Browsing by Subject "heart rate variability"
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Item Effects of Cervical Manipulation on Cardiac Autonomic Control(2006-05-01) Giles, Paul David; Michael Smith; Scott Stoll; Walter WitryolGiles, Paul David, Effects of Cervical Manipulation on Cardiac Autonomic Control. Master of Science (Clinical Research and Education – OMM), May 2006, pp, 1 table, 8 figures, references. Objective: Osteopathic Manipulative Medicine treatment (OMT) regimes often focus on treating the Autonomic Nervous System (ANS) in addition to biomechanics. Techniques focused on the upper cervical spine are theorized to affect the function of the vagus nerve and thereby influence the parasympathetic branch of the ANS. This study was conducted to observe the effect of upper cervical spine manipulation on cardiac autonomic control as measured by heart rate variability (HRV). Methods: Nineteen healthy, young adult subjects were randomly assigned an order in which they would undergo three different experimental protocols: OMT, Sham, and a time control. Six minutes of electrocardiographic data was collected before and after each intervention to be analyzed by power spectral analysis. Results: All baseline data for each protocol and all parameters studied were the same. The OMT protocol and all parameters studied were the same. The OMT protocol caused a change in the standard deviation of the normal-to-normal (SDNN) intervals (0.121 +/- 0.0822 sec, p=0.005) and the change in the high frequency HRV was different from the changes caused by other interventions (p=0.038). Conclusions: This preliminary data supports the hypothesis that under cervical spine manipulation affects the parasympathetic nervous system; however, more data on more subjects needs to be collected in order to clarify some points, and to reach statistical significance in certain measures.Item Effects of Parasympathetic Nerve Activity on Ventricular Irregularity during Atrial Fibrillation(2009-07-01) Pacchia, Christina F.; Smith, Michael L.Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice and is an independent predictor of sudden cardiac death (SCD). AF is characterized by an irregular ventricular rhythm which may produce elevated sympathetic nerve activity (SNA) and increase the risk for SCD. However, limited data suggest that irregular ventricular rhythm during AF is inversely correlated with SCD. It is well established that increased vagal control reduces risk of SCD. However, it is unclear if the ventricular irregularity in AF is a function of vagal control. The purpose of this study was to determine if sinusoidal fluctuations in parasympathetic nerve activity on the ventricle result in an entrainment of the ventricular rhythm in both humans and porcine models of atrial fibrillation. Forced vagal oscillations at two different frequencies were produced by employing deep breathing (0.125 Hz) and neck suction (0.25 Hz) in humans and pigs with AF. In the pig model, glycopyrrolate was administered to block peripheral muscarinic receptors, thus inhibiting vagal transmission to the heart. Heart rate variability was evaluated using power spectral analysis to determine the contribution of the vagus to ventricular irregularity in AF. In all of our human subjects, power spectral analysis identified significant differences between oscillations in heart rhythm during neck suction (0.25Hz) and deep breathing (0.125 Hz) compared to baseline. In addition, the standard deviation of RR intervals was significantly different with neck suction compared to baseline. In our pig model, neck suction and deep breathing increased power at 0.25 and 0.15 Hz respectively and vagal blockade abolished power in both frequencies. In humans and pigs, all frequency-mediated vagal maneuvers increased heart rate variability, suggesting the vagus does, in part, mediate ventricular irregularity during AF. These findings have important clinical implications considering the utility of heart rate variability analysis in patients with sinus rhythm. Reduced vagal tone, measured as heart rate variability, may be used to predict risk of sudden cardiac death in patients with AF.Item Osteopathic Manipulative Medicine in Pregnancy: Acute Physiological and Biomechanical Effects(2009-05-01) Hensel, Kendi L.; Smith, Michael L.Introduction: During pregnancy, a woman’s body is challenged by significant physiological and biomechanical changes which can adversely affect normal function, mobility and quality of life. These changes may also contribute to co-morbid conditions accompanying pregnancy. Osteopathic manipulative medicine (OMM) is theorized to facilitate the body’s adjustment to the physiological and biomechanical demands of pregnancy and improve the outcomes of pregnancy, labor and delivery. Thus, this dissertation research was designed to examine the possible effects of an acute regimen of OMM on the autonomic and hemodynamic control mechanisms and gait and mobility function in women during the third trimester of pregnancy. Methods: Two studies were performed with 60 women at the 30th week of pregnancy. Study 1: The hemodynamic and autonomic (heart rate variability) responses to head-up tilt with and without engagement of the muscle pump via toe raising were assessed before and after a regimen of either randomly assigned OMM, sub-therapeutic placebo ultrasound, or a timecontrol. Study 2: Assessment of a cadre of gait parameters and functions was performed before and after application of the same randomized treatment regimens. Results: In Study 1, the response to tilt was not affected by OMM or placebo ultrasound, however, the systolic blood pressure response to toe raising was increased after OMM and was accompanied by a lower heart rate and enhanced vagal control of heart rate. In study 2, there were no statistically significant differences between groups at baseline. In addition, there were no statistically significant differences between pre-and post-treatment values for any spatiotemporal gait parameters. However, improvements in stride width and base of support trended toward significance. Conclusions: These data suggest that OMM improved hemodynamic control during engaging of the skeletal muscle pump that was most likely due to improvement of structural impediments to venous return. The gait data fail to elucidate a significant effect of OMM on gait parameters during the third trimester of pregnancy.