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Influence of Sympathetic Heart Rate Modulation on RT Interval Rate Adaptation in Conscious Dogs
Author(s) -
PLADYS PATRICK,
MAISONBLANCHE PIERRE,
GOUT BERNARD,
BADILINI FABIO,
BRIL ANTOINE,
CARRÉ FRANÇOIS
Publication year - 2000
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1046/j.1460-9592.2000.01604.x
Subject(s) - medicine , atenolol , heart rate , cardiology , vagal tone , sinus rhythm , heart rate variability , qrs complex , autonomic nervous system , rr interval , electrocardiography , rhythm , prazosin , beat (acoustics) , anesthesia , baroreflex , atrial fibrillation , blood pressure , receptor , physics , acoustics , antagonist
PLADYS, P., et al. : Influence of Sympathetic Heart Rate Modulation on R Interval Rate Adaptation In Conscious Dogs . The objective was to test if changes in autonomic tone still influenced the RT‐RR relationship when full RT adaptation is completed, when heart rate is controlled, and when beat‐to‐beat variability is abolished by atrial pacing. Eight dogs (8–11 kg) were chronically instrumented with atrial pacing electrodes. Digital ECG (1,000 Hz, 12 bits) were recorded from healthy conscious dogs during spontaneous sinus rhythm and during atrial pacing. The protocol was repeated before and after atenolol (2 mg/kg), prazosin (0.5 mg/kg), or atenolol + prazosin. A vocal incitation was used as sympathetic stimulation. Beat‐to‐beat quantitative analysis of the RT interval (from QRS apex to end of T wave) was correlated with the preceding RR by linear regression. In spontaneous rhythm, atenolol increased RR (P < 0.001), RT (P < 0.001), and short‐term heart rate variability (P < 0.01) and decreased RT‐RR slopes (P < 0.001). Prazosin did not significantly modify any parameter. Sympathetic stimulation decreased RR (P < 0.001), RT (P < 0.05), and short‐term heart rate variability (P < 0.01) and increased RT‐RR slopes (P < 0.001). In atrial pacing, the RTRR slopes were steeper during pacing than during spontaneous rhythm but were not modified by pharmacological manipulation of the autonomic nervous system. During sinus rhythm the RT‐RR relationship is increased by sympathetic stimulation and decreased by β–blockade. When heart rate modulation and the effects of the time delay in RT rate adaptation are abolished by atrial pacing, the influence of autonomic tone on RT rate adaptation disappears.