Power Spectral Analysis of Heart Rate and Arterial Pressure Variabilities as a Marker of Sympatho-Vagal Interaction in Man and Conscious Dog

• Published in: Circulation research 1986-08, Vol.59 (2), p.178-193
• Main Authors: PAGANI, MASSIMO, LOMBARDI, FEDERICO, GUZZETTI, STEFANO, RIMOLDI, ORNELLA, FURLAN, RAFFAELLO, PIZZINELLI, PAOLO, SANDRONE, GIULIA, MALFATTO, GABRIELLA, DELL ʼORTO, SIMONETTA, PICCALUGA, EMANUELA, TURIEL, MAURIZIO, BASELLI, GIUSEPPE, CERUTTI, SERGIO, MALLIANI, ALBERTO
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Antagonists; Adult; Age Factors; Animals; Biological and medical sciences; Blood Pressure; Consciousness; Dogs; Fundamental and applied biological sciences. Psychology; Heart; Heart Rate; Humans; Middle Aged; Posture; Respiration; Spectrum Analysis; Sympathetic Nervous System - physiology; Vagus Nerve - physiology; Vertebrates: cardiovascular system
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.res.59.2.178

In 57 normal subjects (age 20–60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90° upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) β-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at ∼0.25 Hz and a low frequency at ∼0.1 Hz, with a normalized low frequencyhigh frequency ratio of 3.6 ± 0.7. With tilt, the low-frequency component became largely predominant (90 ± 1%) withalow frequencyhigh frequency ratio of 21 ± 4. Acute β-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequencyhigh frequency ratio induced by tilt. Chronic β-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequencyhigh frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequencyhigh frequency ratio (0.7 ± 0.1); during tilt, the increase in the low frequencyhigh frequency ratio (8.3 ± 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequencyhigh frequency ratio at rest of 2.8 ± 0.7, which became 17 ± 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increas