Rapid fluctuations in atrial fibrillatory electrophysiology detected during controlled respiration

Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we...

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Published inAmerican journal of physiology. Heart and circulatory physiology Vol. 58; no. 2; pp. H754 - H760
Main Authors HOLMQVIST, Fredrik, STRIDH, Martin, WAKTARE, Johan E. P, BRANDT, Johan, SÖRNMO, Leif, ROIJER, Anders, MEURLING, Carl J
Format Journal Article
LanguageEnglish
Published Bethesda, MD American Physiological Society 01.08.2005
Subjects
Biological and medical sciences
Blood vessels
Electrocardiography
Fundamental and applied biological sciences. Psychology
Nervous system
Vertebrates: cardiovascular system
Fluctuations
Arrhythmia
Atrial fibrillation
Electrophysiology
Cardiovascular disease
Excitability disorder
Vertebrata
spectrum analysis
Mammalia
noninvasive
Autonomic nervous system
Heart disease
Circulatory system
Respiration
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Summary:Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency of the fibrillating atria. Eight patients (four women; median age 63 yr, range 53-68 yr) with chronic atrial fibrillation (AF) and third-degree atrioventricular block treated by permanent pacemaker were studied. ECG was recorded during baseline rest, during 0.125-Hz frequency controlled respiration, and finally during controlled respiration after full vagal blockade. We calculated fibrillatory frequency using frequency analysis of the fibrillatory ECG for overlapping 2.5-s segments; spectral analysis of the resulting frequency trend was performed to determine the spectrum of variations of fibrillatory frequency. Normalized spectral power at respiration frequency increased significantly during controlled respiration from 1.4 (0.76-2.0) (median and range) at baseline to 2.7 (1.2-5.8) (P = 0.01). After vagal blockade, the power at respiration frequency decreased to 1.2 (0.23-2.8) (P = 0.01). Controlled respiration causes cyclic fluctuations in the AF frequency in patients with long-duration AF. This phenomenon seems to be related to parasympathetic modulations of the AF refractory period. [PUBLICATION ABSTRACT]
ISSN:0363-6135
1522-1539