Decreases in heart rate variability are associated with postoperative complications in hip fracture patients

The brain-heart-immune axis: a vago-centric framework for predicting and enhancing resilient recovery in older surgery patients

Nearly all geriatric surgical complications are studied in the context of a single organ system, e.g., cardiac complications and the heart; delirium and the brain; infections and the immune system. Yet, we know that advanced age, physiological stress, and infection all increase sympathetic and decrease parasympathetic nervous system function. Parasympathetic function is mediated through the vagus nerve, which connects the heart, brain, and immune system to form, what we have termed, the brain-heart-immune axis. We hypothesize that this brain-heart-immune axis plays a critical role in surgical recovery among older adults. In particular, we hypothesize that the brain-heart-immune axis plays a critical role in the most common surgical complication among older adults: postoperative delirium. Further, we present heart rate variability as a measure that may eventually become a multi-system vital sign evaluating brain-heart-immune axis function. Finally, we suggest the brain-heart-immune axis as a potential interventional target for bio-electronic neuro-immune modulation to enhance resilient surgical recovery among older adults.

Discriminatory ability of perioperative heart rate variability in predicting postoperative complications in major urologic surgery: a prospective cohort study

We aimed to determine if continuous perioperative heart rate variability (HRV) monitoring could improve risk stratification compared to a short preoperative measurement in radical cystectomy patients. Electrocardiography (ECG) recordings were collected continuously preoperatively to discharge in 83 patients. Two, 5-min ECG signal segments (preoperative and at 24-h post ECG placement) were analyzed offline to extract HRV metrics. HRV metric discriminatory ability to identify patients with 30-day postoperative complications were analyzed using receiver operating characteristics curves. Sixty participants were included for analysis of which 27 (45%) developed a complication within 30 days postoperative. HRV was reduced in patients with complications. Postoperative standard deviation NN intervals and root mean square of successive differences had area under the curves (AUC) of 0.67 (95% CI 0.54 to 0.81) and 0.68 (95% CI 0.54 to 0.82), respectively. Significant discriminatory abilities were also reported for postoperative frequency metrics of absolute low frequency (LF) [AUC = 0.65 (95% CI 0.51 to 0.79)] and high frequency (HF) powers [AUC = 0.69 (95% CI 0.55 to 0.83)] and total power [AUC = 0.66 (95% CI 0.53 to 0.80)]. Postoperative acquired HRV metrics demonstrated improved discriminatory ability. Our findings suggest that longer-term perioperative HRV monitoring presents with superior ability to stratify complication risk.

Time-course of heart rate variability after total hip arthroplasty

Heart rate variability (HRV) is a measure of the autonomic nervous system function and possibly related to postoperative outcome. Despite several HRV studies in different surgical settings, optimal indices and timepoints for measuring have not been adequately determined. Consequently, there is a need for detailed descriptive procedure-specific studies on the time-course of perioperative HRV within a modern fast-track surgical setting. We measured HRV continuously in 24 patients from 4 days before until 9 days after total hip arthroplasty (THA). Statistical methods included mainly ANOVA and t-tests or Kruskal-Wallis and pairwise Wilcoxon test. Patients completed the Orthostatic Discriminant and Severity Scale five times during the study describing autonomic nervous system dysfunction. Standard deviation between normal-to-normal beats and the total power of HRV were reduced for at least 9 days following THA, with a trend towards increased HRV leading up to the day of surgery. The balance between low- and high-frequency power of HRV was reduced in the postoperative evenings. There was increased orthostatic intolerance symptoms on the first postoperative day, with symptoms of pain, fatigue and weakness decreasing after the first postoperative day. Median hospital stay was 1 day. We provide the first detailed description of perioperative time-course of HRV and orthostatic symptoms in fast-track THA, showing reduced HRV after surgery for at least a week, and that HRV changes are sensitive to time of day and timing before and after surgery. These results are helpful in designing future HRV studies in perioperative risk assessment and outcome.

Fascia iliaca compartment block mitigates the fluctuations in heart rate variability and reduces pain with opioid consumption in elderly individuals with hip fractures: A randomized controlled trial

Background

Hip fractures, commonly known as the "terminal fracture of life," frequently necessitate prompt surgical intervention and are accompanied by significant perioperative pain.

Objective

This investigation was performed to assess the impact of fascia iliaca compartment block (FICB) on heart rate variability during the perioperative period in elderly individuals with hip fractures.

Design

Single-center, randomized, controlled clinical trial.

Setting

The study was conducted from September 2021 to February 2023 at one tertiary care hospital in China.

Participants

Patients aged ≥60 years who underwent general anesthesia for hip fracture surgery were screened for enrollment. Eighty patients were initially assessed for eligibility, 70 underwent randomization, and 62 were included in the final analysis.

Methods

Preoperatively, the patients were randomly allocated to either receive (Group F) or not receive (Group C) ultrasound-guided suprainguinal FICB. The primary endpoint was heart rate variability indicators at the corresponding time points. The secondary endpoints included the mean arterial pressure and heart rate measured at different time points [upon admission to the operating room (T1), during positioning (T2), at the time of skin incision (T3), 30 min after the start of surgery (T4), and 6 h postoperatively (T5)] and visual analogue scale (VAS) score, dose of oral pain medication over 24 h, and satisfaction scores were valued.

Results

Compared with Group C, Group F had a significantly reduced low-frequency band, high-frequency band, and low-/high-frequency band ratio at T3, T4, and T5 (P < 0.05). Group F also had a lower heart rate at T2, T3, T4, and T5 (P < 0.05). Moreover, Group F had lower flurbiprofen dosages at 24 h postoperatively (P < 0.05) and lower resting VAS scores at 6 and 24 h postoperatively (P < 0.05).

Conclusion

Utilization of ultrasound-guided FICB has the potential to yield efficacious analgesic effects, mitigate the pronounced fluctuations in heart rate induced by surgical stimulation, and maintain autonomic function stability to a certain degree.

Heart rate variability as a marker and predictor of inflammation, nosocomial infection, and sepsis - A systematic review

PURPOSE

The autonomic nervous system interacts with the immune system via the inflammatory response. Heart rate variability (HRV), a marker of autonomic activity, is associated with inflammation, and nosocomial infections/sepsis, and has clinical implications for the monitoring of at-risk patients. Due to the vagal tone's influence on anti-inflammatory immune response, this association may predominately be reflected by vagally-mediated HRV indices. However, HRV's predictive significance on inflammation/infection remains unclear.

METHODS

843 studies examining the associations/prognostic value of HRV indices on inflammation, and nosocomial infection/sepsis were screened in this systematic review. According to inclusion and exclusion criteria, 68 associative studies and 14 prediction studies were included.

RESULTS

HRV and pro-inflammatory state were consistently associated in healthy subjects and patient groups. Pro-inflammatory state was related to reduced total power HRV including vagally- and non-vagally-mediated HRV indices. Similar, compared to controls, HRV reductions were observed during nosocomial infections/sepsis. Only limited evidence supports the predictive value of HRV in the development of nosocomial infections/sepsis. Reduced very low frequency power HRV showed the highest predictive value in adults, even with different clinical conditions. In neonates, an increased heart rate characteristic score, combining reduced total power HRV, decreased complexity, and vagally-dominated asymmetry, predicted sepsis.

CONCLUSIONS

Pro-inflammatory state is related to an overall reduction in HRV rather than a singular reduction in vagally-mediated HRV indices, reflecting the complex autonomic-regulatory changes occurring during inflammation. The potential benefit of using continuous HRV monitoring for detecting nosocomial infection-related states, and the implications for clinical outcome, need further clarification.

Prediction of episode of hemodynamic instability using an electrocardiogram based analytic: a retrospective cohort study

BACKGROUND

Predicting the onset of hemodynamic instability before it occurs remains a sought-after goal in acute and critical care medicine. Technologies that allow for this may assist clinicians in preventing episodes of hemodynamic instability (EHI). We tested a novel noninvasive technology, the Analytic for Hemodynamic Instability-Predictive Indicator (AHI-PI), which analyzes a single lead of electrocardiogram (ECG) and extracts heart rate variability and morphologic waveform features to predict an EHI prior to its occurrence.

METHODS

Retrospective cohort study at a quaternary care academic health system using data from hospitalized adult patients between August 2019 and April 2020 undergoing continuous ECG monitoring with intermittent noninvasive blood pressure (NIBP) or with continuous intraarterial pressure (IAP) monitoring.

RESULTS

AHI-PI's low and high-risk indications were compared with the presence of EHI in the future as indicated by vital signs (heart rate > 100 beats/min with a systolic blood pressure < 90 mmHg or a mean arterial blood pressure of < 70 mmHg). 4,633 patients were analyzed (3,961 undergoing NIBP monitoring, 672 with continuous IAP monitoring). 692 patients had an EHI (380 undergoing NIBP, 312 undergoing IAP). For IAP patients, the sensitivity and specificity of AHI-PI to predict EHI was 89.7% and 78.3% with a positive and negative predictive value of 33.7% and 98.4% respectively. For NIBP patients, AHI-PI had a sensitivity and specificity of 86.3% and 80.5% with a positive and negative predictive value of 11.7% and 99.5% respectively. Both groups performed with an AUC of 0.87. AHI-PI predicted EHI in both groups with a median lead time of 1.1 h (average lead time of 3.7 h for IAP group, 2.9 h for NIBP group).

CONCLUSIONS

AHI-PI predicted EHIs with high sensitivity and specificity and within clinically significant time windows that may allow for intervention. Performance was similar in patients undergoing NIBP and IAP monitoring.

Predicting Postoperative Emergence Delirium From the Heart Rate Variability of Patients Undergoing Elective Cardiac Surgery

Background and objective The complication of postoperative delirium is directly linked to prognosis, leading to prolonged hospital stays and an increase in mortality. Since there is no magic medicine that cures delirium, the prevention of its onset is important, and the development of simple tools that enable the early assessment of the risk is valuable. In the previous study, we hypothesized that postoperative delirium could be predicted from heart rate variability (HRV) measured by using an electrocardiogram (ECG) on the day before elective esophageal cancer surgery. HRV is calculated based on the fluctuation of RR intervals on ECG. The preoperative high-frequency (HF) power in delirium patients was significantly lower than that in non-delirium patients. The HF component is considered a reflection of parasympathetic function. In the current study, we evaluated the hypothesis that parasympathetic nerve activity is low in the resting HRV on the night before surgery in patients who go on to develop postoperative delirium. To that end, we recorded resting HRV in patients scheduled for cardiac surgery on the night before surgery. We then compared the HRV between patients with and without delirium in the postoperative intensive care unit (ICU). The Confusion Assessment Method for the ICU (CAM-ICU) was used to diagnose delirium. Methods This was a prospective observational study involving patients undergoing elective cardiac surgery. After obtaining approval from the institutional review board, patients aged 65 years and older were enrolled in the study. The day before surgery, a Mini-Mental State Examination (MMSE) was performed. The ECG was used in patients for five minutes. All patients were transferred to the ICU after surgery, and CAM-ICU was measured every eight hours until discharge from the ICU, and positive patients were diagnosed with delirium. Results In this study, 14 patients who developed delirium and 22 patients who did not were included in the analysis. The average MMSE score was 27.4, with no patients diagnosed with preoperative dementia. In the analysis of HRV, the HF component was significantly lower in the group with delirium compared to the group without delirium (Mann-Whitney U test, p<0.05). Conclusion Based on our findings, in patients with postoperative delirium, the activity of parasympathetic nerves was lower than before surgery, and we concluded that it is possible to predict the onset of postoperative delirium based on preoperative ECG measurement.

Detection of Hemodynamic Status Using an Analytic Based on an Electrocardiogram Lead Waveform

OBJECTIVES

Delayed identification of hemodynamic deterioration remains a persistent issue for in-hospital patient care. Clinicians continue to rely on vital signs associated with tachycardia and hypotension to identify hemodynamically unstable patients. A novel, noninvasive technology, the Analytic for Hemodynamic Instability (AHI), uses only the continuous electrocardiogram (ECG) signal from a typical hospital multiparameter telemetry monitor to monitor hemodynamics. The intent of this study was to determine if AHI is able to predict hemodynamic instability without the need for continuous direct measurement of blood pressure.

DESIGN

Retrospective cohort study.

SETTING

Single quaternary care academic health system in Michigan.

PATIENTS

Hospitalized adult patients between November 2019 and February 2020 undergoing continuous ECG and intra-arterial blood pressure monitoring in an intensive care setting.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One million two hundred fifty-two thousand seven hundred forty-two 5-minute windows of the analytic output were analyzed from 597 consecutive adult patients. AHI outputs were compared with vital sign indications of hemodynamic instability (heart rate > 100 beats/min, systolic blood pressure < 90 mm Hg, and shock index of > 1) in the same window. The observed sensitivity and specificity of AHI were 96.9% and 79.0%, respectively, with an area under the curve (AUC) of 0.90 for heart rate and systolic blood pressure. For the shock index analysis, AHI's sensitivity was 72.0% and specificity was 80.3% with an AUC of 0.81.

CONCLUSIONS

The AHI-derived hemodynamic status appropriately detected the various gold standard indications of hemodynamic instability (hypotension, tachycardia and hypotension, and shock index > 1). AHI may provide continuous dynamic hemodynamic monitoring capabilities in patients who traditionally have intermittent static vital sign measurements.

Preoperative heart rate variability as a predictor of perioperative outcomes: a systematic review without meta-analysis

Heart rate variability (HRV) is a predictor of mortality and morbidity after non-lethal cardiac ischemia, but the relation between preoperatively measured HRV and intra- and postoperative complications is sparsely studied and most recently reviewed in 2007. We, therefore, reviewed the literature regarding HRV as a predictor for intra- and postoperative complications and outcomes. We carried out a systematic review without meta-analysis. A PICO model was set up, and we searched PubMed, EMBASE, and CENTRAL. The screening was done by one author, but all authors performed detailed review of the included studies. We present data from studies on intraoperative and postoperative complications, which were too heterogeneous to warrant formal meta-analysis, and we provide a pragmatic review of HRV indices to facilitate understanding our findings. The review was registered in PROSPERO (CRD42021230641). We screened 2337 records for eligibility. 131 records went on to full-text assessment, 63 were included. In frequency analysis of HRV, low frequency to high frequency ratio could be a predictor for intraoperative hypotension in spinal anesthesia and lower total power could possibly predict intraoperative hypotension under general anesthesia. Detrended fluctuation analysis of HRV is a promising candidate for predicting postoperative atrial fibrillation. This updated review of the relation between preoperative HRV and surgical outcome suggests a clinically relevant role of HRV but calls for high quality studies due to methodological heterogeneity in the current literature. Areas for future research are suggested.

Scoping review of the association between postsurgical pain and heart rate variability parameters

Supplemental Digital Content is Available in the Text. This scoping review provides some evidence of a possible association between heart rate variability and postsurgical pain, although significant variability exists among included studies.

Surgical interventions can elicit neuroendocrine and sympathovagal responses, leading to cardiac autonomic imbalance. Cardiac complications account for approximately 30% of postoperative complications. Altered heart rate variability (HRV) was initially described in the 1970s as a predictor of acute coronary syndromes and has more recently been shown to be an independent predictor of postoperative morbidity and mortality after noncardiac surgery. In general, HRV reflects autonomic balance, and altered HRV measures have been associated with anesthetic use, chronic pain conditions, and experimental pain. Despite the well-documented relationship between altered HRV and postsurgical outcomes and various pain conditions, there has not been a review of available evidence describing the association between postsurgical pain and HRV. We examined the relationship between postsurgical pain and HRV. MEDLINE and EMBASE databases were searched until December 2020 and included all studies with primary data. Two reviewers independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Review of Interventions. A total of 8 studies and 1002 participants were included. Studies examined the association of postsurgical pain and HRV or analgesia nociception index derived from HRV. There was a statistically significant association between HRV measures and postsurgical pain in 6 of 8 studies. Heterogeneity of studies precluded meta-analyses. No studies reported cardiovascular outcomes. There is a potential association between postsurgical pain and HRV or analgesia nociception index, although results are likely impacted by confounding variables. Future studies are required to better delineate the relationship between postsurgical pain and HRV and impacts on cardiovascular outcomes.

Preoperative heart rate variability analysis is as a potential simple and easy measure for predicting perioperative delirium in esophageal surgery

Background

Delirium is one of the most common but severe perioperative complications. Autonomic activity evaluated by heart rate variability (HRV) has been recently reported as a useful tool for prediction and for early detection of delirium in acute care medicine, especially in postoperative intensive care unit (ICU) patients. We hypothesized that HRV, by 3-lead electrocardiogram (ECG), one day prior to surgery might correlate with the presence of postoperative delirium.

Materials and methods

This study was cohort prospective pilot study. We measured preoperative HRV and postoperative delirium in patients who underwent surgery for elective esophageal cancer. ECG of the participants was performed for 10 min 6–12 h preceding surgery. Postoperatively, patients were admitted to the ICU or critical care unit and stayed for at least 3 days. Delirium was diagnosed by psychiatrist rounds twice a day.

Results

Delirium was assessed for 3 days after surgery and 30 patients performed the study. Seven patients developed delirium during their ICU stay, while the remaining twenty-three did not. After HRV analysis, the preoperative high frequency power in delirium patients was significantly lower than that in non-delirium patient. Other parameters of HRV, including lower frequency power, total power and the ratio showed no statistically significant difference between the groups.

Conclusion

The results of current study demonstrated that preoperative measurement of HRV may be a useful predictor of delirium. Further investigation could pave the way to a non-invasive, minimally stressful method of predicting postoperative delirium.

•

Delirium is one of the most common and severe postoperative complications.

•

Delirium prediction can provide better treatment for patients.

•

Heart rate variability analysis might predict delirium in esophageal cancer surgery.

Non-Contact Measurement of Heart Rate Variability in Frail Geriatric Patients: Response to Early Geriatric Rehabilitation and Comparison with Healthy Old Community-Dwelling Individuals - A Pilot Study

INTRODUCTION

Frailty is a central geriatric syndrome characterized by a state of increased physiological vulnerability. As the key components of frailty are difficult to capture in their entirety, easily measurable and reliable surrogate parameters are desirable. Since frailty influences heart rate variability (HRV), HRV may be such a surrogate parameter. HRV is typically acquired by an ECG, which, however, may not be tolerated by all patients; in some, it may even trigger delirium. Therefore, we sought to measure HRV in a non-contact and unobtrusive way through photoplethysmography imaging (PPGI). Using our previously presented HRV estimation algorithm for PPGI, we investigated whether PPGI could reveal (1) HRV differences between frail and non-frail individuals and (2) the influences of early geriatric rehabilitation on HRV.

METHODS

The study involved 10 frail geriatric inpatients undergoing early geriatric rehabilitation and 10 healthy community-dwelling older adults. All participants underwent a comprehensive geriatric assessment. HRV measurements using a PPGI system and a reference ECG were made at the beginning and the end of the rehabilitation. HRV in terms of LF/HF ratio was analysed for both intra-individual changes during the geriatric rehabilitation and differences between frail geriatric patients and healthy community-dwelling individuals.

RESULTS

Across all geriatric patients, the median LF/HF ratio obtained with PPGI was found to be reduced by 0.178 (24.8%) during early geriatric rehabilitation. The assessment at the end of the rehabilitation revealed a simultaneous improvement of the functional state. Moreover, frail geriatric patients had a higher LF/HF ratio than their community-dwelling counterparts. Both observations in PPGI-based HRV were confirmed by the reference. The capability of PPGI to track intra-individual HRV changes was also analysed; a Spearman correlation of ρ = 1.0 between PPGI-based HRV and reference was achieved for 58.8% of the participants.

CONCLUSION

Early geriatric rehabilitation improves the functional state, which is associated with an increased HRV. PPGI is capable of detecting HRV changes/trends in that age group. While the tracking of intra-individual HRV changes is also possible, its reliability needs improvement. Nevertheless, the capabilities demonstrated in our study and the non-contact measurement principle of PPGI emphasize its potential for application in geriatric medicine.

Accuracy of heart rate variability estimated with reflective wrist-PPG in elderly vascular patients

Optical heart rate monitoring (OHR) with reflective wrist photoplethysmography is a technique mainly used in the wellness application domain for monitoring heart rate levels during exercise. In the absence of motion, OHR technique is also able to estimate individual beat-to-beat intervals relatively well and can therefore also be used, for example, in monitoring of cardiac arrhythmias, stress, or sleep quality through heart rate variability (HRV) analysis. HRV analysis has also potential in monitoring the recovery of patients, e.g. after a medical intervention. However, in order to detect subtle changes, the calculated HRV parameters should be sufficiently accurate and very few studies exist that asses the accuracy of OHR derived HRV in non-healthy subjects. In this paper, we present a method to estimate beat-to-beat-intervals (BBIs) from reflective wrist PPG signal and evaluated the accuracy of the proposed method in estimating BBIs in a cross-sectional study with 29 hospitalized patients (mean age 70.6 years) in 24-h recordings performed after peripheral vascular surgery or endovascular interventions. Finally, we evaluate the accuracy of more than 30 commonly used HRV parameters and find that the accuracy of certain metrics, for example SDNN and triangular index, shown in the literature to be associated with the deterioration of the status of the patients during recovery from surgical intervention, could be adequate for patient monitoring. On the other hand, the parameters more affected by the high-frequency content of the HRV and especially the LF/HF-ratio should be used with caution.

Low Heart Rate Variability Predicts Stroke and Other Complications in the First Six Postoperative Months After a Hip Fracture Operation

Background: One-year mortality after hip fractures is underestimated and is reported as 25%. An improved risk stratifying could contribute to a better follow up of these patients. Heart Rate Variability (HRV) is an easy point-of-care investigation and is been used in cardiology, endocrinology, and perioperative care. This observational study intended to explore relevant associations between HRV parameters and 6-months mortality and morbidity after a hip fracture. Methods: One hundred and sixty-five patients admitted to two hospitals were included, and short-time HRV measurements (5 min, and 10 min at the two hospitals, respectively) were obtained. Mortality data were gathered by means of the Norwegian central address register. Patients, close relatives of patients, and in some cases their general physicians or nursery home physicians were interviewed 6 months postoperatively regarding the incidence of pneumonia, cardiac events, or stroke. Results: One and hundred fifty-seven (95.2%) patients were followed up after 6 months post-surgery. Twenty-one (13%) died during this period. Twenty patients (13%) developed pneumonia, eight (5 %) stroke, and four (2%) myocardial infarction. No HRV parameter was associated with 6-month general mortality. However, patients who developed stroke had significantly lower High Frequency Power (HF, p < 0.001) and lower Very Low Frequency Power (VLF, p = 0.003) at inclusion compared to patients without complications. Patients who developed pneumonia had at the inclusion lower root mean square of successive differences (RMSSD, p = 0.044). Patients with a history of coronary heart disease (n = 41) showed a mortality of 7%. Mortality in this group was associated with standard deviation of beat-to-beat intervals (SDNN, p = 0.006), Total Power (TP, p = 0.009), HF (p = 0.026), and Low Frequency Power (LF, p = 0.012). Beta-blocker intake was associated with lower heart rate, but not with differences in HRV parameters. Conclusion: In this exploratory study, we present for the first-time significant associations between different preoperative HRV parameters and stroke, myocardial infarction, and pneumonia during a 6-month period after hip fracture. HRV might be a simple and effective tool to identify patients at risk that would warrant better follow-up.

Patients with hip fracture and total hip arthroplasty surgery differ in anthropometric, but not cardiovascular screening abnormalities

Background

With the rising number of hip surgeries, simple and cost-effective tools for surgery risk assessment are warranted. The analysis of heart rate variability (HRV) may not only provide critical insights into the general frailty of patients with hip surgery, but also allow for better differentiation of health profiles in different hip surgery groups. Using HRV analysis, the present study compared cardiovascular as well as anthropometric parameters between patients with hip surgery, the hip fracture surgery group (HFS) and the total hip arthroplasty group (THA), and a control group.

Methods

71 participants (56.3% women), aged 60–85 years, took part, divided into three groups—patients after hip surgery (21 HFS and 30 THA patients) and a control group (20 participants). Electrocardiogram was recorded at baseline and after the application of a physical stressor (grip strength). A 3 (group) × 2 (time) repeated measures ANOVA, and a chi square test were carried out to test for group differences.

Results

Higher weight (p = .002), body mass index (p = .001), and systolic blood pressure (p = .034) were found in THA patients compared to HFS patients. Lower calf circumference (p = .009) and diastolic blood pressure (p = .048) were observed for the HFS group compared to the control group. For cardiovascular parameters, significant differences emerged between the HFS group and the control group in HR (p = .005), SDNN (p = .034) and SD2 (p = .012). No significant differences in cardiovascular parameters were observed between the two hip surgery groups: neither at baseline nor during stressor recovery.

Conclusions

While HRV seems to differentiate well between HFS patients and controls, more research with larger samples is needed to scrutinize similaritites and differences in cardiovascular profiles between HFS and THA patients.

Fitness-Tracker Assisted Frailty-Assessment Before Transcatheter Aortic Valve Implantation: Proof-of-Concept Study

Background

While transcatheter aortic valve replacement (TAVR) has revolutionized the treatment of aortic valve stenosis, wearable health-monitoring devices are gradually transforming digital patient care.

Objective

The aim of this study was to develop a simple, efficient, and economical method for preprocedural frailty assessment based on parameters measured by a wearable health-monitoring device.

Methods

In this prospective study, we analyzed data of 50 consecutive patients with mean (SD) age of 77.5 (5.1) years and a median (IQR) European system for cardiac operative risk evaluation (EuroSCORE) II of 3.3 (4.1) undergoing either transfemoral or transapical TAVR between 2017 and 2018. Every patient was fitted with a wrist-worn health-monitoring device (Garmin Vivosmart 3) for 1 week prior to the procedure. Twenty different parameters were measured, and threshold levels for the 3 most predictive categories (ie, step count, heart rate, and preprocedural stress) were calculated. Patients were assigned 1 point per category for exceeding the cut-off value and were then classified into 4 stages (no, borderline, moderate, and severe frailty). Furthermore, the FItness-tracker assisted Frailty-Assessment Score (FIFA score) was compared with the scores of the preprocedural gait speed category derived from the 6-minute walk test (GSC-6MWT) and the Edmonton Frail Scale classification (EFS-C). The primary study endpoint was hospital mortality.

Results

The overall preprocedural stress level (P=.02), minutes of high stress per day (P=.02), minutes of rest per day (P=.045), and daily heart rate maximum (P=.048) as single parameters were the strongest predictors of hospital mortality. When comparing the different frailty scores, the FIFA score demonstrated the greatest predictive power for hospital mortality (FIFA area under the curve [AUC] 0.844, CI 0.656-1.000; P=.048; GSC-6MWT AUC 0.671, CI 0.487-0.855; P=.42; EFS-C AUC 0.636, CI 0.254-1.000; P=.44).

Conclusions

This proof-of-concept study demonstrates the strong predictive performance of the FIFA score compared to that of the conventional frailty assessments.

Ballistocardiography Can Estimate Beat-to-Beat Heart Rate Accurately at Night in Patients After Vascular Intervention

While bed-integrated ballistocardiography (BCG) has potential clinical applications such as unobtrusive monitoring of patients staying in the general hospital ward, it has so far mainly gained interest in the wellness domain. In this article, the potential of BCG to monitor hospitalized patients after surgical intervention was assessed. Long-term BCG recordings (mean duration 17.7 h) of 14 patients were performed with an EMFit QS bed sensor. In addition, ten healthy subjects were recorded during sleep (mean duration 7.8 h). Using an iterative algorithm, beat-to-beat intervals (BBIs) and the ultra-short-term heart-rate-variability (HRV) parameters standard deviation of NN intervals (SDNN) and root mean square of successive differences (RMSSD) were estimated and compared to an ECG reference in terms of average estimation error and temporal coverage. While the absolute BBI estimation error was found to be higher when full-day patient data was used (16.5 ms), no significant difference between healthy subjects (12.7 ms) and patient nighttime data (11.0 ms) was observed. Nevertheless, temporal coverage of BBI estimation was significantly lower in patients (39.3% overall, 51.7% at night) compared to the healthy sleepers (73.2%). This resulted in reduced HRV estimation coverage (9.7% vs. 37.2%) at comparable estimation error levels.

Dynamics of Vagal Activity Due to Surgery and Subsequent Rehabilitation

Background

Vagal activity is critical for maintaining key body functions, including the stability of inflammatory control. Its weakening, such as in the aftermatch of a surgery, leaves the body vulnerable to diverse inflammatory conditions, including sepsis.

Methods

Vagal activity can be measured by the cardiorespiratory interaction known as respiratory sinus arrhythmia or high-frequency heart-rate variability (HRV). We examined the vagal dynamics before, during and after an orthopedic surgery. 39 patients had their HRV measured around the period of operation and during subsequent rehabilitation. Measurements were done during 24 h circadian cycles on ten specific days. For each patient, the circadian vagal activity was calculated from HRV data.

Results

Our results confirm the deteriorating effect of surgery on vagal activity. Patients with stronger pre-operative vagal activity suffer greater vagal withdrawal during the peri-operative phase, but benefit from stronger improvements during post-operative period, especially during the night. Rehabilitation seems not only to efficiently restore the vagal activity to pre-operative level, but in some cases to actually improve it.

Discussion

Our findings indicate that orthopedic rehabilitation has the potential to strengthen the vagal activity and hence boost inflammatory control. We conclude that providing a patient with a vagal reinforcement procedure prior to the surgery (“pre-habilitation”) might be a beneficial strategy against post-operative complications. The study also shows the clinical usefulness of quantifying the cardiorespiratory interactions.

Acute Effects of Passion Fruit Juice Supplementation on Cardiac Autonomic Function and Blood Glucose in Healthy Subjects

Ascorbic acid supplementation provides beneficial effects on enhancing cardiac autonomic function in patients with heart failure. Ascorbic acid also reduces blood sugar levels and enhances insulin activity, and encourages cardiac autonomic function. Passion fruit is rich in ascorbic acid and potential antioxidants. This study aimed to evaluate the acute effects of passion fruit juice (PFJ) supplementation primarily on cardiac autonomic function and secondary on blood glucose in healthy subjects. A randomized cross-over trial was conducted in 14 healthy subjects aged 21.29±0.73 years. Subjects were supplemented with either 50% PFJ, or glucose and fructose solution as a placebo (PLA) at 3.5 mL/kg body mass with a 1-week washout between treatments in a single-dose design. Short-term heart rate variability and blood glucose levels were evaluated prior to supplementation (T0) and following supplementation for 30, 60, 90, and 120 min (T30, T60, T90, and T120, respectively). Indexes of cardiac autonomic function at T30, including high frequency power (P=0.03) and total power (P=0.01), were significantly higher and the ratio of low frequency/high frequency power was significantly lower (P=0.01) in the PFJ group compared to the PLA group. Blood glucose levels significantly increased at T30 in both PLA (P=0.00) and PFJ (P=0.00) groups. However, there were no significant differences between groups. A single administration of PFJ enhanced cardiac autonomic function through augmentation of parasympathetic activity, although it did not attenuate postprandial hyperglycemia. PFJ may be potentially recognized as beverage able to prevent cardiovascular disease.

Prognostic factors of in-hospital complications after hip fracture surgery: a scoping review

INTRODUCTION

To examine prognostic factors that influence complications after hip fracture surgery. To summarize proposed underlying mechanisms for their influence.

METHODS

We reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Scoping Review extension. We searched MEDLINE, Embase, CINAHL, AgeLine, Cochrane Library, and reference lists of retrieved studies for studies of prognostic factor/s of postoperative in-hospital medical complication/s among patients 50 years and older treated surgically for non-pathological closed hip fracture, published in English on January 2008-January 2018. We excluded studies of surgery type or in-hospital medications. Screening was duplicated by two independent reviewers. One reviewer completed the extraction with accuracy checks by the second reviewer. We summarized the extent, nature, and proposed underlying mechanisms for the prognostic factors of complications narratively and in a dependency graph.

RESULTS

We identified 44 prognostic factors of in-hospital complications after hip fracture surgery from 56 studies. Of these, we identified 7 patient factors-dehydration, anemia, hypotension, heart rate variability, pressure risk, nutrition, and indwelling catheter use; and 7 process factors-time to surgery, anesthetic type, transfusion strategy, orthopedic versus geriatric/co-managed care, multidisciplinary care pathway, and potentially modifiable during index hospitalization. We identified underlying mechanisms for 15 of 44 factors. The reported association between 12 prognostic factors and complications was inconsistent across studies.

CONCLUSIONS

Most factors were reported by one study with no proposed underlying mechanism for their influence. Where reported by more than one study, there was inconsistency in reported associations and the conceptualization of complications differed, limiting comparison across studies. It is therefore not possible to be certain whether intervening on these factors would reduce the rate of complications after hip fracture surgery.

Influence of polypharmacy on heart rate variability in older adults at the Hiroshima Atomic Bomb Survivors Recuperation Research Center, Japan

BACKGROUND

Many studies have identified the risk of polypharmacy, but physiological evidence and methods of evaluation in these studies were poor. The relationship between polypharmacy and heart rate variability in older adults remains unclear. We investigated the relationship between polypharmacy in older adults, including atomic bomb survivors, and heart rate variability.

METHODS

We surveyed 56 older adults who did not need nursing care assistance in the Hiroshima Atomic Bomb Survivors Recuperation Center. Chronic diseases, types of medication, and lifestyle were assessed, and heart rate variability at rest was measured. We calculated heart rate variability indices including standard deviation of normal-to-normal RR intervals (SDNN), total power (TP), and very low frequency (VLF) and analyzed the relationship between the number of daily medication types and heart rate variability indices in older adults. The differences in heart rate variability indices were analyzed using six medications as a cut-off point.

RESULTS

Participants included 36 atomic bomb survivors and 20 non-atomic bomb survivors. The mean number of medication types was 3.6±3.4 (mean±standard deviation). SDNN, TP, and VLF decreased with an increased number of medications in all participants (P<0.01). When the standard of polypharmacy was set to more than six types of medications, SDNN, TP, and VLF were significantly lower in older adults who took six or more medications. Additionally, the mean number of medication types among atomic bomb survivors was higher than that of non-atomic bomb survivors (P = 0.008). The SDNN was significantly lower when atomic bomb survivors took six or more medications (P<0.001).

CONCLUSIONS

We found that a lower heart rate variability in older adults, including atomic bomb survivors, is associated with polypharmacy. We showed physiological evidence of the influence of polypharmacy, which may be important for the healthy life expectancy and prognosis in older adults.

Association between dysfunction of autonomic nervous system activity and mortality in schizophrenia

BACKGROUND

Patients with schizophrenia have a higher mortality risk than the general population. Additionally, the autonomic nervous system (ANS) activity of patients with schizophrenia is lower and more dysfunctional than that of the general population. Nonetheless, the association between ANS dysfunction and mortality in schizophrenia is unclear. The aim of this study was to investigate the association between ANS activity and mortality in schizophrenia and to evaluate the predictive values of heart rate variability for long-term survival.

METHODS

This study involves the 10-year follow-up of a sample population consisting of 59 Japanese inpatients with schizophrenia between 60 and 70 years of age from 2007 to 2016. The ANS activity of all patients was evaluated using heart rate variability in 2007.

RESULTS

Fifty-three participants could be followed up because they stayed in the hospital during the follow-up period. Of these patients, 11 died during follow-up. Their mean age at death was 70.55 ± 3.45 years. The parasympathetic activity of nonsurvivors was significantly lower than that of survivors, and multiple logistic regression analysis showed a significant association between death and parasympathetic activity.

CONCLUSION

We suggest that decreased parasympathetic activity could be associated with 10-year all-cause mortality in older schizophrenic patients.

Hidden Signals-The History and Methods of Heart Rate Variability

The understanding of heart rate variability (HRV) has increased parallel with the development of modern physiology. Discovered probably first in 1847 by Ludwig, clinical applications evolved in the second part of the twentieth century. Today HRV is mostly used in cardiology and research settings. In general, HRV can be measured over shorter (e.g., 5-10 min) or longer (12 or 24 h) periods. Since 1996, most measurements and calculations are made according to the standard of the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. As the first step, the series of times between successive R-peaks in the ECG are in milliseconds. It is crucial, however, to identify and remove extrasystoles and artifacts according to standard protocols. The series of QRS distances between successive heartbeats can be analyzed with simple or more sophisticated algorithms, beginning with standard deviation (SDNN) or by the square root of the mean of the sum of squares of differences between adjacent normal RR (rMSSD). Short-term HRV is frequently analyzed with the help of a non-parametric fast Fourier transformation quantifying the different frequency bands during the measurement period. In the last decades, various non-linear algorithms have been presented, such as different entropy and fractal measures or wavelet analysis. Although most of them have a strong theoretical foundation, their clinical relevance is still debated.

Linear and nonlinear parameters of heart rate variability in ischemic stroke patients

INTRODUCTION

Cardiovascular system presents cortical modulation. Post-stroke outcome can be highly influenced by autonomic nervous system disruption. Heart rate variability (HRV) analysis is a simple non-invasive method to assess sympatho-vagal balance.

OBJECTIVES

The purpose of this study was to investigate cardiac autonomic activity in ischemic stroke patients and to asses HRV nonlinear parameters beside linear ones.

METHODS

We analyzed HRV parameters in 15 right and 15 left middle cerebral artery ischemic stroke patients, in rest condition and during challenge (standing and deep breathing). Data were compared with 15 age- and sex-matched healthy controls.

RESULTS

There was an asymmetric response after autonomic stimulation tests depending on the cortical lateralization in ischemic stroke patients. In resting state, left hemisphere stroke patients presented enhanced parasympathetic control of the heart rate (higher values for RMSSD, pNN50 and HF in normalized units). Right hemisphere ischemic stroke patients displayed a reduced cardiac parasympathetic modulation during deep breathing test. Beside time and frequency domain, using short-term ECG monitoring, cardiac parasympathetic modulation can also be assessed by nonlinear parameter SD1, that presented strong positive correlation with time and frequency domain parameters RMSSD, pNN50, HFnu, while DFA α1 index presented negative correlation with the same indices and positive correlation with the LFnu and LF/HF ratio, indicating a positive association with the sympatho-vagal balance.

CONCLUSIONS

Cardiac monitoring in clinical routine using HRV analysis in order to identify autonomic imbalance may highlight cardiac dysfunctions, thus helping preventing potential cardiovascular complications, especially in right hemisphere ischemic stroke patients with sympathetic hyperactivation.