Periodic premature stimulation of the atrium in isolated rabbit hearts demonstrated that cycle-length dependency of nodal conduction results from complex changes in propagation time at three levels.
This preclinical study demonstrates that cycle-length dependency of AV nodal conduction results from complex propagation time changes at three levels within the node.
To study the intranodal origin of the functional properties of the atrioventricular node, progressive changes in nodal cell activation time and cycle length occurring during complete sequences of periodic premature stimulation of the atrium were determined for 419 nodal cells recorded in 11 isolated rabbit heart preparations. The conduction time in proximal nodal cells including the N cells increased only at very short coupling intervals. Conduction time in the distal node (NH and H cells) first increased and then decreased with increasing prematurity. The major fraction of the basic and premature delays developed between N and NH cell activation, a period devoid of upstrokes. The effective and functional refractory periods were related to the minimum intervals between successive upstrokes at the node entrance and outlet, respectively. These results suggest that the cycle-length dependency of nodal conduction is the result of complex changes in propagation time occurring at three levels in the node, whereas the effective and functional refractory periods reflect reactivation limits of cells located at the node entrance and outlet, respectively.
Jacques Billette (Thu,) reported a other. Periodic premature stimulation of the atrium was evaluated on Changes in nodal cell activation time and cycle length. Periodic premature stimulation of the atrium in isolated rabbit hearts demonstrated that cycle-length dependency of nodal conduction results from complex changes in propagation time at three levels.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: