Frontiers in Physiology

BackgroundThoracic spine mobilization (TSM) has been proposed to influence autonomic nervous system (ANS) activity, yet evidence remains inconsistent and feasibility of standardised protocols is unclear. This study aimed to evaluate whether a randomized TSM protocol can be implemented successfully in healthy participants and to provide preliminary estimates of its effects on heart rate variability (HRV) and heart rate (HR). MethodsA randomized feasibility trial was conducted with healthy young ...

BackgroundOrthostatic intolerance syndromes such as Orthostatic Hypotension (OH) and Postural Orthostatic Tachycardia Syndrome (PoTS) are common symptoms seen in post-infection conditions and other neurological conditions with autonomic dysfunction. The 10-minute National Aeronautics and Space Administration Lean Test (NLT) is an objective clinical test used to assess these symptoms and direct management. There is, however, no robust literature on normative data for this test, particularly from ...

AO_SCPLOWBSTRACTC_SCPLOWThe early phase of acute myocardial ischemia is associated with an elevated risk of ventricular reentrant arrhythmias. Indeed, after partial or total occlusion of a coronary artery, some regions of the heart experience a reduction in myocardial blood flow. This causes metabolic and cellular processes, such as hypoxia, hyperkalemia and acidosis, which lead to changes in the transmembrane ionic dynamics. The effect of such alterations may result in the formation of electric...

ObjectiveAutonomic regulation of organ and tissues may give rise to disruptions of typical functions. The Body Perception Questionnaire Short Form (BPQ-SF) includes items that were developed to assess autonomic symptoms in daily life. This pair of studies aimed to establish previously unexplored psychometric properties of the BPQ-SF, develop normative values for clinical and research use, and validate the self-reports with sensor-based measures. MethodsStudy 1 reports exploratory and confirmato...

ObjectiveTo determine the relationship between electrodermal activity (EDA) and cardiac troponin in patients with paroxysmal sympathetic hyperactivity (PSH). MethodsThis was a study with prospectively-identified patients and a retrospective analysis utilizing electrodermal data taken from the wrist-worn Empatica E4 device (Empatica Srl, Milan, Italy) and troponin values obtained from critically-ill patients with suspected PSH (N=10). The maximum EDA value and temporally-nearest cardiac troponin...

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSAimsC_ST_ABSWe aim to develop a patient-specific computational model to predict the risk of Ventricular Tachycardia (VT) in patients with Biventricular Cardiac Resynchronization Therapy (BiV-CRT) device. Patients are indeed at risk of developing arrhythmias due to BiV-CRT pacing, a known potential complication that puts the cardiologist on guard against its prevention. Materials and MethodsWe consider three non-ischemic fibrotic patients. Patient-specific left ve...

BackgroundVasovagal syncope (VVS) is the most common form of syncope, accounting for 50-60% of unexplained syncope. Currently diagnosis is achieved via clinical assessment combined with the Head-Up Tilt Test (HUT). AimTo examine the utility of the active stand test (AS) to identify those with a positive HUT or diagnosis of VVS. DesignRetrospective study of hemodynamic responses to AS. MethodsContinuous blood pressure responses to AS from 101 patients attending a Falls and Blackouts Unit were ...

ObjectivesTo assess 1) differences in the hemodynamic response to the active stand test in older adults with a clinical diagnosis of vasovagal syncope compared to age-matched controls 2) if the active stand test combined with machine learning approaches can be used to identify the presence of vasovagal syncope in older adults. ApproachAdults aged 50 and over (Vasovagal Syncope N=46 Age=66.9{+/-}10.3; Control N=86 Age=65.3{+/-}9.5) completed an active stand test. Multiple features were extracted...

BackgroundWidened QRS complex confers worse prognosis in both pacing and premature ventricular contraction (PVC), and may predispose to heart failure. In healthy adult patients, cardiac fiber orientation is highly variable. While traversing the myocardial wall from epicardium to endocardium, helix angles are known to range between -90{degrees} and 90{degrees}. It is currently not well understood how the location of ectopy and variable epicardial and endocardial helix angle configurations interac...

BackgroundSpinal cord injury (SCI) above the sixth thoracic spinal cord segment can disrupt autonomic cardiovascular control, leading to increased BP variability (BPV). This study compared BPV, nocturnal dipping patterns, and blood pressure (BP) fluctuations among individuals with cervical SCI (C-SCI), upper-thoracic SCI (UT-SCI), and non-injured controls (NI-C). MethodsUsing 24-hour ambulatory blood pressure monitoring, we analyzed BPV (via standard deviation [SD], coefficient of variation [Co...

Postural orthostatic tachycardia syndrome (POTS) is characterized by an abnormal increase in heart rate upon standing, leading to symptoms such as dizziness, fatigue, and rapid heart rate. Time-restricted eating (TRE), which limits caloric intake to an 8-10 hour daily window, has been shown to decrease inflammation and improve immune, autonomic, and mitochondrial function, as well as cardiometabolic parameters. This single arm pilot study evaluated the effects of TRE on quality of life (QOL), he...

ObjectiveThe Physiology Simulation Coupled Experiment (PSCOPE) is a hybrid modeling framework designed for mechanistic cardiovascular predictive modeling. It couples a physical fluid experiment with a lumped parameter network simulation to replicate the closed-loop feedback between simulated cardiovascular physiology and fluid dynamics in the physical experiment. This study validates PSCOPEs predictions of post-surgical physiology against clinical data in the context of HeartMate 3 left ventricu...

Cardiotoxicity continues to be a major health issue worldwide due to the imperative need to access new or repurposed drugs that are safe and effective. Accessibility to affordable drugs is also key to ensure access to drugs to all patients who require them. In this work we propose a workflow for an in-silico clinical trial at the 3D biventricular human population level, to assess cardiac pro-arrhythmic risk after administration of a single or a combination of potentially cardiotoxic drugs. The ...

Conventional echocardiographic parameters of right ventricular (RV) function are heavily afterload-dependent. Therefore, the incorporation of the RV pressure curve may enable the formulation of new parameters that reflect intrinsic RV function more accurately. Accordingly, we sought to develop an artificial intelligence-based method that can reconstruct the RV pressure curve based on the peak RV pressure. We invasively acquired RV pressure in 29 heart failure patients before and after the impla...

Slow breathing exercises are a key component to many mind-body practices used for stress reduction and modulation of autonomic tone, and it has been shown to reduce blood pressure acutely. Long-term effects on blood pressure and autonomic tone are not well documented. We studied 95 healthy participants (41{+/-}4 years, 76% female) who performed slow breathing exercises for 12 weeks and examined the effect of slow breathing on systolic blood pressure, diastolic blood pressure, and autonomic tone....

ObjectiveTo analyze the hemodynamic response, cerebral blood flow, and the sympathovagal balance between patients with structurally healthy hearts who have a history of syncope and presyncope that exhibited signs or symptoms of presyncope without progressing to syncope during the tilt-table test, and a healthy group. MethodologyA retrospective study was conducted on patients attending the dysautonomia clinic of a tertiary care center. Individuals of both sexes aged 15 to 50 years were included....

BackgroundPhotoplethysmography (PPG) sensors, typically found in wrist-worn devices, can continuously monitor heart rate (HR) in large populations in real-world settings. Resting heart rate (RHR) is an important biomarker of morbidities and mortality, but no universally accepted definition nor measurement criteria exist. In this study, we provide a working definition of RHR and describe a method for accurate measurement of this biomarker, recorded using PPG derived from wristband measurement acr...

BackgroundRepolarization alternans, defined as period-2 oscillation in the repolarization phase of the action potentials, provides a mechanistic link between cellular dynamics and ventricular fibrillation (VF). Theoretically, higher-order periodicities (e.g., periods 4, 6, 8,...) are expected but have minimal experimental evidence. MethodsWe studied explanted human hearts obtained from recipients of heart transplantation at the time of surgery. Optical mapping of the transmembrane potential was...

Autonomic nervous system (ANS) activity causes acute variations in the blood pressure. Blood pressure responds to high intensity interval exercise (HIIE) repeatedly during alternating intensities, however, ANS response to the changing intensities of HIIE is unknown. We characterized the response of beat-to-beat blood pressure variability (BTB BPV) to an acute bout of HIIE using coefficient of variation (CoV) and spectral low frequency [LF], and high frequency [HF] domains. Our hypotheses were me...

BackgroundPulmonary vein isolation (PVI) is key to atrial fibrillation (AF) ablation, but arrhythmia often recurs due to conduction gaps permitting pulmonary vein (PV) reconnection. Currently, gap identification requires invasive remapping. We evaluated whether deep learning applied to surface electrocardiograms (ECGs) could (i) detect the electrophysiologic signature of PVI and (ii) predict PV reconnection at redo ablation. MethodsWe retrospectively studied 176 patients (2012-2023) who had ini...