Observations in XXXX showing A-V junctional echoes with a shorter P-R than R-P interval.

@entity1 @entity11705 @entity713 @entity11706 @entity591 @entity3897
Single test stimulation of the ventricle revealed initiation of echoes with a supraventricular QRS complex with a shorter P-R than R-P interval in 28 of 300 @entity1 consecutively studied with programmed electrical stimulation of the heart because of documented or suspected @entity591 . In all 28 the initiation of echoes was related to a discontinuity in the retrograde conduction curve. In 10 @entity1 a different atrial activation sequence in the endocavitary leads was present before and after the discontinuity in the retrograde conduction curve. In five of these a sustained @entity591 with a shorter P-R than R-P interval could be initiated, and in all five @entity1 an accessory pathway with a long conduction time as the retrograde arm of the @entity591 circuit could be demonstrated. In these five @entity1 spontaneous initiation of @entity591 was observed during sinus rhythm or after @entity11706 . @entity591 accelerated after the administration of @entity3897 . In the remaining 23 @entity1 the initiation of echoes showing a shorter P-R than R-P interval was nonsustained. In these @entity1 spontaneous @entity11705 or initiation by @entity11706 was not observed, and echoes with this relation of the P-R and R-P intervals systematically disappeared after administration of @entity3897 . It is postulated that in these @entity1 a slow atrioventricular (A-V) nodal pathway is used in the retrograde direction during echoes showing a shorter P-R than R-P interval. @entity713 junctional @entity591 showing this relation between P-R and R-P intervals favors incorporation of an accessory pathway with slow retrograde conduction in the @entity591 circuit.
