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Background and purpose This study investigated the effects of deep abdominal breathing on cardiovascular parameters and symptoms in patients with postural orthostatic tachycardia syndrome (POTS) during head‐up tilt‐table (HUT) challenge. Methods Thirty POTS patients completed two consecutive rounds of 10‐min HUT in a crossover design. One round was HUT without intervention, and one round combined the HUT with deep breathing at a rate of 6 breaths/min. Cardiovascular parameters, including mean blood pressure and maximum and mean heart rate (HR), were measured supine and standing. Symptoms were assessed using the Vanderbilt Orthostatic Symptom Score (VOSS). Results During the breathing technique, the mean HR increase was −7.35 bpm (95% confidence interval [CI] = −11.71 to −2.98), and the maximum HR increase was −6.27 bpm (95% CI = −11.85 to −0.68, p = 0.041), significantly lower compared to normal breathing. Additionally, improvements were observed in all absolute cardiovascular parameters during standing, with VOSS symptoms simultaneously and significantly decreasing by −5.38 (95% CI = −10.43 to −0.36). Conclusions Slow deep abdominal breathing can act as a simple technique to reduce the standing HR increase upon HUT in patients with POTS. This suggests that modulation of the cardiopulmonary neurocircuits and the respiratory pump may reduce HR increase and symptoms in patients with POTS. The findings of this study highlight the use of a safe, zero‐cost, and simple behavioral tool to suggest to POTS patients for symptom relief apart from standard treatment. The observed improvements in cardiovascular parameters and symptoms offer a promising therapeutic approach for patients in times of inadequate treatment options.

Background Neurally mediated syncope (NMS) is the primary cause of temporary and self‐limiting loss of consciousness. The tilt table test (TTT) has been consistently employed as a supplementary diagnostic tool for syncope evaluation. However, TTT requires specialized equipment, which is lacking in several emergency room and clinic environments. We hypothesized that patients susceptible to NMS may have higher parasympathetic tone. Thus, this study investigates the correlation between PR interval and Herat rate variability parameters as indicators of parasympathetic tone and TTT results. Methods We included 213 patients referred to our cardiology clinic with an impression of NMS in 2022 and 2023. Data was retrospectively collected from 24‐h ambulatory electrocardiographic monitoring recordings, TTT results, and patients' history and physical examination records. Results The analysis of the PR interval revealed a mean duration of 155 ms (95% CI: 148.61, 161.39) in negative TTT patients and 164.21 ms (95% CI: 158.44, 169.97) in positive TTT patients, indicating a statistically significant difference between two groups (p = 0.035). We also found that patients with a PR interval duration exceeding 160 ms demonstrated a significantly higher prevalence of positive TTT compared to those with a PR interval duration of less than 160 ms (p < 0.001, OR: 3.911, 95% CI: 2.143, 7.140). Conclusions Our study suggests a PR interval longer than 160 milliseconds as a valuable tool for predicting TTT results and identifying patients at higher risk of NMS. A longer PR interval correlates with a positive tilt table test. This suggests that an AEM‐derived PR interval duration longer than 160 ms may be a valuable tool for predicting TTT results and identifying patients at higher risk of NMS.

Background Exercise testing devices for evaluating cardiopulmonary fitness in patients with severe disability after stroke are lacking, but we have adapted a robotics-assisted tilt table (RATT) for cardiopulmonary exercise testing (CPET). Using the RATT in a sample of patients after stroke, this study aimed to investigate test-retest reliability and repeatability of CPET and to prospectively investigate changes in cardiopulmonary outcomes over a period of four weeks. Methods Stroke patients with all degrees of disability underwent 3 separate CPET sessions: 2 tests at baseline (TB1 and TB2) and 1 test at follow up (TF). TB1 and TB2 were at least 24 h apart. TB2 and TF were 4 weeks apart. A RATT equipped with force sensors in the thigh cuffs, a work rate estimation algorithm and a real-time visual feedback system was used to guide the patients’ exercise work rate during CPET. Test-retest reliability and repeatability of CPET variables were analysed using paired t-tests, the intraclass correlation coefficient (ICC), the coefficient of variation (CoV), and Bland and Altman limits of agreement. Changes in cardiopulmonary fitness during four weeks were analysed using paired t-tests. Results Seventeen sub-acute and chronic stroke patients (age 62.7 ± 10.4 years [mean ± SD]; 8 females) completed the test sessions. The median time post stroke was 350 days. There were 4 severely disabled, 1 moderately disabled and 12 mildly disabled patients. For test-retest, there were no statistically significant differences between TB1 and TB2 for most CPET variables. Peak oxygen uptake, peak heart rate, peak work rate and oxygen uptake at the ventilatory anaerobic threshold (VAT) and respiratory compensation point (RCP) showed good to excellent test-retest reliability (ICC 0.65–0.94). For all CPET variables, CoV was 4.1–14.5 %. The mean difference was close to zero in most of the CPET variables. There were no significant changes in most cardiopulmonary performance parameters during the 4-week period (TB2 vs TF). Conclusions These findings provide the first evidence of test-retest reliability and repeatability of the principal CPET variables using the novel RATT system and testing methodology, and high success rates in identification of VAT and RCP: good to excellent test-retest reliability and repeatability were found for all submaximal and maximal CPET variables. Reliability and repeatability of the main CPET parameters in stroke patients on the RATT were comparable to previous findings in stroke patients using standard exercise testing devices. The RATT has potential to be used as an alternative exercise testing device in patients who have limitations for use of standard exercise testing devices.

Purpose Electronic cigarettes are growing in popularity, but the physiological consequences of vaporized nicotine are unknown. Methods Twenty healthy non-smokers inhaled vaporized nicotine and placebo (randomized). Results Nicotine inhalation was associated with higher arterial pressures in the seated position, and increased arterial pressures in the head-up positions with no other effects on autonomic control. Conclusions Our results show that vaporized nicotine inhalation is not innocuous. Longitudinal studies in otherwise healthy non-smokers should be conducted.

Introduction Tilt table testing (TTT) has been used for over fifty years in clinical and basic medicine to study the adaptation of heart rate and blood pressure to changes in body position. In the area of ​​studying local features of electroencephalogram (EEG) and electrocardiogram (ECG) signal synchronization, there is a lack of research devoted to the precise quantitative mathematical analysis of electrophysiological signals recorded during TTT. Furthermore, most studies related to brain activity analysis focus on the development of syncope. Methods This study analyzed electrophysiological signals (EEG and ECG) in 19 healthy men. The TTT procedure was performed in a gentle mode with a slight elevation (45°) of the volunteers after 15 min of horizontal positioning. This procedure eliminated the risk of syncope. Time-frequency analysis of the EEG was performed using a continuous wavelet transform. Synchronization of electrophysiological signals in the brain and cardiac activity was assessed using wavelet bicoherence, assessed pairwise between ECG and EEG signals. Results EEG activity in the brain remained unchanged before and after verticalization of the volunteers. Heart rate increased, on average, from 1.0 to 1.05 Hz in the horizontal position to 1.3–1.4 Hz in the vertical position ( p  < 0.005). Significant changes in synchronization were demonstrated before and after verticalization of the volunteers. Most interesting is the increase in ECG and EEG synchronization in the low-frequency range [0.25; 0.75] Hz in response to the tilt table test. Such changes in synchronization can be interpreted in the context of the activation of the human body’s adaptive responses during this test. Conclusion This study results provide a basis for understanding the physiological relationship between the cardiovascular system and brain activity during the standing position test (SPT) without syncope. These results suggest that low-frequency (below the baseline heart rate) components of P-QRS-T complex variability may be a promising approach for studying neurocardiac interactions.

Study design: Randomized crossover. Objectives: Effects of body-weight-supported treadmill (BWST) and tilt-table standing (TTS) training on skin temperature and blood flow after spinal cord injury (SCI). Setting: McMaster University, Canada. Methods: Seven individuals with SCI participated in BWST and TTS training (3 times per week for 4 weeks, 4-week detraining between protocols). Skin temperature was measured before and after a single session of BWST or TTS, pre- and post-training. Leg blood flow was measured at rest pre- and post-training. Results: Resting skin temperature decreased at four sites after 4 weeks of BWST training in comparison with the pre-training. Four weeks of TTS training resulted in resting skin temperature decreases post-training at the right thigh only. Both BWST and TTS training resulted in altered reactivity of skin temperature at all sites except the right calf in response to a single session of BWST and TTS. Post-BWST training, a single session of BWST stimulated increased temperature at all sites, whereas after TTS training a single session of TTS resulted in temperature decreases at two of the six sites. No changes were observed in resting blood flow with either BWST or TTS training. Conclusion: Increased resting skin temperature and decreased skin temperature reactivity have been linked to the development of pressure sores. BWST and TTS may stimulate different skin temperature responses and the impact on pressure sore development warrants further investigation. Sponsorship: NSERC, ONF and GSSI.

This study aimed at examining three tilt angle-based positive responses and the time to positive response in a head-up tilt test for children with orthostatic intolerance, and the psychological fear experienced at the three angles during head-up tilt test. A total of 174 children, including 76 boys and 98 girls, aged from 4 to 18 years old (mean 11.3±2.8 years old), with unexplained syncope, were randomly divided into three groups, to undergo head-up tilt test at the angles of 60°, 70° and 80°, respectively. The diagnostic rates and times were analysed, and Wong–Baker face pain rating scale was used to access the children’s psychological fear. There were no significant differences in diagnostic rates of postural orthostatic tachycardia syndrome and vasovagal syncope at different tilt angles during the head-up tilt test (p>0.05). There was a significant difference, however, in the psychological fear at different tilt angles utilising the Kruskal–Wallis test (χ2=36.398, p<0.01). It was mildest at tilt angle 60° utilising the Kolmogorov–Smirnov test (p<0.01). A positive rank correlation was found between the psychological fear and the degree of tilt angle (rs=0.445, p<0.01). Positive response appearance time was 15.1±14.0 minutes at 60° for vasovagal syncope children. There was no significant difference in the time to positive response, at different tilt angles during the head-up tilt test for vasovagal syncope or for postural orthostatic tachycardia syndrome. Hence, it is suggested that a tilt angle of 60° and head-up tilt test time of 45 minutes should be suitable for children with vasovagal syncope.

Aims The head‐up tilt test (HUTT) has been markedly changed over the years, especially in the specified time for the passive and active phases. However, a consensus‐based protocol has yet to be established. Methods Seven hundred twenty‐four patients suspected of vasovagal syncope who underwent HUTT through one of the protocols of 15to 20‐min testing for each active/passive phase (the whole test duration was 30 or 40 min, respectively) were evaluated. Then, the positive responses were recorded. Results 470 (64.9%) and 254 (35.1%) patients in the 15‐ and 20‐min groups, respectively. Overall, 238 patients (50.6%) in the 15‐min group and 140 patients (55.1%) in the 20‐min group had positive responses (p = 0.25). There was no significant difference in the number of positive responses between the 15‐ and 20‐min groups in any of the passive (p = 0.53) and active (p = 0.3) phases. Conclusion The 15‐min HUTT protocol has similar results to the 20‐min protocol. Saving 10 min for each test has several potential benefits, such as increasing patient acceptance, decreasing patient discomfort, and enabling the conduct of more tests in a day in a syncope unit. In patients with suspected vasovagal syncope, a 15‐min head‐up tilt test protocol yielded similar diagnostic results to the conventional 20‐min protocol. This shorter approach may improve patient comfort and syncope unit efficiency without compromising diagnostic accuracy.

Background Dual‐chamber pacemakers equipped with anti‐reflex syncope algorithms are an established therapeutic option for preventing recurrent syncope in selected patients with reflex syncope. However, their efficacy in patients under 40 years old and in non‐type 2B syncope remains uncertain and clinical predictors of recurrent syncope post‐implantation are not well established. Objective To identify clinical factors associated with early recurrence of syncope in patients with reflex syncope who received dual‐chamber pacemakers with anti‐syncope functionality. Methods This retrospective cohort study included 117 patients (65% female) with reflex syncope confirmed by a positive tilt‐table test. All received dual‐chamber pacemakers. The primary endpoint was syncope recurrence within 6 months. Results Among 117 paced patients, 15 (12.8%) had recurrent syncope by 6 months. In the reduced Cox model, all three prespecified variables independently predicted recurrence: female sex (HR: 5.386; 95% CI: 1.689–17.175; p = 0.004), systolic blood pressure differential between the end of the passive phase and the syncope onset (HR: 1.036; 95% CI: 1.008–1.064; p = 0.011), number of prior syncope episodes (HR: 2.950; 95% CI: 1.565–5.561; p = 0.001). ROC‐based cutoffs supported descriptive separation (e.g., ≥ 2.5 prior episodes; ΔSBP ≥ 87.5 mmHg; asystole ≥ 13.5 s), but continuous coding was used for modeling to avoid information loss. Conclusion Within 6 months of dual‐chamber pacemaker implantation, recurrent syncope was more likely in female sex, a larger systolic blood pressure differential between the end of the passive phase and syncope onset, and greater pre‐implantation syncope burdens. In this single‐center retrospective cohort of 117 patients with reflex syncope treated with dual‐chamber pacemakers, 12.8% had syncope recurrence within 6 months. Female sex, higher prior syncope burden, and a larger systolic blood pressure differential identified a high‐risk subgroup requiring closer follow‐up and adjunctive measures.

Adequate cerebral perfusion is necessary to maintain consciousness in upright humans. Following maximal anaerobic exercise, cerebral perfusion can become compromised and result in syncope. It is unknown whether post‐exercise reductions in cerebral perfusion can lead to visual‐cognitive deficits prior to the onset of syncope, which would be of concern for emergency workers and warfighters, where critical decision making and intense physical activity are combined. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood velocity, induced by maximal anaerobic exercise and head‐up tilt, result in visual‐cognitive deficits prior to the onset of syncope. Nineteen sedentary to recreationally active volunteers completed a symptom‐limited 60° head‐up tilt for 16 min before and up to 16 min after a 60 sec Wingate test. Blood velocity of the middle cerebral artery was measured using transcranial Doppler ultrasound and a visual decision‐reaction time test was assessed, with independent analysis of peripheral and central visual field responses. Cerebral blood velocity was 12.7 ± 4.0% lower (mean ± SE; P < 0.05) after exercise compared to pre‐exercise. This was associated with a 63 ± 29% increase (P < 0.05) in error rate for responses to cues provided to the peripheral visual field, without affecting central visual field error rates (P = 0.46) or decision‐reaction times for either visual field. These data suggest that the reduction in cerebral blood velocity following maximal anaerobic exercise contributes to visual‐cognitive deficits in the peripheral visual field without an apparent affect to the central visual field. We investigated whether standing upright after very intense exercise generates reductions in cerebral blood velocity of a sufficient magnitude that they result in reduced visual‐cognitive abilities. Our findings show that intense exercise, without proper cool‐down, can result in reduced cerebral blood velocity to the extent that visual‐cognitive deficits in the peripheral visual field are present.