Hemodynamic Function Research Articles

Early Continuous Renal Replacement Therapy In Patients With St-Elevation Myocardial Infarction And Covid-19 After Percutaneous Coronary Intervention: A Case Report

Background: Currently, there is no standardized approach to managing critically ill COVID-19 patients with acute kidney injury and ST-elevation myocardial infarction. Continuous renal replacement therapy is a routinely used technique in managing critical patients in the intensive care unit. This procedure is applicable in patients with unstable hemodynamic, renal, or non-renal indications, such as removing the excess urea and creatinine from patients with acute kidney injury or clearing the tumor necrosis factor from patients with systemic inflammations.
 Method: This was a retrospective case report, after analysis of patient clinical data. The patient provided written informed consent to publish their case details and any accompanying images. The study protocol complies with the requirements of the institute’s committee of Haji Adam Malik Hospital, Medan, Indonesia.
 Results: This report presents a case of ST-Elevation myocardial infarction with COVID-19 infection and acute kidney injury who successfully managed by percutaneous coronary intervention and continuous renal replacement therapy. This patient was prepared for percutaneous coronary intervention and intubated with consideration of strict infection control. To improve the outcomes, we performed continuous renal replacement therapy with continuous venovenous hemodiafiltration mode. The patient improved with a stable hemodynamic and better renal function after 24 hours of continuous renal replacement therapy.
 Conclusion: Early continuous renal replacement therapy might be beneficial in treating COVID-19 patients with AKI, who previously underwent percutaneous coronary intervention for ST-elevation myocardial infarction.

Intranasal (2R, 6R)-hydroxynorketamine for acute pain: Behavioural and neurophysiological safety analysis in mice.

Ketamine is known for its antinociceptive effect and is also used for treatment-resistant depression. However, the efficacy and safety of (2R, 6R)-hydroxynorketamine (HNK), a ketamine metabolite has been sparingly investigated for acute pain management. The current study aims at investigating the antinociceptive effect of intranasal (2R, 6R)-HNK using pre-clinical models of acute pain. Additionally, the behavioural and neurophysiological safety analyses were carried out for the effective time window. Antinociceptive efficacy of (2R, 6R)-HNK was evaluated using the hot plate test and Hargreaves' plantar test. The formalin test was carried out in both the acute and tonic phases. The neurophysiological and behavioural safety analyses were carried out separately for the haemodynamic function, cortical electroencephalography (EEG), and spontaneous behavioural functions. Analgesic effect of (2R, 6R)-HNK was evident by a significant increase in paw-withdrawal latency in both Hargreaves' and hot plate tests. Additionally, the (2R, 6R)-HNK showed a significant ameliorative effect on pain-related behaviour in the second phase of the formalin test. (2R, 6R)-HNK exhibited an anxiolytic effect without causing any significant changes in locomotor activity and haemodynamic parameters. Power spectral density (PSD) analysis of electroencephalogram revealed no significant changes except a comparative increase in the gamma band range. Both the locomotor functions in the open field test and the PSD value of delta wave indicated no sedative effect at the given dose of (2R, 6R)-HNK. The results demonstrated the pain-alleviating effect of (2R, 6R)-HNK without compromising the neurophysiological and behavioural function. Therefore, intranasal (2R, 6R)-HNK is suggested as a safe candidate for further clinical study in the management of acute pain.

Improving the accuracy of single-trial fMRI response estimates using GLMsingle.

Advances in artificial intelligence have inspired a paradigm shift in human neuroscience, yielding large-scale functional magnetic resonance imaging (fMRI) datasets that provide high-resolution brain responses to thousands of naturalistic visual stimuli. Because such experiments necessarily involve brief stimulus durations and few repetitions of each stimulus, achieving sufficient signal-to-noise ratio can be a major challenge. We address this challenge by introducing GLMsingle, a scalable, user-friendly toolbox available in MATLAB and Python that enables accurate estimation of single-trial fMRI responses (glmsingle.org). Requiring only fMRI time-series data and a design matrix as inputs, GLMsingle integrates three techniques for improving the accuracy of trial-wise general linear model (GLM) beta estimates. First, for each voxel, a custom hemodynamic response function (HRF) is identified from a library of candidate functions. Second, cross-validation is used to derive a set of noise regressors from voxels unrelated to the experiment. Third, to improve the stability of beta estimates for closely spaced trials, betas are regularized on a voxel-wise basis using ridge regression. Applying GLMsingle to the Natural Scenes Dataset and BOLD5000, we find that GLMsingle substantially improves the reliability of beta estimates across visually-responsive cortex in all subjects. Comparable improvements in reliability are also observed in a smaller-scale auditory dataset from the StudyForrest experiment. These improvements translate into tangible benefits for higher-level analyses relevant to systems and cognitive neuroscience. We demonstrate that GLMsingle: (i) helps decorrelate response estimates between trials nearby in time; (ii) enhances representational similarity between subjects within and across datasets; and (iii) boosts one-versus-many decoding of visual stimuli. GLMsingle is a publicly available tool that can significantly improve the quality of past, present, and future neuroimaging datasets sampling brain activity across many experimental conditions.

Steroid treatment as anti-inflammatory and neuroprotective agent following out-of-hospital cardiac arrest: a randomized clinical trial

BackgroundPatients resuscitated from out-of-hospital cardiac arrest (OHCA) have a high morbidity and mortality risk and often develop post-cardiac arrest syndrome (PCAS) involving systemic inflammation. The severity of the inflammatory response is associated with adverse outcome, with anoxic irreversible brain injury as the leading cause of death following resuscitated OHCA. The study aimed to investigate the anti-inflammatory and neuroprotective effect of pre-hospital administration of a high-dose glucocorticoid following OHCA.MethodsThe study is an investigator-initiated, randomized, multicenter, single-blinded, placebo-controlled, clinical trial. Inclusion will continue until one hundred twenty unconscious OHCA patients surviving a minimum of 72 h are randomized. Intervention is a 1:1 randomization to an infusion of methylprednisolone 250 mg following a minimum of 5 min of sustained return of spontaneous circulation in the pre-hospital setting. Methylprednisolone will be given as a bolus infusion of 1 × 250 mg (1 × 4 mL) over a period of 5 min. Patients allocated to placebo will receive 4 mL of isotonic saline (NaCl 0.9%). Main eligibility criteria are OHCA of presumed cardiac cause, age ≥ 18 years, Glasgow Coma Scale ≤ 8, and sustained ROSC for at least 5 min. Co-primary endpoint: Reduction of interleukin-6 and neuron-specific-enolase. Secondary endpoints: Markers of inflammation, brain, cardiac, kidney and liver damage, hemodynamic and hemostatic function, safety, neurological function at follow-up, and mortality. A research biobank is set up with blood samples taken daily during the first 72 h from hospitalization to evaluate primary and secondary endpoints.DiscussionWe hypothesize that early anti-inflammatory steroid treatment in the pre-hospital setting can mitigate the progression of PCAS following resuscitated OHCA. Primary endpoints will be assessed through analyses of biomarkers for inflammation and neurological damage taken during the first 72 h of admission.Trial registrationEudraCT number: 2020-000855-11; submitted March 30, 2020ClinicalTrials.gov Identifier: NCT04624776; submitted October 12, 2020, first posted November 10, 2020

Physiological Assessment of Muscle, Heart, and Whole Body Function in the Canine Model of Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by dystrophin deficiency. Patients gradually lose motor function, become wheelchair-bound, and die from respiratory and/or cardiac muscle failure. Dystrophin-null dogs have been used as a large animal model for DMD since 1988 and are considered an excellent bridge between rodent models and human patients. While numerous protocols have been published for studying muscle and heart physiology in mice, few such protocols exist for studying skeletal muscle contractility, heart function, and whole-body activity in dogs. Over the last 20 years, we have developed and adapted an array of assays to evaluate whole-body movement, gait, single muscle force, whole limb torque, cardiac electrophysiology, and hemodynamic function in normal and dystrophic dogs. In this chapter, we present detailed working protocols for these assays and lessons we learned during the development and use of these protocols.

Modulation of Mitochondrial Bioenergetics by Polydopamine Nanoparticles in Human iPSC-Derived Cardiomyocytes.

Myocardial infarction (MI) leads to the formation of an akinetic scar on the heart muscle causing impairment in cardiac contractility and conductance, leading to cardiac remodeling and heart failure (HF). The current pharmacological approaches for attenuating MI are limited and often come with long-term adverse effects. Therefore, there is an urgent need to develop novel multimodal therapeutics capable of modulating cardiac activity without causing any major adverse effects. In the current study, we have demonstrated the applicability of polydopamine nanoparticles (PDA-NPs) as a bioactive agent that can enhance the contractility and beat propagation of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Treatment of hiPSC-CMs with PDA-NPs demonstrated accumulation of the latter into mitochondria and significantly enhanced time-dependent adenosine triphosphate (ATP) production in these cells, indicating improved mitochondrial bioenergetics. Furthermore, the effect of PDA-NPs on hiPSC-CM activity was evaluated by measuring calcium transients. Treatment with PDA-NPs increased the calcium cycling in hiPSC-CMs in a temporal manner. Our results demonstrated a significant reduction in peak amplitude, transient duration, time to peak, and transient decay time in the PDA-NPs-treated hiPSC-CMs as compared to untreated hiPSC-CMs. Additionally, treatment of isolated perfused rat heart ex vivo with PDA-NPs demonstrated cardiotonic effects on the heart and significantly improved the hemodynamic function, suggesting its potential for enhancing whole heart contractility. Lastly, the gene expression analysis data revealed that PDA-NPs significantly upregulated cardiac-specific genes (ACADM, MYL2, MYC, HCN1, MYL7, GJA5, and PDHA1) demonstrating the ability to modulate genetic expression of cardiomyocytes. Taken together, these findings suggest PDA-NPs capability as a versatile nanomaterial with potential uses in next-generation cardiovascular applications.

Deconvolution of the Functional Ultrasound Response in the Mouse Visual Pathway Using Block-Term Decomposition

Functional ultrasound (fUS) indirectly measures brain activity by detecting changes in cerebral blood volume following neural activation. Conventional approaches model such functional neuroimaging data as the convolution between an impulse response, known as the hemodynamic response function (HRF), and a binarized representation of the input signal based on the stimulus onsets, the so-called experimental paradigm (EP). However, the EP may not characterize the whole complexity of the activity-inducing signals that evoke the hemodynamic changes. Furthermore, the HRF is known to vary across brain areas and stimuli. To achieve an adaptable framework that can capture such dynamics of the brain function, we model the multivariate fUS time-series as convolutive mixtures and apply block-term decomposition on a set of lagged fUS autocorrelation matrices, revealing both the region-specific HRFs and the source signals that induce the hemodynamic responses. We test our approach on two mouse-based fUS experiments. In the first experiment, we present a single type of visual stimulus to the mouse, and deconvolve the fUS signal measured within the mouse brain’s lateral geniculate nucleus, superior colliculus and visual cortex. We show that the proposed method is able to recover back the time instants at which the stimulus was displayed, and we validate the estimated region-specific HRFs based on prior studies. In the second experiment, we alter the location of the visual stimulus displayed to the mouse, and aim at differentiating the various stimulus locations over time by identifying them as separate sources.

Retinal functional ultrasound imaging (rfUS) for assessing neurovascular alterations: a pilot study on a rat model of dementia

Fifty million people worldwide are affected by dementia, a heterogeneous neurodegenerative condition encompassing diseases such as Alzheimer’s, vascular dementia, and Parkinson’s. For them, cognitive decline is often the first marker of the pathology after irreversible brain damage has already occurred. Researchers now believe that structural and functional alterations of the brain vasculature could be early precursors of the diseases and are looking at how functional imaging could provide an early diagnosis years before irreversible clinical symptoms. In this preclinical pilot study, we proposed using functional ultrasound (fUS) on the retina to assess neurovascular alterations non-invasively, bypassing the skull limitation. We demonstrated for the first time the use of functional ultrasound in the retina and applied it to characterize the retinal hemodynamic response function in vivo in rats following a visual stimulus. We then demonstrated that retinal fUS could measure robust neurovascular coupling alterations between wild-type rats and TgF344-AD rat models of Alzheimer’s disease. We observed an average relative increase in blood volume of 21% in the WT versus 37% for the TG group (p = 0.019). As a portable, non-invasive and inexpensive technique, rfUS is a promising functional screening tool in clinics for dementia years before symptoms.

Generalized models for quantifying laterality using functional transcranial Doppler ultrasound.

We consider how analysis of brain lateralization using functional transcranial Doppler ultrasound (fTCD) data can be brought in line with modern statistical methods typically used in functional magnetic resonance imaging (fMRI). Conventionally, a laterality index is computed in fTCD from the difference between the averages of each hemisphere's signal within a period of interest (POI) over a series of trials. We demonstrate use of generalized linear models (GLMs) and generalized additive models (GAM) to analyze data from individual participants in three published studies (N=154, 73 and 31), and compare this with results from the conventional POI averaging approach, and with laterality assessed using fMRI (N=31). The GLM approach was based on classic fMRI analysis that includes a hemodynamic response function as a predictor; the GAM approach estimated the response function from the data, including a term for time relative to epoch start (simple GAM), plus a categorical index corresponding to individual epochs (complex GAM). Individual estimates of the fTCD laterality index are similar across all methods, but error of measurement is lowest using complex GAM. Reliable identification of cases of bilateral language appears to be more accurate with complex GAM. We also show that the GAM-based approach can be used to efficiently analyze more complex designs that incorporate interactions between tasks.

Abstract 10589: Effects Of 3-Hydroxybutyrate on Cardiac and Mitochondrial Function During Heart Transplantation

Introduction: Cardiac transplantation following circulatory death (DCD) and normothermic regional perfusion (NRP) is a new strategy that allows assessment of cardiac function and therapeutical interventions before cardiac transplantation. Sodium-3-hydroxybutyric acid (3-OHB) increases cardiac output by 40% in heart failure patients and diminishes ischemia and reperfusion (IR) injury, presumably by improving mitochondrial energy metabolism. Hypothesis: We hypothesize that infusion with 3-OHB during NRP improves cardiac hemodynamic function after NRP and mitochondrial function after cardiac transplantation. Methods: Pigs ~80 kg underwent a 15-minute anoxic cardiac arrest followed by NRP on a heart-lung cardiac bypass machine. During NRP pigs received 3-OHB or Ringer Acetate infusion. We measured hemodynamic function invasively using pressure-volume catheters and mitochondrial function by high resolution respirometry. Results: Infusion with 3-OHB (360mg/kg/h) increased plasma levels of 3-OHB from 0.05±0.06mM to 3.95±1.13mM (P=0.006) following NRP. 3-OHB increased cardiac output by 5.18±0.97 L min -1 (P<0.0001) driven by a 60% reduction in afterload (3-OHB vs. control: 1.4±0.2 vs. 2.2±0.7 mmHg*mL -1 , P=0.02) and an increase in stroke volume of 36±11mL (P=0.006). Following transplantation and 3-OHB infusion, maximally coupled mitochondrial respiration returned to baseline levels corresponding to a 50% improvement compared with control (3-OHB vs. control: 135±25 vs. 78±26 ρmol O 2 *s -1 mg -1 , P=0.0008). The increment was associated with uncoupling of the inner mitochondrial membrane (3-OHB vs. control: 122±19 vs. 70±34 ρmol O 2 *s -1 mg -1 , P=0.018). Transplantation caused a shift in mitochondrial substrate efficiency measured as the respiratory control ratio, favoring 3-OHB over glucose linked substrates (3-OHB vs. glucose: 22±12 vs. 8±4, p=0.0008). Conclusions: Infusion with 3-OHB improved cardiac hemodynamic recovery following NRP. The improvement was driven predominantly by afterload reduction and was associated with an improvement in mitochondrial respiratory capacity.

Multispectral intraoperative imaging for the detection of the hemodynamic response to interictal epileptiform discharges.

Interictal epileptiform discharges (IEDs) are brief neuronal discharges occurring between seizures in patients with epilepsy. The characterization of the hemodynamic response function (HRF) specific to IEDs could increase the accuracy of other functional imaging techniques to localize epileptiform activity, including functional near-infrared spectroscopy and functional magnetic resonance imaging. This study evaluated the possibility of using an intraoperative multispectral imaging system combined with electrocorticography (ECoG) to measure the average HRF associated with IEDs in eight patients. Inter-patient variability of the HRF is illustrated in terms of oxygenated hemoglobin peak latency, oxygenated hemoglobin increase/decrease following IEDs, and signal-to-noise ratio. A sub-region was identified using an unsupervised clustering algorithm in three patients that corresponded to the most active area identified by ECoG.

Pre- and post-surgery brain tumor multimodal magnetic resonance imaging data optimized for large scale computational modelling

We present a dataset of magnetic resonance imaging (MRI) data (T1, diffusion, BOLD) acquired in 25 brain tumor patients before the tumor resection surgery, and six months after the surgery, together with the tumor masks, and in 11 controls (recruited among the patients’ caregivers). The dataset also contains behavioral and emotional scores obtained with standardized questionnaires. To simulate personalized computational models of the brain, we also provide structural connectivity matrices, necessary to perform whole-brain modelling with tools such as The Virtual Brain. In addition, we provide blood-oxygen-level-dependent imaging time series averaged across regions of interest for comparison with simulation results. An average resting state hemodynamic response function for each region of interest, as well as shape maps for each voxel, are also contributed.

Impact of acute and chronic regular exercise on arterial stiffness and reflection measures in coronary artery disease patients: A Protocol for Randomized Clinical Trial

Vascular stiffness due to arteriosclerosis reduces arterial elasticity which is as an independent and non-invasive predictor of future incidence of coronary heart disease and stroke. There is limited evidence of the benefits of regular exercise on arterial stiffness in populations suffering from cardiovascular diseases (CVD) especially coronary artery disease (CAD).Aim. To determine the acute and chronic effects of aerobic, resistance and combined exercise on arterial and hemodynamic function in patients with CAD.Material and methods. This study will be a prospective, single-blind, randomized study examining the effects of exercise on arterial stiffness. The study will be conducted at a tertiary care hospital for a continuous period of one year. Patients with CAD (n=105) will be selected using systematic sampling techniques and allocated randomly to one of the four treatment groups using computer-generated, random number sequence for age, sex and health status of CAD (Group-I: aerobic exercise, Group-II: resistance exercise, Group-III: combined aerobic and resistance exercise, and Group-IV: control) as per the inclusion and exclusion criteria. All recruited subjects will be informed about the assessment and intervention procedure before getting the consent form filled. This project followed the guidelines of standard protocol for randomized clinical trials (spirit).Perspective. It is expected that this study protocol shall through light and be helpful in better quality of life along with decline in drug dependency for the people suffering from CAD. Further this study will be valuable is designing exercise protocol for the people suffering from CAD.

How much do time-domain functional near-infrared spectroscopy (fNIRS) moments improve estimation of brain activity over traditional fNIRS?

.SignificanceAdvances in electronics have allowed the recent development of compact, high channel count time domain functional near-infrared spectroscopy (TD-fNIRS) systems. Temporal moment analysis has been proposed for increased brain sensitivity due to the depth selectivity of higher order temporal moments. We propose a general linear model (GLM) incorporating TD moment data and auxiliary physiological measurements, such as short separation channels, to improve the recovery of the HRF.AimsWe compare the performance of previously reported multi-distance TD moment techniques to commonly used techniques for continuous wave (CW) fNIRS hemodynamic response function (HRF) recovery, namely block averaging and CW GLM. Additionally, we compare the multi-distance TD moment technique to TD moment GLM.ApproachWe augmented resting TD-fNIRS moment data (six subjects) with known synthetic HRFs. We then employed block averaging and GLM techniques with “short-separation regression” designed both for CW and TD to recover the HRFs. We calculated the root mean square error (RMSE) and the correlation of the recovered HRF to the ground truth. We compared the performance of equivalent CW and TD techniques with paired t-tests.ResultsWe found that, on average, TD moment HRF recovery improves correlations by 98% and 48% for HbO and HbR respectively, over CW GLM. The improvement on the correlation for TD GLM over TD moment is 12% (HbO) and 27% (HbR). RMSE decreases 56% and 52% (HbO and HbR) for TD moment compared to CW GLM. We found no statistically significant improvement in the RMSE for TD GLM compared to TD moment.ConclusionsProperly covariance-scaled TD moment techniques outperform their CW equivalents in both RMSE and correlation in the recovery of the synthetic HRFs. Furthermore, our proposed TD GLM based on moments outperforms regular TD moment analysis, while allowing the incorporation of auxiliary measurements of the confounding physiological signals from the scalp.

Reconstruction of time-shifted hemodynamic response

Regression of voxel time course onto expected response is a standard procedure in functional magnetic resonance imaging that relies on exact onset time and shape of superimposed hemodynamic response functions. Elegant capture of time deviation by time derivative regressors appears complicated by shape distortion and limited to ±1 s, and is usually not exploited for reconstructing the true time-shifted response function together with its magnitude. This analysis of the time-derivative approach provides closed-form functional relations between time shift and regression coefficients that allow for hemodynamic shifts of ±5 s and can explain shape distortion and reconstruction behavior. Reliable absolute latencies were no smaller than 0.6 s in a best-case experiment. Confusions of latency are a previously undiscussed shortcoming where current limitation strategy may eliminate correct latencies and protect incorrect ones.

Longitudinal Resting-State Functional Magnetic Resonance Imaging Study: A Seed-Based Connectivity Biomarker in Patients with Ischemic and Intracerebral Hemorrhage Stroke.

Objective: The primary aim of the research was to compare the impact of postischemic and hemorrhagic stroke on brain connectivity and recovery using resting-state functional magnetic resonance imaging. Methods and Procedures: We serially imaged 20 stroke patients, 10 with ischemic stroke (IS) and 10 with intracerebral hemorrhage (ICH), at 1, 3, and 12 months (1M, 3M, and 12M) after ictus. Data from 10 healthy volunteers were obtained from a publically available imaging data set. All functional and structural images underwent standard processing for brain extraction, realignment, serial registration, unwrapping, and denoising using SPM12. A seed-based group analysis using CONN software was used to evaluate the default mode network and the sensorimotor network connections by applying bivariate correlation and hemodynamic response function weighting. Results: In comparison with healthy controls, both IS and ICH exhibited disrupted interactions (decreased connectivity) between these two networks at 1M. Interactions then increased by 12M in each group. Temporally, each group exhibited a minimal increase in connectivity at 3M compared with 12M. Overall, the ICH patients exhibited a greater magnitude of connectivity disruption compared with IS patients, despite a significant intrasubject reduction in hematoma volume. We did not observe any significant correlation between change in connectivity and recovery as measured on the National Institutes of Health Stroke Scale (NIHSS) at any time point. Conclusions: These findings demonstrate that the largest changes in functional connectivity occur earlier (3M) rather than later (12M) and show subtle differences between IS and ICH during recovery and should be explored further in larger samples.

The SOCE Machinery: An Unbalanced Knowledge between Left and Right Ventricular Pathophysiology.

Right ventricular failure (RVF) is the most important prognostic factor for morbidity and mortality in pulmonary arterial hypertension (PAH) or pulmonary hypertension (PH) caused by left heart diseases. However, right ventricle (RV) remodeling is understudied and not targeted by specific therapies. This can be partly explained by the lack of basic knowledge of RV remodeling. Since the physiology and hemodynamic function of the RV differ from those of the left ventricle (LV), the mechanisms of LV dysfunction cannot be generalized to that of the RV, albeit a knowledge of these being helpful to understanding RV remodeling and dysfunction. Store-operated Ca2+ entry (SOCE) has recently emerged to participate in the LV cardiomyocyte Ca2+ homeostasis and as a critical player in Ca2+ mishandling in a pathological context. In this paper, we highlight the current knowledge on the SOCE contribution to the LV and RV dysfunctions, as SOCE molecules are present in both compartments. he relative lack of studies on RV dysfunction indicates the necessity of further investigations, a significant challenge over the coming years.

Characterization of the blood oxygen level dependent hemodynamic response function in human subcortical regions with high spatiotemporal resolution.

Subcortical brain regions are absolutely essential for normal human function. These phylogenetically early brain regions play critical roles in human behaviors such as the orientation of attention, arousal, and the modulation of sensory signals to cerebral cortex. Despite the critical health importance of subcortical brain regions, there has been a dearth of research on their neurovascular responses. Blood oxygen level dependent (BOLD) functional MRI (fMRI) experiments can help fill this gap in our understanding. The BOLD hemodynamic response function (HRF) evoked by brief (<4 s) neural activation is crucial for the interpretation of fMRI results because linear analysis between neural activity and the BOLD response relies on the HRF. Moreover, the HRF is a consequence of underlying local blood flow and oxygen metabolism, so characterization of the HRF enables understanding of neurovascular and neurometabolic coupling. We measured the subcortical HRF at 9.4T and 3T with high spatiotemporal resolution using protocols that enabled reliable delineation of HRFs in individual subjects. These results were compared with the HRF in visual cortex. The HRF was faster in subcortical regions than cortical regions at both field strengths. There was no significant undershoot in subcortical areas while there was a significant post-stimulus undershoot that was tightly coupled with its peak amplitude in cortex. The different BOLD temporal dynamics indicate different vascular dynamics and neurometabolic responses between cortex and subcortical nuclei.

Cardiovascular Function in Different Phases of the Menstrual Cycle in Healthy Women of Reproductive Age.

Background: Sex hormones influence the cardiovascular (CV) function in women. However, it is uncertain whether their physiological variation related to the regular menstrual cycle affects the CV system. We studied changes in the hemodynamic profile and body’s water content and their relation to sex hormone concentration in healthy women during the menstrual cycle. Material and methods: Forty-five adult women were examined during the early follicular, late follicular, and mid-luteal phases of the same menstrual cycle. The hemodynamic profile was estimated non-invasively by cardiac impedance while water content was estimated by total body impedance. Results were compared with repeated measures ANOVA with post-test, if applicable. Results: There were no significant changes in most hemodynamic and water content parameters between the menstrual cycle phases in healthy women. Left ventricular ejection time differed significantly among phases of the menstrual cycle, with shorter values in the mid-luteal phase (308.4 vs. 313.52 ms, p < 0.05) compared to the late follicular phase. However, the clinical relevance of such small differences is negligible. Conclusions: Changes in sex hormones during the physiological menstrual cycle appear to have no considerable effect on healthy women’s hemodynamic function and water accumulation.

Use of a novel handheld ultrasound device with continuous-wave doppler capability for the assessment of valvular heart disease

Abstract Background/Introduction Echocardiography is the primary non-invasive imaging method for the diagnosis and evaluation of valvular heart disease. Doppler echocardiography provides accurate non-invasive evaluation of valve hemodynamics. Recent technological advancements have enabled the acquisition of echocardiographic images at the point-of-care by using small handheld ultrasound devices (HUDs); their availability and relatively low cost compared to the high-end systems have made these devices attractive to use for rapid medical decision making. However, the inability to quantify flow velocity has been a major limitation for HUDs; the lack of spectral Doppler capability has so far hindered the comprehensive assessment of haemodynamic data and valve function. Purpose To evaluate for the first time the accuracy of a novel HUD with continuous-wave (CW) Doppler capability to measure flow velocity in valvular heart disease. Methods We prospectively included 56 consecutive patients who were referred to the echocardiography laboratory of a tertiary hospital. All patients were scanned with both the Kosmos HUD and the standard echocardiography cart-based system (reference standard) in a randomized order. CW Doppler measurements of maximum velocities (Vmax) were obtained from the apical five-chamber view for the aortic ejection and regurgitation and from the apical four-chamber view for the mitral and tricuspid regurgitation (presence assessed by colour Doppler), maintaining a parallel orientation between the ultrasound beam and the blood flow. All measurements were compared to assess inter-method agreement using linear regression and Bland-Altman analysis. Results The acquisition of CW Doppler signal using the HUD was feasible in 55 out of 56 patients (mean age 66±16 years old, 40% female). Among them, there were 31 cases of (at least mild) aortic stenosis and 23 cases of valvular regurgitation (4 aortic, 6 mitral and 13 tricuspid regurgitations). There was excellent correlation between the HUD and the cart-based system CW Doppler for the aortic Vmax measurements (r=0.99, p&amp;lt;0.001) and for the valvular regurgitation Vmax measurements (r=0.98, p&amp;lt;0.001). The corresponding Bland-Altman plots showed a small underestimation bias of −0.13 m/sec (p&amp;lt;0.001), with limits of agreement ±0.41 m/sec for the aortic Vmax and −0.21 m/sec (p=0.003), with limits of agreement ±0.57 m/sec for the valvular regurgitation Vmax measurements. Conclusion A novel HUD with CW Doppler spectral analysis was able to provide peak jet velocity measurements comparable to the standard cart-based echocardiography systems, in patients with valvular stenosis and regurgitation. Such expanded capabilities of HUDs show clinical potential and may lead to the improvement of the assessment of valvular pathology at the point-of-care. Funding Acknowledgement Type of funding sources: None.