Heart Rate Variation Research Articles

Persistent and severe hypotension during radical transabdominal ovarian cancer surgery: A case report.

In radical surgery for ovarian cancer (OC), hypotension that is difficult to correct is usually rare unless there is significant blood loss. We recently encountered a patient who developed persistent and severe hypotension during radical transabdominal OC surgery. A patient was 52 years old with a history of hypertension and well-controlled preoperative blood pressure (BP). A total of 2000 mL of ascites was drained and blood loss was 300 mL when the operation proceeded to 5.5 hours. The patient's cardiopulmonary function and blood gas analysis showed no significant abnormalities. persistent and uncorrectable hypotension. There was no significant edema in the patient's head or face, nor did the surgeon observe noticeable edema in her intestinal walls or other organs. No oozing was seen at the surgical site. Fluid resuscitation and vasopressor administration were continued. As BP control further deteriorated, blood counts, coagulation, and biochemical electrolyte analyses revealed severe hypoalbuminemia (13.5 g/L) and coagulation dysfunction. After intravenous human serum albumin (HSA) and fresh frozen plasma therapy, her hypoalbuminemia and coagulation were gradually corrected. Based on this case, we suggest that in OC patients experiencing mild intraoperative bleeding and minimal heart rate variation but persistent refractory hypotension, hypoalbuminemia should be considered even if preoperative biochemical tests (including serum albumin levels) are normal. Confirming hypoalbuminemia warrants HSA administration to alleviate hypovolemic shock symptoms. Additionally, it is important to be cautious of potential coagulation issues with albumin use, possibly requiring plasma infusion to address coagulopathy.

Changes in short-term variation of antenatal cardiotocography to identify intraamniotic infection: a historical cohort study

Introduction Intraamniotic infection (IAI) is one of the main possible complications of preterm prelabor rupture of membranes (PPROM) and can lead to severe consequences for the neonate, such as early onset neonatal sepsis (EONS). Available diagnostic tools for IAI have poor diagnostic performance, which may result in both over- and underdiagnoses of IAI. In a search for better diagnostic tools, we have examined short-term variation (STV) in fetal heart rate. We have previously shown that in IAI exposed pregnancies, the STV was more than 20% lower in the last cardiotocography trace before the start of labor, as compared to those not exposed to IAI. The association between IAI and STV needs further evaluation and we therefore continued by examining the longitudinal change in STV in association with IAI. Material and methods We performed a historical cohort study on 628 singleton pregnancies with PPROM, delivering between 24 + 0 to 33 + 6 gestational weeks. The main exposure of the study was IAI, using EONS as a proxy as no easily available method exists for confirming IAI antepartum, and IAI and EONS are strongly associated. The main outcome was STV in fetal heart rate. At least two available cardiotocography traces per fetus were required as a minimum, from PPROM or from seven days before birth, whichever came later, until the start of labor or planned cesarean birth. A total of 9 690 cardiotocography traces were analyzed. Results Fetuses exposed to IAI had a 26.5% steeper decline in their STV during the last 24 h before the start of labor when compared to fetuses not exposed (95% CI −32.9% to −19.4%; p < 0.001). After adjustment for antenatal corticosteroids, the decline remained significant. The decline became less prominent but the significance remained when also adjusting for the baseline frequency (−12.7% [95% CI −19.3% to −5.5%], p < 0.001). In the IAI-exposed group, the baseline frequency increased by 11.1 bpm during the last 12 h before the start of labor, beyond those who were not exposed (95% CI 8.3 bpm to 13.8 bpm; p < 0.001). Conclusions In pregnancies affected by IAI the STV declines steeper in the last 24 h before the start of labor as compared to pregnancies not affected by IAI, even after adjustment for increasing baseline frequency. The association of STV in relation to IAI needs to be further studied in order to evaluate and establish STVs usefulness in monitoring patients for IAI.

Visceral Fat Affects Heart Rate Recovery but Not the Heart Rate Response Post-Single Bout of Vigorous Exercise: A Cross-Sectional Study in Non-Obese and Healthy Participants

Body composition could influence exercise physiology. However, no one has ever studied the effect of visceral fat (VF) on heart rate (HR) trends during and after exercise by using bioimpedance analysis (BIA). This study aims to investigate BIA variables as predictors of HR trends during vigorous exercise. Ninety-six participants (age 22.5 ± 4.8 years) were included in the data analysis. After performing BIA, the HR was recorded at three time points: baseline HR (BHR), peak HR (PHR) at the end of vigorous exercise, and resting HR (RHR) 1 min after the end of the exercise. After BHR, a 30 s squat jump test was performed. Linear regression analysis showed the body fat percentage and VF as a predictor of HR recovery post-exercise (p &lt; 0.01). However, body weight has no association with HR recovery (p &gt; 0.05). On the other hand, BIA variables were not associated with the variation of HR from the baseline to the end of the exercise. The results show that higher VF is associated with a slower HR recovery. To schedule a training program, it would be safer to monitor visceral fat before prescribing recovery time.

Relationship Between Heart Rate and Perceived Stress in Intensive Care Unit Residents: Exploratory Analysis Using Fitbit Data.

Intensive care unit (ICU) residents are exposed to high stress levels due to the intense nature of their work, which can impact their mental health and job performance. Heart rate measured through wearable devices has the potential to provide insights into residents' self-reported stress and aid in developing targeted interventions. This exploratory study aims to analyze continuous heart rate data and self-reported stress levels and stressors in ICU residents to examine correlations between physiological responses, stress levels, and daily stressors reported. A secondary data analysis was conducted on heart rate measurements and stress assessments collected from 57 ICU residents over a 3-week period using Fitbit Charge 3 devices. These devices captured continuous physiological data alongside daily surveys that assessed stress levels and identified stressors. The study used Spearman rank correlation, point-biserial correlation analysis, 2-tailed paired t tests, and mixed-effect models to analyze the relationship between heart rate features and stress indicators. The findings reveal complex interactions between stress levels and heart rate patterns. The correlation analysis between stress levels and median heart rate values across different percentile ranges showed that lower percentile heart rates (bottom 5%, 10%, 25%, and 50%) had modest correlations with stress, whereas higher percentiles (top 50%, 25%, 10%, and 5%) did not correlate significantly (all P>.05). The 2-tailed paired t test indicated significant differences in stress levels reported in midday versus end-of-day surveys (P<.001), although these changes in stress levels were not consistently reflected in heart rate patterns. Additionally, we explored and found that stressors related to "other health" issues had the highest positive correlation with stress level changes from midday to end-of-day surveys. However, the weak effect of these stressors on peak heart rate suggests that their impact on physiological measures like heart rate is not yet clear. According to our mixed-effects model, stress levels significantly influenced heart rate variations when hierarchical data were taken into account (P=.03), meaning that as the stress level increased, there was a significant increase in mean heart rate. This study highlights the complexity of using heart rate as an indicator of stress, particularly in high-stress environments like the ICU. Our findings suggest that while heart rate is found to correlate with self-reported stress in the mixed-effect model, its impact is modest, and it should be combined with other physiological and psychological measures to obtain a more accurate and comprehensive assessment of residents' stress levels.

ECG-based epileptic seizure prediction: Challenges of current data-driven models.

Up to a third of patients with epilepsy fail to achieve satisfactory seizure control. A reliable method of predicting seizures would alleviate psychological and physical impact. Dysregulation in heart rate variability (HRV) has been found to precede epileptic seizures and may serve as an extracerebral predictive biomarker. This study aims to identify the preictal HRV dynamics and unveil the factors impeding the clinical application of ECG-based seizure prediction. Thirty-nine adult patients (eight women; median age: 38, [IQR = 31, 56.5]) with 252 seizures were included. Each patient had more than three recorded epileptic seizures, each at least 2 hours apart. For each seizure, one hour of ECG prior to seizure onset was analyzed and 97 HRV features were extracted from overlapping three-minute windows with 10s stride. Two separate patient-specific experiments were performed using a support vector machine (SVM). Firstly, the separability of training data was examined in a non-causal trial. Secondly, the prediction was attempted in pseudo-prospective conditions. Finally, visualized HRV data, clinical metadata, and results were correlated. The mean receiver operating characteristic (ROC) area under the curve (AUC) for the non-causal experiment was 0.823 (±0.12), with 208 (82.5%) seizures achieving an improvement over chance (IoC) classification score (p < 0.05, Hanley & McNeil test). In pseudo-prospective classification, the ROC-AUC was 0.569 (±0.17), and 86 (49.4%) seizures were classified with IoC. Off-sample optimized SVMs failed to improve performance. Major limiting factors identified include non-stationarity, variable preictal duration and dynamics. The latter is expressed as both inter-seizure onset zone (SOZ) and intra-SOZ variability. The pseudo-prospective preictal classification achieving IoC in approximately half of tested seizures suggests the presence of genuine preictal HRV dynamics, but the overall performance does not warrant clinical application at present. The limiting factors identified are often overlooked in non-causal study designs. While current deterministic prediction methods prove inadequate, probabilistic approaches may offer a promising alternative. Many patients with epilepsy suffer from uncontrollable seizures and would greatly benefit from a reliable seizure prediction method. Currently, no such system is available to meet this need. Previous studies suggest that changes in the electrocardiogram (ECG) precede seizures by several minutes. In our work, we evaluated whether variations in heart rate could be used to predict epileptic seizures. Our findings indicate that we are still far from achieving results suitable for clinical application and highlight several limiting factors of present seizure prediction approaches.

Elective extubation during skin-to-skin care in preterm newborns is safe and well-tolerated.

To evaluate the safety and tolerance of elective extubations in preterm newborns (PNB) during skin-to-skin care (SSC) compared to those performed in an incubator. Retrospective observational study including 142 extubations in 93 PNB with gestational age (GA) <32 weeks and/or birth weight (BW) <1500 g performed during the first 2 months of life. Safety, tolerance and extubation success at 72 h were assessed. The median GA was 25.4 weeks in the SSC group versus 26.6 weeks in the incubator group (p = 0.002). The median BW was 700 grams and 880 grams, respectively (p = 0.001). In total, 60 extubations (42.3%) were performed during SSC in 42 PNB and 82 in incubator in 69 PNB. No incidents related to extubation during SSC were recorded. The extubation success rate was 80% in SSC versus 79.3% in incubator (p = 0.915). Most failures occurred between 3 and 24 h after extubation. There were no observed differences in heart rate or FiO2 variations between the groups, nor in the need to escalate respiratory support at 24 h after extubation (SSC 15% vs. incubator 12.2%, p = 0.628). Extubation during SSC is a feasible, safe and well-tolerated practice, while allowing PNB to experience the benefits from SSC.

Exploring the Multidimensional Influences on Sleep and Active Heart Rate Dynamics: A Comprehensive Study

This study offers an in-depth examination of how various social, personal, physiological, environmental, and behavioral factors are associated with both sleep and active heart rate dynamics among college students. Utilizing data collected from 487 participants over a span of 637 days via wearable technology, this research aims to unravel the intricate relationships that influence heart rate variations. Through the application of latent growth-curve modeling, we meticulously analyzed the trajectory of heart rate changes and their associations with a broad spectrum of influencing factors. This methodological approach allowed for a nuanced understanding of the dynamic interplay between heart rate and its determinants over time. The analysis revealed a consistent increase in both sleep and active heart rates across the study period, accompanied by stable standard deviations. Peer influence significantly impacted sleep and active heart rates, especially at rest. Gender and race/ethnicity were associated with heart rate dynamics, as were conscientiousness and depression levels. Environmental factors, including days of the week, academic periods, and weather conditions, exhibited significant effects. Behavioral factors, such as physical activity and daily class attendance, played a substantial role in heart rate patterns. Our findings underscore the complex interplay of factors influencing heart rate dynamics in young adults. Tailored interventions should consider these multifaceted influences to promote optimal cardiovascular well-being.

Fatigue trajectories by wearable remote monitoring of breast cancer patients during radiotherapy

The aim of this pilot study was to assess the compliance of breast cancer (BC) patients with fitness tracker (FT) monitoring program during radiotherapy (RT) and to characterize radiation-induced fatigue (RIF) status through objective evaluation using FT-collected parameters. Thirty-six BC patients were invited to wear FT during their RT course for continuous monitoring of heart rate (HR) and step counts (STP). RIF assessment was performed weekly, according to CTCAE v5.0 and dichotomized into G0 vs. any-grade. A novel concept based on patient Repeated Activity Window (RAW) was introduced to evaluate HR and STP variations during RT. Several Machine Learning (ML) methods were trained to characterize RIF on the basis of HR and STP collected data. RIF of any grade was reported by 17 out of 36 patients (47%) included in the study. None of patient clinical variables were significantly correlated with RIF. All patients accepted the FT monitoring program, and for 32 patients FT collection efficiency was greater than 60%. For each patient, a distinct distribution of RAWs was identifiable over RT and across the entire patient cohort, with a total of 7950 RAWs processed. Six features related to RAWs, HR and STP were identified as associated with RIF. The best-performing classifier was the Bagged Trees model, showing a cross-validated ROC-AUC of 89% (95% CI 88–90%). This study confirms the feasibility of continuous biomedical monitoring of BC patients by FT. We successfully identify objective indicators of RIF through HR and STP variation measures within each patient’s RAW, thus providing a novel and practical approach to assess and manage RIF. This can significantly aid medical staff in evaluating RIF trajectories, potentially leading to better individualized care strategies and improved patient outcomes.

Polygenic risk for psychotic disorders in relation to cardiac autonomic dysfunction in unmedicated patients with schizophrenia.

Cardiac autonomic dysfunction (CADF), mainly characterized by increased heart rate, decreased heart rate variability, and loss of vagal modulation, has been extensively described in patients with schizophrenia (SCZ) and their healthy first-degree relatives. As such, it represents an apparent physiological link that contributes to the increased cardiovascular mortality in these patients. Common genetic variation is a putative underlying mechanism, along with lifestyle factors and antipsychotic medications. However, the extent to which CADF is associated with genetic factors for SCZ is unknown. A sample of 83 drug-naive SCZ patients and 96 healthy controls, all of European origin, underwent a 30-minute autonomic assessment under resting conditions. We incorporated parameters from several domains into our model, including time and frequency domains (mean heart rate, low/high frequency ratio) and compression entropy, each of which provides different insights into the dynamics of cardiac autonomic function. These parameters were used as outcome variables in linear regression models with polygenic risk scores (PRS) for SCZ as predictors and age, sex, BMI, smoking status, principal components of ancestry and diagnosis as covariates. Of the three CADF parameters, SCZ PRS was significantly associated with mean heart rate in the combined case/control sample. However, this association was was no longer significant after including diagnosis as a covariate (p = 0.29). In contrast, diagnostic status is statistically significant for all three CADF parameters, accounting for a significantly greater proportion of the variance in mean heart rate compared to SCZ PRS (approximately 16% vs. 4%). Despite evidence for a common genetic basis of CADF and SCZ, we were unable to provide further support for an association between the polygenic burden of SCZ and cardiac autonomic function beyond the diagnostic state. This suggests that there are other important characteristics associated with SCZ that lead to CADF that are not captured by SCZ PRS.

The Role of Digital Smart Wearable Technology in VO2MAX Measurement to Support Athlete Performance and Public Health

This study employed the systematic literature review to investigate to what extent digital smart wearable technology was used in measuring VO2MAX to support athlete performance and public health. To achieve the goal, data were obtained from articles searched through Google Scholar. The search was conducted in September 2024 using the following keywords: (Smart Wearable OR Wearable Technology AND VO2MAX OR VO2 Max OR Cardiorespiratory Fitness AND Athlete Performance OR Sports Performance OR Athletic Performance AND Public Health OR General Population OR Health Monitoring). The articles were selected by considering predetermined inclusion and exclusion criteria. For example, to be included in this review, the articles should be published in Scopus-indexed journals. Additionally, the publication period should be from 2019 to 2024. Based on this timeframe, 1,110 articles were found. Furthermore, they were screened again in multiple stages, and 16 articles that fit the theme and met the inclusion requirements were selected. During the article selection, this study followed the PRISMA guidelines. The results confirmed that wearable technology played an important role in athlete performance optimization through real-time monitoring of VO2MAX. The device enables exercise adjustments based on metrics such as heart rate and diurnal variations, which can improve exercise effectiveness and reduce the risk of injury. Interestingly, it also contributes significantly to improving public health by promoting active lifestyles, monitoring health parameters, and supporting self-health management, especially for the elderly and individuals with chronic diseases. Nonetheless, technical challenges, such as measurement accuracy, data synchronization issues, and user education needs, must be addressed for wearables to be optimally utilized. With proper development, wearable technology has great potential to improve athlete performance and public health. Keywords: Role, Digital Technology, Smart Wearable, VO2MAX, Athlete Performance, Public Health

To Hear or Not to Hear: Cognitive Load Theory and Learning

ABSTRACT Background: Cognitive load is the amount of information one’s working memory can process at any given time. Key components of cognitive load include germane load, intrinsic load, and extraneous load. Learning is hindered if overload occurs, thus reducing cognitive performance. This study addresses the impact of auditory stimulation on cognitive load through repeated recognition tasks. Methods: Twenty-eight Queen’s University students were recruited and randomly allocated to control and experimental groups who completed the experiment with noise-cancelling headphones and with ambient noise, respectively. The experiment consisted of learning and testing phases. The learning phase involved memorizing a series of words. Subsequently, the testing phase required participants to recall words from the list. Each trial consisted of one learning and one testing phase, with three trials per participant. Cardiovascular measurements were taken prior to the experiment, at the beginning of each phase, and after each trial was completed. Results: Primary outcomes demonstrated that the experimental group experienced greater percent changes in heart rate and rate pressure product, higher perceived mental effort, and greater within-group variation for heart rate compared to controls. Scores decreased as trials progressed. Secondary outcomes showed that the top 33% of participants were less susceptible to changes in heart rate and blood pressure. Overall, four heart rate or blood pressure responders were identified. Conclusions: Exposure to 70 decibels of ambient noise contributes to cognitive load as noted by elevated cardiovascular measure and perceived mental effort. Results can inform educational platforms and hospital logistics.

Comparison of the effect of different extubation techniques on extubation in patients with mechanical ventilation in intensive care unit

To compare the application effects of three different extubation techniques in patients with mechanical ventilation in intensive care unit (ICU). A prospective randomized controlled study was conducted. Mechanical ventilation patients admitted to the critical care department of the First Affiliated Hospital of Guangxi Medical University from July to November 2023 were enrolled. According to the random number table generated by Excel, the patients were divided into negative pressure group, positive pressure group 1 and positive pressure group 2, with 45 cases in each group. On the basis of routine nursing, the negative pressure group used the negative pressure extubation technique to remove the tracheal catheter. In the positive pressure group, the pressure support (PS) and positive end-expiratory pressure (PEEP) of the positive pressure group 1 were 7 cmH2O (1 cmH2O≈0.098 kPa) and 5 cmH2O, and the PS and PEEP of the positive pressure group 2 were 15 cmH2O and 10 cmH2O. The main outcome measures were extubation related complications, including tachypnea, severe cough, sore throat, upper airway obstruction spasm, extubation failure, hypoxemia, and hypercapnia. The secondary outcome measures were the variation of heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure and blood oxygen saturation before and 1, 15 and 30 minutes after extubation. Finally, 42 patients were included in each group. There were no significant differences in gender, age, catheter retention days, duration of mechanical ventilation, acute physiology and chronic health evaluation II (APACHE II), catheter model and diagnosis among the three groups, which were comparable. There were statistically significant differences in the incidence of tachypnea, severe cough, sore throat, upper airway obstruction spasm, hypoxemia and hypercapnia among the three groups, while there was no statistically significant difference in the failure rate of extubation. The incidence of tachypnea, severe cough, sore throat, upper airway obstruction spasm, hypoxemia and hypercapnia after extubation in positive pressure group 1 and positive pressure group 2 were lower than those in negative pressure group (7.14%, 9.52% vs. 33.33%; 7.14%, 4.76% vs. 28.57%; 61.90%, 52.38% vs. 88.10%; 11.90%, 19.05% vs. 45.24%; 7.14%, 7.14% vs. 30.95%; 4.76%, 2.38% vs. 28.57%; all P < 0.05). There were no significant differences in extubation related complications between group 1 and group 2. There were significant differences in the time effect of heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure and blood oxygen saturation 30 minutes after extubation among three groups (F values were 145.792, 49.749, 22.486, 23.622 and 242.664, respectively, all P < 0.01). The intergroup effect of blood oxygen saturation was statistically significant (F = 3.835, P = 0.024), and the blood oxygen saturation in positive pressure group 1 and positive pressure group 2 were higher than those in negative pressure group 1 minute and 30 minutes after extubation (1 minute after extubation: 0.97±0.02, 0.97±0.02 vs. 0.95±0.02; 30 minutes after extubation: 1.00±0.01, 1.00±0.01 vs. 0.99±0.02, all P < 0.05). The interaction effects of heart rate and blood oxygen saturation were statistically significant (F values were 3.512 and 7.226, respectively, both P < 0.01). Compared with negative pressure extubation, positive pressure extubation can effectively reduce extubation related complications in ICU mechanically ventilated patients. It is beneficial to maintain stable blood oxygen saturation within 30 minutes after extubation, and has better clinical application effects. It is recommended to use low pressure extubation.

Estimated transmitral E- and A-wave overlapping predicted prognosis in patient with heart failure with preserved ejection

Abstract Background The impact of heart rate (HR) variability on clinical outcomes in patients with heart failure with preserved ejection fraction (HFpEF) is not fully understood. Variations in HR may affect transmitral blood flow and consequently left ventricular filling and left atrial pressure. Changes in HR can cause the transmitral E-wave and A-wave to merge at higher HRs, while their interval lengthens at slower HRs (Figure: left). A recent study (Izumida. ESC Heart Fail. 2020;7:3231) demonstrated that the degree of overlap or interval between E- and A-waves can be estimated using resting HR and the deceleration time of the E-wave (DcT) on Doppler echocardiography. Purpose This study aims to investigate the relationship between the estimated overlap length between E- and A-waves and prognosis in patients with HFpEF. Methods Echocardiography was performed before hospital discharge in 398 patients (80±9 years, 59.0% female) hospitalized for decompensated HFpEF who were registered in the PURSUIT-HFpEF (Prospective, Multicenter, Observational Study of Patients with Heart Failure with Preserved Ejection Fraction) registry. The overlap length between E- and A waves was estimated using the formula [6.2 × HR (bpm) + 0.81 × DcT (ms) -589 (ms)] as previously described (a negative value means distance between two waves). Patients were divided into four groups based on quartiles of overlap length (Q1 to Q4, with Q4 representing the highest overlap length) and followed for a median duration of 759 days (interquartile range: 370, 1107 days) to observe all-cause mortality. Results The estimated overlap length in the study patients was -167±85 ms, and 105 deaths occurred during follow-up. The overlap length was selected as an independent predictor for all-cause mortality by Cox proportional hazards regression analysis (p=0.04), whereas HR or DcT was not. Kaplan-Meier curves indicated the difference in all-cause mortality among 4 groups (Figure: Right, p=0.02 by log-rank test), and the Q4 group (335 to -123ms) showed significantly higher mortality than the Q2 (-124 to -173 ms, p=0.03). Conclusion The overlap length of E and A predicted mortality in HFpEF patients, and the presence of overlap or shorter interval were associated with higher mortality. Optimal HR based on overlap length may be a new target for HFpEF therapy.Figure 1

Cardioneuroablation for the treatment of carotid sinus syndrome

Abstract Introduction Carotid sinus syndrome (CSS), characterized by exaggerated vagal responses leading to asystolic pauses with carotid sinus massage (CSM), often necessitates pacemaker implantation. This study investigates cardioneuroablation (CNA) as an alternative management strategy for CSS. Methods Prospective study of consecutive patients referred for CNA. All patients underwent CSM, atropine test, 24-hour Holter monitoring and SF-36 quality of life questionary before the procedure and at 6 months. The objective of the study was to assess syncope free survival, grade of cardioinhibition with CSM and heart rate variation (HRV) and quality of life after the procedure. Results A total of 13 patients (84.6% male, mean age 63.8 ± 12.3 years) were included. After a median follow-up of 11.2 (10.6-16.3) months, none of the patients experienced syncope (0%) and none of the patients required pacemaker implantation. After the procedure all the patients had a negative CSM and only one patient (7.7%) had a positive CSM at 6 months (Figure 1). There was an improvement in the energy and health change items in the SF-36 quality of life questionary (Figure 2). There was a reduction in HR increase in the atropine test at 6 months (pre-CNA: 66% (52-84) vs. post-CNA 27.4% (21.9-90.9); p=0.027) and in most of the 24-hour Holter monitoring HRV parameters. Conclusions Cardioneuroablation emerges as a promising and effective alternative to pacemaker implantation in managing cardioinhibitory CSS. Further research is warranted to solidify these findings and explore the long-term effects of CNA in this scenario.Figure 1Figure 2

The importance of heart rate on left ventricular global longitudinal strain in echocardiography: novel insights facilitated by automated deep learning methods

Abstract Background Heart rate (HR) is assumed to influence echocardiographic measurements. Consequently, HR needs to be considered for accurate assessment of cardiac function. Despite left ventricular global longitudinal strain (LV GLS) being recognised as a valuable measure of cardiac function, its normal reference ranges remain confined to patients within a limited range of resting HR. So far, time-consuming manual analyses and high measurement variability have precluded comprehensive assessment of the interplay between HR and LV GLS. Using fully automated GLS measurements provided by novel deep learning (DL) methods, it is now possible to evaluate changes in LV GLS across a wide range of HR. Purpose To improve echocardiographic assessments across a wide range of HR intervals, we aimed to study the influence of controlled HR variations on LV GLS using programmable pacemakers and fully automated DL measurements. Methods Participants with sinus node dysfunction and implanted programmable pacemakers were enrolled. Echocardiographic acquisitions were obtained at baseline HR and during stepwise increments by 10 beats/min, targeting a range from 50 to 140 beats/min. Recordings of cine-loops including 10 cardiac cycles were obtained for the four-chamber, two-chamber, and apical long axis view. LV GLS was measured for all cycles using a fully automated DL method developed by our group, and presented as mean of the three standard apical views for all patients at each HR level. A linear mixed model was used for construction of an overall trendline based on the estimated fixed effects across all 50 patients, stating patient number as the random effect. The correlation between HR and LV GLS was evaluated by a likelihood ratio test. Results Fifty patients were included, 52% females, mean age 68 years (27 to 88 years). All patients had preserved atrioventricular conduction. Resting HR ranged from 50 to 87 beats/min (mean 64 beats/min). At baseline echocardiographic acquisition, most participants were within normal ranges for LV volumes, systolic and diastolic function. A total of about 13,000 cardiac cycles were automatically analysed by the DL method. The overall trend demonstrated a linear relation between increasing HR and decreasing absolute LV GLS (Figure 1). Across HR increments from 50 to 140 beats/min, there was a 32% (22%–42%) reduction in absolute LV GLS, declining from -17.1% to -11.7%. The strong correlation between changes in HR and LV GLS was further supported by a highly significant likelihood ratio test (p-value &amp;lt;0.001). Conclusions There was a reduction of absolute LV GLS with increasing HR. These findings emphasize the importance of integrating HR considerations into clinical echocardiography practice. Moreover, the results highlight that DL methods can unlock substantially richer insights from individual patient data, offering a new pathway towards more personalized and precise cardiac diagnostics.Figure 1

Combination of Intravenous Ondansetron and Intravenous Glycopyrrolate Versus Intravenous Ondansetron and Intramuscular Glycopyrrolate for Reduction of Post-spinal Hypotension in Cesaraen Section: A Randomized Double-Blinded Study.

In parturients, post-spinal hypotension is common due to loss of sympathetic tone. Compression of the inferior vena cava by the gravid uterus further aggravates it. Various pharmacologic and non-pharmacologic techniques are used to reduce the severity of hypotension. Ondansetron, a selective 5-hydroxytryptamine receptor antagonist, nullifies the Bezold Jarisch reflex response to spinal anaesthesia and glycopyrrolate, an anti-cholinergic, has been used to prevent post-spinal hypotension. We estimated the efficacy of intravenous (IV) glycopyrrolate plus IV ondansetronversusintramuscular (IM) glycopyrrolate plus IV ondansetron to reduce post-spinal hypotension in caesarean section. We compared hypotension episodes and the total ephedrine dose required to treat hypotension among the groups. Ninety parturients undergoing elective and emergency caesarean section under spinal anaesthesia were randomly assigned into three groups of 30 each. Group A received prophylactic IV glycopyrrolate 0.2mg plus IV ondansetron 4mg, Group B received IM glycopyrrolate 0.2mg plus IV ondansetron 4mg and Control Group C received 10ml of normal saline plus IV ondansetron 4mg. The total ephedrine dose required to treat hypotension (primary objective), incidence of hypotension and maternal heart rate variations were analysed. Group B required significantly less vasopressor as compared to Group C (6.4286mg±1.6036 vs 8.7mg±3.6288, p=0.0420). There is no statistically significant difference between Group A and Group C for vasopressor requirement (7.8750mg±2.8723 vs 8.7mg±3.6288, p=0.5425). Maternal heart rate in Group A was higher at the eighth minute compared to Group B and Group C (100.2±21.3 vs 95.3±14.4 vs 86.2±19.0, p=0.015). Incidence of hypotension was same in all the groups (46.7% vs 46.7% vs 51.1%, p=0.491) and complications among groups were comparable. Prophylactic use of IM glycopyrrolate plus IV ondansetron decreases total vasopressor required to treat hypotension but does not decrease the incidence of hypotension. Prophylactic use of IV glycopyrrolate increases maternal heart rate.

Endotracheal Tube Cuff Deflation Methods Reduce Stress Response and Incidence of Postoperative Pharyngeal Complications in Patients Treated with Gynecological Laparoscopic Surgery.

This study aims to explore the impact of endotracheal tube cuff deflation methods on extubation stress responses and postoperative pharyngeal complications in patients treated with gynecological laparoscopic surgery. In this study, retrospective clinical data of 94 patients treated with gynecological laparoscopic surgery under general anesthesia in Northwest Women's and Children's Hospital from June 2023 to June 2024 were collected and analyzed. Patients were assigned into two groups based on the cuff deflation methods used after anesthesia: Group A (45 patients) adopted a one-time deflation method, while Group B (49 patients) employed a gradual deflation method. Surgery-associated indicators were recorded, with heart rate (HR), mean arterial pressure (MAP), rate pressure product (RPP), epinephrine (E), norepinephrine (NE), and cortisol (Cor) levels monitored at selected time points: before cuff (T0), immediately after extubation (T1), 1 minute post-extubation (T2), 5 minutes post-extubation (T3), and 10 minutes post-extubation (T4). The incidence of pharyngeal complications was also compared between the two groups. Compared with Group A, Group B displayed smaller variations in HR, MAP, and RPP at T1, T2, and T3 (p < 0.05). Group B also showed smaller variations in E, NE, and Cor levels at T2, T3, and T4 in contrast with Group A (p < 0.05). The incidence of complications such as coughing, sore throat, and hoarseness was conspicuously attenuated in Group B compared to Group A (6.12% vs 22.22%, p < 0.05). Gradual deflation of the endotracheal tube cuff dramatically ameliorates extubation stress responses, stabilizes hemodynamics, and alleviates pharyngeal discomfort in patients treated with gynecological laparoscopic surgery.

Cardiovascular handgrip responses during treadmill exercise: randomized pilot trial.

The isometric exercise performed using the handgrip (HG) acutely promotes elevation of systolic blood pressure (SBP) and diastolic blood pressure (DBP), and in a non-consensual manner among articles elevation or maintenance of heart rate (HR). Currently, although there is a vast literature on the hemodynamic effects of interval training and isometric exercise with HG alone, there is still no consistent evidence of such adjustments occurring in the association between the two. Therefore, the objective of this study was to describe the acute hemodynamic responses found only during interval training and when combined with isometric contraction with HG. This is a pilot study of a crossover clinical trial. Seven male volunteers, aged 24±3.9 years, underwent three protocols on an ergometric treadmill, with a 3-minute warm-up at 30% of heart rate reserve (HRR), four sprints 2 minutes at 50% HRR and active intervals at the same speed as the warm-up. Randomization was carried out in a simple random manner. The protocols were classified according to the use of HG during sprints, as follows: PI = without HG; PII = HG 30% of handgrip strength (HGS) and PIII = 60% of HGS). Variations (Δ) in HR, double product (DP), SBP and DBP were evaluated. The presence of HG did not change HR behavior, but it increased DP (PI: 10,472±2,539 vs. PII: 12,217±1,933 vs. PIII: 13,369±3,089) through SBP, which in PI had a plateau behavior of 15±22.2 mmHg, while PII varied with an average of 41±12.2 mmHg and PIII 47±11.1 mmHg, in the 4th sprint. DBP fell in PI with 12±13.2 mmHg, while PII and PIII showed an drop of 0±19.6 and 6±13.0 mmHg in the last sprint, respectively. The use of HG during interval training directly modulates hemodynamic variables, promoting an increase in SBP elevation, attenuation of the drop in DBP and an increase in DP, without an increase in HR. RBR-78fhyrf. Available in https://ensaiosclinicos.gov.br/rg/RBR-78fhyrf.

Endocardial ablation of ganglionated plexus for the treatment of carotid sinus syndrome.

Carotid sinus syndrome (CSS), characterized by exaggerated vagal responses leading to asystolic pauses with carotid sinus massage (CSM), often necessitates pacemaker implantation. This study investigates cardioneuroablation (CNA) as an alternative strategy for CSS. Prospective study of consecutive patients referred for CNA due to CSS. All patients underwent CSM, atropine test and 24-h Holter monitoring before the procedure and at 6 months. The primary objective was the absence of any cardioinhibitory response to CSM following CNA. Secondary objectives included the combined endpoint of syncope and presyncope-free survival, pacemaker-free survival, differences in heart rate variation (HRV), as well as differences in the pre- and postprocedure atropine tests and in the SF-36 quality-of-life questionnaire. A total of 13 consecutive patients (84.6% male, mean age 63.8 ± 12.3 years) were included. CSM revealed a symptomatic asystolic pause in all patients before CNA (7.3 [5.6-10.5] s). After the procedure, all the patients had a negative CSM, and only one patient (7.7%) had a positive CSM at 6 months. After a median follow-up of 11.2 (10.6-16.3) months, syncope or presyncope-free survival was 84.6%, and none required pacemaker implantation. There was an improvement in the energy and health change items in the SF-36 questionnaire. There was a reduction in HR increase in the atropine test at 6 months (pre-CNA: 66% [52-84] vs. post-CNA 26.0% (19.8-29.3]; p = .008) and in HRV parameters. In this proof-of-efficacy study, performed in patients affected by asystolic CSS, CNA was effective in reducing the rate of cardioinhibitory responses, suggesting a potential efficacy in also reducing syncopal recurrences. Controlled trials are warranted to corroborate clinical findings.

Common tenrecs (Tenrec ecaudatus) reduce oxygen consumption in hypoxia and in hypercapnia without concordant changes to body temperature or heart rate.

Common tenrecs (Tenrec ecaudatus) are fossorial mammals that use burrows during both active and hibernating seasons in Madagascar and its neighboring islands. Prevailing thought was that tenrecs hibernate for 8-9months individually, but 13 tenrecs were removed from the same sealed burrow 1m deep from the surface. Such group hibernation in sealed burrows presumably creates a hypoxic and/or hypercapnic environment and suggests that this placental mammal may have an increased tolerance to hypoxia and hypercapnia. Higher tolerances to hypoxia and hypercapnia have been documented for other mammals capable of hibernation and to determine if this is the case for tenrecs, we exposed them to acute hypoxia (4h of 16 or 7% O2), progressive hypoxia (2h of 16, 10 and 4% O2), or progressive hypercapnia (2h of 2, 5 and 10% CO2) at cold (16°C) or warm (28°C) ambient temperatures (Ta). Oxygen equilibrium curves were also constructed on the whole blood of tenrecs at 10, 25, and 37°C to determine if hemoglobin (Hb)-O2 affinity contributes to hypoxia tolerance. In animals held at 16°C, normoxic and normocapnic levels of oxygen consumption rate ( ), body temperature (Tb), and heart rate (HR) were highly variable between individuals. This inter-individual variation was greatly reduced in animals held at 28°C for oxygen consumption rate and body temperature. Both hypoxia (acute and progressive) and progressive hypercapnia led to decreases in as well as the variation in between animals held at 16°C. The fall in oxygen consumption rate in 7% O2 independent of changes in body temperature in tenrecs held at 16°C is unique and not consistent with the typical hypoxic metabolic response seen in other hibernating species that depends on concomitant falls in Tb. In animals held at 28°C, exposure to O2 levels as low as 4% and CO2 levels as high as 10% had no significant effect on , HR, or Tb, indicative of high tolerance to both hypoxia and hypercapnia. High variation in heart rate remained between individuals in all gas compositions and at all temperatures. Tenrec Hb-O2 affinity was similar to other homeothermic placental mammals and likely does not contribute to the increased hypoxia tolerance. Ultimately, our results suggest changes in Ta dictate physiological responses to hypoxia or hypercapnia in tenrecs, responses more characteristic of reptiles than of most placental mammals. Given that numerous anatomical and physiological characteristics of tenrecs suggest that they may be representative of an ancestral placental mammal, our findings suggest the typical hypoxic metabolic response evolved later in mammalian evolution.