with normal atrioventricular conduction. Quantitative, rather than qualitative, differences distinguish the two groups.
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology*; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006327:Heart Block / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008151:Lown-Ganong-Levine Syndrome / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D013575:Syncope / Q000503:physiopathology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology; D013617:Tachycardia, Supraventricular / Q000503:physiopathology