Peak Blood Flow Research Articles

Severe aortic stenosis is associated with left atrial prothrombotic flow changes that persists despite successful aortic valve replacement

Abstract Background Severe aortic stenosis (AS) is associated with ischaemic stroke independently of atrial fibrillation (AF) or other causes. Even after aortic valve replacement (AVR), patients remain affected by up to 15% five-year rate of incident ischaemic strokes independently of AVR-related complications and with knowledge gaps in the underlying pathophysiology. Purpose To assess whether severe AS leads to prothrombotic left atrial (LA) flow changes with reduction of LA velocities and vorticity which do not normalise after AVR. Methods Seventy-seven participants without history of AF were recruited in this study: N=40 with severe AS (60% male; age 73 ±10 years, BMI 28 ±5 Kg/m2, median CHA2DS2VASc = 3) and N=37 controls with similar clinical risk profile (51% male; age 71 ±6 years, BMI 28 ±5 Kg/m2, median CHA2DS2VASc = 3). All participants underwent a cardiovascular magnetic resonance (CMR) scan to quantify left ventricular (LV) volumes, mass, and ejection fraction (LVEF), LV global longitudinal strain (GLS) as a sensitive marker of longitudinal dysfunction, LA maximum volume and emptying fraction (LAEF), LA blood flow peak velocity and vorticity by 4-dimensional flow CMR. Out of the 40 patients with severe AS, N=23 (58%) underwent a successful AVR and were followed-up with a repeat CMR scan at approximately 6 months after surgery. Results When compared to matched controls, patients with severe AS displayed significantly higher LV mass, smaller LA and LV volumes (i.e. concentric LV hypertrophy), significantly reduced GLS but higher (more hyperdynamic) LVEF (all p<0.05), as expected. LAEF (i.e. global LA function) was not significantly different from controls but despite this, severe AS was associated with slightly lower LA peak flow velocity (mean 0.25 vs. 0.28 m/sec respectively) and lower LA flow vorticity (mean 16.6 vs. 21.1 radians) compared to controls (both p<0.05). Successful AVR led to complete regression of LV hypertrophy (p<0.05) with LV mass that was no longer different from controls (p>0.05). Nevertheless, post-AVR patients displayed a persistent adverse morpho-functional phenotype characterised by persistently smaller LA and LV volumes, persistently hyperdynamic LV function with reduced GLS (all p<0.05), as well as adverse LA flow changes with significantly lower velocity (mean 0.24 vs 0.28 m/sec, p=0.003) and vorticity when compared to controls (17.1 vs 21.1 radians, p<0.001). Conclusions Patients with severe AS display adverse LA physiology and structure (prothrombotic LA flow characteristics in smaller LA size) and LV changes (smaller size with reduced longitudinal function and hyperdynamic function), which persist after successful AVR despite normalisation of the LV hypertrophy.Figure 1

Efficacy of urokinase in maintaining patency of hemodialysis catheters: Ameta-analysis.

Catheter malfunctions are associated with reduced blood flow and interrupted dialysis during hemodialysis. This meta-analysis aimed to determine whether the use of urokinase to lock hemodialysis catheters can maintain their patency and prevent catheter-related bloodstream infections (CRBSIs). The PubMed, Cochrane Library, Web of Science, Embase, and Chinese medical databases were searched for controlled trials of hemodialysis catheter locking using urokinase from database inception until July 15, 2021. The primary outcome was catheter malfunction, and the secondary outcomes were the peak catheter blood flow rate (Qb) and CRBSIs. Across 16 trials, 1,041 patients were randomized to receive either urokinase/urokinase mixture (treated) or heparin (control) locks once or thrice a week. Locking with urokinase alone or in combination with another substance significantly prevented catheter malfunction. The effect on Qb was significant, with that in the treated group being better than in the control group. Similarly, the incidence of CRBSIs in the treated group was lower. Urokinase locking maintains catheter patency more effectively than heparin. Prophylactic locking with urokinase or urokinase mixtures reduces incidences of catheter malfunction, which ensures the smooth progression of hemodialysis and reduces patient medical costs. The results of this study have important clinical implications and will provide guidance to medical practitioners globally.

The value of blood flow velocity and pressure gradient in differentiating patients with different types of heart failure.

Patients with different types of heart failure (HF) exhibit varying rates of blood flow through cardiac chambers and pressure gradients across the aortic valve, attributed to differing degrees of myocardial contractility. Assessment of these dynamics offers insights into early HF diagnosis. This study aimed to analyze left ventricular outflow tract (LVOT) blood flow parameters, specifically peak blood flow velocity and pressure gradient derived from four-dimensional flow cardiovascular magnetic resonance (4D flow CMR), and to evaluate 4D flow CMR's utility in distinguishing HF types. This prospective cross-sectional study recruited 115 HF patients from January 2019 to May 2022 at the General Hospital of Ningxia Medical University, classified by the New York Heart Association Cardiac Function Classification of Heart Failure as class II-IV, alongside a control group (n=30). Participants underwent cardiovascular magnetic resonance (CMR), including 4D flow. HF patients were categorized into heart failure with reduced ejection fraction (HFrEF, n=55), heart failure with mildly reduced ejection fraction (HFmrEF, n=30), and heart failure with preserved ejection fraction (HFpEF, n=30), based on ejection fraction. The cardiac functional parameters and aortic valve flow indices were measured using Circle Cardiovascular Imaging. LVOT 4D flow data were obtained 3 mm below the junction of the aortic valve leaflets, assessing peak velocities above and below the valve. Differences in cardiac function and blood flow parameters between groups were analyzed using one-way analysis of variance (ANOVA). The accuracy of these parameters in identifying subgroups was assessed using the receiver operating characteristic (ROC) curve. Analysis of conventional cardiac function parameters revealed that left ventricular ejection fraction (LVEF) was significantly lower in the HFrEF and HFmrEF groups compared to the HFpEF and control groups (P<0.01). Additionally, end-diastolic volume and end-systolic volume were significantly higher in the HFrEF and HFmrEF groups than in the HFpEF and control groups (P<0.01). However, there were no significant differences in cardiac function parameters between the HFpEF and control groups (P>0.05). Significant differences were observed in aortic valve peak pressure gradients (Supra-APGmax) among the four study groups (5.01±1.09 vs. 6.23±2.94 vs. 7.63±1.81 vs. 8.89±2.97 mmHg, P<0.05). Aortic valve peak velocities in the HFrEF group differed significantly from the HFpEF and control groups (111.31±12.05 cm/s vs. 137.2±16 vs. 147.15±24.55 cm/s, P<0.001). The ROC curve for the pressure gradient below the aortic valve had an area under the curve (AUC) of 0.728 [95% confidence interval (CI): 0.591-0.864, P=0.002], with an optimal threshold of 4.72 mmHg (sensitivity: 0.8, specificity: 0.7, Youden index: 0.5). HF patients exhibit reduced pressure gradients across the aortic valve during systole, indicative of altered intracardiac blood flow dynamics. Combining aortic valve velocities and pressure gradients can aid in distinguishing different types of HF, including HFpEF patients.

Arterial vascular complications predictive score in extrasystolic arrhythmia "EX-prognosis".

The aim of this study was the creation of an optimal model for predicting arterial vascular complications in patients with extrasystolic arrhythmia. A single-center prospective study was performed with involving 634 patients with supraventricular or ventricular extrasystoles (ES) of 700 or more per 24 hours. The control group consisted of 106 people with ES less than 700 per 24 hours. The main and control groups were initially equivalent in anthropometric criteria and concomitant pathology. The list of examinations included laboratory methods (including lipid profile, coagulograms), as well as instrumental studies (transthoracic and/or transesophageal echocardiography (EchoCG), Doppler ultrasound of the brachiocephalic arteries and arteries of the lower extremities, 24-hours ECG monitoring, according to the indications - computed tomography or magnetic resonance imaging of the brain, coronary angiography, stress echocardiography. Prospective observation of patients performed for 1 year after the initial examination. Combined end points: development of arterial vascular complications - stroke, myocardial infarction, distal arterial embolism of other locations. We studied the data on identified complications. Next, we built models for predicting complications in various ways: Decision Tree; Bootstrap Forest; Boosted Tree; Neural Boosted; Support Vector Machines; Fit Stepwise; Nominal Logistic; Generalized Regression Lasso; Generalized Regression Forward Selection; Generalized Regression Pruned Forward Selection; Generalized Regression Elastic Net; Generalized Regression Ridge. To assess the quality of the models and compare them we used cross-validation with 30 replications. The highest profit values with minimal values of false positive results were obtained for the Bootstrap Forest model. Basing on this model, we created arterial vascular complications predictive score in extrasystolic arrhythmia "EX-prognosis" that included the following parameters: atheroma type III in carotid arteries - 3 points; age 69+ years old - 2 points; ES appearing before transmitral blood flow peak in cardiac cycle 700 and more per 24 hours - 1 point; carotid arteries stenosis, non-significant - 1 point. If total number is 3 and more points, the risk of arterial vascular complications within 1 year is high. We recommend to use the scale "EX-prognosis" in the clinical practice. For a quick assessment of the total risk, it is optimal to implement the risk14.exe program - calculator - developed by us for a personal computer, based on this scale.

Feasibility and effectiveness of a foam rolling intervention in pregnant women requiring bed rest for foetal protection: a randomised controlled trial

BackgroundBed rest during pregnancy can lead to reduced physical activity, impairing lower limb venous blood flow and increasing the risk of deep vein thrombosis (DVT) and muscle atrophy. We investigated the clinical efficacy of foam rolling intervention (FRI) in enhancing lower limb venous blood flow, mitigating the risk of DVT and muscle atrophy in pregnant women on bed rest.MethodsThis single-blind, randomised controlled trial enrolled 86 pregnant women with long-term bed rest for foetal protection (≥ 7 days), gestational age ≥ 20 weeks, and maternal age < 40 years. Participants were randomly assigned to a control or experimental group using a random number table. The control group received standard care, whereas the experimental group underwent FRI. Researchers and statisticians were aware of the treatment groups, however, the participants were blinded. Lower limb blood flow velocity, D-dimer levels, incidence of DVT, and the extent of lower limb muscle atrophy were assessed in both groups at baseline and post-intervention (day 7). To account for a 5% attrition rate and potential sampling error, the estimated sample size for each experimental and control group was 40.ResultsBefore the intervention, no significant differences were observed between the experimental and control groups in peak blood flow, mean flow velocity, D-dimer values, or leg circumference (P > 0.05), however, the peak blood velocities of the popliteal veins were significantly higher in the control group (P = 0.031). On the seventh day post-intervention, the experimental group had significantly higher mean and peak blood velocities in femoral and popliteal veins, significantly (P < 0.05), lower mean D-dimer levels (P = 0.035), and a significantly smaller reduction in thigh and calf circumference (P < 0.001). Consequently, the rate of thigh muscle atrophy was significantly slower in the experimental group (P = 0.011).ConclusionsFRI is an effective intervention for improving lower limb venous blood flow, mitigating the risk of DVT and muscle atrophy in pregnant women on bed rest.Trial registrationThis trial was retrospectively registered with the Chinese Clinical Trial Registry on June 18, 2024 (registration number: ChiCTR2400085770).

Cold Pressor Test Induces Significant Changes in Internal Jugular Vein Flow Dynamics in Healthy Young Adults.

BACKGROUND The cold pressor test (CPT), which has long been used to test autonomic functions by causing sympathetic excitation, increases systolic and diastolic blood pressure and heart rate and causes coronary vasodilation within physiological limits in healthy individuals. This study aimed to evaluate internal jugular vein (IJV) flow parameters using the CPT with systolic and diastolic blood pressure and heart rate in 40 healthy volunteers aged 18-40 years. MATERIAL AND METHODS The volunteers' IJV diameter, blood flow peak velocity, and volumetric flow values were recorded. Then, their right hands were immersed in a bucket of cold water maintained at 1°C up to the wrist level. At the end of the first minute (CPT-1), systolic and diastolic blood pressure, heart rhythm, IJV diameter, peak velocity, and volumetric flow measurements were performed again. RESULTS Systolic and diastolic blood pressure values were significantly higher at CPT-1 compared to baseline values (P<0.001, P<0.001). Heart rate and peak velocity values also showed a significant increase at CPT-1 compared to baseline values (P<0.001, P=0.001). While diameter values showed a significant decrease compared to baseline, volumetric flow rate values showed a significant increase at CPT-1 (P=0.003, P<0.001). CONCLUSIONS Sympathetic nervous system activation triggered by CPT increases IJV volumetric flow and flow velocity in healthy young individuals, and sympathetic nervous system activation causes a venoconstrictive effect in the IJV.

Investigation of Type A Aortic Dissection Using Computational Modelling.

Aortic dissection is a catastrophic failure of the endothelial wall that could lead to malperfusion or rupture. Computational modelling tools may help detect arterial damage. Technological advancements have led to more sophisticated forms of modelling being made available to low-grade computers. These devices can create 3D models with clinical data, where the clinical blood pressure waveforms' model can be used to form boundary conditions for assessing hemodynamic parameters, modelling blood flow propagation along the aorta to predict the development of cardiovascular disease. This study presents patient-specific data for a rare case of severe Type A aortic dissection. CT scan images were taken nine months apart, consisting of the artery both before and after dissection. The results for the pre-dissection CT showed that the pressure waveform at the ascending aorta was higher, and the systolic pressure was lagging at the descending aorta. For the post-dissection analysis, we observed the same outcome; however, the amplitude for the waveform (systolic pressure) at the ascending aorta increased in the false lumen by 25% compared to the true lumen by 3%. Also, the waveform peak (systolic) was leading by 0.01 s. The hemodynamic parameter of wall shear stress (WSS) predicted the aneurysm's existence at the ascending aorta, as well as potential aortic dissection. The high WSS contours were located at the tear location at the peak blood flow of 0.14 s, which shows the potential of this tool for earlier diagnosis of aortic dissection.

Sixweeks of localized passive heat therapy elicits some exercise-like improvements in resistance artery function.

The purpose of this study was to examine the effects of 6weeks of localized, muscle-focused (quadriceps femoris) passive heat therapy (PHT) on resistance artery function, exercise haemodynamics and exercise performance relative to knee extension (KE) exercise training (EX). We randomized 34healthy adults (ages 18-36; n=17 female, 17male) to receive either PHT or sham heating sessions (120min, 3days/week), or EX (40min, 3days/week) over 6weeks. Blood flow was assessed with Doppler ultrasound of the femoral artery during both passive leg movement (PLM) and a KE graded exercise test. Muscle biopsies were taken from the vastus lateralis at baseline and after 6weeks. Peak blood flow during PLM increased to the same extent in both the EX (∼10.5% increase, P=0.009) and PHT groups (∼8.5% increase, P=0.044). Peak flow during knee extension exercise increased in EX (∼19%, P=0.005), but did not change in PHT (P=0.523) and decreased in SHAM (∼7%, P=0.020). Peak vascular conductance during KE increased by ∼25% in EX (P=0.030) and PHT (P=0.012). KE peak power increased in EX by ∼27% (P=0.001) but did not significantly change in PHT and SHAM groups. Expression of endothelial nitric oxide synthase increased significantly in both EX (P=0.028) and PHT (P=0.0095), but only EX resulted in increased angiogenesis. In conclusion, 6weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not yield significant improvements in performance. KEY POINTS: Many for whom exercise would be most beneficial are either unable to exercise or have a very low exercise tolerance. In these cases, an alternative treatment to combat declines in resistance artery function is needed. We tested the hypothesis that passive heat therapy (PHT) would increase resistance artery function, improve exercise haemodynamics and enhance exercise performance compared to a sham treatment, but less than aerobic exercise training. This report shows that 6weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not improve exercise performance. Additionally, muscle biopsy analyses revealed that endothelial nitric oxide synthase expression increased in both PHT and exercise training groups, but only exercise resulted in increased angiogenesis. Our data demonstrate the efficacy of applying passive heat as an alternative treatment to improve resistance artery function for those unable to receive the benefits of regular exercise.

Cerebral Microvascular Density, Permeability of the Blood-Brain Barrier, and Neuroinflammatory Responses Indicate Early Aging Characteristics in a Marfan Syndrome Mouse Model.

Marfan Syndrome (MFS) is a connective tissue disorder due to mutations in fibrillin-1 ( Fbn1 ), where a Fbn1 missense mutation ( Fbn1 C1039G/+ ) can result in systemic increases in the bioavailability and signaling of transforming growth factor-β (TGF-β). In a well-established mouse model of MFS ( Fbn1 C1041G/+ ), pre-mature aging of the aortic wall and the progression of aortic root aneurysm are observed by 6-months-of-age. TGF-β signaling has been implicated in cerebrovascular dysfunction, loss of blood-brain barrier (BBB) integrity, and age-related neuroinflammation. We have reported that pre-mature vascular aging in MFS mice could extend to cerebrovasculature, where peak blood flow velocity in the posterior cerebral artery (PCA) of 6-month-old (6M) MFS mice was reduced, similarly to 12-month-old (12M) control mice. Case studies of MFS patients have documented neurovascular manifestations, including intracranial aneurysms, stroke, arterial tortuosity, as well as headaches and migraines, with reported incidence of pain and chronic fatigue. Despite these significant clinical observations, investigation into cerebrovascular dysfunction and neuropathology in MFS remains limited. Using 6M-control ( C57BL/6 ) and 6M-MFS ( Fbn1 C1041G/+ ) and healthy 12M-control male and female mice, we test the hypothesis that abnormal Fbn1 protein expression is associated with altered cerebral microvascular density, BBB permeability, and neuroinflammation in the PCA-perfused hippocampus, all indicative of a pre-mature aging brain phenotype. Using Glut1 staining, 6M-MFS mice and 12M-CTRL similarly present decreased microvascular density in the dentate gyrus (DG), cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) regions of the hippocampus. 6M-MFS mice exhibit increased BBB permeability in the DG, CA1, and CA3 as evident by Immunoglobulin G (IgG) staining, which was more comparable to 12M-CTRL mice. 6M-MFS mice show a higher number of microglia in the hippocampus compared to age-matched control mice, a pattern resembling that of 12M-CTRL mice. This study represents the first known investigation into neuropathology in a mouse model of MFS and indicates that the pathophysiology underlying MFS leads to a systemic pre-mature aging phenotype. This study is crucial for identifying and understanding MFS-associated neurovascular and neurological abnormalities, underscoring the need for research aimed at improving the quality of life and managing pre-mature aging symptoms in MFS and related connective tissue disorders.

Chronic inflammation with microglia senescence at basal forebrain: impact on cholinergic deficit in Alzheimer's brain haemodynamics.

Cholinergic innervation in the brain is involved in modulating neurovascular function including cerebral blood flow haemodynamics in response to neuronal activity. Cholinergic deficit is associated with pathophysiology in Alzheimer's disease, albeit the aetiology remains to be clarified. In the current study, neocortex cerebral blood flow response to acetylcholine was evaluated by Laser-Doppler Flowmetry (LDF) in 3xTgAD Alzheimer's disease model) and wild-type mice of two age groups. The peak of cerebral blood flow to acetylcholine (i.v.) from baseline levels (% ΔrCBF) was higher in young 3xTgAD versus in wild-type mice (48.35; 95% CI:27.03-69.67 versus 22.70; CI:15.5-29.91, P < 0.05); this was reversed in old 3xTgAD mice (21.44; CI:2.52-40.35 versus 23.25; CI:23.25-39). Choline acetyltransferase protein was reduced in neocortex, while cerebrovascular reactivity to acetylcholine was preserved in young 3×TgAD mice. This suggests endogenous acetylcholine deficit and possible cholinergic denervation from selected cholinergic nuclei within the basal forebrain. The early deposition of tauopathy moieties (mutant hTau and pTau181) and its coincidence in cholinergic cell clusters (occasionaly), were observed at the basal forebrain of 3xTgAD mice including substantia innominate, nucleus Basalis of Meynert and nucleus of horizontal limb diagonal band of Broca. A prominent feature was microglia interacting tauopathy and demonstrated a variety of morphology changes particularly when located in proximity to tauopathy. The microglia ramified phenotype was reduced as evaluated by the ramification index and Fractal analysis. Increased microglia senescence, identified as SASP (senescence-associated secretory phenotype), was colocalization with p16Ink4ɑ, a marker of irreversible cell-cycle arrest in old 3xTgAD versus wild-type mice (P = 0.001). The p16Ink4ɑ was also observed in neuronal cells bearing tauopathy within the basal forebrain of 3xTgAD mice. TNF-ɑ, the pro-inflammatory cytokine elevated persistently in microglia (Pearson's correlation coefficient = 0.62) and the loss of cholinergic cells in vulnerable basal forebrain environment, was indicated by image analysis in 3xTgAD mice, which linked to the cholinergic deficits in neocortex rCBF haemodynamics. Our study revealed the early change of CBF haemodynamics to acetylcholine in 3xTgAD model. As a major effector of brain innate immune activation, microglia SASP with age-related disease progression is indicative of immune cell senescence, which contributes to chronic inflammation and cholinergic deficits at the basal forebrain. Targeting neuroinflammation and senescence may mitigate cholinergic pathophysiology in Alzheimer's disease.

Оценка кровоснабжения миокарда методом допплерографии коронарных артерий после пантовой бальнеотерапии

The purpose of this study was to objectively assess the effectiveness of rehabilitation using balneotherapy with velvet antler products. Materials and methods. Doppler assessment of coronary artery blood flow was performed. As a reference vessel, we chose the anterior descending artery, which is the largest branch of the left coronary artery and has its own numerous branches providing blood supply to the main part of the functionally active left ventricle myocardium. We studied the following groups of patients, whose rehabilitation included balneotherapy with velvet antler products: 1) 48 subjects with stage 2 arterial hypertension and 2) 49 subjects with coronary artery disease after balloon angioplasty and coronary artery stenting. In addition to balneotherapy, group 1 received standard hypotensive therapy with angiotensin-converting-enzyme inhibitors, beta blockers and thiazide diuretics, while group 2 was given indirect anticoagulants, beta blockers and new generation statins. Before and upon completing the treatment course, each patient’s peak blood flow velocity was measured, as well as blood flow integral in the proximal segment of the anterior descending artery. Results. After the balneotherapy course, most patients in both groups showed quiet and increased activation of high reactivity level. According to our observations, patients tolerated the treatment well. Initially, peak blood flow velocity and blood flow integral were recorded within the range of 28–45 cm/s (mean: 36.9 ± 4.4 cm/s) and 9–14 cm (mean: 11.00 ± 1.25 cm), respectively, without between-group differences. After the multimodality treatment that included balneotherapy with velvet antler products, these parameters were recorded within the range of 39–52 cm/s (mean: 45.7 ± 3.5 cm/s) and 11–16 cm (mean: 14.0 ± 1.3 cm), respectively, with no between-group differences either. The increase in peak blood flow velocity was statistically significant (p ˂ 0.001). Thus, balneotherapy using innovative velvet antler products combined with medication treatment and physical therapy, presumably, contributed to improving coronary blood circulation in patients with stable ischemic heart disease and arterial hypertension.

Improved MRI methods to quantify retinal and choroidal blood flow applied to a model of glaucoma.

Blood flow (BF) of the retinal and choroidal vasculatures can be quantitatively imaged using MRI. This study sought to improve methods of data acquisition and analysis for MRI of layer-specific retinal and choroidal BF and then applied this approach to detect reduced ocular BF in a well-established mouse model of glaucoma from both eyes. Quantitative BF magnetic resonance imaging (MRI) was performed on glaucomatous DBA/2J and normal C57BL/6J mice. Arterial spin labeling MRI was applied to image retinal and choroidal BF using custom-made dual eye coils that could image both eyes during the same scan. Statistics using data from a single eye or two eyes were compared. BF values were calculated using two approaches. The BF rate per quantity of tissue was calculated as commonly done, and the peak BF values of the retinal and choroidal vasculatures were taken. Additionally, the BF rate per retinal surface area was calculated using a new analysis approach to attempt to reduce partial volume and variability by integrating BF over the retinal and choroidal depths. Ocular BF of both eyes could be imaged using the dual coil setup without effecting scan time. Intraocular pressure was significantly elevated in DBA/2J mice compared to C57BL/6J mice (P<0.01). Both retinal and choroidal BF were significantly decreased in DBA/2J mice in comparison to the age-matched normal C57BL/6J mice across all measurements (P < 0.01). From simulations, the values from the integrated BF analysis method had less partial volume effect, and from in vivo scans, this analysis approach also improved power. The dual eye coil setup allows bilateral eye data acquisition, increasing the amount of data acquired without increasing acquisition times in vivo. The reduced ocular BF found using the improved acquisition and analysis approaches replicated the results of previous studies on DBA/2J mice. The ocular hypertensive stress-induced BF reduction found within these mice may represent changes associated with glaucomatous progression.

Distinct profiles of cerebral oxygenation in focal vs. secondarily generalized EEG seizures in children undergoing cardiac surgery.

Seizures are common in children undergoing cardiopulmonary bypass (CPB). Cerebral oxygen saturation (ScO2) by near-infrared spectroscopy is routinely monitored in many centers, but the relations between the levels and changes of ScO2 and brain injuries remain incompletely understood. We aimed to analyze the postoperative profiles of ScO2 and cerebral blood flow velocity in different types of EEG seizures in relation to brain injuries on MRI. We monitored continuous EEG and ScO2 in 337 children during the first 48 h after CPB, which were analyzed in 3 h periods. Cerebral blood flow peak systolic velocity (PSV) in the middle cerebral artery was measured daily by transcranial Doppler. Postoperative cerebral MRI was performed before hospital discharge. Based on the occurrence and spreading types of seizures, patients were divided into three groups as patients without seizures (Group N; n = 309), those with focal seizures (Group F; n = 13), or with secondarily generalized seizures (Group G; n = 15). There were no significant differences in the onset time and duration of seizures and incidence of status epilepticus between the two seizures groups (Ps ≥ 0.27). ScO2 increased significantly faster across Group N, Group G, and Group F during the 48 h (p < 0.0001) but its overall levels were not significantly different among the three groups (p = 0.30). PSV was significantly lower (p = 0.003) but increased significantly faster (p = 0.0003) across Group N, Group G, and Group F. Group F had the most severe brain injuries and the highest incidence of white matter injuries on MRI among the three groups (Ps ≤ 0.002). Postoperative cerebral oxygenation showed distinct profiles in secondarily generalized and particularly focal types of EEG seizures in children after CPB. A state of 'overshooting' ScO2 with persistently low PSV was more frequently seen in those with focal seizures and more severe brain injury. Information from this study may have important clinical implications in detecting brain injuries when monitoring cerebral oxygenation in this vulnerable group of children after CPB.

Decreasing the blood flow of non-compressible intra-abdominal organs with non-invasive transcutaneous electrical stimulation

Non-invasive neuromodulation of non-compressible internal organs has significant potential for internal organ bleeding and blood-shift in aero/space medicine. The present study aims to investigate the potential influences of the non-invasive transcutaneous electrical nerve stimulation (TENS) on multiple non-compressible internal organs’ blood flow. Porcine animal model (n = 8) was randomized for a total of 48 neuromodulation sessions with two different TENS stimulation frequencies (80 Hz, 10 Hz) and a placebo stimulation. A combination of two different electrode configurations (Abdominal-only or Abdominal and hind limb) were also performed. Intraarterial blood flow measurements were taken during pre and post-stimulation periods at the left renal artery, common hepatic artery, and left coronary artery. Intracranial, and extracranial arterial blood flows were also assessed with digital subtraction angiography. TENS with abdominal-only electrode configurations at 10 Hz demonstrated significant reductions in average peak blood flow velocity (APV) of the common hepatic artery (p = 0.0233) and renal arteries (p = 0.0493). Arterial pressures (p = 0.0221) were also significantly lower when renal APV was reduced. The outcome of the present study emphasises the potential use of TENS in decreasing the blood flow of non-compressible internal organs when the correct combination of electrodes configuration and frequency is used.

Peripheral Endothelial and Microvascular Function with Repeated Far-infrared Sauna in Adults with Obesity

Obesity can lead to vascular dysfunction and elevated cardiovascular risk. Repeated far-infrared sauna bathing has improved cardiovascular function in cardiac patients. It is unknown if repeated far-infrared sauna bathing improves vascular function in adults with obesity. Purpose: We hypothesized that brachial artery flow-mediated dilation (FMD) and post-occlusion reactive hyperemia would be improved after 30 far-infrared sauna sessions in adults with obesity. Methods: Five adults with obesity (4 men, 1 woman; age: 33 ± 11; BMI: 36.3 ± 4.2 kg/m2) were assigned to a heat therapy (n=3) or time-control group (n=2). The heat therapy group completed 30 sessions of far-infrared sauna bathing (43 ± 4 min at 54 ± 2°C) at 3-4 times/week for 9 weeks. Peripheral vascular function was assessed before (PRE) and after (POST) the intervention. Brachial artery diameter and blood velocity were recorded via Doppler ultrasound for 1 min of baseline, 5 min of forearm occlusion, and 3 min of post-occlusion. FMD was calculated as the percent change from baseline diameter to peak diameter during post-occlusion. Relevant shear rate was calculated as the area under the curve (AUC) to peak dilation. Peak post-occlusion reactive hyperemia was defined as the peak blood flow during post-occlusion. Total post-occlusion reactive hyperemia was calculated as the AUC for blood flow above baseline for 3 min. Results: Baseline diameter did not differ at PRE vs. POST or between Control (3.76 ± 0.08 vs. 3.78 ± 0.09 mm) and Heat (4.25 ± 0.03 vs. 4.25 ± 0.02 mm) (all p &gt; 0.3977). FMD did not differ at PRE vs. POST and between Control (11.2 ± 5.2 vs. 10.6 ± 10.2%) or Heat (2.8 ± 2.4 vs. 6.2 ± 4.2%) (all p &gt; 0.2684). Relevant shear rate AUC did not differ at PRE vs. POST or between Control (27,412 ± 7,506 vs. 31,251 ± 20,608 a.u.) and Heat (16,538 ± 11,617 vs. 24,952 ± 10,639 a.u.) (all p &gt; 0.2577). Peak post-occlusion reactive hyperemia did not differ at PRE vs. POST or between Control (396 ± 42 vs. 387 ± 17 ml/min) and Heat (464 ± 40 vs. 441 ± 32 ml/min) (all p &gt; 0.1049). Total post-occlusion reactive hyperemia AUC was lower in Heat (140 ± 7 ml) vs Control (262 ± 12 ml) at PRE but did not differ across time or between groups at POST for Heat (212 ± 35 ml) vs Control (246 ± 66 ml). Conclusions: These preliminary data suggest there is no effect of 30 sessions of far-infrared sauna bathing on peripheral endothelial and microvascular function in adults with obesity. This may be due to the duration, frequency, and intensity of the far-infrared sauna compared to other passive heating modalities that have generated beneficial vascular adaptations in other studies. AHA 19TPA34890033. 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.

Passive Heat Stress, Like Exercise Training, Leads to Improved Vascular Function

Epidemiological data indicate that repeated heat stress improves cardiovascular health, making passive heat therapy (PHT) a potential alternative for those unable to exercise. Few studies to date have examined the potential exercise mimetic effects in humans, and it is unclear how adaptations compare in magnitude to exercise training. OBJECTIVE: To examine the effects of 6 weeks of localized, muscle-focused PHT on resistance artery vascular function, exercise hemodynamics and performance, molecular regulators of vascular tone, and skeletal muscle capillarization relative to the adaptations observed following high-intensity aerobic exercise training focused on the same muscles. HYPOTHESIS: 6 weeks of PHT, applied to the knee extensor muscles through pulsed shortwave diathermy (2 hr, 3 days/week), would improve both resistance artery function and exercise hemodynamics, as well as increase vascular tone regulators more than a sham treatment, but less than single-leg knee extension (KE) exercise training (EX; 40 min, 3 days/week). Methods: We randomized 34 sedentary but otherwise healthy, young adults (ages 18–36; n = 17 female, 17 male) to receive PHT, EX, or sham heating sessions (SHAM; 2 hr, 3 days/week) over 6 weeks. Vascular function was determined through the blood flow response during both a passive leg movement (PLM) assessment and a knee extension graded exercise test (GXTmax). Muscle biopsies were taken from the vastus lateralis at baseline and after 6 weeks of intervention. Results: Peak blood flow during PLM increased to the same extent in both the EX (~10.5% increase, P=0.009) and PHT groups (~8.5% increase, P=0.044). KE peak flow increased in EX (~19%, P=0.005), but did not change in PHT (P=0.523) and decreased in SHAM (~7%, P=0.020). Peak vascular conductance during KE increased by ~25% in EX (P=0.030) and PHT (P=0.012). KE peak power increased in EX by ~27% (P=0.001) but did not significantly change in PHT (P=0.175) and SHAM groups (P=0.111). EX, but not PHT or SHAM, increased muscle capillary-to-fiber ratio (P = 0.0003), capillary density (P = 0.0428), and the Capillary to Fiber Perimeter Exchange Index (P = 0.0089). Protein expression of endothelial nitric oxide synthase (eNOS) increased significantly in both EX (P=0.0028) and PHT (P=0.0095), but only EX resulted in increased angiogenesis. CONCLUSIONS: 6 weeks of localized PHT, when applied to young healthy individuals, improved resistance artery function at rest and during exercise to the same extent as exercise training. Moreover, our data suggest that these PHT-induced improvements can be primarily attributed to increased expression of the regulators of vascular tone and not neo-angiogenesis. In conclusion, passive heat therapy mimics many, but not all the vascular benefits of exercise training. Funding for this study was provided by the Department of Exercise Sciences at Brigham Young University. 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.

L-Citrulline Supplementation Improves Leg Endothelial Function and Blood Flow Responses to Plantarflexion Exercise in Hypertensive Postmenopausal Women

Menopause and hypertension are associated with macro- and microvascular endothelial dysfunction at rest. Arginine deficiency and low nitric oxide (NO) synthesis may contribute to reduced muscle blood flow (BF) and oxygen delivery to exercising muscles. Improving BF to calf muscles may enhance physical activity. L-Citrulline supplementation (CIT) has improved resting macrovascular endothelial function via increased arginine availability for NO synthesis. Thus, the purpose of this study was to examine the effects of CIT on resting microvascular endothelial function and BF responses to plantarflexion exercise (PFE) in hypertensive postmenopausal women. We hypothesized that CIT would improve microvascular function and BF responses to PFE compared to placebo (PL). Twenty-one hypertensive postmenopausal women were randomized to 4 weeks of CIT (10g/day, n=10) or PL ( n=11). Superficial femoral macro- (flow-mediated dilation; FMD) and microvascular function (5s average peak blood velocity and flow during reperfusion) were assessed by ultrasound at 0 and 4 weeks. Femoral artery BF and vascular conductance (VC) were measured via ultrasound at rest and during 3-minute stages of rhythmic PFE at 5%, 15%, and 30% of 1-repetition maximum (1RM) at 0 and 4 weeks. BF and VC responses to PFE were analyzed as the change from rest to the last minute of each stage. There were no differences between groups in FMD, 5s peak velocity and flow during reperfusion, and vascular responses to PFE at 0 weeks. CIT significantly increased FMD (CIT:Δ1.28 ± 0.42 vs PL:Δ0.01 ± 0.40%, p = 0.04) and 5s peak velocity (CIT:Δ17.44 ± 4.21 vs PL:Δ0.09 ± 4.01 cm/s, p = 0.01) and flow (CIT:Δ220 ± 54 vs PL:Δ35 ± 51 mL/min, p = 0.02) during reperfusion compared to PL. CIT had no effect on BF and VC responses to 5% PFE ( p &gt; 0.05). CIT significantly augmented BF responses to 15% PFE (CIT:Δ82 ± 16 vs PL:Δ22 ± 15 mL/min, p &lt; 0.01) and 30% PFE (CIT:Δ156 ± 33 vs PL:Δ38 ± 32 mL/min, p &lt; 0.01) and VC responses to 15% PFE (CIT:Δ0.80 ± 0.16 vs PL:Δ0.11 ± 0.15 mL*100mmHg/min, p &lt; 0.01) and 30% PFE (CIT:Δ1.49 ± 0.29 vs PL:Δ0.24 ± 0.27 mL*100mmHg/min, p &lt; 0.01) compared to PL. Improvements in FMD were not correlated with BF or VC responses to PFE ( p &gt; 0.05). Improvements in 5s peak velocity were positively correlated with BF responses to 15% PFE ( r = 0.498, p = 0.02) and 30% PFE ( r = 0.532, p = 0.01), and with VC responses to 15% PFE ( r = 0.542, p = 0.01) and 30% PFE ( r = 0.633, p &lt; 0.01). Similarly, augmented 5s flow was positively correlated with BF ( r = 0.461, p = 0.04) and VC ( r = 0.558, p = 0.01) responses to 30% PFE. These findings indicate that CIT improved superficial femoral artery macro- and microvascular endothelial function at rest. However, only improvements in microvascular endothelial function influenced vascular function during leg exercise in hypertensive postmenopausal women. 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.

Combining antibiotic-loaded bone cement-based free vastus lateralis muscle-sparing flap with split-thickness skin grafts: A reliable strategy for reconstructing diabetic foot ulcers at non-weight-bearing areas.

Diabetic foot ulcers (DFUs) present significant challenges due to their associated amputation rates, mortality, treatment complexity and excessive costs. Our earlier work introduced a wound surgical integrated treatment (WSIT) for DFUs, yielding promising outcomes. This study focuses on a specific WSIT protocol employing antibiotic-loaded bone cement (ALBC) in the first Stage, and free vastus lateralis muscle-sparing (VLMS) flaps and split-thickness skin grafts (STSGs) in the second stage to repair non-weight-bearing DFUs. From July 2021 to July 2023, seven DFU patients (aged 47-71 years) underwent this treatment. Demographic data, hospital stay and repair surgery times were collected. Histological and immunohistochemical analyses assessed angiogenesis, collagen deposition and inflammation. SF-36 questionnaire measured pre- and postoperative quality of life. Preoperative ultrasound Doppler showed that the peak blood flow velocity of the recipient area artery was significantly >30 cm/s (38.6 ± 6.8 cm/s) in all patients. Muscle flap sizes varied from 8 × 3.5 × 1 to 18 × 6 × 2 cm. The operation time of the repair surgery was 156.9 ± 15.08 minutes, and the hospital stay was 18.9 ± 3.3 days. Histological analysis proved that covering DFUs with ALBC induced membrane formation and increased collagen, neovascularization and M2 macrophages fraction while reducing M1 macrophages one. All grafts survived without amputation during a 7- to 24-month follow-up, during which SF-36 scores significantly improved. A combination of ALBC with free VLMS flaps and STSGs proved to be safe and effective for reconstructing non-weight-bearing DFUs. It rapidly controlled infection, enhanced life quality and foot function, and reduced hospitalization time. We advocate integrating this strategy into DFU treatment plans.

Effects of Hormonal Contraception and the Menstrual Cycle on Fatigability and Recovery From an Anaerobic Exercise Test.

Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res 38(7): 1256-1265, 2024-This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD ; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg·m -2 ) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p ≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases ( p > 0.05). Although not significant, AP was higher in LHP for OC (Δ -248.2 ± 1,301.4 W) and EUM (Δ -19.5 ± 977.7 W) and higher in HHP for H-IUD (Δ 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (Δ 2.0%) and reduced blood lactate clearance (Δ 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle.

The Improvement in Exercise Performance during Reduced Muscle Mass Exercise is Associated with an Increase in Femoral Blood Flow in Older and Younger Endurance-Trained Athletes.

This study investigated whether the improved performance observed with maximal self-paced single-leg (SL), compared with double-leg (DL) cycling, is associated with enhanced femoral blood flow and/or altered tissue oxygenation. The hyperaemic response to exercise was assessed in younger and older athletes. Power output was measured in 12 older (65 ± 4 y) and 12 younger (35 ± 5 y) endurance-trained individuals performing 2 x 3 min maximal self-paced exercise using SL and DL cycling. Blood flow (BF) in the femoral artery was assessed using Doppler ultrasound and muscle oxygenation was measured using near-infrared spectroscopy on the vastus lateralis. SL cycling elicited a greater power output (295 ± 83 vs 265 ± 70 W, P < 0.001) and peak femoral BF (1749.1 ± 533.3 vs 1329.7 ± 391.7 ml/min, P < 0.001) compared with DL cycling. Older individuals had a lower peak BF in response to exercise (1355.4 ± 385.8 vs 1765.2 ± 559.6 ml/min, P = 0.019) compared with younger individuals. Peak BF in response to exercise was correlated with power output during SL (r = 0.655, P = 0.002) and DL (r = 0.666, P = 0.001) cycling. The greater exercise performance during SL compared with DL cycling may be partly explained by a greater hyperaemic response when reducing active muscle mass. Despite regular endurance training, older athletes had a lower femoral BF in response to maximal self-paced exercise compared with younger athletes.