Mechanisms Underlying Very-Low-Frequency RR-Interval Oscillations in Humans
- 11 August 1998
- journal article
- other
- Published by Ovid Technologies (Wolters Kluwer Health) in Circulation
- Vol. 98 (6), 547-555
- https://doi.org/10.1161/01.cir.98.6.547
Abstract
Background —Survival of post–myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency RR-interval variability in 10 young healthy subjects. Methods and Results —We recorded RR intervals and arterial pressures during three separate sessions, with the patient in supine and 40 degree upright tilt positions, during 20-minute frequency (0.25 Hz) and tidal volume–controlled breathing after intravenous injections: saline (control), atenolol (0.2 mg/kg, β-adrenergic blockade), atropine sulfate (0.04 mg/kg, parasympathetic blockade), atenolol and atropine (complete autonomic blockade), and enalaprilat (0.02 mg/kg, ACE blockade). We integrated fast Fourier transform RR-interval spectral power at very low (0.003 to 0.03 Hz), low (0.05 to 0.15 Hz), and respiratory (0.2 to 0.3 Hz) frequencies. β-Adrenergic blockade had no significant effect on very-low- or low-frequency RR-interval power but increased respiratory frequency power 2-fold. ACE blockade had no significant effect on low or respiratory frequency RR-interval power but modestly (≈21%) increased very-low-frequency power in the supine (but not upright tilt) position ( P Conclusions —Although very-low-frequency heart period rhythms are influenced by the renin-angiotensin-aldosterone system, as low and respiratory frequency RR-interval rhythms, they depend primarily on the presence of parasympathetic outflow. Therefore the prognostic value of very-low-frequency heart period oscillations may derive from the fundamental importance of parasympathetic mechanisms in cardiovascular health.This publication has 24 references indexed in Scilit:
- Effect of quinapril or metoprolol on heart rate variability in post-myocardial infarction patientsThe American Journal of Cardiology, 1996
- Effects of enalapril on heart rate variability in patients with congestive heart failureThe American Journal of Cardiology, 1995
- Effects of digoxin and enalapril on heart period variability and response to head-up tilt in normal subjectsThe American Journal of Cardiology, 1993
- ACE inhibition improves vagal reactivity in patients with heart failureAmerican Heart Journal, 1990
- Kinetic-dynamic relations and individual responses to enalapril.Hypertension, 1990
- Enalaprilat, a new parenteral angiotensin-converting enzyme inhibitor: Rapid changes in systemic and coronary hemodynamics and humoral profile in chronic heart failureJournal of the American College of Cardiology, 1987
- Pressure-Dependent Renin Release: The Kidney Factor in Long-Term Control of Arterial Blood Pressure in Conscious DogsClinical and Experimental Hypertension. Part A: Theory and Practice, 1987
- Vasodepressor role of endogenous bradykinin assessed by a bradykinin antagonist.Hypertension, 1986
- Power Spectrum Analysis of Heart Rate Fluctuation: A Quantitative Probe of Beat-to-Beat Cardiovascular ControlScience, 1981
- Autonomic blockade by propranolol and atropine to study intrinsic myocardial function in manJCI Insight, 1969