Dynamics of the uncorrected QT interval during vagal-induced lengthening of RR intervals.
Analysis of 21 episodes of vagal-induced atrioventricular block showed that the uncorrected QT intervals at the end of the corresponding RR pauses were not prolonged, in reference to the pre-block QT intervals, with pauses shorter than 1,280 ms. Subsequently, they gradually lengthened as the RR pauses progressively increased to 13,710 ms. This dynamic behavior of the QT interval in subjects without structural heart disease could have resulted from a complex interaction between the cumulative effects of previous cycle lengths (memory effect?) and the autonomic nervous system.
Castellanos
A
A
University of Miami School of Medicine, Division of Cardiology, Florida 33101, USA.
Moleiro
F
F
Lopera
G
G
Huikuri
H
H
Interian
A
A
Myerburg
R J
RJ
D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000503:physiopathology; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D006327:Heart Block / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology*; D016276:Ventricular Function / Q000502:physiology