Higher Increase In Heart Rate Research Articles

Incidental parasympathetic cardiac denervation during atrial fibrillation ablation using high power short duration: a marker of long-term success.

There are multiple factors in both technique and substrate that lead to recurrence of atrial fibrillation after ablation. We sought to examine whether the degree of heart rate increase (HRI) caused by concurrent high-power-short-duration (HPSD) incidental parasympathetic denervation during AF ablation predicts long term success. Between December 2018 and December 2021, prospectively enrolled 214 patients who presented in sinus rhythm at AF ablation. Used 50 W of power and contact force (CF) of 5-15g and 10-20g at a flow rate of 40mL/min on the anterior and posterior left atrial walls, respectively. Males were 143 (66.8%) and paroxysmal was 124 (57.9%) patients. Mean age 61.1 ± 12.3years and follow-up time was 32.8 ± 13.2months. Arrhythmia occurred after 90days in 39 (18.2%) patients, 19 (48.7%) from the paroxysmal and 20 (51.3%) from the persistent AF patients. Recurrence group showed a lower HRI from a mean of 57 ± 7.7 to 64.4 ± 10.4bpm (12.3%) while in success group HRI was from 53.8 ± 9.7 to 66.8 ± 11.6bpm [(24.2%) p = 0.04]. We divided HRI in 3 percentiles of ≤ 8%, > 8 ≤ 37% and > 37%. A predictor of recurrence was identified in those in the first (< 8%, p = 0.006) and a predictor of success in the later (> 37%, p = 0.01) HRI percentile. Atrial fibrillation ablation with HPSD incidental cardiac parasympathetic denervation identified that patients with lower heart rate increase are prone to recurrence while those with higher heart rate increase had higher maintenance of sinus rhythm at a long-term follow-up.

Abstract 058: Factors Contributing To Postprandial Hypotension In Neurogenic Orthostatic Hypotension

Postprandial hypotension (PPH) is defined as a sudden and substantial decrease (&gt;20 mmHg or &gt;10 mmHg) in blood pressure (BP) within two hours post meal intake; This condition is highly prevalent in neurogenic orthostatic hypotension (nOH) and is associated with pre-syncopal symptoms and postprandial syncope. We studied factors contributing to PPH in nOH. Patients were admitted at the Vanderbilt clinical research center and placed on a sodium-controlled diet. Autonomic function testing, including continuous recording of BP and heart rate (HR) during head up tilt, sinus arrhythmia, and Valsalva Maneuver, was performed. Subjects took a high-carbohydrate meal (~500 Kcal). Hemodynamic parameters were monitored every 5 mins for 30 minutes before and up to 120 minutes afterwards. Results: We recruited 13 patients with peripheral autonomic failure (Parkinson’s Disease), 62% males, 73±9.08 y.o. and 13 with central autonomic failure (Multiple System Atrophy), 69% males, 62±8.23 y.o. All subjects had a substantial SBP (-42.9 ±27.90 mmHg) and DBP (-20.8 ±15.2 mmHg) decrease within 3 mins of standing, without compensatory HR increase (11.64 ± 5.97 bpm). The orthostatic increase in HR adjusted by decrease in SBP was abnormal (0.4±0.43, normal&gt;0.5), sinus arrhythmia ratio was abnormal (1.05±0.04, normal&gt;1.2). Pressor response in Valsalva Maneuver showed impaired sympathetic vasoconstriction. Postprandial hemodynamic changes were analyzed with area under the curve (AUC) and at 30-min timepoint post meal, which was the nadir. PD had a larger DBP increase (907±214.83 mmHg vs.1209±277.68 mmHg MSA, P=0.016), MSA had a higher HR increase (1102±236 mmHg vs. 1318±199.82 mmHg, P=0.029). No difference was found in AUC SBP, however at 30-min post-meal, SBP was lower in PD (-25±24.19 mmHg vs. -3.3±15.05 mmHg MSA, P=0.026). Only supine SBP predicted the postprandial decrease in SBP at 30 min (r=-0.5, P=0.04). Conclusion: PPH is more severe in peripheral autonomic failure; supine BP was associated with PPH.

A 2-week high-intensity interval training intervention improves ejaculation control among men with premature ejaculation.

Premature ejaculation (PE), which leads to substantial distress in men and their partners, is a common male sexual dysfunction worldwide. However, there is still a lack of effective treatments without side effects. We investigated the effect of high-intensity interval training (HIIT) on PE symptoms. We recruited 92 Chinese men aged 18-36 to complete the experiment. There were 22 (13 in the control group; 9 in the HIIT group) men diagnosed with PE and 70 (41 in the control group; 29 in the HIIT group) men with normal ejaculatory function. In the HIIT group, participants completed HIIT exercises every morning for 14 days. Participants also completed surveys inquiring about demographic information, erectile function, PE symptoms, body image (including sexual body image), physical activity, and sexual desire. The heart rate was measured before and after each HIIT. In the control group, participants were instructed not to do HIIT, but other procedures were the same as in the HIIT group. Results indicated that the HIIT intervention alleviated PE symptoms in men with PE. In addition, in the HIIT group, men with PE who had a higher heart-rate increase during the HIIT intervention reported the greatest overall decrements in PE symptoms. In men with normal ejaculatory function, HIIT did not decrease PE symptoms. In addition, increments in the heart rate during the intervention were associated with more pronounced PE symptoms post-intervention in this group. Analyses of secondary outcome measures suggested that the HIIT intervention improved general and sexual body image satisfaction of men with PE compared to before the intervention. In summary, HIIT intervention may reduce PE symptoms in men with PE. The heart-rate increase during the intervention may be a key factor influencing the effect of the HIIT intervention on PE symptoms.

Influence of N95 Mask-related Hypoxemia on Headache, Stress, Anxiety, and Quality of Sleep during COVID-19 Patient Care among Frontline Health Care Professionals.

Prolonged use of N95 masks by healthcare workers might affect physical health due to mask-related hypoxia in addition to the psychological effects of N95 masks. We tried to explore the association of N95 mask-related hypoxia and headache with stress, quality of sleep, and anxiety in the current study. The sample (N = 78) consisted of 41 doctors and 37 nurses involved in COVID-19 patient care and using N95 masks with or without PPE for at least 4 hours. Perceived stress scale (PSS), Coronavirus anxiety scale (CAS), and Pittsburgh sleep quality index (PSQI) were administered, and physical parameters like heart rate and oxygen saturation (SpO2) were measured. Around 42% of the study participants experienced headaches after wearing an N95 mask and had a higher increase in heart rate (mean percent:10.5% vs 6.3%) and decline in SpO2 (mean percent: 2.6% vs 1.5%) compared to those who didn't develop a headache after N95 mask use. Independent samples t-test showed a mean difference for PSS and CAS between those who experienced headaches and those who didn't. The mean PSQI scores among the study participants were 8.91 ± 5.78; the score among those participants with and without headache was 10.57 ± 3.11 and 7.68 ± 2.53, respectively. Perceived corona anxiety, poor sleep quality, and corona anxiety are associated with N95-related headaches and SpO2 drop among health professionals who wear N95 masks for at least 4 hours.

Comparison of outcomes with low-power long duration versus high-power short duration of ablation: the role of the acute change in sinus rhythm after the ablation as a predictor of long-term success.

Different results are described after atrial fibrillation ablation and multiple predictors of recurrence are well established. Evaluate and analyze if heart rate increase (HRI) during a first atrial fibrillation (AF) ablation with low-power long-duration (LPLD) and subsequently with high-power short-duration (HPSD) can impact. Retrospectively analyzed 340 consecutive patients (pts) undergoing first AF ablation. There were 158 pts in LPLD group: 113 (71.5%) paroxysmal AF with ablation with a power of 30/20w, on anterior and posterior left atrial (LA) wall, respectively, and contact force of 10-30g for 30s. There were 182 pts in HPSD group: 106 (58.2%) paroxysmal AF, who underwent ablation with 45/50w, contact force of 8-15g/10-20g and 35mL/min flow rate on anterior and posterior left atrial wall, respectively. Median follow-up was 32 ± 16months. Success was observed in 94 (59.5%) patients in LPLD and 152 (83.5%) in HPSD, in LPLD group we documented a median HRI of 4.3bpm (8%), compared to preablation heart rate, while a higher HRI in HPSD group of HRI 13.5bpm (27.2%) was noted. Heart rate increase was associated with a higher success rate in both ablation techniques and independently showed an important impact on the success rate after AF ablation. HPSD compared to LPLD showed a higher proportion of HRI and also demonstrated a superiority in maintaining sinus rhythm at a long-term follow-up.

Orthostatic Intolerance in Adults Reporting Long COVID Symptoms Was Not Associated With Postural Orthostatic Tachycardia Syndrome.

In this observational cross-sectional study, we investigated predictors of orthostatic intolerance (OI) in adults reporting long COVID symptoms. Participants underwent a 3-min active stand (AS) with Finapres® NOVA, followed by a 10-min unmedicated 70° head-up tilt test. Eighty-five participants were included (mean age 46 years, range 25–78; 74% women), of which 56 (66%) reported OI during AS (OIAS). OIAS seemed associated with female sex, more fatigue and depressive symptoms, and greater inability to perform activities of daily living (ADL), as well as a higher heart rate (HR) at the lowest systolic blood pressure (SBP) point before the first minute post-stand (mean HRnadir: 88 vs. 75 bpm, P = 0.004). In a regression model also including age, sex, fatigue, depression, ADL inability, and peak HR after the nadir SBP, HRnadir was the only OIAS predictor (OR = 1.09, 95% CI: 1.01–1.18, P = 0.027). Twenty-two (26%) participants had initial (iOH) and 5 (6%) classical (cOHAS) orthostatic hypotension, but neither correlated with OIAS. Seventy-one participants proceeded to tilt, of which 28 (39%) had OI during tilt (OItilt). Of the 53 who had a 10-min tilt, 7 (13%) had an HR increase >30 bpm without cOHtilt (2 to HR > 120 bpm), but six did not report OItilt. In conclusion, OIAS was associated with a higher initial HR on AS, which after 1 min equalised with the non-OIAS group. Despite these initial orthostatic HR differences, POTS was infrequent (2%). ClinicalTrials.gov Identifier: NCT05027724 (retrospectively registered on August 30, 2021).

Effect of Dynamic Hyperinflation on Cardiac Response to Exercise of Patients With Chronic Obstructive Pulmonary Disease

IntroductionAlthough the major limitation to exercise performance in patients with COPD is dynamic hyperinflation (DH), little is known about its relation with cardiac response to exercise. Our objectives were to compare the exercise response of stroke volume (SV) and cardiac output (CO) between COPD patients with or without DH and control subjects, and to assess the main determinants. MethodsFifty-seven stable COPD patients without cardiac comorbidity and 25 healthy subjects were recruited. Clinical evaluation, baseline function tests, computed tomography and echocardiography were conducted in all subjects. Patients performed consecutive incremental exercise tests with measurement of operating lung volumes and non-invasive measurement of SV, CO and oxygen uptake (VO2) by an inert gas rebreathing method. Biomarkers of systemic inflammation and oxidative stress, tissue damage/repair, cardiac involvement and airway inflammation were measured. ResultsCOPD patients showed a lower SV/VO2 slope than control subjects, while CO response was compensated by a higher heart rate increase. COPD patients with DH experienced a reduction of SV/VO2 and CO/VO2 compared to those without DH. In COPD patients, the end-expiratory lung volume (EELV) increase was related to SV/VO2 and CO/VO2 slopes, and it was the only independent predictor of cardiac response to exercise. However, in the regression models without EELV, plasma IL-1β and high-sensitivity cardiac troponin T were also retained as independent predictors of SV/VO2 slope. ConclusionDynamic hyperinflation decreases the cardiac response to exercise of COPD patients. This effect is related to systemic inflammation and myocardial stress but not with left ventricle diastolic dysfunction.

Effect of Dynamic Hyperinflation on Cardiac Response to Exercise of Patients With Chronic Obstructive Pulmonary Disease

IntroductionAlthough the major limitation to exercise performance in patients with COPD is dynamic hyperinflation (DH), little is known about its relation with cardiac response to exercise. Our objectives were to compare the exercise response of stroke volume (SV) and cardiac output (CO) between COPD patients with or without DH and control subjects, and to assess the main determinants. MethodsFifty-seven stable COPD patients without cardiac comorbidity and 25 healthy subjects were recruited. Clinical evaluation, baseline function tests, computed tomography and echocardiography were conducted in all subjects. Patients performed consecutive incremental exercise tests with measurement of operating lung volumes and non-invasive measurement of SV, CO and oxygen uptake (VO2) by an inert gas rebreathing method. Biomarkers of systemic inflammation and oxidative stress, tissue damage/repair, cardiac involvement and airway inflammation were measured. ResultsCOPD patients showed a lower SV/VO2 slope than control subjects, while CO response was compensated by a higher heart rate increase. COPD patients with DH experienced a reduction of SV/VO2 and CO/VO2 compared to those without DH. In COPD patients, the end-expiratory lung volume (EELV) increase was related to SV/VO2 and CO/VO2 slopes, and it was the only independent predictor of cardiac response to exercise. However, in the regression models without EELV, plasma IL-1β and high-sensitivity cardiac troponin T were also retained as independent predictors of SV/VO2 slope. ConclusionDynamic hyperinflation decreases the cardiac response to exercise of COPD patients. This effect is related to systemic inflammation and myocardial stress but not with left ventricle diastolic dysfunction.

Cardiovascular and Orthostatic Responses to a Festive Meal Associated With Alcohol in Young Men.

Aim: Sharing a festive meal associated with alcohol is quite common. While the cardiovascular changes occurring after meal ingestion of different nutrient composition has been well-established, the effects of ingesting a festive versus a standard meal accompanied with alcohol are less clear. Here, we compared the postprandial hemodynamics, cutaneous and psychomotor performance responses after ingestion of a classical Swiss festive meal [cheese fondue (CF)] versus a light ready-meal [Nasi Goreng (NG)], both accompanied with white wine.Methods: In a randomized cross over design, we examined in 12 healthy young men, the continuous cardiovascular, cutaneous, and reaction time responses to ingestion of cheese fondue versus a standard meal at rest (sitting position) and hemodynamic changes in response to orthostatic challenge (active standing) in pre- and postprandial phases.Results: Breath alcohol concentration after wine ingestion was similar after both meal types. Compared to the standard meal, consumption of CF induced higher increases in heart rate (HR), cardiac output (CO), double product (DP) and cardiac power output (CPO), greater vasodilation, and rises in skin blood flow and skin temperature. Greater increases in HR, DP, and mean blood pressure (MBP) were observed during orthostatic challenges with CF compared to NG. A two-choice reaction time task revealed similar reaction times with both meals, suggesting no influence of meal composition on psychomotor performance.Conclusion: In sitting position, CF ingestion induced a more important cardiovascular load compared to NG. Although the dose of alcohol and the festive meal used here did not lead to orthostatic hypotension, eating CF induced a greater cardiometabolic load suggesting that hemodynamic reserves have been encroached during active standing. This may impede the cardiovascular capacity during physical exercise or stress situations, particularly in elderly subjects who are at greater risk for postprandial hypotension and cardiovascular diseases.

Adiponectin, biomarkers of inflammation and changes in cardiac autonomic function: Whitehall II study

BackgroundBiomarkers of inflammation and adiponectin are associated with cardiovascular autonomic neuropathy (CAN) in cross-sectional studies, but prospective data are scarce. This study aimed to assess the associations of biomarkers of subclinical inflammation and adiponectin with subsequent changes in heart rate (HR) and heart rate variability (HRV) in non-diabetic and diabetic individuals.MethodsData are based on up to 25,050 person-examinations for 8469 study participants of the Whitehall II cohort study. Measures of CAN included HR and several HRV indices. Associations between baseline serum levels of high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, IL-1 receptor antagonist (IL-1Ra) and adiponectin and 5-year changes in HR and six HRV indices were estimated using mixed-effects models adjusting for age, sex, ethnicity, body mass index (BMI), metabolic covariates and medication. A modifying effect of diabetes was tested.ResultsHigher levels of IL-1Ra were associated with higher increases in HR. Additional associations with measures of HRV were observed for hsCRP, IL-6 and IL-1Ra, but these associations were explained by BMI and other confounders. Associations between adiponectin, HR and HRV differed depending on diabetes status. Higher adiponectin levels were associated with more pronounced decreases in HR and increases in three measures of HRV reflecting both sympathetic and vagal activity, but these findings were limited to individuals with type 2 diabetes.ConclusionsHigher IL-1Ra levels appeared as novel risk marker for increases in HR. Higher adiponectin levels were associated with a more favourable development of cardiovascular autonomic function in individuals with type 2 diabetes independently of multiple confounders.

Rehabilitation training in artificially heated environment.

Sauna has become a popular club house facility where the dweller enjoys relaxation. Some exercise groups like yoga and Qigong practitioners, are making use of the heated environment to achieve quicker and better results of trainings. Sauna therapy is producing a thermal stress through hyperthermia. The cardiovascular system readily responds by increasing the heart rate which can become double the resting stage within minutes and cardiac output may have a 70% increase. The body’s surface response to heat leads to a 40% of decrease in peripheral vascular resistance, thus allowing rapid peripheral blood flow which is responsible for greater heat dispersal directly from the skin. The chained physiological reactions of increased cardiac and pulmonary outputs, while blood pressure drops suggest that Sauna could be good for chronic diseases. When active stretching are executed simultaneously with controlled breathing in a smooth synchronized chain of activities under the individual’s free will, a harmonized state of mind reaching the level of meditation follows. Sauna room environment initiates a physiological stat equivalent to moderate exercises. Qigong practice is typical anaerobic training. Both Sauna and Qigong lead to a tranquility of the mind. The unique nature of practicing Qigong in a heated environment is therefore clear. A small pilot study on Qigong practice within the Sauna room showed a higher increase in heart rate which amounted to 30%–40% above the pre-exercise level. The blood pressure checked after Qigong, on the contrary, remained stable or even slightly decreased.

Attachment Status Affects Heart Rate Responses to Experimental Ostracism in Inpatients with Depression.

Depression is assumed to be both a risk factor for rejection and a result of it, and as such constitutes an important factor in rejection research. Attachment theory has been applied to understand psychological disorders, such as depression, and can explain individual differences in responses to rejection. Research on autonomic nervous system activity to rejection experiences has been contradictory, with opposing strings of argumentation (activating vs. numbing). We investigated autonomic nervous system-mediated peripheral physiological responses (heart rate) to experimentally manipulated ostracism (Cyberball) in 97 depressed patients with organized (n = 52) and disorganized attachment status (n = 45). Controlling for baseline mean heart rate levels, depressed patients with disorganized attachment status responded to ostracism with significantly higher increases in heart rate than depressed patients with organized attachment status (p = .029; ηp2 = .051). These results suggest that attachment status may be a useful indicator of autonomic responses to perceived social threat, which in turn may affect the therapeutic process and the patient-therapist relationship.

Human-animal interactions and safety during dairy cattle handling—Comparing moving cows to milking and hoof trimming

Cattle handling is a dangerous activity on dairy farms, and cows are a major cause of injuries to livestock handlers. Even if dairy cows are generally tranquil and docile, when situations occur that they perceive or remember as aversive, they may become agitated and hazardous to handle. This study aimed to compare human-animal interactions, cow behavior, and handler safety when moving cows to daily milking and moving cows to more rarely occurring and possibly aversive hoof trimming. These processes were observed on 12 Swedish commercial dairy farms. The study included behavioral observations of handler and cows and cow heart rate recordings, as well as recording frequencies of situations and incidents related to an increased injury risk to the handler. At milking, cows were quite easily moved using few interactions. As expected, the cows showed no behavioral signs of stress, fear, or resistance and their heart rate only rose slightly from the baseline (i.e., the average heart rate during an undisturbed period before handling). Moving cows to hoof trimming involved more forceful and gentle interactions compared with moving cows to milking. Furthermore, the cows showed much higher frequencies of behaviors indicative of aversion and fear (e.g., freezing, balking, and resistance), as well as a higher increase in heart rate. The risk of injury to which handlers were exposed also increased when moving cows to hoof trimming rather than to routine milking. Some interactions (such as forceful tactile interactions with an object and pulling a neck strap or halter) appeared to be related to potentially dangerous incidents where the handler was being kicked, head-butted, or run over by a cow. In conclusion, moving cows to hoof trimming resulted in higher frequencies of behaviors indicating fear, more forceful interactions, and increased injury risks to the handler than moving cows to milking. Improving potentially stressful handling procedures (e.g., by better animal handling practices and preparation of cows to cope with such procedures) can increase handler safety, animal welfare, ease of handling, and efficiency.

PP.19.07

Objective: Glucagon-like peptide-1 (GLP-1) agonists are increasingly used in the management of type 2 diabetes mellitus (T2DM), but their long-term cardiovascular safety is not yet confirmed. Therapy with GLP-1 receptor agonist liraglutide has been associated with improvements in blood pressure but also with higher increases in heart rate (HR) compared to other GLP-1 receptor agonists. In the present study, we assessed effects of liraglutide on systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR in overweight T2DM. Design and method: A total of 42 overweight T2DM with normal or mildly decreased (estimated GFR > 60 mlmin-11.73 m2) renal function were included in this study and followed for 7 months (age 58 ± 7 years, 18 M/24F, body mass index (BMI) 38.5 ± 5.6 kg/m2, weight 111 ± 21 kg, HbA1c 8.1 ± 0.9%, duration of diabetes 13 ± 6 years, serum creatinine 71 ± 15 μmol/L, estimated GFR 90 ± 13 mlmin-11.73m2). Blood pressure was measured twice in the sitting position with a mercury sphygmomanometer after a resting period of 10 minutes. HR was determined using a standard 12-lead ECG after a resting period of 10 minutes. Liraglutide was started as 0.6 mg once daily dose and increased to 1.2 mg once daily after one week. Results: Treatment with liraglutide caused a significant decrease in BMI from 38 ± 5 to 36 ± 6 kg/m2 (p < 0.001), weight from 111 ± 21 to 106 ± 23 kg (p < 0.001), and waist circumference from 120 ± 14 to 114 ± 15 cm (p = 0.006), while HbA1c (from 8.1 ± 0.9 to 8.0 ± 1.3% (p = 0.1)) did not significantly changed. However, the 7-months administration of liraglutide caused a significant decrease in SBP from 145 ± 20 to 135 ± 18 mmHg (p = 0.005) and DBP from 88 ± 8 to 82 ± 8 mmHg (p < 0.001), while HR (from 78 ± 14 to 73 ± 8 beats/min (p = 0.2)) did not significantly changed. Conclusions: The results of our study suggest that therapy with GLP-1 receptor agonist liraglutide may significantly reduce SBP and DBP by 6 to 10 mmHg and may offer an alternative therapy for hypertension in overweight T2DM. In addition, in our study therapy with liraglutide was associated with a small decrease in HR.

Variant cardiovascular regulation in children with postural tachycardia syndrome

Postural tachycardia syndrome (POTS) manifests as marked tachycardia while standing. We noticed two forms of circulatory response to orthostatic stress in POTS. We investigated cardiovascular and autonomic nervous response to orthostatic stress in the two forms. We studied 79 patients with POTS and 38 healthy control subjects (Ct). Beat-to-beat blood pressure (BP) and heart rate (HR) were non-invasively and continuously measured in the supine and standing positions. Autonomic nervous function was evaluated on power spectral analysis of HR variability and diastolic BP variability. We divided the subjects into two groups: standing-induced tachycardia (SI group; increase in HR ≥35 beats/min) and supine tachycardia (Su group; standing HR ≥115 beats/min with standing-induced HR increase <35 beats/min). The Su group had higher supine BP and HR compared with the other groups, indicating dominant sympathetic control of the heart in the supine position. While rising, the SI group had a higher increase in HR than the Ct group, indicating excessive withdrawal of vagal tone. The Su group had a smaller increase in HR and a greater decrease of systolic BP and cardiac index by standing compared with the SI group. These results suggest that compensatory mechanisms of sympathetic function during standing failed in the Su group, probably because of exhaustion by the nearly maximum effort to generate sympathetic drive even in the supine position with low central blood volume. There is a difference between the two types of POTS, in the balance of resting autonomic function and hemodynamic response to standing.

Variability in mechanisms associated with tolerance to progressive reductions in central blood volume (1157.3)

High tolerance to reductions in central blood volume has been associated with higher heart rate (HR), sympathetic nerve activity (SNA), and cardiac baroreflex sensitivity (BRS). Using subjects classified as high tolerance to lower body negative pressure (LBNP), we tested the hypothesis that subjects with BRS &gt; 1.0 would demonstrate greater LBNPtolerance associated with higher HR, PVR, and SNA than subjects with BRS &lt;1.0. Methods: 112 subjects underwent LBNP to presyncope. SNA was measured via microneurography (N= 19) and arterial pressure (AP) was measured by finger photoplethysmography. BRS was auto‐calculated (WinCPRS) as ∆RR/∆AP. BRS was used to dichotomize subjects into two groups (Group 1 = BRS &gt; 1.0, N = 49, and Group 2 = BRS &lt; 1.0, N = 67). Results: Both groups had similar tolerance times (1849±260 vs. 1839 ±253 sec), AP (78±11 vs. 79±12 mmHg), and cardiac output (4.5±1.2 vs. 4.7 ± 1.1 L/min) at presyncope. Group 1 (BRS&gt;1.0) had lower HR (107 ± 19 vs. 131 ± 20 beats/min), higher SV (45 ± 15 vs. 36 ± 15 ml), less SNA (45 ± 13 vs. 53 ± 7 bursts/min), and less increase in PVR (4.1 ± 1.3 vs. 4.5 ± 2.6) compared to Group 2 (BRS &lt; 1.0). Conclusions: Contrary to our hypothesis, higher HR, SNA and BRS were not associated with greater tolerance to reduced central blood volume. In a cohort of high tolerant subjects, some individuals rely on cardiac filling and vagal withdrawal to defend AP while others rely on sympathoexcitation.Grant Funding Source: Department of Defense

Cardiovascular Safety of Anagrelide in Healthy Subjects: Effects of Caffeine and Food Intake on Pharmacokinetics and Adverse Reactions

BackgroundEssential thrombocythaemia (ET) is a rare clonal myeloproliferative disorder characterized by a sustained elevation in platelet count and megakaryocyte hyperplasia. Anagrelide is used in the treatment of ET, where it has been shown to reduce platelet count. Anagrelide is metabolized by cytochrome P450 (CYP) 1A2, and previous studies of the effect of food on the bioavailability and pharmacokinetics of anagrelide were conducted prior to the identification of the active metabolite, 3-hydroxyanagrelide.ObjectivesThe objectives of this study were to determine the effect of food and caffeine on the pharmacokinetics of anagrelide and its active metabolite, 3-hydroxyanagrelide, to monitor electrocardiogram (ECG) parameters following drug administration, and to document the relationship between palpitations, ECG changes and caffeine intakeMethodsThirty-five healthy subjects who received 1 mg of anagrelide following either a 10-h fast or within 30 min of a standardized breakfast, including two cups of coffee, were studied.ResultsTime to maximum (peak) plasma concentration (Cmax) of anagrelide was 4.0 h in the fed and 1.5 h in the fasted group (p < 0.05); similar results were observed for 3-hydroxyanagrelide. The mean Cmax of anagrelide was 4.45 ± 2.32 ng/mL and 5.08 ± 2.99 ng/mL in the fed/caffeine and fasted groups, respectively; peak concentrations were higher for 3-hydroxyanagrelide in both the fed/caffeine and fasted groups. The most frequent adverse events (AEs) were headache (60 %) and palpitations (40 %). There were no serious AEs and all ECGs were normal, although significant reductions in PR interval, QRS length and QT interval were observed in both groups. Heart rate increased after anagrelide administration in both fed/caffeine and fasted states (p < 0.01); however, increased heart rate was significantly more frequent in the fed/caffeine state than in the fasted state (p < 0.001 for heart rate increase in the first hour after drug administration). There was a trend towards a greater heart rate increase in subjects reporting palpitations than in those without (mean heart rate ± SD at 1 h: 10.1 ± 6.4 vs. 8.0 ± 8.4 beats/min [p = 0.35]; at 4 h: 12.7 ± 7.5 vs. 9.1 ± 8.8 beats/min [p = 0.10], respectively).ConclusionWe conclude that food/caffeine delayed absorption of anagrelide. Anagrelide was generally well tolerated and had small effects on ECG parameters and heart rate. Caffeine may be implicated in a higher increase in heart rate and increased frequency of palpitations observed following administration of anagrelide with food/caffeine versus fasting.

Determinants of muscle metaboreflex and involvement of baroreflex in boys and young men

This study aimed to assess the arterial pressure (AP) determinants during the muscle metaboreflex in boys and men and to investigate the contribution of baroreflex and sympathovagal function to the metaboreflex-induced responses. Fourteen pre-adolescent boys and 13 men performed a protocol involving: baseline, isometric handgrip exercise, circulatory occlusion, and recovery. The same protocol was repeated without occlusion. During baseline, boys had lower beat-to-beat AP, higher heart rate (HR), and lower low/high frequency HR variability. During exercise, a parasympathetic withdrawal was evident in both groups. In adults, HR was the key contributor to the pressure response, with no changes in stroke volume, whereas in boys, the lower HR increase was counterbalanced by an increase in stroke volume, resulting in similar relative increases in AP in both groups. In recovery, boys exhibited a faster rate of HR-decay, rapid vagal reactivation, and greater decrease in TPR than men. An overshoot in baroreceptor sensitivity was observed in men. The isolated metaboreflex resulted in a similar AP elevation in both age groups (by ~15mmHg), and attenuated spontaneous baroreceptor sensitivity. However, during the metaboreflex, pre-adolescent males exhibited a lower increase in peripheral resistance and a greater bradycardic response than adults, and a fast restoration of vagal activity to non-occlusion levels. During metaboreflex, boys were capable of eliciting a pressure response similar to the one elicited by men; however, the interplay of the mechanisms underlying the rise in AP differed between the two groups with the vagal contribution being greater in the younger participants.

Heart Rate as a Marker of Stress in Ambulance Personnel: A Pilot Study of the Body's Response to the Ambulance Alarm

Studies have demonstrated the presence of stress and post-traumatic stress among ambulance personnel, but no previous research has focused on the body's reaction in the form of the change in heart rate of ambulance staff in association with specific occupational stress. The purpose of this study is to investigate whether work as an ambulance professional generates prolonged physiological arousal that can be measured by heart rate in different situations. Twenty participants carried a pulse-meter in the form of a wristwatch, which continuously measured and stored their heart rate 24 hours per day for a period of seven days. All ambulance alarms that occurred during the test period were recorded in journals, and the participants completed diaries and a questionnaire describing their experiences. The alarms were divided into different phases. Correlations between heart rate in the different phases were computed. Analysis of study data indicated a significant rise of heart rate unrelated to physical effort during an emergency alarm and response. This increased heart rate was noticed throughout the mission and it was not related to the length of experience the staff had in the ambulance profession. In addition, a non-significant trend suggested that alarms involving acutely ill children lead to an even higher increase in heart rate. In addition, this research showed that constant tension existed during sleep, while available for an emergency, indicated by a noticeable increase in heart rate during sleep at work compared to sleeping at home. A rise in heart rate was experienced during all acute emergency missions, regardless of a subject's experience, education, and gender. Missions by themselves generated a rate increase that did not seem to correlate with physical effort required during an emergency response. This study shows that working on an ambulance that responds to medical emergencies is associated with a prolonged physiological arousal.

Patient-cooperative control increases active participation of individuals with SCI during robot-aided gait training

BackgroundManual body weight supported treadmill training and robot-aided treadmill training are frequently used techniques for the gait rehabilitation of individuals after stroke and spinal cord injury. Current evidence suggests that robot-aided gait training may be improved by making robotic behavior more patient-cooperative. In this study, we have investigated the immediate effects of patient-cooperative versus non-cooperative robot-aided gait training on individuals with incomplete spinal cord injury (iSCI).MethodsEleven patients with iSCI participated in a single training session with the gait rehabilitation robot Lokomat. The patients were exposed to four different training modes in random order: During both non-cooperative position control and compliant impedance control, fixed timing of movements was provided. During two variants of the patient-cooperative path control approach, free timing of movements was enabled and the robot provided only spatial guidance. The two variants of the path control approach differed in the amount of additional support, which was either individually adjusted or exaggerated. Joint angles and torques of the robot as well as muscle activity and heart rate of the patients were recorded. Kinematic variability, interaction torques, heart rate and muscle activity were compared between the different conditions.ResultsPatients showed more spatial and temporal kinematic variability, reduced interaction torques, a higher increase of heart rate and more muscle activity in the patient-cooperative path control mode with individually adjusted support than in the non-cooperative position control mode. In the compliant impedance control mode, spatial kinematic variability was increased and interaction torques were reduced, but temporal kinematic variability, heart rate and muscle activity were not significantly higher than in the position control mode.ConclusionsPatient-cooperative robot-aided gait training with free timing of movements made individuals with iSCI participate more actively and with larger kinematic variability than non-cooperative, position-controlled robot-aided gait training.