Cognitive function is associated with impaired heart rate variability in ageing adults: the Irish longitudinal study on ageing wave one results

Objective

To examine the independent association between heart rate variability (HRV) and cognitive performance, in a nationally representative population study of older adults.

Methods

Cross-sectional analysis of wave 1 data from the Irish longitudinal study on ageing (TILDA) was performed. A subset of 4,763 participants who underwent ECG recording during resting and paced breathing periods were used for the analysis. HRV indices were divided into quintiles for comparison of values and cognitive performance was defined using the Montreal cognitive assessment (MOCA) score. Multivariate linear regression was used to model the association between cognition and different quintiles of each HRV index, after adjustment for covariates.

Results

The mean age was 61.7 ± 8.3 years and 2,618 (55 %) were female. Lower quintiles of SDNN (P = 0.01-paced), LF (P = 0.001-paced), and LF:HF ratio (P = 0.049-paced) were significantly associated with lower MOCA scores (during both recording periods), independent of confounders. Sub-domains of MOCA responsible for the relationship were predominantly memory recall and language.

Interpretation

Reduced HRV is significantly associated with lower cognitive performance at a population level in people aged 50 and older. This further strengthens the relationship between autonomic dysfunction and cognitive disorders.     

Effect of hormone replacement therapy on cardiac autonomic modulation

Objective

To investigate the effects of hormone replacement therapy (HRT) on heart rate variability (HRV) in healthy postmenopausal women.

Methods

Two groups were evaluated: group 1 (G1): 20 women not undergoing HRT (60 ± 5.89 years), group 2 (G2): 20 women undergoing HRT (59 ± 5.70 years). The HRTs involved were either conjugated equine estrogen with or without medroxyprogesterone, synthetic estrogen hormone, estradiol associated with norethisterone acetate or isoflavonoids. Electrocardiogram was recorded in the supine position for 10 min. Spectral analysis included low and high frequencies in absolute (LF and HF) and normalized units (LFnu and HFnu), which are predominantly cardiac sympathetic modulation (CSM) and cardiac vagal modulation (CVM) indicators, respectively. The LF/HF ratio was also calculated. Symbolic analysis involved the following indexes: 0V % (CSM indicator), 1V % (CSM and CVM indicators), 2LV % (predominantly CVM indicator) and 2UV % (CVM indicator). Shannon and conditional entropies were also calculated.

Results

Spectral analysis demonstrated that HRT affected HRV. LF, LFnu and LF/HF ratio were higher (showing increased CSM), while HFnu was lower (representing decreased CVM) in G2 than in G1. Correlations between complexity indices and HFnu were significant and positive only in G1.

Interpretation

Women undergoing HRT presented higher CSM and lower CVM than those who were not. Moreover, the expected positive relationship between CVM and complexity of HRV was found only in control group, thus indicating that CVM in women under therapy drop below a minimal value necessary to the association to become apparent, suggesting an unfavorable cardiac autonomic modulation in spite of HRT.     

Resting heart rate variability and heart rate recovery after submaximal exercise

Purpose

Aerobic training accelerates Heart Rate Recovery after exercise in healthy subjects and in patients with coronary disease. As shown by pharmacological autonomic blockade, HRR early after exercise is dependent primarily on parasympathetic reactivation. Thus, accelerated HRR early after exercise in endurance-trained athletes may be attributed to augmented parasympathetic reactivation. In the present study, we tested the hypothesis that the HRR early after submaximal exercise is related to the pre-exercise parasympathetic modulation.

Methods

Thirty endurance-trained athletes (20 males, 50 ± 7 years) and thirty control subjects (20 males, 52 ± 6 years) performed a submaximal exercise on a cyclo-ergometer. Pre-exercise resting short-term heart rate variability (HRV) parameters in time and frequency-domains were correlated with HRR during the first 30 s, 1 and 2 min after cessation of exercise.

Results

We found that HRR was statistically significantly faster in athletes than in controls at all examination time points (p < 0.05). HF, SDNN and RMSSD were statistically significantly higher in athletes than in controls (p < 0.05), but other resting HRV parameters were not statistically different between groups. After 30 s, 1 and 2 min of recovery, HRR correlation with total power, HF, HFnu and RMSSD was positive, while the correlation with LF/HF was negative for small and positive for larger values. The opposite was true for SDNN.

Conclusions

These findings support the hypothesis that HRR early after submaximal exercise is related to resting parasympathetic modulation in the middle-aged subjects. In addition, they suggested an optimal range of HRV for maximal HRR after exercise.     

The effect of oxybutynin on cardiac autonomic modulation in healthy subjects

Purpose

The aim of this study was to assess the various doses of oral oxybutynin on cardiac autonomic modulation by measuring short-term heart rate variability (HRV) indexes during supine rest position.

Methods

Eight male healthy subjects (20–23 years) participated in the double-blind crossover randomized study. The single dose of oxybutynin (2.5, 5 and 10 mg) or placebo was given to the volunteers in four sessions within 5-day intervals. Before and minutes of 30, 60, 90 and 120 after administration, lead II electrocardiogram (ECG) was recorded for 5 min. ECG extracted RR intervals data became the base of the calculation of time domain and frequency domain HRV parameters, which indicate cardiac autonomic activity. Statistical analysis was done by using the nonparametric Wilcoxon and Kruskal–Wallis tests.

Results

The data analysis has revealed that MNN (P < 0.001), SDNN (P < 0.05), PNN50% (P < 0.01), RMSSD (P < 0.001), HFnu (P < 0.05) and LF/HF ratio (P < 0.05) values were significantly increased relative to baseline at various time points in all the groups except in placebo group. LFnu (P < 0.05) values were significantly increased relative to baseline at various time points in all the groups except in placebo group.

Conclusions

Our findings have revealed that acute consumption of 2.5, 5 and 10 mg oxybutynin (an anticholinergic compound) in the juvenile healthy male subjects produces a cholinergic effect according to time and frequency domain of HRV indexes.     

Association Between Smoking and Heart Rate Variability Among Individuals with Depression

Background

Both depression and smoking have been independently associated with lower heart rate variability (HRV), suggesting dysregulation of cardiac autonomic function. However, no studies have systematically explored the effects of smoking on HRV among depressed patients.

Purpose

This study examined differences in HRV based on smoking status among depressed individuals.

Methods

Electrophysiological data were examined among 77 adult outpatients without a history of myocardial infarction, who met criteria for major depressive disorder or dysthymia. Frequency domain [low frequency (LF), high frequency (HF), LF/HF ratio, respiratory sinus arrhythmia (RSA)] parameters of HRV, and heart rate and inter-beat interval (IBI) data were compared between depressed smokers (n?=?34) and depressed nonsmokers (n?=?44).

Results

After controlling for covariates, depressed smokers, compared to depressed nonsmokers, displayed significantly lower LF, HF, and RSA.

Conclusions

Among depressed patients, smoking is associated with significantly lower HRV, indicating dysregulated autonomic modulation of the heart.     

Autonomic dysfunction responses to head-up tilt in anorexia nervosa

Purpose

Autonomic dysfunction of the cardiovascular system in anorexia nervosa (AN) was reported not only in the rest position, but also in the standing position in some previous studies, which might contribute to cardiac complications such as lethal arrhythmia. However, there has not been sufficient literature in this issue. Therefore, we performed a head-up tilt test, and compared the changes after tilting in indices of autonomic function between AN patients and healthy subjects by heart rate variability (HRV) and blood pressure variability (BPV).

Methods

The subjects were 21 females with AN and 30 age-matched healthy women. A head-up tilt test was performed following the protocol recommended by the American Heart Association. Blood pressure and heart rate data were collected for 10 min before and after tilting. In the frequency analysis, the powers of low-frequency (LF) and high-frequency (HF) components were calculated by a fast Fourier transformation.

Results

Regarding interactions between groups and head-up tilting, the head-up tilting-induced reduction of the HF component of HRV was significantly greater in the AN group. In addition, increases in the LF/HF of HRV and the LF component of BPV after head-up tilting were significantly smaller in the AN group.

Conclusions

Regardless of the posture, changes in HF and LF/HF of HRV and LF of BPV in AN patients suggested the presence of autonomic insufficiency.     

Heart rate variability associates with asymptomatic coronary atherosclerosis

Purpose

Heart rate variability (HRV) becomes impaired in symptomatic coronary artery disease (CAD), particularly, after myocardial infarction. The mechanism how CAD results in impairment of cardiac autonomic regulation is not known. Whether it results rather from coronary atherosclerosis itself than myocardial ischemia and myocardial injury has remained elusive.

Methods

Quantitative coronary angiography was performed in 30 subjects without history of myocardial ischemia, but with high familial risk for CAD. HRV was measured from 24-h ambulatory ECG recordings in time and frequency domain and also non-linear HRV variables SD1 and SD2 in Poincare plot were calculated. Myocardial ischemia was excluded by Tc-99m sestamibi scintigraphy at rest and during exercise.

Results

Coronary angiography revealed mean diameter stenosis of 32 ± 19 % in left anterior descending coronary artery, 26 ± 16 % in left circumflex coronary artery and 25 ± 20 % in right coronary artery. An inverse correlation was found between pNN50 and global severity of coronary artery diameter stenosis (r = ?0.415, p < 0.05). Correspondingly, power of HF spectral component correlated negatively with global extent of coronary atherosclerosis (r = ?0.366, p < 0.05). In Poincare plot, SD1/SD2 ratio correlated with global extent (r = ?0.394, p < 0.05) and global burden (r = ?0.388, p < 0.05) of coronary arteries.

Conclusions

The severity and extent of coronary atherosclerosis were related to a shift of cardiac autonomic regulation towards sympathetic predominance in asymptomatic subjects without evidence of myocardial ischemia.     

A meta-analysis of HIV and heart rate variability in the era of antiretroviral therapy

Background

Heart rate variability (HRV) has been used to assess autonomic dysfunction since the beginning of the HIV epidemic. Although autonomic failure was commonly detected in HIV and AIDS patients prior to the advent of antiretroviral therapy (ART), the effect of HIV on HRV in the current era of widespread ART availability is more ambiguous.

Methods

A systematic search and review was conducted on cross-sectional observational and case–control studies published in the era of ART (1996–2015) that compared HRV between HIV + individuals treated with ART and HIV ? controls. Eight out of the 20 studies identified, enrolling a total of 292 HIV + adults (mean age 38.7 years) and 201 HIV seronegative controls (mean age 35.1 years), were included in a meta-analysis based on stringent methodological criteria.

Results

At rest, individuals with HIV showed lower HRV in the time (g) = ?0.72, 95 % CI (?1.03 to ?0.42) and low-frequency (LF) domain (g) = ?0.51, (?0.81 to ?0.21); markers of lower parasympathetic tone in the time (g) = ?0.55, (?0.85 to ?0.25) and high-frequency (HF) domain (g) = ?0.42, (?0.71 to ?0.12); and higher LF:HF ratio (g) = 0.46, (0.12–0.86) in the frequency domain, suggestive of parasympathetic withdrawal.

Conclusion

This meta-analysis confirmed, within a relatively young cohort of HIV + adults on ART, a general reduction in autonomic function with a shift toward sympathetic dominance. This shift may predispose HIV patients to early and elevated risk of arrhythmias, cardiac events, and accelerated HIV disease progression.

     

Alteration of skin laser-Doppler flux response to local cooling in gestational hypertension

Purpose

The pathophysiology of the pregnancy-induced hypertension is still poorly understood, especially with regard to the central autonomic nervous system control and peripheral vascular factors.

Methods

Our study therefore aimed to investigate simultaneously the responses of blood pressure, heart rate, heart rate variability (HRV), and laser-Doppler (LD) flux to local cooling in healthy non-pregnant women (N = 12), in pregnant women with normal pregnancy (N = 16) and in women with gestational hypertension (N = 10).

Results

The direct and indirect LD flux responses to local cold exposure were diminished in normotensive pregnant females (Dunnett’s test, p < 0.05) when compared to non-pregnant females with normal menstrual cycle, but not in females with pregnancy-induced hypertension. In addition, blood pressure increased and heart rate decreased during cold exposure only in normotensive pregnant females, but not in pregnant hypertensive females (paired t test, p < 0.05). Simultaneously calculated heart rate variability total power of HRV and LF power values typically increased during local cold provocation test in non-pregnant females and in normotensive pregnant females (paired t test, p < 0.05). In hypertensive pregnant females HRV indices remained unchanged.

Conclusion

Our results indicate that the cardiovascular reactivity adaptation seen in normal pregnancy is absent in gestational hypertension.     

Autonomic dysfunction of overweight combined with low muscle mass

Objective

To examine the relationship between overweight combined with low muscle mass and the cardiac autonomic nervous system using heart rate variability (HRV) in healthy workers.

Methods

A total of 1,150 workers were included, with a mean age of 43.55 ± 11.45 years. The subjects were classified as low muscle mass if their appendicular skeletal muscle mass was below the 50th percentile of the study sample. Similarly, subjects were classified as overweight if their body mass index was above 25 kg/m². Electrocardiography recordings were obtained for 5 min, and the time-domain and frequency-domain indices of HRV were analyzed.

Results

Compared with the high muscle mass and non-overweight (HMM) group, the low-frequency power and the standard deviation of normal-to-normal intervals were significantly decreased in both the overweight and high muscle mass (OHMM) group and the overweight and low muscle mass (OLMM) group. The significantly decreased high-frequency (HF) power and square root of the mean squared differences of successive differences, which reflects efferent parasympathetic activity, was indicative of reduced parasympathetic modulation in the OHMM and OLMM groups. In addition, the OLMM group had a lower HF power than did the OHMM group.

Conclusions

This study suggests that HRV is reduced in overweight combined with low muscle mass group than overweight and HMM group.     

Post-exercise heart-rate recovery correlates to resting heart-rate variability in healthy men

Justificative

The relationship between post-exercise heart-rate recovery (HRR) and resting cardiac autonomic modulation is an incompletely explored issue.

Objective

To correlate HRR with resting supine and orthostatic autonomic status.

Method

HRR at the 1st, 3th, and 5th min following maximal treadmill exercise were correlated with 5-min time-domain (CV, pNN50 and rMSSD) and frequency-domain (TP, LF, HF, LFn, HFn, and LF/HF ratio) indices of heart-rate variability (HRV) in both supine and standing positions in 31 healthy physically active non-athletes men. Statistical analysis employed non-parametric tests with two-tailed p value set at 5 %.

Results

Absolute HRR and Δ %HRR at each post-exercise time did not correlated with HRV in supine position, as well as at 1st min in standing position. At the 3rd min and 5th min, these measures negatively correlated with pNN50, rMSSD, TP, and HF indices, and only in the 5th min, they showed negative correlation with HFn and positive correlation with LF, LFn, and LF/HF ratio in the standing position. Coefficient of HRR (CHRR) at the 1st min negatively correlated with pNN50 and rMSSD and at 3rd and 5th min showed positive correlation with LFn and LF/HF ratio in supine position. With HRV indices in standing position CHRR from the 1st to 5th min showed the same respective negative and positive correlations as the other measures.

Conclusion

HRR from the 1st to 5th min post-exercise negatively correlated with parasympathetic modulation in resting orthostatic, but showed no correlation in supine position. At the 3rd and 5th min, a positive correlation with combined sympathetic-parasympathetic modulation in both positions was observed.

     

Cardiovascular variability in Parkinson’s disease and extrapyramidal motor slowing

Objective

Parkinson’s disease (PD) is a degenerative neurological condition, associated with cardiovascular dysfunction. Many studies have utilised heart rate variability (HRV) to assess the autonomic nervous system in PD, but blood pressure variability (BPV) has received less attention. The purpose of the present study was to compare HRV and BPV between participants with established PD, extrapyramidal motor slowing (EPMS) (not reaching clinical criteria for PD), older healthy controls (OHC), and young healthy controls (YHC), in order to ascertain whether either of these measures can be used as an early marker of non-motor symptoms in PD.

Methods

HRV was assessed at rest and during 2?min of slow deep breathing in 97 participants, divided into four groups: YHC (20–30?years; n?=?19); OHC (67–83?years; n?=?28); EPMS (59–91?years; n?=?25) and PD (61–84?years; n?=?25).

Results

Spectral analysis of blood pressure was performed on stable non-invasive recordings of blood pressure obtained in 76 of the participants. Low frequency (LF) and high frequency (HF) components, and the LF/HF ratio, were measured. Significant differences were only seen between the YHC and the three older groups. For HRV this was seen at rest and during 2?min of slow deep breathing, whereas for BPV this was only seen during 2?min of slow deep breathing.

Interpretation

These data indicate that there are only age-related changes in HRV and BPV, and that neither technique is sensitive enough to provide an index of pre-clinical PD.     

Cardiac autonomic modulation and blood pressure responses to isometric handgrip and submaximal cycling exercise in individuals with down syndrome

Purpose

Individuals with Down syndrome (DS) exhibit autonomic dysfunction, manifested as attenuated heart rate (HR) and blood pressure (BP) responses to sympathoexcitation. Whether a subgroup of individuals with DS with a normal HR response would have normal autonomic responses to sympathoexcitation remains unclear.

Methods

We compared autonomic modulation using HR variability (HRV) and BP responses in individuals with and without DS (controls) matched for the HR change to isometric handgrip (HG) (10 DS, 8 controls) and submaximal cycling exercise (CE) (9 DS, 9 controls). HG was performed for 2 min at 30 % of maximal voluntary contraction. CE included two 6-min stages at 0 W and at 50 % of body weight. Beat-to-beat HR and BP were recorded. HRV variables were natural log transformation (Ln) of low frequency (LF), high frequency (HF), LF/HF ratio, total power (TP), and the root mean square of successive differences (RMSSD).

Results

In the HG study, although individuals with DS exhibited an overall lower systolic BP, LF/HF ratio, and LnLF/LnHF, their BP and HRV responses to HG were similar to those of the controls. In the CE study, individuals with DS exhibited lower resting LnLF and an overall lower systolic BP and mean arterial pressure compared with controls. During the CE, individuals with DS exhibited an increased diastolic BP and a smaller reduction in LnTP than controls. These differences disappeared after controlling for confounders.

Conclusions

Our results suggest that despite normal HR responses to sympathoexcitatory tasks, HRV was largely similar to controls, with some evidence of autonomic dysfunction in individuals with DS.

     

Obstructive sleep apnea and heart rate asymmetry microstructure during sleep

Purpose

Heart rate decelerations and accelerations have unequal input to heart rate variability (HRV) and patterns created by consecutive cardiac cycles—this phenomenon is known as heart rate asymmetry (HRA). The analysis of monotonic runs of heart rate decelerations and accelerations provides a detailed insight into the HRA microstructure and thus of HRV.

Aim

To evaluate the relation between the severity of obstructive sleep apnea (OSA) and the HRA microstructure during sleep.

Methods

Seventy-eight patients with suspected OSA underwent overnight polysomnography. The 300-min ECGs from the polysomnography were selected and analyzed. The HRA microstructure was quantified by measuring (1) the contribution of monotonic runs of decelerations or accelerations of different lengths to the number of all sinus beats, and (2) the length of the longest deceleration and acceleration runs.

Results

There were 19 patients with no/mild OSA (Apnea/Hypopnea Index (AHI) 5.1 ± 2.5/h), 18 with moderate OSA (AHI 21.8 ± 4.0/h) and 41 with severe OSA (AHI 42.8 ± 17.4/h). Patients with severe OSA had significantly reduced deceleration and acceleration runs of length 1 compared to the moderate OSA group, and compared to patients with no/mild OSA they had an increased number of longer runs (from 5 to 10 for accelerations and from 5 to 8 for decelerations; p < 0.05 for all comparisons). The longest acceleration runs were significantly longer in severe OSA group (p < 0.05) than in subjects with no/mild OSA.

Conclusions

HRA microstructure is related with OSA severity. An increased number of longer deceleration and acceleration runs is more common in severe OSA patients.     

Infarct Volume After Hyperacute Infusion of Hypertonic Saline in a Rat Model of Acute Embolic Stroke

Introduction

Hypertonic saline (HS) can treat cerebral edema arising from a number of pathologic conditions. However, physicians are reluctant to use it during the first 24 h after stroke because of experimental evidence that it increases infarct volume when administered early after reperfusion. Here, we determined the effect of HS on infarct size in an embolic clot model without planned reperfusion.

Methods

A clot was injected into the internal carotid artery of male Wistar rats to reduce perfusion in the middle cerebral artery territory to less than 40 % of baseline, as monitored by laser-Doppler flowmetry. After 25 min, rats were randomized to receive 10 mL/kg of 7.5 % HS (50:50 chloride:acetate) or normal saline (NS) followed by a 0.5 mL/h infusion of the same solution for 22 h.

Results

Infarct volume was similar between NS and HS groups (in mm³: cortex 102 ± 65 mm³ vs. 93 ± 49 mm³, p = 0.72; caudoputamenal complex 15 ± 9 mm³ vs. 21 ± 14, p = 0.22; total hemisphere 119 ± 76 mm³ vs. 114 ± 62, p = 0.88, respectively). Percent water content was unchanged in the infarcted hemisphere (NS 81.6 ± 1.5 %; HS 80.7 ± 1.3 %, p = 0.16), whereas the HS-treated contralateral hemisphere was significantly dehydrated (NS 79.4 ± 0.8 %; HS 77.5 ± 0.8 %, p < 0.01).

Conclusions

HS reduced contralateral hemispheric water content but did not affect ipsilateral brain water content when compared to NS. Infarct volume was unaffected by HS administration at all evaluated locations.     

Sympathetic cardiovascular hyperactivity precedes brain death

Objective

The time preceding brain death is associated with complex dysregulation including autonomic dysfunction that may compromise organ perfusion, thus inducing final organ failure. In this study, we assessed autonomic function in patients prior to brain death.

Methods

In 5 patients (2 women, median 60 years, age range 52–75 years) with fatal cerebral hemorrhage or stroke and negative prognosis, we monitored RR-intervals (RRI), systolic and diastolic blood pressure (BP), and oxygen saturation. Adjustment of mechanical ventilation remained constant. We assessed autonomic function from spectral powers of RRI and BP in the mainly sympathetic low- (LF, 0.04–0.15 Hz) and parasympathetic high-frequencies (HF, 0.15–0.5 Hz), and calculated the RRI-LF/HF-ratio as index of sympathovagal balance. Three patients required norepinephrine (0.5–1.6 mg/h) for up to 72 h to maintain organ perfusion. Norepinephrine was reduced to 0.2–0.5 mg/h within 2 h before brain death was diagnosed according to the criteria of the German Medical Association. Wilcoxon test compared average values of ten 2-min epochs determined 2–3 h (measurement 1) and 1 h (measurement 2) before brain death.

Results

We found higher systolic (127.3 ± 15.9 vs. 159.4 ± 44.8 mmHg) and diastolic BP (60.1 ± 15.6 vs. 74.0 ± 15.2 mmHg), RRI-LF/HF-ratio (1.2 ± 1.6 vs. 3.9 ± 4.0), and BP-LF-powers (2.7 ± 4.8 vs. 23.1 ± 28.3 mmHg²) during measurement 2 than during measurement 1 (p < 0.05).

Conclusions

The increase in BPs, in sympathetically mediated BP-LF-powers, and in the RRI-LF/HF-ratio suggests prominent sympathetic activity shortly before brain death. Prefinal sympathetic hyperactivity might cause final organ failure with catecholamine-induced tissue damage which impedes post-mortem organ transplantation.     

Threat-induced autonomic dysregulation in panic disorder evidenced by heart rate variability measures

Objective

The objective was to compare autonomic response to threatening stimuli between patients with panic disorder (PD) and healthy volunteers by using 5-min recordings of heart rate variability (HRV).

Methods

Twenty-seven patients with PD and 20 healthy controls were recruited. The first 5-min measurement of HRV was conducted at resting state. HRV measurement during threatening stimuli was conducted while participants were viewing 15 threatening pictures. Spectral analyses measures included high-frequency (HF; 0.15–0.4 HZ) component, low-frequency (LF; 0.04–0.15 Hz) component and LF/HF ratio.

Results

There was no significant HRV difference between the two groups at the resting state. During threatening stimuli, the PD group had significantly higher LF power and LF/HF ratio and significantly lower HF power than the healthy controls (for all, P< .01). A two-way analysis of variance was employed to determine the effect of group (patient and control) and condition (threatening and resting) on all three HRV measures. The analysis showed a significant main effect of group (F= 12.21; P< .01), condition (F= 14.21; P< .001) and interaction effect between group and condition (F= 4.83; P< .05) on LF/HF ratio.

Conclusions

The findings from the present study suggest that patients with PD exhibit a sympathetic predominance when faced with threatening stimuli compared with normal control subjects.     

Gynecological and menstrual disorders in women with vasovagal syncope

Purpose

Vasovagal syncope (VVS) is a chronic debilitating condition seen mostly in young women of reproductive age. There are anecdotal reports of increased syncope and presyncope around menstruation. This case–control study assessed the effects of the menstrual cycle on lightheadedness episodes and compared the gynecological and pregnancy history of VVS patients to healthy subjects.

Methods

A custom-designed gynecological and menstrual cycle questionnaire was previously developed for patients with orthostatic intolerance. This questionnaire was administered to female patients with VVS (n = 128) as a part of the multicenter Second Prevention of Syncope Trial, and to gender-matched healthy subjects (n = 92).

Results

VVS patients and healthy subjects reported significant variability in self-reported lightheadedness throughout the menstrual cycle. Both cohorts experienced greatest lightheadedness during menses (53 ± 2 vs. 56 ± 4), which decreased during the follicular phase (44 ± 2 vs. 41 ± 4). VVS patients reported less severity in premenstrual symptoms (Fisher’s method P = 2.7E?06) compared to healthy controls. There is no difference in the incidence of gynecological abnormalities (Fisher’s exact P = 0.193) and pregnancy complications (P = 1.0) between the two cohorts. VVS patients have similar pregnancy rates compared to healthy subjects (P = 0.674).

Conclusion

The severity of lightheadedness varies during the menstrual cycle and is similar in both VVS patients and healthy controls. VVS patients have no greater risk of gynecological abnormalities and pregnancy complications than healthy subjects.     

Autonomic changes in young smokers: acute effects of inspiratory exercise

Purpose

One of the most important consequences of smoking is the development of cardiovascular diseases. However, little is known about the early consequences of smoking and the acute effects of a single inspiratory muscle exercise session (IME). We evaluated the acute effects of an IME on cardiac parameters of young smokers.

Methods

Twelve nonsmokers (C) and fifteen smokers [S; 2.08 (1.0–3.2) pack-years] underwent an acute IME. We evaluated blood pressure (BP) and lactate, and we recorded RR interval for posterior analysis of heart rate variability (HRV), before and after IME.

Results

At baseline, systolic BP and HRV parameters in time and frequency domains were changed in S group in comparison with the C. Following IME, S group reduced systolic BP (?8 %), low frequency band (LF) (?21.4 %), LF/high frequency (HF) (?57 %), as well as increased RR variance (+105 %) and HF band.

Conclusions

Our findings indicate that a single session of inspiratory muscle exercise was able to both reduce systolic BP and improve parasympathetic and sympathetic modulations in young smokers. The results of the current study highlight the importance of furthering research on this area to better elucidate the acute and chronic effects of inspiratory muscle training on early cardiovascular and pulmonary changes of cigarette smoking.

     

Cerebrovascular Pressure Reactivity and Cerebral Oxygen Regulation After Severe Head Injury

Background

To investigate the relationship between cerebrovascular pressure reactivity and cerebral oxygen regulation after head injury.

Methods

Continuous monitoring of the partial pressure of brain tissue oxygen (P_brO₂), mean arterial blood pressure (MAP), and intracranial pressure (ICP) in 11 patients. The cerebrovascular pressure reactivity index (PRx) was calculated as the moving correlation coefficient between MAP and ICP. For assessment of the cerebral oxygen regulation system a brain tissue oxygen response (TOR) was calculated, where the response of P_brO₂ to an increase of the arterial oxygen through ventilation with 100 % oxygen for 15 min is tested. Arterial blood gas analysis was performed before and after changing ventilator settings.

Results

Arterial oxygen increased from 108 ± 6 mmHg to 494 ± 68 mmHg during ventilation with 100 % oxygen. P_brO₂ increased from 28 ± 7 mmHg to 78 ± 29 mmHg, resulting in a mean TOR of 0.48 ± 0.24. Mean PRx was 0.05 ± 0.22. The correlation between PRx and TOR was r = 0.69, P = 0.019. The correlation of PRx and TOR with the Glasgow outcome scale at 6 months was r = 0.47, P = 0.142; and r = ?0.33, P = 0.32, respectively.

Conclusions

The results suggest a strong link between cerebrovascular pressure reactivity and the brain’s ability to control for its extracellular oxygen content. Their simultaneous impairment indicates that their common actuating element for cerebral blood flow control, the cerebral resistance vessels, are equally impaired in their ability to regulate for MAP fluctuations and changes in brain oxygen.