Patterns of human atrioventricular nodal accommodation to a sudden acceleration of atrial rate

• Published in: The American journal of cardiology Vol. 53; no. 1; pp. 71 - 76
• Main Authors: Lehmann, Michael H., Denker, Stephen, Mahmud, Rehan, Akhtar, Masood
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 1984
• Subjects: Adaptation, Physiological; Adult; Aged; Atrial Function; Atrioventricular Node - physiology; Cardiac Pacing, Artificial; Electrocardiography; Female; Heart Conduction System - physiology; Heart Rate; Humans; Male; Middle Aged
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/0002-9149(84)90686-6

Atrioventricular nodal (AVN) accommodation to an abrupt increase in atrial rate was systematically studied in 10 patients using a pacing protocol incorporating a programmable pause (S 1S 2) between the last beat of basic atrial drive (S 1S 1) and the onset of an 18-beat paced atrial train (S 2S 2) of shorter constant cycle length (CL) than that of S 1S 1. Pacing was repeated, varying S 1S 2 while keeping S 1S 1 and S 2S 2 CLs fixed. In all patients there existed a zone of 1 or more critical S 1S 2 intervals for which the new steady-state AVN conduction time (S 2H 2) was attained “instantaneously,” that is, with the first beat, and maintained for subsequent beats of the S 2S 2 train. At S 1S 2 intervals that exceeded or were less than critical values, S 2H 2 progressively increased (crescendo pattern) or decreased (decrescendo pattern), respectively, until the steady-state value was achieved. The zone of S 1S 2 intervals that resulted in decrescendo or instantaneous AVN accommodation contracted when either the S 1S 1 CL was increased or the S 2S 2 CL was shortened. These findings have relevance to the interpretation of electrophysiologic studies and explain the spectrum of AVN accommodation patterns observed at the onset of supraventricular tachycardia.