Hemodynamic Patterns Research Articles

Особливості мозкового кровотоку у пацієнтів з різними видами головного болю

Introduction. Currently, the most common types of neurological diseases presenting with headache are migraine (M), tension-type headache (TTH) and cervicogenic headache (CH). At the current level, the use of such a highly informative method as duplex scanning in the diagnosis of various types of headache is relevant. A large number of works are devoted to the study of cerebral hemodynamic disorders in patients with migraine with and without aura, in the period between attacks and during an attack. In patients with M, a change in the tone of the vessels of the arterial bed, an increase in interictal hypotension, a decrease in cerebral blood flow reserves, and the phenomenon of venous dysemia were determined. Paradoxical vascular reaction and disruption of autoregulation were noted in patients with TTH. Hemodynamic characteristics of TTH were signs of increased tone in extracranial arteries and decreased tone in intracranial vessels; decrease in cerebral blood flow reserves; signs of venous dyscirculation. In patients with CH the most pronounced changes in hemodynamics in the form of a decrease in speed and an increase in blood flow kinematic indices are observed in VA and BA. Also, in patients with CH, there is a correlation between the severity of vertebral dysfunction and cerebral dysgemia In the available works, hemodynamic patterns characteristic of certain types of headache were not determined. Nor was a comparison of hemodynamic characteristics in patients with M, TTH and CH. In connection with the above, the question of the role of vascular factors is relevant for the study of pathogenetic mechanisms of the development of various types of headache. The aim of the work was to study the features of blood circulation in extra- and intracerebral vessels in patients with migraine, tension type headache and cervicogenic headache. Materials and methods. 458 young patients (16-44 years old, men – 203, women – 255) with various types of headache were studied; including migraine – 124 patients, tension type headache – 186 patients, cervicogenic headache – 146 patients. The indicators of peak systolic blood flow velocity (Vs), time-averaged maximum blood flow velocity (TAMX), pulsatility (PI) and resistance (RI) indices in general (CCA), external (ECA), internal carotid (ICA), vertebral (VA) in segments V2 and V4, anterior (ACA), middle (MCA), posterior (PMA) cerebral, and basilar (BA) arteries were studied The results. In all clinical groups, there was a decrease in speed indicators and an increase in the values of the resistance index in VA. Changes in hemodynamics in the V2 segments are possibly due to extravasal compression and hypoplasia of the VA. In patients with M, the flow rate along the MCA was significantly increased. Patients with TTH showed excessive perfusion of BA. Pulsation index in MCA was increased in TTH and in M. PI values in patients with TTH were moderately increased in PMA and BA. In patients with M and TTH an increase in the PI index was observed in the MCA, the PI index was increased in the PMA in patients with CH and decreased in the groups with M and TTH. This index was increased in VA and BA in all clinical groups. In the group of patients with M, the peak-like variant of the spectrum in MCA prevailed. A characteristic feature of the group of patients with CH was the dominance of the peak-like spectrum in VA. Conclusions. Hemodynamic indicators in the extracranial segments of VA were reduced in all clinical groups, which is probably caused in most cases by vertebral impact and structural changes. Patterns of excessive perfusion in MCA were characteristic for patients with M and TTH, in PMA – for patients with M, in VA – for patients with CH, in BA – for patients with M and CH. In the group of patients with CH, the leading hemodynamic pattern was the presence of vasospastic reactions in the vertebral vessels. Pulsation indices increased in patients with TTH in MCA, as well as in patients with CH in PMA and BA. The predominance of the peak-like spectrum of the Doppler curve was noted in MCA in patients with M and in VA in patients with CH.

Incorporating EEG and fNIRS Patterns to Evaluate Cortical Excitability and MI-BCI Performance during Motor Training.

As electroencephalography (EEG) is nonlinear and nonstationary in nature, an imperative challenge for brain-computer interfaces (BCIs) is to construct a robust classifier that can survive for a long time and monitor the brain state stably. To this end, this research aims to improve BCI performance by incorporation of electroencephalographic and cerebral hemodynamic patterns. A motor imagery (MI)-BCI based visual-haptic neurofeedback training (NFT) experiment was designed with sixteen participants. EEG and functional near infrared spectroscopy (fNIRS) signals were simultaneously recorded before and after this transient NFT. Cortical activation was significantly improved after repeated and continuous NFT through time-frequency and topological analysis. A classifier calibration strategy, weighted EEG-fNIRS patterns (WENP), was proposed, in which elementary classifiers were constructed by using both the EEG and fNIRS information and then integrated into a strong classifier with their independent accuracy-based weight assessment. The results revealed that the classifier constructed on integrating EEG and fNIRS patterns was significantly superior to that only with independent information (~10% and ~18% improvement respectively), reaching ~89% in mean classification accuracy. The WENP is a classifier calibration strategy that can effectively improve the performance of the MI-BCI and could also be used to other BCI paradigms. These findings validate that our proposed methods are feasible and promising for optimizing conventional motor training methods and clinical rehabilitation.

Fate of the Right Ventricular Outflow Tract Following Valve-Sparing Repair of Tetralogy of Fallot

Valve-sparing repair (VSR) of tetralogy of Fallot (TOF) tends to result in higher residual right ventricular outflow tract (RVOT) gradients. We evaluated the progression and clinical implications of RVOT gradients following VSR of TOF. Demographic, clinical, and operative data were retrospectively collected from consecutive TOF patients who underwent VSR at our institution between 01/2010 and 06/2021. RVOT gradient, pulmonary valve annulus (PVA) diameter and Boston Z-scores were recorded from serial echocardiograms. Data are presented as median and interquartile range or number and percentage. A total of 156 children (boys 92, 59%) underwent VSR at 6.5 (4.9-8.4) months of age and 6.6 kg (5.6- 7.7) weight. There was 1 (0.6%) operative mortality. The remaining 155 patients were followed for 69.4 months (4-106.2). RVOT gradient was 2.4m/s (1.7-2.9) at discharge. It transiently increased, then declined and stabilized during follow-up. PVA Z-score was -1.7 (-3.1 to 0.5) at discharge and 'grew' to -0.8 (-1.7 to 0.4) at last follow-up. Freedom from RVOT re-intervention was 97%, 94% and 91% at 1, 5 and 10-year follow-up. Among 67 (43%) patients with PVA Z-score < -2, a similar RVOT gradient pattern was observed and freedom from RVOT re-intervention was 97%, 95% and 95% at 1, 5 and 8-year follow-up. Following VSR of TOF, RVOT gradients transiently increase and then fall as PVA growth catches up, resulting in durable intermediate outcomes. Patients with PVA Z-score < -2 demonstrated a similar pattern of hemodynamics in the RVOT and excellent freedom from reintervention.

Dual-task related frontal cerebral blood flow changes in older adults with mild cognitive impairment: A functional diffuse correlation spectroscopy study.

In a worldwide aging population with a high prevalence of motor and cognitive impairment, it is paramount to improve knowledge about underlying mechanisms of motor and cognitive function and their interplay in the aging processes. We measured prefrontal cerebral blood flow (CBF) using functional diffuse correlation spectroscopy during motor and dual-task. We aimed to compare CBF changes among 49 older adults with and without mild cognitive impairment (MCI) during a dual-task paradigm (normal walk, 2- forward count walk, 3-backward count walk, obstacle negotiation, and heel tapping). Participants with MCI walked slower during the normal walk and obstacle negotiation compared to participants with normal cognition (NC), while gait speed during counting conditions was not different between the groups, therefore the dual-task cost was higher for participants with NC. We built a linear mixed effects model with CBF measures from the right and left prefrontal cortex. MCI (n = 34) showed a higher increase in CBF from the normal walk to the 2-forward count walk (estimate = 0.34, 95% CI [0.02, 0.66], p = 0.03) compared to participants with NC, related to a right- sided activation. Both groups showed a higher CBF during the 3-backward count walk compared to the normal walk, while only among MCI, CFB was higher during the 2-forward count walk. Our findings suggest a differential prefrontal hemodynamic pattern in older adults with MCI compared to their NC counterparts during the dual-task performance, possibly as a response to increasing attentional demand.

Respiratory training in older women: Unravelling central and peripheral hemodynamic slow oscillatory patterns

We hypothesized that inspiratory muscle training (IMT) increases the respiratory-induced low-frequency oscillations of mean blood pressure (MBP) and middle cerebral artery blood velocity (MCAv), upregulating cerebrovascular function in older women. Firstly, participants were recorded with free-breathing (FB) and then breathed at a slow-paced frequency (0.1 Hz; DB test) supported by sonorous metronome feedback. Blood pressure was recorded using finger photoplethysmography method, ECG, and respiration using a thoracic belt. To obtain the MCAv a transcranial ultrasound Doppler device was used. Spectral analysis of MBP, R-R intervals, and mean MCAv time series was obtained by an autoregressive model. The transfer function analysis (TFA) was employed to calculate the coherence, gain, and phase. After that, older women were enrolled in a randomized controlled protocol, the IMT-group (n = 8; 64 ± 3 years-old) performed IMT at 50 % of maximal inspiratory pressure (MIP), and Sham-group, a placebo training at 5 % MIP (Sham-group; n = 6; 66 ± 3 years-old). Participants breathed against an inspiratory resistance twice a day for 4-weeks. DB test is repeated post IMT and Sham interventions. IMT-group, compared to Sham-group, augmented tidal volume responses to DB (Sham-group 1.03 ± 0.41 vs. IMT-group 1.61 ± 0.56 L; p = 0.04), increased respiratory-induced MBP (Sham-group 26.37 ± 4.46 vs. IMT-group 48.21 ± 3.15 mmHg2; p = 0.04) and MCAv (Sham-group 14.16 ± 31.26 vs. IMT-group 79.90 ± 21.76 cm2s−2; p = 0.03) slow oscillations, and reduced TFA gain (Sham-group 2.46 ± 1.32 vs. IMT-group 1.78 ± 1.30 cm·s−1.mmHg−1; p = 0.01). Our findings suggest that IMT increases the respiratory-induced oscillations in MBP and MCAv signals and reduces TFA gain. It seems compatible with an improved dynamic cerebrovascular regulation following IMT in older women.

Clinical effects of wasabi extract containing 6-MSITC on myalgic encephalomyelitis/chronic fatigue syndrome: an open-label trial

BackgroundWasabi (Eutrema japonicum) is a common pungent spice used in Japan. 6-Methylsulfinylhexyl isothiocyanate (6-MSITC) found in the rhizome of wasabi has been shown to have anti-inflammatory and antioxidant effects, as well as improve neuroinflammation and memory. Therefore, we hypothesized that these effects would be beneficial for treating myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The present study was conducted to investigate the effectiveness of wasabi extract containing 6-MSITC on ME/CFS in an open-label trial.MethodsFifteen patients (3 males, 12 females, 20–58 years old) were orally administered wasabi extract (9.6 mg of 6-MSITC/day) for 12 weeks. The following parameters and test results were compared pre- and post-treatment: performance status (PS), self-rating questionnaires, pressure pain threshold (PPT) on the occiput, Trail Making test-A (TMT-A), and hemodynamic patterns determined by an active standing test.ResultsAfter treatment with 6-MSITC, PS improved significantly (p = 0.001). Although the scores on the 11-item Chalder Fatigue scale (CFS-11) and numerical rating scale (NRS) of fatigue did not show significant changes, subjective symptoms improved significantly, including headache frequency (4.1 to 3.0 times/week, p = 0.001) and myalgia (4.1 to 2.4 times/week, p = 0.019), NRS brain fog scores (5.7 to 4.5, p = 0.011), difficulty finding appropriate words (4.8 to 3.7, p = 0.015), photophobia (4.8 to 3.5, p = 0.008), and the Profile of Mood Status vigor score (46.9 to 50.0, p = 0.045). The PPT of the right occiput (17.3 to 21.3 kPa, p = 0.01) and TMT-A scores (53.0 to 38.1 s, p = 0.007) also changed, suggesting reduced pain sensitivity, and improved cognitive function, respectively. Orthostatic patterns determined by a standing test did not show remarkable changes. There were no serious adverse reactions.ConclusionThis study suggests that 6-MSITC improves PS as well as subjective symptoms such as pain and cognitive dysfunction, and psychological vitality of patients with ME/CFS. It also improved cognitive performance and increased pain thresholds in these patients. 6-MSITC may be a promising therapeutic option especially for improving cognitive dysfunction associated with ME/CFS.

Hemodynamic indicators of the formation of tandem intracranial aneurysm based on a vascular restoration algorithm.

Hemodynamic factors are believed to be closely related to IA growth. However, the underlying pathophysiological mechanism that induces the growth sequence in tandem intracranial aneurysms (IAs) remains unclear. This study involved five patients with tandem IAs. Aneurysm models were reconstructed based on image datasets. A novel vascular restoration algorithm was proposed to generate the hypothetical geometry of the healthy parent vessel before each IA formation in the concatenated structure. Detailed hemodynamic patterns and morphological features were revealed under various growth sequences of tandem IAs to investigate the flow-driven mechanism of IA growth. Potential hemodynamic indicators of IA formation were proposed. The patient cases were divided into two groups based on the size difference of tandem IAs. In the group with a similar size of tandem IAs, the position of the vortex core was associated with the site of the secondary aneurysm, while in the group with a significant size difference of the IAs, the position with the maximum curvature of the parent vessel plays a significant role in aneurysm formation. This study preliminarily revealed key hemodynamic and morphological indicators that determine the formation of tandem IAs. The proposed vascular restoration algorithm that provided the pre-aneurysm vasculature might be useful in investigating the flow-driven mechanism of IA growth, thus contributing to the risk evaluation of secondary aneurysm formation.

Combining robust level extraction and unsupervised adaptive classification for high-accuracy fNIRS-BCI: An evidence on single-trial differentiation between mentally arithmetic- and singing-tasks.

Functional near-infrared spectroscopy (fNIRS) is a safe and non-invasive optical imaging technique that is being increasingly used in brain-computer interfaces (BCIs) to recognize mental tasks. Unlike electroencephalography (EEG) which directly measures neural activation, fNIRS signals reflect neurovascular-coupling inducing hemodynamic response that can be slow in time and varying in the pattern. The established classifiers extend the EEG-ones by mostly employing the feature based supervised models such as the support vector machine (SVM) and linear discriminant analysis (LDA), and fail to timely characterize the level-sensitive hemodynamic pattern. A dedicated classifier is desired for intentional activity recognition of fNIRS-BCI, including the adaptive acquisition of response relevant features and accurate discrimination of implied ideas. To this end, we herein propose a specifically-designed joint adaptive classification method that combines a Kalman filtering (KF) for robust level extraction and an adaptive Gaussian mixture model (a-GMM) for enhanced pattern recognition. The simulative investigations and paradigm experiments have shown that the proposed KF/a-GMM classification method can effectively track the random variations of task-evoked brain activation patterns, and improve the accuracy of single-trial classification task of mental arithmetic vs. mental singing, as compared to the conventional methods, e.g., those that employ combinations of the band-pass filtering (BPF) based feature extractors (mean, slope, and variance, etc.) and the classical recognizers (GMM, SVM, and LDA). The proposed approach paves a promising way for developing the real-time fNIRS-BCI technique.

Hemodynamic profiling: cardiac phenotypes and multiorgan organ failure in acute myocardial infarction with cardiogenic shock

Abstract Introduction Cardiogenic shock (CS) is a spectrum of phenotypes and multiorgan failure (MOF). Recent works [1] approach the typification, but no continuous hemodynamic patterns has been associated with these phenotypes nor MOF. Methods 295 AMI-CS patients (SBP ≤90 mmHg, vasopressor use, cardiac index ≤2.2 L/min/m2, or lactate ≥2 mmol/L) and pulmonary artery (PA) catheter. Cut-off values were used to divide in 3 phenotypes cardiac [C0] (no organ involvement), cardiorenal [CR] (eGFR &amp;lt;45 ml/min/1.73 m2), and cardiometabolic [CM] (renal+hepatic [AST or ALT &amp;gt;3 ULN]) [2] SCAI definitions were used [3]. MODS score defines MOF as ≥2 organs [4]; AKI (rise Cr &amp;gt;0.3 mg/dL) and electric instability (VT/VF). Repeated measures ANOVA was used to compare 24 h hemodynamic data. 30-day mortality hazard ratios were obtained (Fig. 1E). Results C0 represent 64.41% (190), CR 14.91% (44) and CM 20.68% (61). SCAI C was more in C0 (24.74 vs 0, 0%), E in the CM (23.16, 38.64 vs 63.93%); SCAI D had differences in CR and CM (61.36 vs 36.07%). C0 were younger (59, vs CR 66, CM 62; p&amp;lt;0.001); diabetes was more common in CM (60.66) vs CR (56.82) or C0 (42.63%) (p=0.024). Hypertension predominates in CR (72.73 vs CM 57.38, C0 44.21%). GRACE score was lower in C0 (180.64, 157–206) against CR (211.07, 186.5–237), CM (218, 195–247) (p&amp;lt;0.001). AKI was higher in CR, CM (79.55, 86.89 vs 65.79%, p&amp;lt;0.001), as hemodialysis (18.18 and 34.43 vs 6.32, p&amp;lt;0.001) compared to C0. In CM: leukocytes, BUN, Cr, AST, ALT, and CRP were higher with lower levels of eGFR and platelets. C0 had fewer vasoactive requirements (p&amp;lt;0.001). IABP (p=0.741) and VT/FV (p=0.687) had no differences. MOF prevalence was C0 62.6% vs CR 86.4% and CM 96.7% (p&amp;lt;0.001). MODS ≥4 was C0 39.5, CR 65.9, CM 85.2% and SOFA ≥7 was C0 32.6, CR 63.6, CM 83.6%. Mortality was higher in CR (56.82%) and CM (54.1%) compared to C0 (39.47%, p=0.032) (p=0.001, Fig. 1A). RAP (p&amp;lt;0.001, Fig. 2A), PCWP (0.007, Fig. 2C), cardiac output (&amp;lt;0.001, Fig. 2B), index (0.001), power (0.001), perfusion pressure (PP = MAP-RAP, 0.028) and PAPi (0.043) discriminate the C0 phenotype. AKI had lower survival (p&amp;lt;0.001, Fig. 1B) related to lower SBP (&amp;lt;0.001), DBP (0.003), MAP (&amp;lt;0.001, Fig. 2F) cardiac output (0.002), index (&amp;lt;0.001), power (&amp;lt;0.001, Fig. 2E), and PP (&amp;lt;0.001, Fig. 2D) and higher RAP (0.003), PADP (0.024), PAMP (0.011), PCWP (0.001). Electrical instability had lower survival (p&amp;lt;0.001, Fig. 1C), lower SBP (0.004), DBP (0.011), MAP (0.001, Fig. 2G), cardiac outpu t(0.036), index (0.019), power (0.003, Fig. 2I), PP (0.002, Fig. 2H) and higher PAMP (0.04). Finally, multiorgan failure had a decreased survival (p=0.016, Fig. 1D), higher heart rates (p=0.018), RAP (0.001, Fig. 2K), PCWP (&amp;lt;0.001), PADP (0.02) and lower SBP (0.017), DBP (0.002), MAP (&amp;lt;0.001) cardiac output (&amp;lt;0.001), index (0.004), power (&amp;lt;0.001), PP (&amp;lt;0.001, Fig. 2J), PAPi (&amp;lt;0.001, Fig. 2L). Conclusions We demonstrated associations with hemodynamic trajectories across time, which has not been reported before, could reveal AMI-CS phenotypes and related organ dysfunction patterns. Funding Acknowledgement Type of funding sources: None.

P.82 Case-Control cardiopulmonary exercise testing for patients with neuromuscular disease

Patients with neuromuscular diseases (NMD) present with disease-specific muscle weakness and fatigue and are largely sedentary and deconditioned. This sedentary lifestyle leads to additional weakness, fatigue and loss of function. This deconditioning cycle results in reduced cardiorespiratory fitness (CRF), which is strongly related to increased risk for cardiovascular and pulmonary diseases (e.g. hypertension, diabetes mellitus, coronary artery disease, chronic obstructive pulmonary disease). These largely preventable diseases are the leading causes of morbidity and mortality for those with and without NMD. The gold standard for the assessment of CRF is peak oxygen consumption (peak VO2), assessed with cardiopulmonary exercise testing (CPX). Several small studies have suggested a role for CPX for patients with NMD, who present with hyperventilatory and hypercirculatory patterns, but with inconsistent results. We performed CPX in 37 patients with NMD and 8 controls using a Keiser wheelchair accessible total body trainer and a CosMed K5 wearable metabolic system. We were able to perform high quality CPX by both subjective and objective measures. Compared to controls, individuals with NMD presented with reduced exercise performance as measured by peak wattage and peak VO2. Disturbed hemodynamic and ventilatory patterns were noted, with borderline chronotropic incompetence and low O2 pulse, early and marked ventilatory inefficiency and severely reduced oxygen uptake efficiency slope and a high proportion of patients displaying exercise oscillatory breathing. Importantly, we observed that relative effort as illustrated by equivalent RPE and RER was not significantly different than controls. Our data illustrate that high quality CPX can be conducted in this population and suggest that performing CPX in patients with NMD will reveal distinct physiological profiles that may lead to a better understanding of cardiopulmonary and metabolic pathology in these individuals.

Accelerated sequences of 4D flow MRI using GRAPPA and compressed sensing: A comparison against conventional MRI and computational fluid dynamics.

To evaluate hemodynamic markers obtained by accelerated GRAPPA (R= 2, 3, 4) and compressed sensing (R= 7.6) 4D flow MRI sequences under complex flow conditions. The accelerated 4D flow MRI scans were performed on a pulsatile flow phantom, along with a nonaccelerated fully sampled k-space acquisition. Computational fluid dynamics simulations based on the experimentally measured flow fields were conducted for additional comparison. Voxel-wise comparisons (Bland-Altman analysis, -norm metric), as well as nonderived quantities (velocity profiles, flow rates, and peak velocities), were used to compare the velocity fields obtained from the different modalities. 4D flow acquisitions and computational fluid dynamics depicted similar hemodynamic patterns. Voxel-wise comparisons between the MRI scans highlighted larger discrepancies at the voxels located near the phantom's boundary walls. A trend for all MR scans to overestimate velocity profiles and peak velocities as compared to computational fluid dynamics was noticed in regions associated with high velocity or acceleration. However, good agreement for the flow rates was observed, and eddy-current correction appeared essential for consistency of the flow rates measurements with respect to the principle of mass conservation. GRAPPA (R= 2, 3) and highly accelerated compressed sensing showed good agreement with the fully sampled acquisition. Yet, all 4D flow MRI scans were hampered by artifacts inherent to the phase-contrast acquisition procedure. Computational fluid dynamics simulations are an interesting tool to assess these differences but are sensitive to modeling parameters.

Temel Duygusal Durumların Hemodinamik Karşılıklarının Taşınabilir bir İşlevsel Yakın Kızılaltı Spektroskopi Sistemi ile Tanımlanması

Aim: The aim of this study was to evaluate the feasibility of a functional near infrared spectroscopy (fNIRS) system, for quantification of the similarities and differences in the spatial localization of cerebral hemodynamic activation, induced by visual presentation of neutral, negative and positive valence emotional stimuli.Method: Thirteen healthy subjects viewed neutral, pleasant and unpleasant pictures from the International Affective Picture System (IAPS) database in a block design experiment while the prefrontal cortical hemodynamic changes induced by emotional stimuli were continuously recorded with a 20 channel fNIRS system that covered the forehead region.Results: Negative valence pictures induced higher hemodynamic activity in right lateralized regions involving dorsolateral and orbitofrontal cortex, when compared to neutral and positive valence stimuli (pFDR&amp;lt;0.05). Each stimulus condition induced a distinct cortical activation pattern that could be identified with fNIRS.Conclusion: Our findings support the notion that different basic emotions have distinct localization and separable hemodynamic correlates in the prefrontal cortex region, which can be detected with a mobile fNIRS system. The distinct cortical hemodynamic activity patterns associated with each emotional state show the potential of fNIRS technology for decoding and differentiating basic emotions objectively and real time for future clinical and daily life applications.

The role of 4-dimensional flow in the assessment of bicuspid aortic valve and its valvulo-aortopathies.

Bicuspid aortic valve is the most common congenital cardiac malformation and the leading cause of aortopathy and aortic stenosis in younger patients. Aortic wall remodelling secondary to altered haemodynamic flow patterns, changes in peak velocity, and wall shear stress may be implicated in the development of aortopathy in the presence of bicuspid aortic valve and dysfunction. Assessment of these parameters as potential predictors of disease severity and progression is thus desirable. The anatomic and functional information acquired from 4D flow MRI can allow simultaneous visualisation and quantification of the pathological geometric and haemodynamic changes of the aorta. We review the current clinical utility of haemodynamic quantities including velocity, wall sheer stress and energy losses, as well as visual descriptors such as vorticity and helicity, and flow direction in assessing the aortic valve and associated aortopathies.

Slice-based and time-specific hemodynamic measurements discriminate carotid artery vulnerable atherosclerotic plaques

Background and objectiveHemodynamic patterns play key roles in progression of carotid vulnerable plaques. However, most of previous studies utilized maximum or averaged value of hemodynamic measurements which is not an ideal representative of hemodynamic patterns. This study aimed to investigate the association of slice-based and time-specific hemodynamic measurements with carotid vulnerable plaque using magnetic resonance (MR) vessel wall imaging and histology. MethodsThirty-two patients (mean age: 63.9±8.1 years; 25 males) with carotid atherosclerotic stenosis (≥50% stenosis) referred to carotid endarterectomy were recruited and underwent MR vessel wall imaging. Carotid plaque burden was evaluated on MR images and vulnerable plaque features including calcification, lipid-rich necrotic core, and intra-plaque hemorrhage (IPH) were identified by histology. The slice-based and time-specific hemodynamic measurements were extracted from computational fluid dynamics simulation of 3D carotid arterial model. Correlation coefficients between hemodynamic measurements and carotid plaque features were calculated and the logistic regressions with generalized estimating equation (GEE) were conducted. The value in discriminating carotid vulnerable plaque features was determined by receiver-operating-characteristic analysis. ResultsOf 102 MR-histology matched slices from 32 patients, time-averaged wall shear stress (TAWSS) (r=0.263, p=0.008), oscillatory shear index (OSI) (r=-0.374, p<0.001), and peakWSS (r=0.232, p=0.019) were significantly associated with carotid IPH. The logistic regression with GEE revealed that peakWSS (OR, 1.206; 95% CI, 1.026-1.418; p, 0.023) and TAWSS (OR, 0.364, 95% CI, 0.138-0.959; p, 0.041) were significantly associated with presence of IPH after adjusting for age and BMI. In discriminating carotid IPH, the AUC of TAWSS, OSI, combined TAWSS with maximum wall thickness (MWT) and combined OSI with MWT was 0.656, 0.722, 0.761, and 0.764, respectively. ConclusionsSlice-based and time-specific hemodynamic characteristics could effectively discriminate carotid IPH. Combination of hemodynamic measurements with carotid plaque burden might be a stronger indicator for carotid vulnerable plaque features than each measurement alone.

Multimodal Noninvasive Functional Neurophotonic Imaging of Murine Brain‐Wide Sensory Responses (Adv. Sci. 24/2022)

Neuroimaging Decoupling the complex interplay of neurovascular coupling and dynamical physiological states has remained challenging when employing single-modality functional neuroimaging readings. In article number 2105588, Shy Shoham, Daniel Razansky, and co-workers devise a hybrid fluorescence optoacoustic tomography (FLOT) platform combined with a custom data processing pipeline based on statistical parametric mapping, attaining the first noninvasive observation of simultaneous calcium and hemodynamic activation patterns using optical contrasts.

Prediction of wall stress and oxygen flow in patient-specific abdominal aortic aneurysms: the role of intraluminal thrombus.

In this study, the biomechanical role of intraluminal thrombus (ILT) in an abdominal aortic aneurysm (AAA) is investigated. The implications of ILT in AAA are controversial in literature. Previous studies have demonstrated that ILT provides a biomechanical advantage by decreasing wall stress, whereas other studies have associated ILT with inhibiting oxygen transport and inducing aortic wall weakening. Therefore, we sought to explore the connection between ILT, mechanical stresses, and oxygen flow in different geometries of patient-specific aneurysms with varying ILT morphologies. The objective is to investigate the extent to which ILT influences the prediction of aneurysmal wall stresses that are associated with rupture, as well as oxygen concentrations to measure tissue oxygen deprivation. Three patient-specific AAA geometries are considered, and two models, one with ILT and one without ILT, are created for each patient to assess the effect of ILT presence. A fluid-structure interaction approach is used to couple the blood flow, wall deformation, and oxygen mass transport. Results are presented for hemodynamics patterns, wall stress measures, and oxygen metrics within the arterial wall. While ILT is found to reduce wall stress, simulations confirm that ILT decreases oxygen transport within the tissue significantly, leading to wall hypoxia.

Impact of Vessel Narrowing and Changes in Blood Flow on the Development of Ischemia in Cervical Arterial Dissection Using Quantitative Magnetic Resonance Angiography

Background Up to 3% of all ischemic strokes are secondary to dissections; however, cerebral hemodynamic patterns in cervical arterial dissection and their association with cerebral ischemia are unknown. This study represents the first to assess blood flow using quantitative magnetic resonance angiography in patients with cervical arterial dissection and their presentation with ischemia. Methods Retrospective chart review was completed in patients with cervical arterial dissection between 2009 and 2019. Inclusion criteria were adults with dissection of internal carotid artery or vertebral artery who underwent baseline magnetic resonance imaging (MRI) and quantitative magnetic resonance angiography. Cases were reviewed for presentation, management, and imaging findings. Flow index was calculated using ipsilateral vessel flow divided by contralateral flow. Results A total of 37 patients with a mean age of 45.95±11.95 years were included. Of the patients, 19 (51.2%) had internal carotid artery dissections, 17 (45.9%) with vertebral artery dissections, and 1 with both. Patients with ischemia on MRI demonstrated lower flow in the ipsilateral vessel when compared with those patients without ischemia ( P =0.003). Using the flow index in receiver operating characteristic analysis to predict ischemia on MRI yielded an area under the curve of 0.833 ( P =0.002); receiver operating characteristic analysis of the percent of total flow for ischemia on MRI found an area under the curve of 0.895 ( P =0.000), and receiver operating characteristic analysis of percent vessel narrowing calculated an area under the curve of 0.887 ( P =0.000). Multivariate analysis identified vessel narrowing as significantly associated with ischemia on MRI ( P =0.03). Conclusion This study represents the first to evaluate blood flow in patients with cervical arterial dissection using quantitative magnetic resonance angiography and its relationship with cerebral ischemia. Patients with lower flow as a result of dissection appear to be at higher risk of ischemia on presentation, emphasizing the role of hemodynamics in underlying pathophysiology, and vessel narrowing appears paramount in the association with developing ischemia.

Effects of Pulsatile Flow Rate and Shunt Ratio in Bifurcated Distal Arteries on Hemodynamic Characteristics Involved in Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study.

The pulsatile flow rate (PFR) in the cerebral artery system and shunt ratios in bifurcated arteries are two patient-specific parameters that may affect the hemodynamic characteristics in the pathobiology of cerebral aneurysms, which needs to be identified comprehensively. Accordingly, a systematic study was employed to study the effects of pulsatile flow rate (i.e., PFR−I, PFR−II, and PFR−III) and shunt ratio (i.e., 75:25 and 64:36) in bifurcated distal arteries, and transient cardiac pulsatile waveform on hemodynamic patterns in two internal carotid artery sidewall aneurysm models using computational fluid dynamics (CFD) modeling. Numerical results indicate that larger PFRs can cause higher wall shear stress () in some local regions of the aneurysmal dome that may increase the probability of small/secondary aneurysm generation than under smaller PFRs. The low and relatively high oscillatory shear index () could appear under a smaller PFR, increasing the potential risk of aneurysmal sac growth and rupture. However, the variances in PFRs and bifurcated shunt ratios have rare impacts on the time-average pressure () distributions on the aneurysmal sac, although a higher PFR can contribute more to the pressure increase in the ICASA−1 dome due to the relatively stronger impingement by the redirected bloodstream than in ICASA−2. CFD simulations also show that the variances of shunt ratios in bifurcated distal arteries have rare impacts on the hemodynamic characteristics in the sacs, mainly because the bifurcated location is not close enough to the sac in present models. Furthermore, it has been found that the vortex location plays a major role in the temporal and spatial distribution of the WSS on the luminal wall, varying significantly with the cardiac period.

Progressive Obstruction of Inferior Vena Cava by Ameroid Constrictor: The Canine Model of Revealing Hemodynamic and Compensatory Patterns of Tumor Thrombus Formation at the Renal Hilus Level.

Background: To develop an efficient and stable canine model of inferior vena cava (IVC) progressive obstruction at the renal hilus level. Methods: The model was established in two beagles by encircling an ameroid constrictor (AC) on the IVC at the renal hilus level. Abdominal wall varicosity and animal weight variations were observed weekly after operation. Ultrasound examination was performed weekly after surgery to observe the AC position, the diameter, and the velocity in the IVC. Six weeks after surgery, IVC angiography and CT scan were performed to observe the collateral circulation establishment and internal organ variation. Blood samples were taken regularly to monitor for variation in critical biochemical parameters. Renal biopsy was performed at 0, 2, 4, and 6 weeks after surgery. Results: Superficial varicose veins were observed on the abdominal wall at 2 weeks after surgery. Four weeks after operation, the IVC diameter increased by ∼30%, whereas the IVC velocity decreased by more than 50%. Collateral circulation was observed by IVC angiography at 6 weeks through multiple dilated veins along with neovascularization. CT scan showed congestive alteration in the kidney. The body weight, kidney, and liver function were not significantly affected. Chronic congestive renal injury was detected in the renal tubular epithelium by kidney biopsy after surgery. Conclusions: A canine model of IVC progressive obstruction at the renal hilus level was stably and safely established for the first time by using an AC, which may be helpful for preserving pivotal collateral circulation and nontumor-side kidney function in the IVC thrombus surgery.

Multimodal Noninvasive Functional Neurophotonic Imaging of Murine Brain-Wide Sensory Responses.

Modern optical neuroimaging approaches are expanding the ability to elucidate complex brain function. Diverse imaging contrasts enable direct observation of neural activity with functional sensors along with the induced hemodynamic responses. To date, decoupling the complex interplay of neurovascular coupling and dynamical physiological states has remained challenging when employing single‐modality functional neuroimaging readings. A hybrid fluorescence optoacoustic tomography platform combined with a custom data processing pipeline based on statistical parametric mapping is devised, attaining the first noninvasive observation of simultaneous calcium and hemodynamic activation patterns using optical contrasts. Correlated changes in the oxy‐ and deoxygenated hemoglobin, total hemoglobin, oxygen saturation, and rapid GCaMP6f fluorescence signals are observed in response to peripheral sensory stimulation. While the concurrent epifluorescence serves to corroborate and complement the functional optoacoustic observations, the latter further aids in decoupling the rapid calcium responses from the slowly varying background in the fluorescence recordings mediated by hemodynamic changes. The hybrid imaging platform expands the capabilities of conventional neuroimaging methods to provide more comprehensive functional readings for studying neurovascular and neurometabolic coupling mechanisms and related diseases.