Paweł Zalewski

Deactivation of carotid body chemoreceptors by hyperoxia decreases blood pressure in hypertensive patients

Previous studies have shown that hyperoxia-induced deactivation of carotid body chemoreceptors reduces sympathetic activity in hypertensive patients but it does not affect blood pressure. The maintenance of blood pressure can be explained by the direct, vasoconstrictive effect of hyperoxia, which offsets diminished sympathetic activity. This study compares the effect of acute hyperoxia on hemodynamic parameters between hypertensive and normotensive subjects. Twelve males with hypertension (age 39.4±2.4 years; body mass index 27.4±1.1 kg m−2) and 11 normotensive males (age 39.9±2.7 years; body mass index 25.4±0.7 kg m−2) received, via non-rebreathing mask ventilation, ambient air, followed by 100% oxygen for 20 min. The stroke volume, heart rate, cardiac output, blood pressure, total peripheral resistance, respiratory rate, baroreceptor control of heart rate and oxygen saturation were recorded continuously. Several 30 s periods were analyzed before, during and after inducing hyperoxia. At baseline, the hypertensive subject’s blood pressure was higher and their baroreflex control of heart rate was lower when compared with the normotensive control group. After the first 30 s of hyperoxia, systolic, diastolic and mean blood pressures, as well as the total peripheral resistance, decreased significantly in hypertensives but not in normotensives. After 20 min of 100% oxygen ventilation, systolic and mean blood pressures and total peripheral resistance was increased in hypertensive patients, and the cardiac output and stroke volume had decreased in both groups. The results of this study confirm that deactivation of carotid body chemoreceptors can acutely decrease blood pressure in humans.

Impaired blood pressure variability in chronic fatigue syndrome—a potential biomarker

INTRODUCTION Autonomic dysfunction is common in chronic fatigue syndrome (CFS). This study set out to derive an autonomic biomarker using a comprehensive assessment of heart rate and blood pressure variability. METHODS Heart rate and non-invasive continuous blood pressure measurements (task force monitor) at rest and on standing were performed in CFS (Fukuda n = 68) and matched controls (n = 68) to derive high frequency (HF; parasympathetic) and low frequency (LF; sympathetic) heart rate variability (HRV), systolic (SBPV) and diastolic (DBPV) blood pressure variability. Variables of significance were combined using receiver operator curves to explore the diagnostic utility of parameters particularly at rest. RESULTS At rest, LF-HRV (sympathetic) was significantly increased in CFS compared to controls, while parasympathetic markers were significantly reduced (P = 0.006). Total DBP spectral power was increased (P = 0.0003) across all domains, with a shift towards sympathetic and away from parasympathetic SBPV (P = 0.05). On standing, overall SBPV response was significantly reduced with reductions in both sympathetic and parasympathetic components of SBPV (all P < 0.0001). Change in LF-DBP and relative balance of LF/HF DBP on standing differed between CFS and controls (P < 0.0001). Using the 85% sensitivity levels, we determined a threshold for three chosen resting BPV parameters of LF DBP >3.185, rest HF DBP >0.86, rest total DBP >7.05. Achieving all of these differentiated between CFS and controls with 77% sensitivity and 53% specificity. CONCLUSION This study has shown that there are objectively measured abnormalities of blood pressure variability in CFS and that these abnormalities have the potential to be a bedside diagnostic tool.

Resistance exercise improves autonomic regulation at rest and haemodynamic response to exercise in non-alcoholic fatty liver disease.

Autonomic dysfunction has been reported in patients with NAFLD (non-alcoholic fatty liver disease) and is associated with clinical presentations. To date, there are no therapies to improve autonomic regulation in people with NAFLD. The present study defines the impact of a short-term exercise programme on cardiac autonomic and haemodynamic regulation in patients with NAFLD. A total of 17 patients with clinically defined NAFLD [age, 55±12 years; BMI (body mass index), 33±5 kg/m²; liver fat, 17±9%] were randomized to 8 weeks of resistance exercise or a control group to continue standard care. Resting and submaximal exercise (50% of peak oxygen consumption) autonomic and cardiac haemodynamic measures were assessed before and after the intervention. Resistance exercise resulted in a 14% reduction in HR (heart rate) and 7% lower SBP (systolic blood pressure) during submaximal exercise (16 beats/min, P=0.03 and 16 mmHg, P=0.22). Sympathovagal balance, expressed as LF/HF (low-frequency/high-frequency) ratio of the mean HR beat-to-beat (R-R) interval, was reduced by 37% (P=0.26). Similarly sympathovagal balance of DBP (diastolic blood pressure) and SBP variability decreased by 29% (P=0.33) and 19% (P=0.55), respectively in the exercise group only. BRS (baroreflex sensitivity) increased by 31% (P=0.08) following exercise. The mean R-R interval increased by 23% (159 ms, P=0.09). Parasympathetic regulation was decreased by 17% (P=0.05) and overall sympathovagal balance in BP regulation (LF/HF ratio) increased by 26% (P=0.02) following resistance exercise. Resting haemodynamic measures remained similar between groups. Resistance exercise therapy seems to improve autonomic and submaximal exercise haemodynamic regulation in NAFLD. Further studies are required to define its role in clinical management of the condition.

Defining cardiac adaptations and safety of endurance training in patients with m.3243A>G-related mitochondrial disease

Background Cardiac hypertrophic remodelling and systolic dysfunction are common in patients with mitochondrial disease and independent predictors of morbidity and early mortality. Endurance exercise training improves symptoms and skeletal muscle function, yet cardiac adaptations are unknown. Methods and results Before and after 16-weeks of training, exercise capacity, cardiac magnetic resonance imaging and phosphorus-31 spectroscopy, disease burden, fatigue, quality of life, heart rate variability (HRV) and blood pressure variability (BPV) were assessed in 10 adult patients with m.3243A>G-related mitochondrial disease, and compared to age- and gender-matched sedentary control subjects. At baseline, patients had increased left ventricular mass index (LVMI, p < 0.05) and LV mass to end-diastolic volume ratio, and decreased longitudinal shortening and myocardial phosphocreatine/adenosine triphosphate ratio (all p < 0.01). Peak arterial–venous oxygen difference (p < 0.05), oxygen uptake (VO2) and power were decreased in patients (both p < 0.01) with no significant difference in cardiac power output. All patients remained stable and completed ≥ 80% sessions. With training, there were similar proportional increases in peak VO2, anaerobic threshold and work capacity in patients and controls. LVMI increased in both groups (p < 0.01), with no significant effect on myocardial function or bioenergetics. Pre- and post-exercise training, HRV and BPV demonstrated increased low frequency and decreased high frequency components in patients compared to controls (all p < 0.05). Conclusion Patients with mitochondrial disease and controls achieved similar proportional benefits of exercise training, without evidence of disease progression, or deleterious effects on cardiac function. Reduced exercise capacity is largely mediated through skeletal muscle dysfunction at baseline and sympathetic over-activation may be important in pathogenesis.

Thermal and hemodynamic response to whole-body cryostimulation in healthy subjects.

Whole-body cryotherapy (WBC) is an increasing applied cryotherapeutic method, that involves application of a cryotherapeutic factor to stimulate the body by the means of intense hypothermia of virtually the bodys entire area. This method is still not well recognized in Western Europe. However in recent years it is becoming increasingly popular in sports medicine and also in clinical application. Cryotherapeutic agents used in WBC are considered to be a strong stress stimulus which is associated with a variety of changes in functional parameters, particularly of the cardiovascular and autonomic nervous systems. However, such strong influence upon the entire body could be associated with the risk of unexpected reactions which might be dangerous for homeostasis. The present study evaluated the complex hemodynamic physiological reactions in response to WBC exposure in healthy subjects. Thirty healthy male volunteers participated. Each subject was exposed to WBC (-120°C) for 3-min. None of the participants had been exposed to such conditions previously. The research was conducted with modern and reliable measurements techniques, which assessed complex hemodynamic reactions and skin temperature changes non-invasively. All measurements were performed four times (before WBC, after WBC, WBC+3h and WBC+6h) with a Task Force Monitor (TFM - CNSystems, Medizintechnik, Gratz, Austria). Body superficial temperature was measured by infrared thermographic techniques - infra-red camera Flir P640 (Flir Systems Inc., Sweden). Our results show a significant decrease in heart rate, cardiac output, and increase in stroke volume, total peripheral resistance and baroreceptors reflex sensitivity. These changes were observed just after WBC exposure. At stages WBC+3h and WBC+6h there was observed a significant drop in baroreceptors reflex sensitivity due to increased thermogenesis. In conclusion, the present findings suggest that WBC strongly stimulates the baroreceptor cardiac reflex in response to body fluid changes which sequentially modulate HR and BP control in supine and resting healthy subjects. The study was performed on randomized and homogenic group of young healthy subjects. Our findings are important for WBC safety determination in research and clinical studies.

The Role of Multidrug Interactions in the Safety of Pharmacotherapy forConcomitant ParkinsonâÂÂs Disease and Arterial Hypertension in Poland

Purpose: Multidrug interactions are amongst to the most frequent problems of pharmacotherapy. Such potentially harmful interactions are likely to occur in Parkinson’s disease (PD) patients treated with concomitant arterial hypertension. The aim of this study was to analyze the prevalence of interactions between selected antiparkinson and hypotensive agents. Methods: The analysis included data on the pharmacotherapy of PD and arterial hypertension, obtained from 80 men and women, diagnosed with Hoehn and Yahr stage II and III. However, the table presented data refer to persondrugs (n=186), as some of the respondents were prescribed more than one antiparkinson and/or hypotensive agent. Results: A total of 53 (28.5%) person-interactions were documented in the study group, among them 20 (10.8%) minor, 28 (25.8%) moderate and 5 (28.5%) major ones. The presence of interactions was documented in 37 (46.3%) patients. The number of different interactions present in a single patient amounted to three (n=3, 3.8%), two (n=10, 12.5%), one (n=24, 30.0%). Conclusions: Currently, we lack any detailed guidelines regarding pharmacotherapy of arterial hypertension and selection of hypotensive agents for patients with PD. Achieving desired hypotensive effect and reduction of adverse events resulting from drug-to-drug interactions constitute prerequisites of efficacious hypotensive treatment in patients with PD.

Reduced thoracic fluid content in early stage primary biliary cirrhosis that associates with impaired cardiac inotropy

Primary biliary cirrhosis (PBC) is a chronic liver disease characterized by cholestasis. Recent MRI studies have confirmed the presence of cardiac abnormalities in noncirrhotic PBC patients. However, cardiorespiratory consequences of these abnormalities have not been explored. Thoracic fluid content (TFC) is a noninvasive bioelectrical impedance measure of the electrical conductivity of the chest cavity. We explored TFC and its relationship with cardiac contractility parameters in early-stage PBC patients, compared with chronic liver disease and community controls. TFC was measured in early-stage PBC (noncirrhotic; n = 78), nonalcoholic fatty liver disease (n = 23), and primary sclerosing cholangitis (n = 18) and in a community control population (n = 78). Myocardial contractility was measured as index of contractility, acceleration index, cardiac index, stroke index, left ventricular ejection time, and left ventricular work index. We also measured total arterial compliance and the Heather Index (HI; cardiac inotropy). The PBC group had significantly lower TFC compared with controls and the chronic liver disease groups (P < 0.0001). There was an association between increasing TFC and markers of cardiac function (cardiac index, stroke index, end-diastolic index, index of contractility, and acceleration index), together with indicators of cardiac inotropy and total arterial compliance. Multivariate analysis confirmed that the only parameter that independently associated with TFC was the marker of cardiac inotropy HI (P = 0.037; β 0.5). This study has confirmed that TFC is reduced in those with PBC, that this is specific to PBC, and that it associates independently with markers of cardiac inotropy.

Whole-body cryostimulation increases parasympathetic outflow and decreases core body temperature

The cardiovascular, autonomic and thermal response to whole-body cryostimulation exposure are not completely known. Thus the aim of this study was to evaluate objectively and noninvasively autonomic and thermal reactions observed after short exposure to very low temperatures. We examined 25 healthy men with mean age 30.1 ± 3.7 years and comparable anthropomorphical characteristic. Each subject was exposed to cryotherapeutic temperatures in a cryogenic chamber for 3 min (approx. -120 °C). The cardiovascular and autonomic parameters were measured noninvasively with Task Force Monitor. The changes in core body temperature were determined with the Vital Sense telemetric measurement system. Results show that 3 min to cryotherapeutic temperatures causes significant changes in autonomic balance which are induced by peripheral and central blood volume changes. Cryostimulation also induced changes in core body temperature, maximum drop of core temperature was observed 50-60 min after the stimulation. Autonomic and thermal reactions to cryostimulation were observed up to 6 h after the exposure and were not harmful for examined subjects.

Cardiovascular and Thermal Response to Dry-Sauna Exposure in Healthy Subjects

Dry-sauna is a strong thermal stimulus and is commonly used all over the world. The aim of this experiment was to comprehensively analyse cardiovascular and autonomic changes that result from an increase in core body temperature during sauna bath. The study included 9 healthy men with mean age 26.7 ± 3.0 years and comparable anthropomorphical characteristics. Each subject was exposed to one 15-minute session of dry-sauna treatment at 100°C and 30–40% humidity. The autonomic and baseline cardiovascular (i.e., hemodynamic and contractility) parameters were measured noninvasively with Task Force Monitor. Cardiovascular autonomic functions were assessed using baroreceptor reflex sensitivity (BRS) and spectral analysis of heart rate (HRV) and blood pressure (BPV) variability. Measurements were performed four times, at the following stages “before sauna,” “after sauna,” “sauna

The impact of laser irradiation on global stability in patients with vertebrobasilar insufficiency: A clinical report

Summary Background The purpose of our experiment was to determine whether laser stimulation can improve microcirculation in the posterior regions of the brain in patients with vertebrobasilar insufficiency (VBI). Material/Methods We studied 25 patients (20 female, 5 male, mean age 64) diagnosed with chronic VBI. All were evaluated using the De Klyn test, followed by qualitative assessment of stability using a Berg Balance Scale and evaluation of global stability using an electronic balance platform. A CTL-1100 low power laser was used with standard parameters. We established a protocol for laser irradiation at 5 points along the vertebral artery in the cervical region bilaterally. Irradiation was performed 10 times over two weeks. Results Significant improvement occurred after therapy in headache (p=0.0005), vertigo (p<0.0000), and tinnitus (p=0.0387). No significant differences were observed in nausea or nystagmus caused by head rotation. The Berg Balance Scale results showed significant differences in almost all features. There was a tendency towards improved stability in all parameters, and statistically significant differences in the total surface of support and the spread surface of support for the left foot. Conclusions Laser stimulation as applied in this study can be useful in the treatment of patients with VBI. The main reason for improvement in global stability, balance, and other VBI symptoms is better blood perfusion.