Cardiac sympathetic and parasympathetic activity during self-regulation of heart period.

Fourteen subjects attempted to increase and 15 attempted to decrease cardiac interbeat interval (IBI) while being provided with biofeedback of IBI, T-wave vector magnitude (TWVM), or respiratory sinus arrhythmia (RSA). Subjects in both groups showed directional change in IBI relative to a tracking control task, but the three types of feedback did not differentially affect performance. Voluntary IBI increases were associated with significant increases in TWVM and RSA, and voluntary IBI decreases were associated with significant reductions in RSA and nonsignificant reductions in TWVM. This pattern of results suggests that alterations in cardiac vagal tone are involved in voluntary IBI increase and decrease tasks. The results also suggest a role for cardiac sympathetic nervous activity in voluntary IBI increase. The role of changing respiration cycle period was also investigated.     

Self-regulation of respiratory sinus arrhythmia

Respiratory sinus arrhythmia (RSA) — the peak-to-peak variations in heart rate caused by respiration — can be used as a noninvasive measure of parasympathetic cardiac control. In the present study four strategies to increase RSA amplitude are investigated: (1) biofeedback of RSA amplitude, (2) biofeedback of RSA amplitude plus respiratory instructions, (3) respiratory biofeedback, and (4) respiratory instructions only. All four procedures produce a significant increase of RSA amplitude from the first physiological control trial compared to baseline. This increase is faster for the groups that received respiratory biofeedback and respiratory instructions only than for the two groups that received biofeedback of RSA amplitude, the increases being equivalent for the four groups in the third session. All subjects of the group that received biofeedback of RSA amplitude only reported respiratory strategies in order to achieve the increase in RSA. Possible clinical implications of these results for parasympathetic cardiac control and cardiovascular disorders are discussed.This research was supported by a grant to the first author from the University of Granada (Spain).     

Self-regulation of respiratory sinus arrhythmia.

Respiratory sinus arrhythmia (RSA)--the peak-to-peak variations in heart rate caused by respiration--can be used as a noninvasive measure of parasympathetic cardiac control. In the present study four strategies to increase RSA amplitude are investigated: (1) biofeedback of RSA amplitude, (2) biofeedback of RSA amplitude plus respiratory instructions, (3) respiratory biofeedback, and (4) respiratory instructions only. All four procedures produce a significant increase of RSA amplitude from the first physiological control trial compared to baseline. This increase is faster for the groups that received respiratory biofeedback and respiratory instructions only than for the two groups that received biofeedback of RSA amplitude, the increases being equivalent for the four groups in the third session. All subjects of the group that received biofeedback of RSA amplitude only reported respiratory strategies in order to achieve the increase in RSA. Possible clinical implications of these results for parasympathetic cardiac control and cardiovascular disorders are discussed.     

The control of pulse transit time independently of interbeat interval by providing feedback from both

Sixteen subjects took part in a two-stage cardiovascular biofeedback experiment. For five sessions all subjects attempted to control their pulse wave transit time(TT), using TT feedback. The eight subjects who achieved control were given a further five sessions, during which they attempted to control their transit time without altering their interbeat interval(IBI) when provided with TT and IBI feedback. No evidence was found for complete dissociation of TT and IBI. When the single TT contingency was in operation, all subjects who had significant control of TT also showed significant changes in IBI in the same direction. When the dual contingency was introduced, subjects either controlled TT but failed to keep IBI stable or kept IBI stable but failed to control TT.     

Respiratory Sinus Arrhythmia Versus Neck/Trapezius EMG and Incentive Inspirometry Biofeedback for Asthma: A Pilot Study

This pilot study compared biofeedback to increase respiratory sinus arrhythmia (RSA) with EMG and incentive inspirometry biofeedback in asthmatic adults. A three-group design (Waiting List Control n = 5, RSA biofeedback n = 6, and EMG biofeedback n = 6) was used. Six sessions of training were given in each of the biofeedback groups. In each of three testing sessions, five min. of respiratory resistance and EKG were obtained before and after a 20-min biofeedback session. Additional five-min epochs of data were collected at the beginning and end of the biofeedback period (or, in the control group, self-relaxation). Decreases in respiratory impedance occurred only in the RSA biofeedback group. Traub-Hering-Mayer (THM) waves (.03-.12 Hz) in heart period increased significantly in amplitude during RSA biofeedback. Subjects did not report significantly more relaxation during EMG or RSA biofeedback than during the control condition. However, decreases in pulmonary impedance, across groups, were associated with increases in relaxation. The results are consistent with Vaschillo's theory that RSA biofeedback exercises homeostatic autonomic reflex mechanisms through increasing the amplitude of cardiac oscillations. However, deep breathing during RSA biofeedback is a possible alternate explanation.     

The Effects of Respiratory Sinus Arrhythmia Biofeedback on Heart Rate Variability and Posttraumatic Stress Disorder Symptoms: A Pilot Study

Recent studies have found a significant association between PTSD and low heart rate variability (HRV), a biomarker of autonomic dysregulation. Research indicates that respiratory sinus arrhythmia (RSA) biofeedback increases HRV while reducing related pathological symptoms. This controlled pilot study compared RSA biofeedback to progressive muscle relaxation (PMR) as adjunctive interventions for 38 persons with PTSD symptoms in a residential treatment facility for a substance use disorder. Both groups were assessed at pre-intervention and 4-week post-intervention. Group × time interactions revealed significantly greater reductions in depressive symptoms and increases in HRV indices for the RSA group. Both groups significantly reduced PTSD and insomnia symptoms and a statistical trend was observed for reduced substance craving for the RSA group. Increases in HRV were significantly associated with PTSD symptom reduction. Overall, these results provide preliminary support for the efficacy of RSA biofeedback in improving physiological and psychological health for individuals with PTSD.     

Circadian Variation in Cardiac Autonomic Activity: Reactivity Measurements to Different Types of Stressors

The role of endogenous circadian rhythmicity in autonomic cardiac reactivity to different stressors was investigated. A constant routine protocol was used with repeated exposure to a dual task and a cold pressor test. The 29 subjects were randomly divided into two groups in order to manipulate prior wakefulness. Group 1 started at 09:00 h immediately after a monitored sleep period, whereas group 2 started 12 h later. Measures of interbeat intervals (IBI), respiratory sinus arrythmia (RSA, a measure of parasympathetic activity), pre-ejection period (PEP, a measure of sympathetic activity), as well as core body temperature (CBT) were recorded continuously. Multilevel regression analyses (across-subjects) revealed significant (mainly 24 h) sinusoidal circadian variation in the response to both stressors for IBI and RSA, but not for PEP. Individual 24 + 12 h cosine fits demonstrated a relatively large interindividual variation of the phases of the IBI and RSA rhythms, as compared to that of the CBT rhythm. Sinusoidal by group interactions were found for IBI and PEP, but not for RSA. These findings were interpreted as an indication for endogenous circadian and exogenous parasympathetic (vagal) modulation of cardiac reactivity, while sympathetic reactivity is relatively unaffected by the endogenous circadian drive and mainly influenced by exogenous factors.     

Circadian variation in cardiac autonomic activity: reactivity measurements to different types of stressors

The role of endogenous circadian rhythmicity in autonomic cardiac reactivity to different stressors was investigated. A constant routine protocol was used with repeated exposure to a dual task and a cold pressor test. The 29 subjects were randomly divided into two groups in order to manipulate prior wakefulness. Group 1 started at 09:00 h immediately after a monitored sleep period, whereas group 2 started 12 h later. Measures of interbeat intervals (IBI), respiratory sinus arrythmia (RSA, a measure of parasympathetic activity), pre-ejection period (PEP, a measure of sympathetic activity), as well as core body temperature (CBT) were recorded continuously. Multilevel regression analyses (across-subjects) revealed significant (mainly 24 h) sinusoidal circadian variation in the response to both stressors for IBI and RSA, but not for PEP. Individual 24 + 12 h cosine fits demonstrated a relatively large interindividual variation of the phases of the IBI and RSA rhythms, as compared to that of the CBT rhythm. Sinusoidal by group interactions were found for IBI and PEP, but not for RSA. These findings were interpreted as an indication for endogenous circadian and exogenous parasympathetic (vagal) modulation of cardiac reactivity, while sympathetic reactivity is relatively unaffected by the endogenous circadian drive and mainly influenced by exogenous factors.     

Yawning: A possible confounding variable in EMG biofeedback studies

An elderly hemiplegic patient participating in an EMG biofeedback training program was observed to produce a synergistic flexion movement of the plegic (determined by functional evaluations) upper limb while yawning. In the course of the training sessions the electrical activity of the anterior deltoid (the target muscle) was recorded during yawning. These peak EMG values were greatly facilitated in comparison with the session mean peak values obtained during an attempted maximum voluntary isometric contraction (shoulder flexion) of the same limb (e.g., Trial 1: 85.00 vs. 4.33 µV). The possibility of yawning as a confounding variable in EMG biofeedback studies is presented and discussed.This research was supported in part by Health and Welfare Canada (NHRDP).     

Effects of hypercapnia and hypoxemia on respiratory sinus arrhythmia in conscious humans during spontaneous respiration

Normally, at rest, the amplitude of respiratory sinus arrhythmia (RSA) appears to correlate with cardiac vagal tone. However, recent studies showed that, under stress, RSA dissociates from vagal tone, indicating that separate mechanisms might regulate phasic and tonic vagal activity. This dissociation has been linked to the hypothesis that RSA improves pulmonary gas exchange through preferential distribution of heartbeats in inspiration. We examined the effects of hypercapnia and mild hypoxemia on RSA-vagal dissociation in relation to heartbeat distribution throughout the respiratory cycle in 12 volunteers. We found that hypercapnia, but not hypoxemia, was associated with significant increases in heart rate (HR), tidal volume, and RSA amplitude. The RSA amplitude increase remained statistically significant after adjustment for respiratory rate, tidal volume, and HR. Moreover, the RSA amplitude increase was associated with a paradoxical rise in HR and decrease in low-frequency-to-high-frequency mean amplitude ratio derived from spectral analysis, which is consistent with RSA-vagal dissociation. Although hypercapnia was associated with a significant increase in the percentage of heartbeats during inspiration, this association was largely secondary to increases in the inspiratory period-to-respiratory period ratio, rather than RSA amplitude. Additional model analyses of RSA were consistent with the experimental data. Heartbeat distribution did not change during hypoxemia. These results support the concept of RSA-vagal dissociation during hypercapnia; however, the putative role of RSA in optimizing pulmonary perfusion matching requires further experimental validation.     

Biofeedback treatments of generalized anxiety disorder: Preliminary results

Forty-five individuals with generalized anxiety (38 with GAD as defined by DSM-III) were randomized to 4 treatment conditions or a waiting list control. Patients received 8 sessions of either frontal EMG biofeedback, biofeedback to increase EEG alpha, biofeedback to decrease EEG alpha, or a pseudomeditation control condition. All treated subjects showed significant reductions in STAI-Trait Anxiety and psychophysiologic symptoms on the Psychosomatic Symptom Checklist. Only alpha-increase biofeedback subjects showed significant reductions in heart rate reactivity to stressors at a separate psychophysiological testing session. Decreased self-report of anxiety was maintained at 6 weeks posttreatment.     

Biofeedback Assisted Control of Respiratory Sinus Arrhythmia as a Biobehavioral Intervention for Depressive Symptoms in Patients After Cardiac Surgery: A Preliminary Study

The current study investigated whether biofeedback training aimed at increasing respiratory sinus arrhythmia (RSA), a measure of cardiac vagal modulation, can reduce depressive symptoms in patients after cardiac surgery. This randomized controlled study enrolled 26 patients after first-time cardiac surgery. The patients were randomly assigned to an RSA-biofeedback group (N = 13) or to a treatment as usual group (N = 13). The biofeedback training consisted of five 45 min sessions designed to increase RSA. The outcome was assessed as changes in RSA and in the Centre for Epidemiologic Studies of Depression (CES-D) values from pre- to post-training. Both groups were comparable for demographic and biomedical characteristics. RSA increased significantly in patients who underwent RSA-biofeedback compared to controls. Moreover, the CES-D scores were reduced significantly from pre- to post-training in the RSA-biofeedback group compared to the controls. Changes in RSA were inversely related to changes in CES-D scores from pre- to post-training. These findings extend the effectiveness of RSA-biofeedback for increasing vagal modulation as well as for reducing depressive symptoms in post-surgical patients. Overall, the current study also suggests that this biobehavioral intervention may add to the efficacy of postoperative risk reduction programs and rehabilitation protocols in cardiac surgery patients.     

Simple electromyographic biofeedback treatment for chronic pediatric constipation/encopresis: Preliminary report

Pediatric constipation/encopresis is thought to be due, in part, to paradoxical constriction of the external anal sphincter (EAS) muscle during attempted defecation. This inappropriate contraction can lead to delayed, impacted, painful, and infrequent bowel movements. Standard Medical Care (SMC) involves disimpaction with enemas, followed by laxative therapy and diet modification, to maintain frequent soft stools. Using the case control method, the efficacy of SMC alone was compared with SMC plus EAS electromyographic biofeedback aimed at eliminating paradoxical contraction. Thirteen consecutive chronically constipated children received SMC plus biofeedback, and were compared with 13 age- and sex-matched children who received only SMC. Biofeedback subjects demonstrated post-treatment elimination of EAS paradoxical constriction. At 16 months follow-up parents of biofeedback children reported significantly greater improvement in constipation, encopresis, laxative use, and painful bowel movements compared to SMC.This research report was supported by the NIH under grant No. RO1 HD 28160.     

Modification of Baroreceptor Cardiac Reflex Function by Biofeedback

Baroreceptor sensitivity (BRS) is considered a powerful prognostic factor in cardiovascular health. This study investigated the possibility of modifying the baroreflex cardiac function through biofeedback. Thirty-two psychology students underwent 3 biofeedback sessions, with four 5-min trials each, in which they had to increase and decrease baroreflex function. BRS was assessed by a system that analyzed baroreflex cardiac function on-line using a noninvasive spontaneous sequence method in the time domain. Baroreceptor parameters were differentiated in terms of blood pressure increases ("up" sequences) or blood pressure decreases ("down" sequences). BRS in the "up" sequences increased during the Increase Condition and decreased during the Decrease Condition. BRS in the "down" sequences decreased during the Decrease Condition but was unchanged during the Increase Condition. The increase in BRS during the Increase Condition was associated with a significant reduction in blood pressure and increase in heart period. The opposite cardiovascular changes were observed during the Decrease Condition. Suggestions for future research were discussed.     

Biochemical changes associated with thermal biofeedback treatment of hypertension

Fifty-two hypertensive patients whose blood pressure (BP) was controlled on two medications received either 16 sessions of thermal biofeedback (n=30) for hand warming or 8 sessions of progressive muscle relaxation (n=22) prior to medication withdrawal. A number of biochemical measures, including plasma norepinephrine (NEPI) (supine and standing), plasma renin activity, plasma aldosterone, and urinary sodium and potassium, were taken before treatment and after treatment while medication remained constant. Results for the biofeedback-treated patients showed significant reductions in mean arterial pressure as well as in both supine and standing NEPI, while the other biochemical measures were unchanged. There were no significant changes on any variable for the relaxation-treated patients. Although the group data support a reduction in peripheral sympathetic tone as associated with the decrease in BP for the thermal biofeedback condition, dose-response relations were not significant.This research was supported by a grant from NHLBI, HL-27622.     

The Use of Thermal Biofeedback in the Treatment of Pain Associated with Endometriosis: Preliminary Findings

Endometriosis is a common gynecological disease that causes marked physical and emotional distress in lives of women, resulting in dysmenorrhea, pain, or both throughout the menstrual cycle in over 96% of cases. A multiple case study design (N = 5) was employed to investigate the use of thermal biofeedback in the treatment of pain associated with endometriosis. The majority of participants (4 out of 5) were able to demonstrate mastery over hand temperature through thermal biofeedback. Of those participants, significant reductions in various aspects of pain were observed by the end of the study; one had a significant increase in Life Control; two had reductions in Pain Severity; three had a decrease in Affective Distress; and all 4 demonstrated reduction in Life Interference, as measured by the West Haven-Yale Multidimensional Pain Inventory. This is a preliminary study with a small sample size and without a control sample; hence, the results are considered only as suggestive of the potential use of biofeedback therapy in alleviating pain and associated symptomatology related to endometriosis. Further research is warranted.     

Respiratory Sinus Arrhythmia Feedback in a Stressed Population Exposed to a Brief Stressor Demonstrated by Quantitative EEG and sLORETA

Previous investigations of electroencephalograms during relaxation have identified increases in slow wave band power, correlations between increased levels of alpha activity with lower levels of anxiety, and autonomic changes characterized by otherwise documented decreased sympathetic activity. This study was carried out to determine the overall changes in quantitative electroencephalographic activity and the current source as a result of an acute session of respiratory sinus arrhythmia (RSA) biofeedback in a population of subjects experiencing stress. This study’s findings provide physiological evidence of RSA feedback effect and suggest that RSA training may decrease arousal by promoting an increase of alpha band frequencies and decrease in beta frequencies overall and in areas critical to the regulation of stress. It was of interest that novices could achieve these objective alterations in EEG activity after minimal training and intervention periods considering that the previous literature on EEG and meditative states involve experienced meditators or participants who had been given extensive training. Additionally, these effects were present immediately following the training suggesting that the intervention may have effects beyond the actual practice.     

Effects of auditory stimulus timing in the respiratory cycle on the evoked cardiac response in man at rest

The present experiments were carried out in 21 healthy adults to study the effects of auditory stimulus timing within the respiratory cycle on evoked cardiac response. The stimulus (80 dB white noise) was started by the first and finished by the second R-wave after change in respiratory phase, and presented in different series in either early inspiration or early expiration. The spirogram and eight sequential interbeat intervals (IBI) after respiratory phase change were recorded. The mean of IBI and standard deviation (SD) were calculated separately for each IBI of 20 trials for each subject, during both the prestimulus and poststimulus phases. The stimulus effects were expressed as changes from prestimulus conditions, in terms of delta IBI and delta SD. The mean of each of the eight IBI and its SD were found to vary consistently in the same direction, i.e., SD increased with increasing mean IBI. Stimulation during early inspiration did not produce any effect during this respiratory phase. It was not before the beginning of the following expiration that a significant deceleration was evoked, which was associated with an enhanced delta SD, whereas stimulation during early expiration promptly evoked a biphasic cardiac response of the deceleration - acceleration pattern and an increase and decrease in delta SD, respectively. While SD was found to be a function of age, no such finding was obtained for delta IBI and delta SD. These results are discussed in terms of the "vagal gating" hypothesis.     

Integrating a Portable Biofeedback Device into Clinical Practice for Patients with Anxiety Disorders: Results of a Pilot Study

This study examined the effectiveness of a portable Respiratory Sinus Arrhythmia (RSA) biofeedback device as an adjunct to CBT in persons with anxiety disorders and other disorders associated with autonomic dysfunction attending outpatient treatment. Participants were 24 individuals attending outpatient cognitive behavioral treatment for a range of anxiety disorders. Participants were assessed over a 3 week period. Outcomes included measures of anxiety (STAI-Y), sleep disturbances (PSQI), anger (STAEI), and subjective questions about the effectiveness of the device as a treatment adjunct. Significant reductions were found for anxiety and anger and for certain sleep variables (e.g. sleep latency). There was a significant dos–effect in that those who were more compliant had significantly greater reductions in most domains including sleep, anger and trait anxiety. Overall, participants found the device more helpful than other relaxation techniques such as mediation, yoga and unassisted breathing techniques but less helpful than exercise. The most frequently endorsed side effects were dizziness (15%) and sleepiness (55%). These preliminary results suggest that portable RSA biofeedback appears to be a promising treatment adjunct for disorders of autonomic arousal and is easily integrated into treatment. Results support the need for further investigation with more rigorous experimental designs. This study was conducted at the Behavioral Associates and The CBT Institute in New York, NY from 6/06 through 8/06.