© 1999 by European Society of Cardiology
Copyright © 1999, European Society of Cardiology
Role of the differential bombardment of atrial inputs to the atrioventricular node as a factor influencing ventricular rate during high atrial rate
Department of Cardiology, Electrophysiology Section, The Cleveland Clinic Foundation, Cleveland, OH, USA
* Corresponding author. Correspondence address: Hôpital Cardiologique du Haut-Lévêque, 19, Avenue de Magellan, Clinical Cardiac Pacing and Electrophysiology Department, Pr. J. Clémenty and Pr. M. Haïssaguerre, 33600 Pessac, France. Tel.: +33-556-556-471; fax: +33-556-556-509 stgarrigue{at}aol.com
Objectives: The role of the atrial inputs for the conduction through the atrioventricular node (AVN) at slow rates and during reentrant tachycardia is well acknowledged, although still controversial. However, the relationship between the sequence and rate of atrial engagement of the AVN inputs and the resulting ventricular rate during high atrial rate remains unclear. This study provides quantitative description of complex AVN input—output correlations determining the ventricular rate during random high atrial rate. Methods and results: 12 rabbit heart preparations were used to evaluate the ventricular rate during programmed regular high atrial rate pacing or random pacing from eight atrial sites. Electrograms were recorded at the posterior (P) and anterior (A) AVN inputs, and at the bundle of His along with nodal cellular action potentials. Lorenz-plots and input—output-rate correlations were used to quantify the ventricular rate under different pacing protocols. Small alternations in the sequence of activation of P and A resulted in substantial changes of the organization of the intranodal cellular responses and the ventricular rate. The ventricular rate was shown to be significantly dependent on the site of high rate pacing (P<0.01) and on the resulting mean rate of inputs activation. Furthermore, the asymmetry between P- and A-bombardment was an important determinant, so that high ventricular rate was associated with large difference between the inputs’ rates and vice versa (P<0.05). Conclusions: The prevailing ventricular rate during high atrial rate is a complex dynamic parameter that depends not only on the global mean atrial rate but, in a major part, on the differential bombardment of the AVN inputs and on the site of initiation of the atrial wave fronts.
KEYWORDS A=anterior AVN input; also, electrograms recorded at this location; AA=interval measured between two consecutive electrograms at the A-input; AVN=atrioventricular node; HAR=high atrial rate; HH=interval measured between two consecutive His electrograms; P=posterior AVN input; also, electrograms recorded at this location; PP=interval measured between two consecutive electrograms at the P-input
1 Dr. Garrigue has been Research Fellow at the Cleveland Clinic Foundation during these studies.