ECG Measurements Research Articles

Abstract 4112524: Novel Contactless and AI-Based Method Can Determine Heart Rate and Cardiac-Induced Vibrations of Chest

Introduction: Seismocardiography (SCG) - measurements of cardiovascular-induced vibrations on the chest - has shown potential for providing clinical information for cardiac conditions. SCG is conventionally recorded by an accelerometer attached to a single point on chest. Recent research suggests multichannel SCG (mSCG) - measurements from multiple chest locations - can provide extra and more accurate clinical information. Current mSCG methods are limited to accelerometer arrays, laser Doppler vibrometry, and airborne ultrasound that are either costly, difficult for inexperienced users, or need bulky equipment, thereby impeding their use beyond research or clinical settings. Hypothesis: mSCG signals can be accurately estimated from tiny chest movements in chest videos recorded by ordinary cameras, e.g., those in smartphones. Methods: We enrolled 10 subjects (sbjs) with no history of CVDs (21.7 ± 1.7 years, 40% women). ECG and chest video of sbjs were recorded at rest for 15 sec during breath hold at the end of inhalation followed by another 15 sec recording during breath hold at the end of exhalation. We developed an AI-powered mobile app to record the chest videos and convert them to 0-30 Hz mSCG in right-to-left (RL) and head-to-foot (HF) directions (Fig 1a). Heart rate (HR) based on ECG RR interval and mSCG was measured and compared. Results: HR estimated from mSCG in both RL and HF directions had a good agreement with ECG-based HR using Bland-Altman analysis [RL: bias = 1.4 bpm, 95% CI = 5.6 bpm; HF: bias = 0.8 bpm, 95% CI = 6.2 bpm (Fig 1b)]. High-quality mSCG and ECG measurements were obtained for all sbjs. Conclusion: Clinically relevant information can be accurately extracted from chest videos using our novel, contactless, AI-based method. Given that the vast majority of Americans have access to a camera phone, future developments of this method may provide new means of remote and accessible cardiac monitoring.

MOBILE HEALTH: ECG MONITORING FOR ATRIAL FIBRILLATION DETECTION

This systematic review examines the use of mobile health (mHealth) technologies, such as smartphone apps and wearable devices, for detecting atrial fibrillation (AF). The review includes studies assessing the quality and performance of mobile apps and smartwatch algorithms, as well as the clinical validity of ECG measurement and photoplethysmography technology. Findings suggest diverse results, with some studies indicating promising sensitivity and specificity for AF detection. However, there is a need for further research to develop reliable algorithms for diagnosing and managing cardiovascular conditions using mHealth technologies.

The added value of deep learning to submaximal exercise electrocardiogram for the 10-year prediction of major adverse cardiovascular and cerebrovascular events

Abstract Background The added value of exercise ECG data to traditional risk factors in predicting cardiovascular events remains unclear. Deep learning of ECG signals has demonstrated state-of-the-art performance in detecting subtle abnormalities indicative of cardiovascular disease. We investigated whether deep learning analysis of exercise ECGs could improve the prediction of major cardiovascular and cerebrovascular events (MACCE) with respect to established risk models in a large population-based cohort. Purpose To assess the added value of submaximal exercise ECG measurements to established cardiovascular risk prediction models. Methods We obtained ECG recordings from 41,076 UK Biobank participants without cardiovascular disease (CVD) who underwent a submaximal exercise ECG test. We obtained ECG recordings from 41,076 UK Biobank participants without cardiovascular disease (CVD) who underwent a submaximal exercise ECG test. We created two deep neural network ECG risk scores: one derived from conventional ECG parameters, measured at rest, peak exercise and late-stage recovery, and another based on the complete ECG (Q-ECG). We assessed the added value of conventional ECG parameters and Q-ECG risk scores to the UK's current prediction algorithm (QRISK3). We estimate the association between ECG parameters and MACCE, using Cox Proportional hazard models, following adjustment for traditional risk factors. All models were internally validated via 5-fold cross-validation and 1000 bootstrap iterations. Predictive performance was evaluated using Harrel's C-index, Net Reclassification Index (NRI) and net benefit. Findings: Incident MACCE was reported in 4,082 (9.9%) individuals in the study population and 3,463(9.7%) individuals with valid ECG parameters over a median follow-up period of 12.5 years. We found combined conventional ECG and Q-ECG scores were independently associated with MACCE, following adjustment for multiple testing: adjusted hazard ratio [HZ] = 1.76 (95% CI:1.63-1.91); HZ = 1.14 (95% CI:1.10-1.18), respectively, per standard deviation increase. Both conventional ECG parameters and Q-ECG were predictive of MACCE, independent of clinical risk factors, C-index = 0.64 (95%CI 0.63-0.65); net benefit = 0.09(95% CI 0.07 - 0.11) and C-index = 0.56 (95% CI 0.55-0.57); net benefit = 0.07(95% CI 0.05 - 0.09). ECG measurement's modestly improved model discrimination over the bassline QRISK3 risk score when combined with QRISK3 risk factors for conventional markers and Q-ECG score, respectively; ΔC-index 0.03 (95% CI: 0.02 – 0.04) and ΔC-index 0.03 (95% CI: 0.02 – 0.03); However, we observed no significant improvements in classification at the current recommended threshold of 10%. Conclusion In individuals without a history of prior cardiovascular disease, ECG measures independently predict the risk of MACCE. When combined with QRISK3, neural-network-derived ECG risk scores marginally improve cardiovascular risk prediction over QRISK3.

Validation of chest-belt ECG evaluation using artificial intelligence

Abstract Background Simple, cheap wearables for long-term ECG monitoring with automatic analysis of all measurements using a bespoke artificial intelligence (AI) are scarce. Annotated single-lead ECG data from a chest-belt are missing. Methods We have developed a complex software environment to acquire raw ECG data from the Polar H10 chest-belt, and a bespoke, original AI to detect artifacts, QRS complexes and the presence of atrial fibrillation (AF) from chest-belt recordings. Original manually annotated ECG recordings from real patients from cardiology departments using the chest-belt and a public MIT-BIH database as reference were used for validation. Results QRS determination by AI (version Q4/23) in evaluating MIT-BIH database of ECG samples had a 97.67 % sensitivity and a 97.73 % positive predictive value. AF in MIT-BIH database was detected by AI with 90.31 % sensitivity and 92.09 % positive predictive value. To assess AI accuracy in ECG from a chest-belt, 150 consecutive measurements using Polar H10 chest-belt (215 hours of ECG recordings in total) from individual patients were included in the analysis. Patients were not limited in any physical activity during measurements. 7.15 % of the length of all recordings (15.4 hours) was assessed as noise by AI and excluded from the analysis. AF lasting longer than 30 seconds was present in 14 of 150 (9.3 %) manually evaluated recordings. QRS determination by AI in evaluating manually annotated chest-belt data had 99.76 % sensitivity and 99.74 % positive predictive value. AF in manually annotated chest-belt data was detected by AI with 92.86 % sensitivity and 100 % positive predictive value. Conclusion A chest-belt can be used to reliably detect QRS complexes and the presence of atrial fibrillation with high accuracy when using a bespoke artificial intelligence for the evaluation. Commonly available devices capable of long ECG measurements could be used for patient-empowered screening for important arrhythmias.Atrial fibrillation on chest-belt ECG

Empagliflozin's role in reducing ventricular repolarization heterogeneity: insights into cardiovascular mortality decline from the EMPATHY-HEART trial

Abstract Introduction The incidence of myocardial infarction (MI) and sudden cardiac death (SCD) is significantly higher in individuals with Type 2 Diabetes Mellitus (T2DM). Predictive measures for fatal arrhythmias are often inadequate, highlighting the need for novel non-invasive diagnostic tools. The T-wave heterogeneity (TWH) index, which measures variations in ventricular repolarization, has emerged as a promising predictor for severe ventricular arrhythmias. Although the EMPA-REG trial reported reduced cardiovascular mortality with empagliflozin, the underlying mechanisms remain unclear. This study investigates the potential of empagliflozin in mitigating electrical instability in patients with T2DM and coronary heart disease (CHD) by examining changes in TWH. Methods Participants were adult outpatients with T2DM and CHD, exhibiting a baseline TWH of at least 80 µV. They received a 25mg daily dose of empagliflozin and were evaluated clinically, including ECG measurements at baseline and after 4 weeks. TWH was computed from leads V4, V5, and V6 using a validated technique. The primary study outcome was the alteration in TWH following empagliflozin administration, assessed via the Wilcoxon test, with a significance threshold of p<0.05. Results An initial review of 6,000 medical records pinpointed 800 patients for TWH evaluation. Of these, 412 exhibited TWH above 80 µV, with 144 completing clinical assessments and 90 meeting the criteria for high cardiovascular risk enrollment. Empagliflozin adherence exceeded 80%, resulting in notable reductions in blood pressure without affecting heart rate. Side effects were generally mild, with 13.3% experiencing mostly Level 1 hypoglycemia, alongside infrequent urinary and genital infections. The treatment consistently reduced median TWH from 116 to 103 µV (p=0.01), as detailed in Figure 1. Conclusion The EMPATHY-HEART trial preliminarily suggests that empagliflozin decreases heterogeneity in ventricular repolarization among patients with T2DM and CHD. This reduction in TWH may provide insight into the mechanism behind the decreased cardiovascular mortality observed in previous trials, potentially offering a therapeutic pathway to mitigate the risk of severe arrhythmias in this population.Table 1 Figure 1

Electrocardiographic abnormalities are frequently detected in healthy adult Borzoi with a normal echocardiogram.

Borzoi reportedly experience sudden death. The objective of this study was to report ECG intervals, amplitudes, and frequency of ECG abnormalities in clinically healthy Borzoi. 98 clinically healthy Borzoi were prospectively recruited and underwent echocardiogram, ECG, and cardiac troponin I testing between October 2020 and December 2022. Standard ECG measurements were obtained. Early repolarization notches and slurs were recorded. Of 82 Borzoi with a structurally normal echocardiogram, ventricular arrhythmias were documented in 8 (10%) dogs, all of which had normal cardiac troponin I concentrations. Median P wave duration was 55 milliseconds (range, 45 to 70 milliseconds). Median PR interval was 125 milliseconds (range, 80 to 175 milliseconds). Thirty-one (38%) Borzoi had first-degree atrioventricular block (PR interval > 130 milliseconds). Median QRS duration was 65 milliseconds (range, 48 to 90 milliseconds). Median QT interval was 235 milliseconds (range, 185 to 275 milliseconds). Twenty-nine (35%) and 15 (18%) of 82 Borzoi had QT intervals > 240 or > 250 milliseconds, respectively. Sixty-seven of 82 (82%) Borzoi had early repolarization notches or slurs. Seventeen of 82 (21%) Borzoi had an abnormality of the ST segment, most commonly convexity/doming. Convexity of the ST segment was intermittent (n = 9) or persistent (4). Ventricular arrhythmias, early repolarization, prolonged QT intervals, and ST segment abnormalities are not infrequent in clinically healthy Borzoi. P, PR, and QRS durations are commonly prolonged compared to general canine reference intervals. Future study into heritable channelopathies in Borzoi is warranted given the frequency of ventricular arrhythmias, repolarization abnormalities, and sudden death in the breed. Breed-specific ECG reference intervals are needed.

Validity and Reliability of Movesense HR+ ECG Measurements for High-Intensity Running and Cycling.

Low-cost, portable devices capable of accurate physiological measurements are attractive tools for coaches, athletes, and practitioners. The purpose of this study was primarily to establish the validity and reliability of Movesense HR+ ECG measurements compared to the criterion three-lead ECG, and secondarily, to test the industry leader Garmin HRM. Twenty-one healthy adults participated in running and cycling incremental test protocols to exhaustion, both with rest before and after. Movesense HR+ demonstrated consistent and accurate R-peak detection, with an overall sensitivity of 99.7% and precision of 99.6% compared to the criterion; Garmin HRM sensitivity and precision were 84.7% and 87.7%, respectively. Bland-Altman analysis compared to the criterion indicated mean differences (SD) in RR' intervals of 0.23 (22.3) ms for Movesense HR+ at rest and 0.38 (18.7) ms during the incremental test. The mean difference for Garmin HRM-Pro at rest was -8.5 (111.5) ms and 27.7 (128.7) ms for the incremental test. The incremental test correlation was very strong (r = 0.98) between Movesense HR+ and criterion, and moderate (r = 0.66) for Garmin HRM-Pro. This study developed a robust peak detection algorithm and data collection protocol for Movesense HR+ and established its validity and reliability for ECG measurement.

Time course of cognitive functions and physiological response under heat exposure: Thermal tolerance exposure time based on ECG and fNIRS

Thermal discomfort has a great dynamic impact on cognitive performance and occupants’ well-being during prolonged working. However, few studies have focused on the dynamic changes in cognitive functions and physiological responses under extreme heat stress. This study investigated the cognitive impairment over exposure time at various ambient temperatures, ranging from 21.15℃ WBGT to 38.93℃ WBGT, and its underlying physiological mechanism. 30 well-trained volunteers and 8 occupational operators participated in the experiments, with typical cognitive tests, ECG, and fNIRS measurements. Negative correlations were mainly observed between cognitive test accuracy, ECG RRI, ECG RMSSD, ECG HF/LF, fNIRS ALFF, fNIRS functional connectivity (CORRz, COH, PLV), and exposure time. This indicated that increased physical load, stress, and decreased regulation ability to sudden changes, cognitive resource input, and inter-regional brain cooperation were key factors contributing to cognitive impairments over time. A comprehensive performance index (CPI) was established by the weighted sum of accuracy in cognitive tests and physiological features of ECG and fNIRS. The weights suggested fNIRS ALFF, ECG RRI, and fNIRS functional connectivity could be potential biomarkers for cognitive assessment. A set of linear quantitative CPI curves over exposure time was supplied to calculate the thermal tolerance exposure time at various risk tolerances and ambient temperatures. A power-law relationship (R2>0.997) was observed between the thermal tolerance exposure time and the standardized temperature. This study provides a physiological insight into cognitive impairment under prolonged heat exposure, and quantitative thermal tolerance exposure curves to evaluate safe thermal working duration for both low-risk groups (officers and drivers) and high-risk groups (operators in industry).

Monitoring the health of patients using a nodal potential map

Purpose: The article presents the developed device and methods for monitoring the heart's condition using a nodal potential map. The proposal enables monitoring of the patient's health condition. Methods: Testing the heart's electrical activity in our device's case uses a "nodal potential map" BSPM (Body Surface Potential Mapping) technique. This is an extended version of the standard ECG measurement, which, instead of 12 leads, uses several dozen or even several hundred measurement electrodes placed in appropriate locations on the front and back of the chest. Results: The developed solution enables monitoring of heart function in a noninvasive way and is more precise than a standard ECG test. The collected measurements allowed us to determine the health and condition of the patient's heart—no anomalies were detected during its operation. Discussion: The next stage of work will be the development of machine learning algorithms trained on the measurements obtained from the vest. The results obtained so far indicate the potential of models classifying heart diseases.

Role of Cardiac Biomarkers in Stroke and Cognitive Impairment.

This topical review assesses the growing role of cardiac biomarkers beyond cardiovascular health and focuses on their importance in stroke and dementia. The first part describes blood-based cardiac biomarkers in patients with stroke and highlights applications in the setting of early diagnosis, poststroke complications, outcome prediction as well as secondary prevention. Among other applications, natriuretic peptides can be helpful in differentiating stroke subtypes. They are also currently being investigated to guide prolonged ECG monitoring and secondary prevention in patients with stroke. Elevated cardiac troponin after ischemic stroke can provide information about various poststroke complications recently termed the stroke-heart syndrome. The second part focuses on the role of cardiac biomarkers in vascular cognitive impairment and dementia, emphasizing their association with structural brain lesions. These lesions such as silent brain infarcts and white matter hyperintensities often co-occur with cardiac disease and may be important mediators between cardiovascular disease and subsequent cognitive decline. ECG and echocardiogram measurements, in addition to blood-based biomarkers, show consistent associations with vascular brain changes and incident dementia, suggesting a role in indicating risk for cognitive decline. Together, the current evidence suggests that cardiac blood-based, electrophysiological, and imaging biomarkers can be used to better understand the heart and brain connection in the setting of not only stroke but also dementia.

Validity of Ultra-Short-Term Heart Rate Variability Derived from Femoral Arterial Pulse Waveform in a British Military Cohort.

Various non-electrocardiogram (ECG) based methods are considered reliable sources of heart rate variability (HRV) measurement. However, the ultra-short recording of a femoral arterial waveform has never been validated against the gold-standard ECG-based 300s HRV and was the aim of this study.A validity study was conducted using a sample from the first follow-up of the longitudinal ADVANCE study UK. The participants were adult servicemen (n = 100); similar in age, rank, and deployment period (Afghanistan 2003-2014). The femoral arterial waveforms (14s) from the pulse wave velocity (PWV) assessment, and ECG (300s) were recorded at rest in the supine position using the Vicorder™ and Bittium Faros™ devices, respectively, in the same session. HRV analysis was performed using Kubios Premium. Resting heart rate (HR) and root mean square of successive differences (RMSSD) were reported. The Bland-Altman %plots were constructed to explore the PWV-ECG agreement in HRV measurement. A further exploratory analysis was conducted across methods and durations.The participants' mean age was 38.0 ± 5.3 years. Both PWV-derived HR (r = 0.85) and RMSSD (rs=0.84) showed strong correlations with their 300s-ECG counterparts (p < 0.001). Mean HR was significantly higher with ECG than PWV (mean bias: -12.71 ± 7.73%, 95%CI: -14.25%, -11.18%). In contrast, the difference in RMSSD between the two methods was non-significant [mean bias: -2.90 ± 37.82% (95%CI: -10.40%, 4.60%)] indicating good agreement. An exploratory analysis of 14s ECG-vs-300s ECG measurement revealed strong agreement in both RMSSD and HR.The 14s PWV-derived RMSSD strongly agrees with the gold-standard (300s-ECG-based) RMSSD at rest. Conversely, HR appears method sensitive.

Role of Apigenin in Rats with Type 1 Diabetic Complications

Abstract Background and Aim The main factor contributing to diabetes morbidity and mortality is cardiovascular problems. Apigenin, a naturally occurring flavonoid with anti-inflammatory and anti-diabetic characteristics, was investigated for its cardioprotective potential. Methods Type 1 diabetes model was induced using single injection of streptozotocin and diabetic rats were injected with apigenin. ECG recording and measurement of blood pressure were performed. Biochemical analyses of serum glucose, lipid profile, and creatine kinase were done. Histological examination of cardiac tissues was also performed. Results Diabetic rats had higher levels of glucose and creatine kinase, and impaired lipid profile as compared to the control group. Apigenin improved glycemic control, dyslipidemia, and cardiac function markers. Diabetic group had significantly higher blood pressure values as compared to the control group. The mean systolic and diastolic blood pressure levels dropped after apigenin treatment. ECG showed decrease in heart rate and increase in R-voltage after apigenin-injection as compared to diabetic rats. Moreover, apigenin-injection resulted in reduced histological changes of cardiac tissues compared to diabetic rats. Conclusion Apigenin could serve as potential therapeutic agent to reverse effects of hyperglycemia and its cardiovascular complications in diabetes.

Loss of protein phosphatase 2A regulatory subunit PPP2R5A is associated with increased incidence of stress-induced proarrhythmia.

Protein phosphatase 2A (PP2A) is a serine/threonine-selective holoenzyme that controls Ca2+ homeostasis and contractility of the heart via dephosphorylation of regulatory proteins. In some genetically modified mouse models with increased arrhythmogenicity, a reduced expression of the regulatory subunit B56α of PP2A was found as a concomitant effect. Whether there is a general correlation between the abundance of B56α and the promotion of cardiac arrhythmogenesis remains unclear. The aim of this study was therefore to investigate the role of PP2A-B56α in the propensity for arrhythmic activity in the heart. The experimental analysis of this question has been addressed by using a mouse model with deletion of the PP2A-B56α gene, PPP2R5A (KO), in comparison to wild-type animals (WT). Evidence for arrhythmogenicity was investigated in whole animal, isolated heart and cardiomyocytes by ECG, recording of monophasic action potential (MAP) induced by programmed electrical stimulation (PES), measurement of Ca2+ transients under increased pacing frequencies and determination of total K+ channel currents (I K). ECG measurements showed a prolongation of QT time in KO vs. WT. KO mice exhibited a higher rate of premature ventricular contractions in the ECG. MAP measurements in Langendorff-perfused KO hearts showed increased episodes of ventricular tachyarrhythmia induced by PES. However, the KO hearts showed values for MAP duration that were similar to those in WT hearts. In contrast, KO showed more myocardial cells with spontaneous arrhythmogenic Ca2+ transient events compared to WT. The whole-cell patch-clamp technique applied to ventricular cardiomyocytes revealed comparable peak potassium channel current densities between KO and WT. These findings support the assumption that a decrease or even the loss of PP2A-B56α leads to an increased propensity of triggered arrhythmias. This could be based on the increased spontaneous Ca2+ tansients observed.

Preprocedural atrial fibrillation burden is associated with recurrence in patients undergoing atrial fibrillation ablation: findings from the ISOLATION AF Ablation Cohort Study

Abstract Background Non-invasive quantification of electrophysiological properties of the atria is increasingly used for outcome prediction in atrial fibrillation (AF) patients. Data on the benefit of the current classification of AF compared to AF burden based on single lead ECG measurements to predict AF recurrences are scarce. Objective This study sought to assess the predictive performance of low versus high AF burden compared to the conventional AF classification for predicting recurrences after AF catheter ablation. Methods A cross-sectional analysis was conducted in AF patients scheduled for catheter ablation included in the prospective multicenter ISOLATION cohort study between July 2020 and November 2022. Clinical characteristics, routine tests, blood tests and rhythm monitoring through single lead ECGs were collected prior to ablation. ECGs were recorded three times daily for four weeks, with additional measurements in case of the onset or relief of symptoms. The primary endpoint was "ablation success" defined as freedom from documented arrhythmia after the blanking period. Of 650 included patients, pre-procedural rhythm monitoring was available in 580. 261 patients had at least 14 days of ECG measurements and completed 12 months of follow-up. In these patients, we compared the recurrences after 12 months between paroxysmal and persistent AF and high versus low AF burden through survival analysis. Maximally selected rank statistics were used to determine the best cut-off value for AF burden. Results In 261 patients, the mean age was 64 ± 9 years, and 33.7% were female. Physicians classified 170 patients (65.1%) as paroxysmal AF and 91 (34.9%) as persistent AF based on medical history. The AF burden is shown in Figure 1. The optimal calculated cut-off value for AF burden was 42%. Out of 170 patients with paroxysmal AF, 17 (10%) had a burden of &amp;gt; 42%. Of the 91 patients with persistent AF, 35 (38%) had a burden of &amp;lt; 42%. After 12 months, a significant difference in recurrences was observed between patients with paroxysmal AF versus persistent AF (p= 0.015). Patients with high AF burden, had more recurrences after 12 months, than patients with a low AF burden (p= 0.006) (Figure 2). Conclusion Our preliminary results suggest that the addition of a new classification of AF based on burden might provide additional benefit in predicting AF recurrences after catheter ablation compared to the current existing classification and may improve prognostication. Completion of patient follow-up is necessary to determine the predictive value of AF burden derived from single lead ECGs for the prediction of AF recurrence.Figure 2.

Continuous QT interval monitoring using insertable cardiac monitors during antiarrhythmic loading hospitalization: Results from the "LINQ QT" Study

Abstract Background QT interval prolongation is associated with the development of potentially lethal cardiac arrhythmias. An implantable cardiac monitor (ICM) capable of longitudinal QT monitoring may allow for mobile assessment of dynamic changes in QT and assist in predicting long term cardiotoxicity. Objective Determine feasibility of continuous QTc interval monitoring in patients with ICM hospitalized for antiarrhythmic drug loading. Methods The previously described QT detection algorithm for an ICM determines the QT interval for every beat thus providing continuous long-term QT trends. QT intervals detected from continuously collected ICM ECG data from patients enrolled in a prospective clinical study from three sites was analyzed with the primary objective of studying the long-term QT interval trends in patients undergoing antiarrhythmic drug loading in an inpatient setting. The ICM ECG was processed through the QT detection algorithm which calculates the QTc interval for every beat to generate continuous long term QTc trends. Metrics including mean and median QTc, minimum and maximum QTc, and magnitude of QTc change were studied during the hospitalization period. Continuous QTc interval trend is presented from a patient displaying increase in QTc interval following antiarrhythmic drug loading during the hospitalization period. Results 5 out of 17 patients enrolled (avg. age 71±7.3 years, 40% females) in the QT clinical study had continuous telemetered ICM ECG data available during the index antiarrhythmic loading hospitalization period. All patients were loaded with Sotalol during the hospitalization. All 5 patients had hypertension and atrial fibrillation (AF). 3 patients (60%) had a history of myocardial infarction (MI), congestive heart failure (CHF), and coronary artery disease (CAD) while 1 patient (20%) had diabetes. The magnitude of change in QTc over the hospitalization period was 139±42 msec with over 100 msec QTc change noticed in 4 of 5 patients (80%) (figure 1). Figure 2 shows continuous QTc interval trend observed from a patient (Male; Age:75; history of AF, hypertension, CHF, stroke) from this study showing a continuous increase in QTc interval. Overall, there was over 150 msec change in QTc observed for this patient during the hospitalization period. Premature ventricular complexes (PVCs) in a pattern of bigeminy were observed from ICM ECG for a 3-hr period from 12 pm-3 pm following the second antiarrhythmic dose which coupled with QT prolongation could indicate early signs of cardiotoxicity (figure 2). The five static 12-lead ECG measurements taken for this patient during the hospitalization period is also reported with the difference between these 12-lead QTc measurements and algorithm measured QTc being 22±8 msec. Conclusion ICM QT monitoring performed utilizing a QT interval detection algorithm can provide longitudinal and long-term dynamic QT trends in patients implanted with ICM.

#2570 Non-invasive blood pressure monitoring in dialysis patients using pulse wave velocity

Abstract Background and Aims Dialysis patients are at high risk of circulatory dysregulation and hypotension during treatment. Intradialytic hypotension (IDH) is a potentially life-threatening complication. The main causes are high ultrafiltration volumes and high ultrafiltration rates when patients tend to gain a lot of weight between dialysis treatments. A lack of patient compliance with regard to drinking volumes and a lack of residual diuresis are risk factors for this. Close circulatory monitoring and therapy settings to avoid absolute or relatively high UF rates to prevent IDH are frequently used. These are primarily the frequent non-invasive measurement of blood pressure using cuffs, the measurement of relative blood volume and the adjustment of ultrafiltration rates to these values. Prophylactically, the dialysis time can be extended, ultrafiltration profiles or ultrafiltration breaks can be planned, the dialysate temperature can be lowered and the composition of the dialysate can be adjusted. Despite all attempts, however, the incidence of IDH in everyday clinical practice is too high. The non-invasive measurements with cuffs are not carried out frequently enough, the measurement of the relative blood volume only covers a partial range, sudden changes in vascular tension or cardiac output are not recorded. Method The pulse wave velocity (PWV) is a well-known parameter for describing the propagation of the pressure wave after ejection of the heart beat volume in the arteries. The PWV is dependent on blood pressure, vessel wall tension and cardiac output. Changes in blood pressure can therefore be recognised by measuring the PWV. With the help of a measuring device (PESAS) for the ECG signal and peripheral pulse plethysmography, PWV can be measured non-invasively, continuously, for every heartbeat and, above all, hardly noticed by the patient. The PESAS allows the time-synchronised measurement of ECG and peripheral plethysmography curves and thus the determination of PWV. It is an experimental device. We would like to present a study showing the use of a measuring device (PESAS) in 15 prevalent dialysis patients for the detection of IDH. All study participants were examined during 3 dialysis treatments. Results The measurement of PWV in chronic dialysis patients during treatment is technically feasible. The measurement is tolerated by the patients. Changes in PWV could be detected in the patients during the course of dialysis; these were also dependent on the ultrafiltration rates. Individual patient reactions to volume withdrawal varied, with both increases and decreases in PWV being demonstrated. An acute change in PWV was usually associated with a drop in blood pressure. Continuous measurement allowed IDH events to be detected earlier than intermittent blood pressure measurement with cuffs. Sudden drops in blood pressure could be detected better and earlier with the PESAS system than by measuring the relative blood volume. Conclusion The PESAS system is suitable for monitoring dialysis patients to prevent IDH. Further adjustments and optimisation of the evaluation algorithms are necessary.

Defining cardiac stability during Langendorff perfusion

The Langendorff heart preparation is a valuable ex vivo technique for studying cardiac electrophysiology. For the past century it has been used in toxicology studies, drug testing, and disease modeling and has contributed significantly to understanding cardiac physiology, development, and pathological states. This study aimed to investigate the stability and reproducibility of the modern Langendorff heart preparation under various experimental conditions and to establish cardiac metric standards with corresponding exclusion criteria. Isolated hearts were extracted from adult Sprague Dawley rats and retrograde perfused with a modified Krebs-Henseleit buffer. A cohort of isolated hearts were used to establish a control baseline of multiple physiological parameters measured over time (e.g., electrocardiogram, flow rate, electrophysiology, electrical and calcium dynamics). These control baseline values were then compared to hearts exposed to the most common media additives in Langendorff studies (e.g., blebbistatin(−/−), bovine serum albumin, and voltage and calcium indicator dye). Over a three-hour period, cardiac metrics were monitored in stable Langendorff-perfused hearts. The addition of blebbistatin, DMSO or dyes did not change EP or ECG measurements as compared to control baseline. The most significant drift in all the EP values was ventricular effective refractory period (VERP). With or without blebbistatin, VERP increased from 40 to 60ms over the course of three hours. In that time heart rate and flow also decreased slightly. Blebbistatin was associated with an increased action potential duration but did not alter calcium transient duration. It was also observed that 1% circulating bovine serum albumin quenched the rh237 voltage dye signal 80% as measured by signal to noise. Constant pressure Langendorff-perfusion with a crystalloid buffer provides a reliable and reproducible model for cardiac electrophysiology research with a few caveats. The total length of study should be carefully considered to account for adaptations in cardiac physiology during longer perfusion times. As an excitation-contraction uncoupler, blebbistatin reduces motion artifact but delays action potential duration. Although BSA is used to minimize cardiac edema, it interferes with membrane bound voltage dyes. This study sets physiological parameters as a useful guide for future cardiac studies that use the isolated heart as a research model. American Physiological Society, R01HD108839 to N.G.P. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Performance Evaluation of Cardiac Signal Recording Framework (CARDIF)-A Quantitative Assessment for Long Term Monitoring Applications

Background: Personal health monitoring with wearable electronics has gained momentum in the recent years due to its usage in flexible textile-based sensors/electrodes for recording of physiological vital parameters. Such system provides scope for long term ambulatory ECG measurement and motion tracking applications. The selection /design of textile sensors play a vital role as it has to overcome skin irritations, improve the skin-electrode impedance required for conductivity. The composition of textile materials, shape and size of the textile electrodes contributes significantly towards the conductivity. Objective: To assess the proposed Cardif system for its suitability to introduce in the clinical routine Method: The proposed textile electrodes were designed using knit jersey conductive material. The skin –contact impedance of the proposed textile material, was measured using two electrode impedance method and measurement was done for different age groups by varying the frequency. Results: The measurement results showed that the impedance was decreasing with increasing frequency and was found to be below 1.5Mohm/cm2 in the frequency range of 20Hz to 1KHz for three different age groups. The performance of the CARDIF was assessed using heart rate, RR interval, SNR as well as qualitative assessment through visual inspection and were compared with gel based disposable Ag/AgCl electrodes. Qualitative and quantitative analysis was performed and the various results confirm the proposed textile electrodes for continuous patient monitoring applications.

The Effect of Cardiovascular Medication on Heart Rate Variability in Patients Presenting with Early Sepsis at the Emergency Department: A Prospective Cohort Study

Our SepsiVit study showed that long-term, automatically analyzed ECG recordings can be used to determine heart rate variability (HRV) features associated with the clinical deterioration of early septic patients at the ED. This study focus on the influence of cardiovascular medication on HRV in patients with early sepsis at the ED. This study is an exploratory post-hoc analysis of our SepsiVit study. Eligible patients were connected to a mobile bedside monitor for continuously ECG measurements. The first 3 hours were analyzed for this study. Between January 2017 and December 2018, 171 patients were included with early sepsis, defined as infection and two or more systemic inflammatory response syndrome criteria. We excluded sixteen patients because of insufficient measurements. Therefore, we included 155 patients in the final analysis: 72.9% with sepsis, 2.6% with septic shock, and 24.5% classified as infection. In 9.0% of the patients, medication directly impacting cardiac contractility was administered, while 22.6% received medication with an indirect effect. A combination of both types of medication was prescribed to 17.4% of the patients. The majority of patients (51.0%) did not utilize any cardiovascular medication. Patients using both medication with direct and indirect effect were on average 10 years older than patients using no cardiovascular medication (p 0.037). No differences in vital signs or HRV parameters were found in patients using cardiovascular medication. Our results showed that HRV is not influenced by cardiovascular medication. Consequently, the correction of HRV features for the use of cardiovascular medication is unnecessary when analyzing, modelling, and interpreting these signals.

Evaluation of the cardiac safety of parsaclisib, a selective PI3Kδ inhibitor, in patients with previously treated B-cell malignancies: Results from the CITADEL-101 study.

Parsaclisib, a potent and selective phosphatidylinositol 3 kinase δ inhibitor, has been investigated for the treatment of B-cell malignancies and studied in patients with autoimmune diseases and myelofibrosis. The CITADEL-101 study (NCT02018861) assessed safety, tolerability, and preliminary efficacy of parsaclisib in patients with relapsed or refractory non-Hodgkin lymphoma. This study evaluated the cardiac safety of parsaclisib as monotherapy based on data from 72 patients enrolled in the CITADEL-101 study. Time-matched pharmacokinetic and ECG measurements were collected at specified times for 69 patients receiving monotherapy in doses of 5, 10, 15, 20, 30, and 45 mg once daily. Based on the categorical outlier analysis, no dose-dependent effect was observed on the incidence of outliers in QT interval corrected for heart rate (HR) by Fridericia's method (QTcF), HR, or cardiac conduction. Based on central tendency analysis, the least square means (LSMs) (90% confidence interval [CI]) of ΔQTcF from the central tendency analysis ranged from -6.83 (-18.8 to 5.19) to 4.75 ms (0.410-9.09) across dose groups (below 20 ms, the threshold of large QT effects) and was not considered dose dependent. Moreover, the LSMs of ΔHR, ΔPR interval, and ΔQRS interval were minor. From the concentration-ΔQTcF analyses, the predicted ΔQTcF (90% CI) for all dose levels was between 0.365 (-1.75 to 2.48) and 7.87 ms (0.921-14.8), with the highest upper limit of CIs well below 20 ms, and therefore, a large QT/QTc effect was ruled out up to the highest dose level (45 mg) investigated. Overall, parsaclisib at the dose ranges studied did not reveal concentration-dependent effects on change in QTcF and did not have a significant effect on HR or cardiac conduction.