A quantitative description of normal AV nodal conduction curve in man

Abstract

The AV nodal conduction curve generated by the atrial extrastimulus technique has been described only qualitatively in man, making clinical comparison of known normal curves with those of suspected AV nodal dysfunction difficult. Also, the effects of physiological and pharmacological interventions have not been quantifiable. In 50 patients with normal AV conduction as defined by normal AH (less than 130 ms), normal AV nodal effective and functional refractory periods (less than 380 and less than 500 ms), and absence of demonstrable dual AV nodal pathways, we found that conduction curves (at sinus rhythm or longest paced cycle length) can be described by an exponential equation of the form delta = Ae-Bx. In this equation, delta is the increase in AV nodal conduction time of an extrastimulus compared to that of a regular beat and x is extrastimulus interval. The natural logarithm of this equation is linear in the semilogarithmic plane, thus permitting the constants A and B to be easily determined by a least-squares regression analysis with a hand calculator.

The Effects of Aging on AV Nodal Recovery Properties

“…[1][2][3] By plotting AV nodal resting intervals against the resultant AV nodal conduction time (AH interval), it is noticed that the latter is an exponential function of the former. [4][5][6][7] Although in children and young adults we found that there was an age dependent increase in the exponential time constant and the AV nodal effective refractory period (AVNERP), 8 in the older population this information was not available. The purpose of this study was to evaluate the effects of aging on these AV nodal recovery properties in the adults.…”

Variability of Ventricular Excitation Interval Does Not Reflect Fluctuation in Atrial Excitation Interval during Exercise in Humans: AV Nodal Function as Stabilizer

“…However, if it modulates the PR interval, this interval will be changed in parallel with the PP interval [1,2]. On the other hand, an intrinsic mechanism that the AV node possesses affects AV conduction time, as opposed to an alteration in sinoatrial rhythm [3,4]. Therefore the intrinsic mechanism of the AV node, rather than the extrinsic vagal mechanism, can contribute to such compensatory modulation of the PR interval.…”

“…On the other hand, an intrinsic mechanism that the AV node has affects AV conduction time as opposed to an alteration in sinoatrial rhythm. For example, when atrial pacing decreases cardiac cycle length, the AV interval lengthens [3,4,[8][9][10]. Neither the autonomic blockade nor cardiac denervation affects the response in AV conduction, supporting an intracardiac origin of the cycle length dependent effect [4,[8][9][10].…”

“…The AV conduction time is monitored as a PR interval from an electrocardiogram (ECG) or as a time interval between atrial and ventricular or His-bundle potentials from intracardiac electrodes. The beat-to-beat changes in AV conduction are controlled by both extrinsic and intrinsic mechanisms [1][2][3][4]. Both divisions of the autonomic nervous system richly innervate the AV node [2,5,6].…”

Characterization and Modeling of Atrioventricular Conduction during Atrial Fibrillation

“…The mathematical formulation presented in equation 2.1 has been widely used as the basis for later works [66,67,68,69,70,71,72,73,74]. Although, in some other works, the usefulness of hyperbolic or pseudo-linear approximations has also been suggested [75,76].…”