Search Results (89)

The development of optical noninvasive methods for assessing the functional state of peripheral vessels, including the microcirculatory vascular bed, requires advances in modeling peripheral hemodynamics in order to interpret diagnostic data in terms of vascular tone, wall stiffness, and other related parameters. This study proposes a simple theoretical evaluation model of the dynamics of skin perfusion by blood during a functional test with brachial artery occlusion. As a development of conventional volume-chamber and pressure-volume approaches, this study introduces a problem-oriented three-chamber hemodynamic model of an arm, which allows simulating blood circulation during occlusion of major brachial veins and arteries. The model describes the Poiseuille flow of incompressible viscous blood in vessels with compliant walls, the lumen area of which is regulated by internal blood pressure and vascular tone. The initial diagnostic data for model validation were obtained in clinical trials with the use of the incoherent optical fluctuation flowmetry technique. Comparison of clinical and theoretical results revealed a fundamental qualitative agreement. In this field of medical diagnostics, for the first time, the dynamics of optical signals during the occlusion were successfully interpreted and substantiated as a response to changes in blood pressure and vascular tone in the microcirculatory system. Full article

Intact regulation of cerebral blood flow (CBF) is essential for preserving cognitive function and reducing the risk of cerebrovascular events, particularly in the aging population. Autoregulation of CBF is one of the fundamental mechanisms that ensure constant supply for brain tissue by maintaining relatively stable perfusion despite fluctuations in systemic blood pressure. It also acts as a critical protective mechanism, shielding the fragile cerebral microcirculation from potentially harmful pressure fluctuations and hence excessive pulsatility. The loss or attenuation of this protective mechanism with aging or disease increases the vulnerability of the microvasculature to structural damage, blood–brain barrier (BBB) disruption, and the development of cerebral small vessel disease. This mini-review summarizes current understanding of how aging affects cerebral autoregulation, highlighting underlying mechanisms, clinical consequences, and potential strategies to preserve cerebrovascular health in older adults. Full article

Hemodynamic monitoring is essential in the postoperative management of neonates undergoing cardiac surgery, enabling early identification of circulatory failure and its underlying cause, optimization of oxygen delivery to tissues, and evaluation of treatment response. Despite its significant role, there is still no consensus and there remains substantial heterogeneity in bedside hemodynamic monitoring practices. Pediatric intensivists typically rely on macro- and microcirculatory indicators, including arterial blood pressure, urine output, capillary refill time, mixed venous oxygen saturation, lactate concentration, and serial echocardiographic evaluations. However, most of these are indirect hemodynamic indicators and provide only intermittent snapshots of the hemodynamic status, which can be very fluctuating following cardiac surgery. Technological advancements have driven a shift toward continuous, noninvasive monitoring techniques, such as near-infrared spectroscopy (NIRS), electrical biosensing technology, and microcirculatory assessment tools. Real-time, simultaneous tracking of multiple physiological variables through a multimodal hemodynamic monitoring protocol facilitates the understanding of systemic and regional perfusion and oxygenation. This narrative review aims to summarize current techniques and innovations in neonatal hemodynamic monitoring following cardiac surgery, combining clinical evaluation with both intermittent and continuous noninvasive techniques. Full article

Background: Obstructive sleep apnea (OSA) is prevalent and often underdiagnosed in cardiology. Worldwide, approximately 936 million adults aged 30–69 are affected by OSA, with the highest numbers in the USA, China, Brazil, and India. In cardiovascular clinics, OSA is found in about 40–80% of patients with hypertension, heart failure, coronary artery disease, atrial fibrillation, or stroke. Meta-analyses link OSA to nearly twice the risk of cardiovascular disease, stroke, and all-cause mortality. Continuous positive airway pressure (CPAP) therapy addresses the underlying mechanisms of OSA and enhances intermediate cardiovascular indicators. Materials and Methods: We conducted a narrative review using major medical search engines (PubMed, Embase, Cochrane) to examine recent statements, meta-analyses, large cohorts, and key trials. The review focused on the cardiovascular burden of sleep apnea and its pathophysiology—including arrhythmic, hemodynamic, vascular, and coagulation aspects—as well as the effects of CPAP on intermediate cardiovascular outcomes. We aimed to provide a synthesised overview of current cardiovascular evidence related to the burden and mechanisms of OSA, and to summarise the effects of continuous positive airway pressure (CPAP) on intermediate and clinical cardiovascular outcomes. Results: Intermittent hypoxia, sleep fragmentation, and major negative fluctuations in intrathoracic pressure create a clear pathway leading to adverse cardiovascular outcomes. This occurs through mechanisms like sympathetic activation, RAAS activation, endothelial dysfunction, oxidative stress, and inflammation, linking OSA to these health issues. Studies show that greater severity of OSA correlates with higher cardiovascular risk, including increased incidence and recurrence of AF, resistant hypertension, and new cases of heart failure. CPAP effectively lowers AHI and enhances nocturnal oxygen levels, as well as intermediate cardiovascular indicators such as blood pressure, sympathetic activity, and certain aspects of ventricular function, with clinical benefits most evident in adherent patients. Conclusions: OSA is a significant, modifiable risk factor for cardiovascular disease. Routine cardiovascular care should include targeted screening for OSA, especially in cases of resistant hypertension, atrial fibrillation, and heart failure, along with timely sleep testing and adherence-focused CPAP therapy, in addition to traditional risk-reduction methods. Full article

Background: Guillain-Barré syndrome (GBS) is an acute immune-mediated polyneuropathy often associated with autonomic dysfunction. Although transient cardiovascular instability is common, severe dysautonomia leading to cardiac arrest is rarely documented in children. Methods: We report the case of an 11-year-old previously healthy boy who initially presented with acute ophthalmoplegia and rapidly progressed to quadriplegia and areflexia. He developed fluctuating blood pressure and bradycardia, culminating in cardiac arrest due to asystole at 24 h after admission, requiring 17 min of resuscitation. Results: Electrophysiological studies confirmed a demyelinating polyneuropathy. Although intravenous immunoglobulin (IVIG) was initiated 5 h after admission, clinical improvement was achieved only after subsequent plasmapheresis on day 20, with the recovery of autonomic function by day 35. He was extubated on day 45 and discharged on day 83 with a near-complete recovery after prolonged intensive care and rehabilitation. Conclusion: This case highlights the potential for rapid and life-threatening autonomic instability in pediatric GBS. Unlike typical cases, the patient progressed to cardiac arrest within 24 h despite IVIG, highlighting the need to consider plasmapheresis for non-responders. Continuous hemodynamic monitoring is essential to prevent fatal outcomes, even in patients with initially mild or atypical presentations. Full article

Background and Objectives: Circadian fluctuations in blood pressure, particularly the non-dipping pattern characterized by the absence of a nocturnal decline, are associated with an increased risk of microvascular complications. The retina, as a highly sensitive microvascular tissue, offers a valuable window into systemic hemodynamic alterations. However, the literature lacks detailed structural analyses that evaluate all retinal regions by segmenting nighttime into specific time intervals. Notably, the early morning period (04:00–08:00), during which stress hormones such as cortisol and catecholamines rise physiologically, leads to increased blood pressure that may significantly affect retinal microcirculation. This prospective study aims to assess retinal microvascular structures in dipper and non-dipper individuals using structural optical coherence tomography and to investigate their relationship with blood pressure parameters by dividing nighttime into distinct time segments. Materials and Methods: A total of 60 participants were classified as dipper (n = 26) or non-dipper (n = 34) based on 24 h ambulatory blood pressure monitoring results. Structural optical coherence tomography was used to evaluate superficial and deep capillary plexus densities in the foveal, parafoveal, and perifoveal regions, along with the area and perimeter of the foveal avascular zone (FAZ) and flow density (FD). Blood pressure values, including systolic, diastolic, mean arterial, and pulse pressure, were recorded during two nighttime intervals (00:00–04:00 and 04:00–08:00), and correlations with retinal parameters were analyzed. Results: No significant differences were observed in retinal microvascular parameters between the dipper and non-dipper groups. Deep capillary densities, particularly in the parafoveal and perifoveal regions, showed significant positive correlations with serum total protein, albumin, and very low-density lipoprotein (VLDL) levels. Furthermore, systolic and mean arterial pressures measured during the 04:00–08:00 interval demonstrated significant positive correlations with deep retinal vascular densities. The FAZ perimeter was negatively correlated with pulse pressure variability, while FD showed a negative correlation with mean arterial pressure variability. Conclusions: This prospective study is among the first to investigate the effects of circadian blood pressure patterns on retinal microvascular structures by segmenting nighttime into specific intervals and employing comprehensive structural optical coherence tomography across the entire retina. The findings suggest that retinal microvascular structure may be associated with fluctuations in blood pressure. Analyses of blood pressure measurements between 04:00 and 08:00 may offer supplementary insights into the evaluation of retinal microvascular structure. Full article

Background: Blood pressure variability (BPV) has emerged as an important clinical factor in acute ischemic stroke (AIS), with evidence linking excessive fluctuations in systolic blood pressure (SBP) to secondary brain injury. This study aimed to assess the association between SBP variability during the first week of hospitalization and the risk of early post-stroke complications, specifically hemorrhagic transformation and infarct growth. Methods: We conducted a prospective cohort study involving 138 AIS patients admitted to the Pius Brinzeu County Emergency Hospital, Timișoara, between November 2022 and December 2024. Systolic blood pressure (SBP) was assessed three times daily over a period of seven days, with variability determined as the standard deviation (SD) of the recorded values. Patients were categorized based on treatment modality (conservative versus intravenous thrombolysis), and complications were evaluated using repeated computed tomography (CT) imaging. Results: SBP variability was significantly higher in patients who developed hemorrhagic transformation (OR 3.64, 95% CI: 2.21–5.99, p < 0.001) or infarct growth (OR 1.80, 95% CI: 1.24–2.61, p = 0.001). A monotonic trend was observed across SBP variability categories, with complication rates increasing significantly with higher variability levels (p < 0.001 for hemorrhagic transformation; p = 0.001 for infarct growth). In multivariable models, SBP variability remained an independent predictor of hemorrhagic transformation in both the conservative group (OR 4.78, 95% CI: 2.07–37.14, p = 0.02) and thrombolysis group (OR 1.47, 95% CI: 1.13–2.08, p = 0.01), and was also associated with infarct growth in the thrombolysis group (OR 1.51, 95% CI: 1.13–2.25, p = 0.02). Conclusions: Medium-term SBP variability is an independent predictor of early ischemic and hemorrhagic complications following AIS, particularly in patients receiving thrombolysis. These findings support the need for targeted strategies to stabilize BP during the acute phase of stroke care. Full article

This narrative review examines the complex relationship between sleep changes during the menopausal transition and cardiometabolic risks. The most common complaint about sleep is increased awakenings during sleep. Other complaints include having trouble falling asleep, waking up too early, insufficient and non-restorative sleep, and overall poor quality. Sleep determined using objective methods also indicates that greater awakenings after sleep onset are associated with the period of menopausal transition. Polysomnography recordings suggest physiological hyperarousal during sleep. Changes in other sleep metrics, such as sleep latency and sleep duration, are less consistent, and some studies suggest they may not worsen during the menopausal transition. These sleep issues are influenced by multiple factors, such as hormonal fluctuations, vasomotor symptoms, and psychosocial factors, and evidence suggests that hypothalamic kisspeptin/neurokinin B/dynorphin (KNDy) neurons are key underlying mechanisms for these associations. The menopausal transition is also associated with increases in cardiometabolic risk factors, such as body fat, altered lipid profiles, blood pressure, and vascular health. Emerging evidence suggests that poor sleep health during this period is associated with increased cardiometabolic risks and adverse cardiovascular outcomes. Thus, addressing sleep disturbances is crucial for comprehensive healthcare during the menopausal transition to safeguard long-term cardiometabolic health. Future research is needed to investigate interventions that can improve sleep and their impact on cardiometabolic health in this population experiencing increases in cardiometabolic risk. Full article

Ischemic stroke following percutaneous coronary intervention (PCI) is a rare complication, with an overall incidence of 0.56%. Most embolic strokes result from the dislodgement of atherosclerotic plaques, thrombi formed on catheter surfaces, procedural maneuvers, or, less commonly, air or metallic emboli originating from fractured guidewires. We present a unique case of stroke following PCI due to a previously unreported mechanism—arterial tunica media embolization associated with arterial access. A 57-year-old female presented with chest pain at rest and with exertion, accompanied by episodes of anxiety and fluctuating blood pressure, for which coronary angiography was performed, revealing 90–99% stenosis of the left anterior descending artery and necessitating PCI. During the procedure, the patient developed an eye deviation, aphasia, and left-sided hemiparesis. Cerebral angiography identified a M2 segment occlusion of the right middle cerebral artery (MCA) and a subocclusion of the right anterior cerebral artery (ACA). Thrombectomy was performed, retrieving two white, tubular emboli resembling fragments of a vessel wall, histologically confirmed to be arterial tunica media. While PCI is associated with a low complication rate, its increasing frequency necessitates awareness of emerging complications. This case underscores a previously undocumented potential embolic complication arising from the performance of PCI. Full article

This study presents an innovative approach to quantifying uncertainty in Herschel–Bulkley (H-B) fluid flow through rectangular ducts, analyzing four scenarios: uncertain apparent viscosity (Case I), uncertain pressure gradient (Case II), uncertain boundary conditions (Case III) and uncertain apparent viscosity and pressure gradient (Case IV). Using the stochastic finite difference with homogeneous chaos (SFDHC) method, we produce probability density functions (PDFs) of fluid velocity with exceptional computational efficiency (243 times faster), matching the accuracy of Monte Carlo simulation (MCS). Key statistics and maximum velocity PDFs are tabulated and visualized for each case. Mean velocity shows minimal variation in Cases I, III, and IV, but maximum velocity fluctuates significantly in Case I (63.95–187.45% of mean), Case II (50.15–156.68%), and Case IV (63.70–185.53% of mean), vital for duct design and analysis. Examining the effects of different parameters, the SFDHC method’s rapid convergence reveals the fluid behavior index as the primary driver of maximum stochastic velocity, followed by aspect ratio and yield stress. These findings enhance applications in drilling fluid management, biomedical modeling (e.g., blood flow in vascular networks), and industrial processes involving non-Newtonian fluids, such as paints and slurries, providing a robust tool for advancing understanding and managing uncertainty in complex fluid dynamics. Full article

Background: In systemic sclerosis (SSc), endothelial dysfunction, inflammation, and reduced nitric oxide levels may disrupt circadian blood pressure (BP) regulation. There are studies showing that inflammatory and certain other cells in diseases like SSc exhibit diurnal rhythms. In our study, we examined the effect of SSc on BP. In particular, the frequency of the non-dipper pattern (lack of nighttime BP reduction) in SSc patients has not been adequately investigated. The aim of this study was to evaluate the 24 h BP profile in SSc patients and to compare the frequency of the non-dipper pattern with that of the non-scleroderma group. Additionally, the identification of disrupted circadian BP patterns in SSc patients aims to contribute to the development of personalized, time-sensitive BP monitoring strategies in the future and to support the applicability of personalized medicine in this context. Methods: A total of 31 SSc patients diagnosed according to the 2013 ACR/EULAR classification criteria and 30 age- and sex-matched individuals without SSc were included in this prospective study. BP changes between day and night were evaluated by measuring BP every 30 min with a 24 h ambulatory blood pressure monitoring (ABPM) device. The non-dipper pattern was defined as a decrease in BP of less than 10% during the night compared to the day. To better assess BP fluctuations during the night, nighttime measurements were divided into two time periods: first, 24:00–04:00, and then 04:00–08:00. Additionally, laboratory and clinical parameters and SSc subtypes were compared between the groups. Results: The ABPM findings were compared between the groups with and without SSc. The non-dipper pattern was significantly more common in the SSc group at all time intervals. The non-dipper pattern was observed in 25.8% of the non-SSc group and 83.9% of SSc patients (p < 0.001). In the period between 24:00 and 04:00, the prevalence was 25.8% in the control group and 71.0% in SSc patients (p < 0.001), and between 04:00 and 08:00, it was 35.5% in the control group and 80.6% in SSc patients (p < 0.001). No significant difference was found in non-dipper patterns between individuals with diffuse and limited cutaneous forms of systemic sclerosis. Conclusions: The non-dipper BP pattern is significantly more common in patients with SSc, indicating the disruption of the circadian rhythm affecting BP. Analysis performed by dividing the night into specific time periods revealed that this deterioration continued throughout the night. The findings highlight the importance of circadian BP monitoring in SSc patients and may contribute to future risk stratification and treatment strategies. Circadian BP analysis in SSc may help to develop strategies that are personalized for these patients and tailored to their physiological rhythm. Full article

Hypertension and blood pressure variability (BPV) are major risk factors for cardiovascular disease (CVD). Single-channel photoplethysmography (PPG) has emerged as a promising daily blood pressure (BP) monitoring tool. However, estimating BP trends presents challenges due to complex temporal dependencies and continuous fluctuations. Traditional methods often address BP prediction as isolated tasks and focus solely on temporal dependencies within a limited time window, which may fall short of capturing the intricate BP fluctuation patterns implied in varying time spans, particularly amidst constant BP variations. To address this, we propose a novel deep learning model featuring a two-stage architecture and a new input structure called contextual cycles. This model estimates beat-to-beat systolic blood pressure (SBP) trends as a sequence prediction task, transforming the output from a single SBP value into a sequence. In the first stage, parallel ResU Blocks are utilized to extract fine-grained features from each cycle. The generated feature vectors are then processed by Transformer layers with relative position encoding (RPE) to capture inter-cycle interactions and temporal dependencies in the second stage. Our proposed model demonstrates robust performance in beat-to-beat SBP trend estimation, achieving a mean absolute error (MAE) of 3.186 mmHg, a Pearson correlation coefficient applied to sequences (${\mathrm{R}}_{\mathrm{seq}}$) of 0.743, and a variability error (VE) of 1.199 mmHg. It excels in steady and abrupt substantial fluctuation states, outperforming baseline models. The results reveal that our method meets the requirements of the AAMI standard and achieves grade A according to the BHS standard. Overall, our proposed method shows significant potential for reliable daily health monitoring. Full article

Aortic dissection (AD) is a highly lethal cardiovascular emergency, and clinical studies have found that a high percentage of AD patients are hypertensive. In previous studies, the AD model was simplified, such as by treating the vessel wall as a single-layer rigid material, ignoring the complex biomechanical factors of the vascular lumen. This study elucidates key biomechanical mechanisms by which hypertension promotes primary AD progression using multiscale modeling. First, based on experimental data from longitudinal and circumferential uniaxial tensile testing of porcine aortic walls (5–7-month-old specimens), a constitutive model of the aortic wall was developed using the Holzapfel–Gasser–Ogden (HGO) framework. The material parameters were calibrated via inverse optimization in ABAQUS-ISIGHT, achieving close alignment with mechanical properties of the human aorta. Using this validated model to define the hyperelastic properties of the aortic wall, a multiphysics coupling platform was constructed in COMSOL Multiphysics 6.2, integrating computational fluid dynamics (CFD) and fluid–structure interaction (FSI) algorithms. This framework systematically quantified the effects of blood pressure (bp) fluctuations on compressive stresses, von Mises stresses, and deformation of the intimal flap within the AD lesion region. With constant blood rheology, elevated blood pressure enhances wall stresses (compressive and von Mises), and intima-media sheet deformation, this can trigger initial rupture tears, false lumen dilation, and branch arterial flow obstruction, ultimately deteriorating end-organ perfusion. Full article

Negative pressure wound therapy (NPWT) is widely recognized for its efficacy in treating diabetic wounds, but the mechanisms involved in the wound healing process remain unclear. By examining changes in blood cytokine levels as molecular signaling precursors, we aim to provide a comprehensive cytokine profile to support adjunctive therapy research and clinical applications. A diabetic mouse wound model was established to compare cytokine profiles between NPWT-treated and standard dressing groups, identifying key signaling candidates that may facilitate wound healing. By integrating normal mouse data with large-scale cytokine analysis, we developed a time-stratified NPWT approach to track acute-phase cytokine fluctuations in diabetic conditions. NPWT did not significantly enhance coagulation-related cytokine expression but effectively reduced inflammation, albeit with a delayed regulatory effect compared to wild-type mice. A one-sided binomial test revealed that NPWT advanced the cytokine expression peak from 16 to 2 h, partially restoring the early healing pattern seen in normal mice and suggesting its potential role in modulating early-stage wound repair. These findings provide novel insights into early cytokine regulation during wound healing and highlight the potential of NPWT to inform therapeutic strategies. This refined monitoring approach may contribute to improved clinical decision-making and support enhanced wound management in diabetic patients. Full article

Low-frequency oscillations of blood components have been observed when the plasma is diluted by crystalloid fluid. The present study explores whether oscillations also occur during the infusion of hyper-oncotic albumin 20%. For this purpose, the hemoglobin-derived plasma dilution, plasma colloid osmotic pressure, and plasma albumin concentration were measured on 15 occasions over 5 h in 72 volunteers. All of them received 3 mL/kg of albumin 20% over 30 min in various clinical settings. Quality checks excluded 35% of the concentration–time curves, leaving 137 for analysis. Fourier transforms applied to the residuals after curve-fitting showed that the dominating frequency was 144 ± 42 min (mean ± SD), corresponding to 0.007 Hz and a wave amplitude of 1.8 ± 0.9%. The highest percentile of the amplitudes corresponded to a “peak-to-peak” variation in the plasma volume by 6%, which corresponds to a fluctuation of 180 mL, or 45% of the maximum volume expansion following the infusion of albumin 20%. Differences between settings (volunteers, surgery, postoperative, and post-burn) were small. In conclusion, oscillations with very low frequency occurred after infusion of albumin 20%. They varied the plasma volume by 3.6% and by up to 6% in the percentile with the highest amplitudes. The oscillations are large enough to affect measurements of cardiovascular function. Full article