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Background: In the research of coronary artery disease, the precise initial injury that starts the atherosclerotic cascade remains unidentified. Moreover, the mechanisms governing the progression or regression of coronary plaque are not yet fully understood. Based on the concept that the cardiovascular system is a network of pumps and pipes, could fluid mechanics principles and practices elucidate the question of atherosclerosis using flow dynamics images from a novel angiographic technique, focusing on antegrade and retrograde flows and their collisions in iliac and coronary arteries? Methods: From January 2023 to May 2024, coronary angiograms of all hemodynamically stable patients with stable or unstable angina were screened. The angiograms displaying either no lesions (normal) or mild-to-moderate lesions were selected. Each patient underwent an evaluation of flow dynamics and arterial phenomena in both iliac and right coronary arteries. For each artery, data were categorized based on the following parameters: laminar versus non-laminar flow, presence versus absence of collisions, and presence versus absence of retrograde flow. Additionally, in two sub-studies, we analyzed the relationship between retrograde flow and blood pressure, and artificial intelligence algorithms were used to detect the retrograde flow in the right coronary artery. Results: A total of 95 patients were screened, and 51 were included in this study. The results comprised quantitative data (prevalence of laminar flows, collisions, and retrograde flows) and qualitative data (morphological characteristics of antegrade laminar flow, retrograde contrast flow, and instances of flow collision). The results showed that in the iliac artery, laminar flow was observed in 47.06% (24/51) of cases, with collisions noted in 23.53% (12/51). Retrograde flow was present in 47.06% (24/51) of cases, and notably, 75% (18/24) of these cases were associated with uncontrolled diastolic blood pressure (DBP) above 80 mmHg (p < 0.001). Conversely, in the RCA, laminar flow was observed in 54.9% (28/51) of cases, with collisions noted in only 3.92% (2/51). Retrograde flow was identified in 7.84% (4/51) of cases, and all these cases (100%, 4/4) were associated with uncontrolled systolic blood pressure (SBP) above 120 mmHg, though statistical significance was not reached due to the small sample size (p > 0.05). Conclusions: Based on the concept that the cardiovascular system is a network of pumps and pipes, this research methodology provides intriguing insights into arterial flow behaviors by integrating fluid mechanics practices with novel angiographic observations. The preliminary results of this study identified laminar flow as the predominant pattern, with retrograde flow and collisions occurring infrequently. The implications of vortex, collision, and disorganized flow highlight potential mechanisms for endothelial damage and atherosclerosis initiation. Moreover, the correlation with blood pressure underscores the critical role of hypertension management in preventing adverse hemodynamic events. Future directions include refining imaging techniques and further exploring the mechanistic links between flow dynamics and vascular pathophysiology to enhance diagnostic and therapeutic strategies for cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Background: In the research of coronary artery disease, the precise initial injury that starts the atherosclerotic cascade remains unidentified. Moreover, the mechanisms governing the progression or regression of coronary plaque are not yet fully understood. Based on the concept that the cardiovascular system is a network of pumps and pipes, could fluid mechanics principles and practices elucidate the question of atherosclerosis using flow dynamics images from a novel angiographic technique, focusing on antegrade and retrograde flows and their collisions in iliac and coronary arteries? Methods: From January 2023 to May 2024, coronary angiograms of all hemodynamically stable patients with stable or unstable angina were screened. The angiograms displaying either no lesions (normal) or mild-to-moderate lesions were selected. Each patient underwent an evaluation of flow dynamics and arterial phenomena in both iliac and right coronary arteries. For each artery, data were categorized based on the following parameters: laminar versus non-laminar flow, presence versus absence of collisions, and presence versus absence of retrograde flow. Additionally, in two sub-studies, we analyzed the relationship between retrograde flow and blood pressure, and artificial intelligence algorithms were used to detect the retrograde flow in the right coronary artery. Results: A total of 95 patients were screened, and 51 were included in this study. The results comprised quantitative data (prevalence of laminar flows, collisions, and retrograde flows) and qualitative data (morphological characteristics of antegrade laminar flow, retrograde contrast flow, and instances of flow collision). The results showed that in the iliac artery, laminar flow was observed in 47.06% (24/51) of cases, with collisions noted in 23.53% (12/51). Retrograde flow was present in 47.06% (24/51) of cases, and notably, 75% (18/24) of these cases were associated with uncontrolled diastolic blood pressure (DBP) above 80 mmHg (p < 0.001). Conversely, in the RCA, laminar flow was observed in 54.9% (28/51) of cases, with collisions noted in only 3.92% (2/51). Retrograde flow was identified in 7.84% (4/51) of cases, and all these cases (100%, 4/4) were associated with uncontrolled systolic blood pressure (SBP) above 120 mmHg, though statistical significance was not reached due to the small sample size (p > 0.05). Conclusions: Based on the concept that the cardiovascular system is a network of pumps and pipes, this research methodology provides intriguing insights into arterial flow behaviors by integrating fluid mechanics practices with novel angiographic observations. The preliminary results of this study identified laminar flow as the predominant pattern, with retrograde flow and collisions occurring infrequently. The implications of vortex, collision, and disorganized flow highlight potential mechanisms for endothelial damage and atherosclerosis initiation. Moreover, the correlation with blood pressure underscores the critical role of hypertension management in preventing adverse hemodynamic events. Future directions include refining imaging techniques and further exploring the mechanistic links between flow dynamics and vascular pathophysiology to enhance diagnostic and therapeutic strategies for cardiovascular diseases.

When returning blood to the pulmonary artery (PA), the inflow jet interferes with local hemodynamics. We investigated the consequences for several connection scenarios using transient computational fluid dynamics simulations. The PA was derived from CT data. Three aspects were varied: graft flow rate, anastomosis location, and inflow jet path length from anastomosis site to impingement on the PA wall. Lateral anastomosis locations caused abnormal flow distribution between the left and right PA. The central location provided near-physiological distribution but induced higher wall shear stress (WSS). All effects were most pronounced at high graft flows. A central location is beneficial regarding flow distribution, but the resulting high WSS might promote detachment of local thromboembolisms or influence the autonomic nervous innervation. Lateral locations, depending on jet path length, result in lower WSS at the cost of an unfavorable flow distribution that could promote pulmonary vasculature changes. Case-specific decisions and further research are necessary. [ABSTRACT FROM AUTHOR]

Background and Purpose: The Facial Artery Musculomucosal (FAMM) flap for reconstruction of oral cavity defects is being popularized in recent years due to its obvious advantages. The aim of our study is to evaluate the cases operated at our institute for the reconstruction of oral cavity defects using FAMM flap and assess their outcomes. Method: In this retrospective study, we included all patients in whom the FAMM flap was used to reconstruct oral cavity defects operated at our institute from January 2017 to December 2020. From the available records, patients' data like age, sex, diagnosis, treatment plan, complications, flap viability, and need for pedicle revision were retrieved and tabulated. Results: FAMM flap was used in ten patients (8 male, 2 female) with ages ranging from 40 to 54 years. In six patients with superior defects e.g., maxilla/palate, retrograde FAMM flap was used and in the other 4 patients with inferior defects e.g., tongue/ floor of the mouth, antegrade FAMM flap was used. None of the patients developed complications like flap failure/necrosis or dehiscence. The donor site healed uneventfully in all patients. Conclusion: FAMM flap offers various advantages for oral cavity reconstruction including mucosa reconstruction with alike mucosal tissue, muscle portion providing bulk, minimal donor site morbidity along with easier harvesting approach. There are no associated significant long-term complications if the technique is properly followed. FAMM should be considered a viable option for the reconstruction of a variety of oral cavity defects. [ABSTRACT FROM AUTHOR]

Purpose: Internal thoracic veins are increasingly used as recipient's vessels in chest wall reconstructive surgery due to their predictable anatomy and to the possibility to make a double venous anastomosis, exploiting the retrograde flow within them. Over the years, retrograde flow had been explained by the absence of valves in internal thoracic veins, which have been found recently instead. Therefore, our aim is to analyze the retrograde flow and its relationship with valves in the internal thoracic veins. Methods: We evaluated 32 internal thoracic veins of 16 fresh-frozen specimens with undamaged thoracic cages by dynamic analysis focused on retrograde flow assessment through a partial external circulation system obtained cannulating the subclavian veins. Gross anatomical and morphological evaluations about the presence of valves and their pattern were then made. Results: Efficient, partial, and absent retrograde flow was, respectively, found in 17/30, 8/30 and ITVs and 5/30 internal thoracic veins. Following Arnez's classification, 20/32 Type I and 12/32 Type II internal thoracic veins were identified. Valves were observed in 10/16 specimens (62.50%) corresponding to 36.67% of examined veins (11/30). Three valves were found between the 2nd intercostal space and 12 valves in the 3rd intercostal space. 13/15 valves were bicuspid, 2/15 tricuspid. A significant correlation (p < 0.001) between the retrograde flow and the presence of valves in internal thoracic veins was observed. Conclusion: Our study suggests a possible influence of the presence and the number of valves in the efficient retrograde flow of the internal thoracic veins, suggesting that, especially for more complex cases, a preoperative or intraoperative evaluation of the chest wall drainage should be recommended. [ABSTRACT FROM AUTHOR]

In the context of development, tissue homeostasis, immune surveillance, and pathological conditions such as cancer metastasis and inflammation, migrating amoeboid cells commonly form protrusions called blebs. For these spherical protrusions to inflate, the force for pushing the membrane forward depends on actomyosin contraction rather than active actin assembly. Accordingly, blebs exhibit distinct dynamics and regulation. In this review, we first examine the mechanisms that control the inflation of blebs and bias their formation in the direction of the cell’s leading edge and present current views concerning the role blebs play in promoting cell locomotion. While certain motile amoeboid cells exclusively form blebs, others form blebs as well as other protrusion types. We describe factors in the environment and cell-intrinsic activities that determine the proportion of the different forms of protrusions cells produce.

Objective: To report a rare event of a retrograde flow of cement leakage during balloon kyphoplasty and discuss the possible mechanism. Methods: We present a 55-year-old male patient, who underwent a 4-level balloon kyphoplasty for Langerhans histiocytosis that had spread to the spine. With the patient prone under general anesthesia, intrathoracic pressure was raised as a precaution measure to prevent cement embolic complications as a protocol reported elsewhere. Results: During the last vertebral body procedure (L1), cement leakage was noticed to flow downward in a retrograde fashion into the segmental vertebral vein and the procedure was immediately discontinued. Cement leak did not follow the predictable upward blood flow through the anterior or lateral segmental vein into the vena cava, but instead, the cement followed a retrograde downward path into the Batson's vein. No adverse cardiopulmonary effect was observed. Evidence of pulmonary cement embolism was detected in a routine thoracic computed tomography six week later. Conclusion: To our knowledge this is the first case in the English-speaking literature to highlight a retrograde cement intravascular flow most likely as a result of increased intrathoracic pressure. [ABSTRACT FROM AUTHOR]

Median arcuate ligament syndrome (MALS) is a rare condition in which the median arcuate ligament (MAL) exerts external compression on the celiac trunk. Most cases are asymptomatic and diagnosed incidentally on radiographic imaging; however, some patients may experience gastrointestinal (GI) symptoms related to foregut ischemia and/or celiac neuropathy. In the following case, we present a patient with hemorrhagic peptic ulcer disease of the duodenum, which resulted in episodes of hemodynamic instability requiring multiple blood transfusions. Upon attempted transarterial angioembolization of the gastroduodenal artery (GDA), celiac stenosis and retrograde arterial flow from the superior mesenteric artery confirmed the presence of MALS. This rendered GDA angioembolization a contraindication, as the GDA became the dominant arterial supply for the distal celiac organs. The patient then received open surgical MAL release with concurrent surgical ligation of the hemorrhaging duodenal artery, which resolved his symptoms without the need for further intervention., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Almaguer et al.)

Increased regurgitant blood flow has been linked to endocardial cushion defects and resultant congenital heart diseases (CHDs). Prenatal alcohol exposure (PAE) has been shown to alter early blood flow resulting in abnormal endocardial cushions and CHDs. Compounds, including folic acid (FA), mitigate PAE effects and prevent CHDs, but few studies have assessed their effects on blood flow. We modeled binge drinking in quail embryos at gastrulation. Embryos were exposed to ethanol alone, FA (3.2 µg/egg) alone, and the two simultaneously. We quantified in cardiac looping stages (equivalent to 4wk of human gestation), the regurgitant blood flow with Doppler optical coherence tomography (OCT) and endocardial cushion volumes using OCT imaging. Incidences of abnormal body curvature and heart rates were also measured. Embryos exposed to ethanol showed significantly increased regurgitant blood flow compared with controls, whereas embryos given FA with ethanol had significantly reduced regurgitant blood flow but without returning to control levels. Ethanol exposure led to significantly smaller, abnormal endocardial cushions, and the addition of FA improved their size, but they remained smaller than controls. Abnormal body curvatures after PAE were reduced in incidence but not fully prevented by FA. FA supplementation partially alleviated PAE-induced abnormal cardiovascular function and morphology. Normal blood flow and endocardial cushions are both required to produce a healthy four-chambered heart. These findings support that FA supplementation should begin early in pregnancy to prevent heart as well as neural tube defects. Investigations into the efficacy of combinations of compounds to prevent PAE-induced defects are warranted. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the impact of compliance with anatomical guidelines on outcomes of endovascular aortic aneurysm repair using "bell-bottom" stent grafts (BBSGs). Methods: This is a retrospective review from January 1999 to May 2012 of patients who underwent endovascular infrarenal abdominal aneurysm repair and whose iliac limbs were greater than 18 mm in diameter. Computed tomography angiography was utilized for compliance with anatomical guidelines as stated in manufacturer's instructions for use (IFU). The primary outcome observed was iliac limb events. The secondary outcome observed was the need for re-intervention due to BBSG failure. Results: Of the 376 BBSGs, 55 (15%) in 27 patients met IFU. Aneurysm exclusion was achieved in all patients. The mean follow-up was 44 ± 30 months. Twenty-eight patients (11%) had 29 iliac limb events (12 type 1b endoleaks, 4 aneurysm sac growth, 4 stenosis/kink, 4 retrograde migrations, 2 component separations, 2 ruptures and 1 limb occlusion); all among patients treated outside of IFU (p < 0.04). The rate of aneurysm sac enlargement was similar between both groups, at 56%, respectively, between those treated within and those treated outside of IFU. On multivariate regression analysis, larger common iliac artery (CIA) (HR 1.088, 95% CI 1.016–1.166, p = 0.016), greater CIA tortuosity (HR 2.352, 95% CI 1.004–5.509, p = 0.048) and limbs with more than two characteristics that did not meet IFU criteria (HR 3.84, 95% CI 1.15–12.83, p = 0.03) were associated with higher rates of BBSG events and re-interventions. Conclusions: BBSGs effectively seal ectatic CIAs. But rates of iliac limb events and re-interventions are higher among patients who do not meet IFU criteria. The larger CIA diameter, the greater CIA tortuosity and more than two criteria not met by IFU were associated with BBSG failure and re-intervention. [ABSTRACT FROM AUTHOR]

Background  Additional second vessels may be required to handle multiple flaps used to add breast volume, boost blood flow for supercharging, or use salvage recipient vessels. In these situations, retrograde internal mammary vessel flow can be used although this causes doubts and concerns. Patients and Methods  Forty sides of the chests of 20 fresh cadavers with intact thoracic cages and internal mammary veins (IMV) were used in the study. IMV valve numbers and locations were checked, and the bifurcation was confirmed. A retrograde fluorescent angiography and a saline infusion test were followed to confirm flow direction. Results  Twenty-eight vessels were identified in 40 sides of the chest; of them, 45% had no valves. A mean 0.7 valves per chest side were identified; 23 (82.1%) of 28 valves were located above the second intercostal space (ICS). A mean 1.76 communicating veins were found between the IMV bifurcation. In all cadavers, a crossing vein connecting the left and right medial IMV was confirmed just below the xiphoid process. Fluorescent angiography and a saline infusion test proved that the retrograde flow was caudal through the bifurcated IMV to the communicating, intercostal, and crossing veins. Conclusion  The IMV valve was present in 55% of our subjects and located concentrically above the second ICS level. It is highly unlikely that the retrograde flow was disturbed because the retrograde anastomosis level was below the second ICS. Furthermore, the bifurcation, intercostal, and crossing veins across the xiphoid process enabled valve-less detour flow. Thus, retrograde IMV flow is considered safe. [ABSTRACT FROM AUTHOR]

The orchestrated assembly of actin and actin-binding proteins into cytoskeletal structures coordinates cell morphology changes during migration, cytokinesis, and adaptation to external stimuli. The accurate and unbiased visualization of the diverse actin assemblies within cells is an ongoing challenge. We describe here the identification and use of designed ankyrin repeat proteins (DARPins) as synthetic actin binders. Actin-binding DARPins were identified through ribosome display and validated biochemically. When introduced or expressed inside living cells, fluorescently labeled DARPins accumulated at actin filaments, validated through phalloidin colocalization on fixed cells. Nevertheless, different DARPins displayed different actin labeling patterns: some DARPins labeled efficiently dynamic structures, such as filopodia, lamellipodia, and blebs, while others accumulated primarily in stress fibers. This differential intracellular distribution correlated with DARPin-actin binding kinetics, as measured by fluorescence recovery after photobleaching experiments. Moreover, the rapid arrest of actin dynamics induced by pharmacological treatment led to the fast relocalization of DARPins. Our data support the hypothesis that the localization of actin probes depends on the inherent dynamic movement of the actin cytoskeleton. Compared to the widely used LifeAct probe, one DARPin exhibited enhanced signal-to-background ratio while retaining a similar ability to label stress fibers. In summary, we propose DARPins as promising actin-binding proteins for labeling or manipulation in living cells.

Microchannels often serve as highways for cancer migration, and their topology largely determines the migration efficiency. Curvature, a topological parameter in biological systems, has recently been reported to be efficient in guiding cell polarization and migration. Curvature varies widely along curved microchannels, while its influence on cell migration remains elusive. Here, we recapitulated the curved microchannels, as observed in clinical tumor tissues with hydrogels, and studied how cancer cells respond to curvature. We found that cells bend more significantly in a larger curvature and exhibit less spreading as well as lower motility. The underlying mechanism is probably based on the hindrance of the movement of cytoskeletal molecules at the curved microchannel walls. Collectively, our results demonstrated that the accelerated actin retrograde flow rate under local curvature has an effective negative regulation on cell motility and morphology, leading to shortened and bent cell morphologies as well as hampered cell migration efficiency.

Retrograde perfusion may occur during disease, surgery or extracorporeal circulation. While it is clear that endothelial cells sense and respond to changes in blood flow, the consequences of retrograde perfusion are only poorly defined. Similar to shear stress or disturbed flow, retrograde perfusion might result in vasomotor responses, edema formation or inflammation in and around vessels. In this study we investigated in rats the effects of retrograde perfusion in isolated systemic vessels (IPV) and in pulmonary vessels of isolated perfused lungs (IPL). Anterograde and retrograde perfusion was performed for 480 min in IPV and for 180 min in the IPL. Perfusion pressure, cytokine levels in perfusate and bronchoalveolar lavage fluid (BALF), edema formation and mRNA expression were studied. In IPV, an increased perfusion pressure and initially also increased cytokine levels were observed during retrograde perfusion. In the IPL, increased edema formation occurred, while cytokine levels were not increased, though dilution of cytokines in BALF due to pulmonary edema cannot be excluded. In conclusion, effects of flow reversal were visible immediately after initiation of retrograde perfusion. Pulmonary edema formation was the only effect of the 3 h retrograde perfusion. Therefore, further research should focus on identification of possible long-term complications of flow reversal.

We investigate the flow past two transcatheter aortic valves (TAVs) and one severely calcified valve in an anatomically realistic aorta geometry to evaluate the ability of the TAVs to establish a healthier aortic flow compared to a diseased case. Velocity measurements of pulsatile flow are carried out using the 3D-particle tracking velocimetry technique. We present a novel approach based on the Smagorinsky model to assess the important subvoxel-scale (here smaller than 750 μ m) shear stress contribution that is usually unavailable in experiments. Both TAV models feature a small retrograde flow of about 5% of the stroke volume and a lower number of coherent vortical structures. Turbulence past the TAVs is strongly suppressed as evidenced by the lower levels of turbulent kinetic energy even though the newer generation TAV performs better than the old one. Also lysis indices are substantially reduced in both models. The new generation TAV displays a slightly higher risk for thrombogenicity due to longer exposure times. We anticipate that our new approach to include turbulence and shear stress related quantities may help to validate the design of cardiovascular devices. [ABSTRACT FROM AUTHOR]

Introduction: Flow alteration can affect endothelial function, which is associated with cardiovascular disease (1). Peripheral arterial flow is determined by the pressure gradient between the proximal and distal points in the vessel. The pressure gradient could be a potential alternative for assessing vascular health. Methods: Anterograde and retrograde brachial artery pressure gradients were estimated from the positive and negative components of the first derivative of the non-invasive beat-to-beat brachial pressure waveform and carotid-radial pulse wave velocity in 90 patients with ischemic heart disease. Retrograde flow was assessed using a pulsedwave doppler. Cardiovascular disease severity was evaluated using Single Positron Emission Computerized Tomography imaging and quantified as %perfusion defect from the summed stress score, using a 20-segment cardiac model. Endothelial function was assessed by ultrasound-based measurement of flow-mediated dilation (FMD). Results: A significant association was seen between retrograde flow velocity (RBFVAUC and RBFVpeak) and retrograde pressure gradient (Rt-dP/dxAUC and Rt-dP/dxpeak) (r = 0.34, p = 0.003 and r = 0.38, p = 0.0006 respectively). RBFVAUC and Rt-dP/dxpeak showed a significant negative correlation with %FMD (r = - 0.24, p = 0.026 and r = - 0.22, p = 0.047 respectively). Ratio of retrograde to total pressure gradient (Rt-dP/dxpeak/(At-dP/dxpeak + Rt-dP/dxpeak) showed a significant positive correlation with %perfusion defect (r = 0.24, p = 0.025). This association was independent of aortic systolic pressure, age, heart rate and total cholesterol. Conclusion: Brachial pressure gradient is related to pathophysiological alterations in arterial flow and can be incorporated into developing an alternative method for assessing endothelial dysfunction and cardiovascular disease severity. Anterograde and Retrograde brachial pressure gradients were calculated separately from the peak and mean of the first derivative of the brachial pressure waveform and the carotid-radial pulse wave velocity. [ABSTRACT FROM AUTHOR]

Objectives: To test the hypothesis that variants in cerebrovascular anatomy will affect the number of patients demonstrating a plausible retrograde embolization mechanism from plaques in the descending aorta (DAo).Methods: Thirty-five patients (aged 63 ± 17 years) with cryptogenic stroke underwent 4D flow MRI for the assessment of aortic 3D blood flow and MR angiography for the evaluation of circle of Willis, posterior circulation, and aortic arch architecture. In patients with proven DAo plaque, retrograde embolization was considered a potential mechanism if retrograde flow extended from the DAo to a supra-aortic vessel supplying the cerebral infarct territory.Results: Retrograde embolization with matching cerebral infarct territory was detected in six (17%) patients. Circle of Willis and aortic arch variant anatomy was found in 60% of patients, leading to reclassification of retrograde embolization risk as present in three (9%) additional patients, for a total 26% of cryptogenic stroke patients.Conclusion: 4D flow MRI demonstrated 26% concordance with infarct location on imaging with retrograde diastolic flow into the feeding vessels of the affected cerebral area, identifying a potential etiology for cryptogenic stroke. Our findings further demonstrate the importance of cerebrovascular anatomy when determining concordance of retrograde flow pathways with vascular stroke territory from DAo plaques.Key Points: • Retrograde embolization from descending aortic plaques constitutes a plausible etiology in cryptogenic stroke. • Common variants of cerebrovascular anatomy are important in determining retrograde embolization mechanism. • Variant cerebrovascular anatomy can link retrograde flow pathways with vascular stroke territory. [ABSTRACT FROM AUTHOR]

Mechanical circulatory support devices (MCSDs) have gained widespread clinical acceptance as an effective heart failure (HF) therapy. The concept of harnessing the kinetic energy (KE) available in the forward aortic flow (AOF) is proposed as a novel control strategy to further increase the cardiac output (CO) provided by MCSDs. A complete mathematical development of the proposed theory and its application to an example MCSDs (two-segment extra-aortic cuff) are presented. To achieve improved device performance and physiologic benefit, the example MCSD timing is regulated to maximize the forward AOF KE and minimize retrograde flow. The proof-of-concept was tested to provide support with and without KE control in a computational HF model over a wide range of HF test conditions. The simulation predicted increased stroke volume (SV) by 20% (9 mL), CO by 23% (0.50 L/min), left ventricle ejection fraction (LVEF) by 23%, and diastolic coronary artery flow (CAF) by 55% (3 mL) in severe HF at a heart rate (HR) of 60 beats per minute (BPM) during counterpulsation (CP) support with KE control. The proposed KE control concept may improve performance of other MCSDs to further enhance their potential clinical benefits, which warrants further investigation. The next step is to investigate various assist technologies and determine where this concept is best applied. Then bench-test the combination of kinetic energy optimization and its associated technology choice and finally test the combination in animals. [ABSTRACT FROM AUTHOR]

Background: Retrograde brain embolization from complex plaques of the proximal descending aorta (DAo) has been identified as a new potential mechanism of stroke. Our purpose was to identify predictors of increased retrograde aortic blood flow indicating an elevated risk of brain embolization from the DAo. Methods: A total of 485 patients with acute ischemic stroke were prospectively included and underwent transesophageal echocardiography. Blood flow velocities in the proximal DAo were studied using 2D pulse-wave Doppler ultrasound. Velocity--time integrals (VTI) were calculated for antegrade and retrograde velocity directions. The ratio (VTIretrograde /VTIantegrade) was used to estimate retrograde flow extent. Associations between patient demographics, cardiovascular risk factors, echocardiographic parameters, and VTI ratio were analyzed using multivariate linear regression. Results: Retrograde blood flow in the DAo occurred in all patients. Velocity profiles in the proximal DAo were as follows (mean ± SD): VTIantegrade = 21.1 ± 6.5, VTIretrograde = 11.0 ± 3.6, and VTIratio = 0.54 ± 0.16. Diameter ( r = 0.25, p < 0.001), presence of complex plaques ( r = 0.12, p = 0.007), and reduced strain of the DAo ( r = -0.23, p < 0.001) had significant partial effects in a predictor model based on predefined variables, which predicted 26% (adjusted R² = 0.26) of the variance in VTI ratio . A unit increase in the DAo diameter was associated with a 2% increase in VTIratio (95% CI 1-2.8%, p < 0.001). Presence of complex plaques increased VTI ratio by 7% (95% CI 2-13%, p = 0.007) and an increase in strain by 0.1 indicated a decrease in VTI ratio by about 11% (95% CI 6.2-15.5%, p < 0.001). Complex atheroma was found in the proximal DAo of 79 subjects, of which 40 (50.6%) had a VTIratio above average (VTIratio ≥ 0.54) compared to 87 of 261 (33.3%) patients without any complex plaques ( p < 0.001). Twenty-five of 79 (31.7%) patients with complex DAo plaques had a VTIratio ≥ 0.60, which indicates a high likelihood of retrograde path line length of ≥ 3 cm and thus increased risk of retrograde cerebral embolization. Stroke etiology of those 25 patients was determined in 13 and cryptogenic in 12 cases. Conclusions: Retrograde blood flow in the DAo was found in all stroke patients. However, it increased further in patients with concomitant complex plaques, low strain, and/ or large aortic diameter, that is, in those with atherosclerosis of the DAo. Accordingly, such patients may be predisposed to retrograde embolization in case of occurrence of a complex plaque in proximity to a brain-supplying artery. [ABSTRACT FROM AUTHOR]

Summary Actin and myosin II play major roles in cell migration. Whereas pseudopod extension by actin polymerization has been intensively researched, less attention has been paid to how the rest of the actin cytoskeleton such as the actin cortex contributes to cell migration. In this study, cortical actin and myosin II filaments were simultaneously observed in migrating Dictyostelium cells under total internal reflection fluorescence microscopy. The cortical actin and myosin II filaments remained stationary with respect to the substratum as the cells advanced. However, fluorescence recovery after photobleaching experiments and direct observation of filaments showed that they rapidly turned over. When the cells were detached from the substratum, the actin and myosin filaments displayed a vigorous retrograde flow. Thus, when the cells migrate on the substratum, the cortical cytoskeleton firmly holds the substratum to generate the motive force instead. The present studies also demonstrate how myosin II localizes to the rear region of the migrating cells. The observed dynamic turnover of actin and myosin II filaments contributes to the recycling of their subunits across the whole cell and enables rapid reorganization of the cytoskeleton.

Vesicoureteral reflux (VUR) is defined as retrograde flow of urine from the bladder to the ureter. It is usually asymptomatic but commonly found in children with urinary tract infection (UTI). The prevalence is about 1-2% in general pediatric population.1 However, the prevalence in children with UTI is much higher, reaching 30-57%.1,2 Similar prevalence (45.8%) is also reported in CiptoMangunkusumo Hospital. 3