Venous Flow Research Articles

Venous Excess Ultrasound for Fluid Assessment in Complex Cardiac Patients With Acute Kidney Injury.

The introduction of point-of-care ultrasound (POCUS) into clinical practice has revolutionized bedside hemodynamic assessment in recent years. POCUS has expanded its utility to include evaluating and grading venous congestion through Doppler analysis of venous blood flow. This innovative technique, VExUS (venous excess ultrasound), comprehensively evaluates venous congestion across multiple sites, including the inferior vena cava (IVC), hepatic vein, portal vein, and intrarenal vasculature. The aim of the current study was to determine whether venous excess ultrasound can help guide fluid therapy in complex patients with acute kidney injury (AKI) in addition to the standard physical examination and imaging. Our current study shows instructive 18 clinical adult cases (enrolled between January 2024 and May 2024) to determine whether venous excess ultrasound can help guide fluid therapy in complex cardiac patients with acute kidney injury, in addition to the standard physical examination and imaging. VExUS was pivotal in guiding fluid therapy in all complex patients with AKI and suspected right ventricular dysfunction. By integrating VExUS findings with clinical data and cardiac ultrasound results, clinicians were able to make patient-favouring decisions regarding fluid management, diuresis, and vasopressor therapy, addressing critical aspects of conditions such as septic shock, heart failure, and acute kidney injury. In our study of VExUSin sick patients with AKI, we concluded that VExUS proved to be a valuable tool for fluid assessment and management. By providing real-time visualization of venous congestion, VExUS allowed for more precise and individualized fluid management strategies. This led to improved decision-making regarding fluid administration and removal, helping to prevent both fluid overload and hypovolemia. Consequently, the use of VExUS contributed to better clinical outcomes in patients with AKI, demonstrating its potential as a critical component in the management of fluid balance in this vulnerable patient population.

Pre-treatment with tocilizumab reduces lipopolysaccharide-induced acute lung injury in biliary cirrhotic rats

Infection-related lipopolysaccharide (LPS) release causes cytokine storm and acute lung injury. Emerging data show that the interleukin 6 (IL-6) inhibitor tocilizumab can improve lung damage in patients with sepsis. This study aimed to investigate the therapeutic effect of tocilizumab on acute lung injury in cirrhotic rats. Biliary cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (BDL). Sham-operated rats served as surgical controls. Tocilizumab was administered on post-operative day 21, and LPS was injected intraperitoneally on day 29. Three hours after LPS injection, hemodynamic parameters, biochemistry data, and arterial blood gas analysis were evaluated, along with measurements of IL-6 and tumor necrosis factor-α (TNF-α). Liver and lung histology was examined, and protein levels were analyzed. LPS administration reduced portal pressure, portal venous flow and cardiac index in the BDL rats. In addition, LPS administration induced acute lung injury, hypoxia and elevated TNF-α and IL-6 levels. Pre-treatment with tocilizumab did not affect hemodynamic and biochemistry data, but it ameliorated lung injury and decreased TNF-α, IL-6, and CD68-positive macrophage infiltration. Moreover, tocilizumab administration improved hypoxia and gas exchange in the BDL rats, and downregulated hepatic and pulmonary inflammatory protein expression. In conclusion, LPS administration induced acute lung injury in biliary cirrhotic rats. Pre-treatment with tocilizumab reduces lung damage and hypoxia, possibly by downregulating inflammatory proteins and reducing IL-6, TNF-α and CD68-positive macrophage recruitment in the lung.

Endovascular Treatment for Renal Vein Embolism by a Renal Calculus After Percutaneous Nephrolithotomy.

This report presents the endovascular strategies adopted to treat a kidney calculus venous embolism after percutaneous nephrolithotomy and the versatility of endovascular techniques to manage even the most unexpected renovascular complications after urological intervention. According to the literature available in PubMed, Cochrane, SciELO, and Science.gov repositories, this is the first case to our knowledge of renal vein calculus embolism as a complication of percutaneous treatment of kidney stones. A 62-year-old woman underwent percutaneous nephrolithotomy to treat a left kidney 2.8-cm staghorn calculi. The stone cracked, leaving a residual fragment in the ureteropelvic junction. Abdominal computed tomography revealed a 0.9-mm extrarenal calculus located inside the left retroaortic renal vein. Calculus was captured using a basket catheter system through a 6F 45-cm sheath positioned in the left common femoral vein (CFV) and accessed by dissection to safely conclude the calculus extraction by venous cut down. The patient was asymptomatically discharged 48 hours after the endovascular procedure, under a rivaroxaban anticoagulation regimen, with no symptoms or renal function impairment until the 6 months of follow-up. The endovascular strategy proposed in this case was effective for calculus rescue and venous flow restoration. This case reinforces the adaptability of endovascular therapy in an unexpected scenario. A potentially life-threatening extremely rare adverse event following a common urological procedure could be treated with minimally invasive hybrid treatment, preserving renal function and maintaining venous vascular patency. This report may add a discussion of procedures to manage similar events and bring to the literature a possible strategy to solve the problem.

Neuro-Ophthalmic Manifestations of Carotid Cavernous Fistulas: A Systematic Review and Meta-Analysis.

Carotid-cavernous fistulas (CCFs) are pathologic, arteriovenous communications between the carotid artery and cavernous sinus. They cause various complex neuro-ophthalmic symptoms by shunting the flow of arterial blood into the venous system. In this study, a systematic review is conducted on the neuro-ophthalmic presentations associated with CCFs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses2020 guidelines were followed during the systematic review. We searched PubMed, Scopus, and Web of Science from inception to December 31, 2023. Articles written in English on patients with confirmed CCFs reporting clinical features, diagnostic modalities, treatment approaches, and outcomes were included. Abstracted data included demography, clinical presentations, venous flow dynamics, trauma history, investigative methodology, approaches to treatment, and outcomes. Overall, 33 studies with a total number of 403 patients were included. The mean age at presentation was 42.99 years for patients with direct CCFs and 55.88 years for those with indirect CCFs. Preponderance was observed in male patients with direct CCFs, constituting 51.56%, while females predominated in those with indirect CCFs, at 56.44%. The clinical symptoms in all patients with CCFs were proptosis in 58 cases (14.39%), conjunctival congestion in 29 patients (7.20%), diplopia in nine patients (2.23%), vision blurring in four patients (0.99%), eyelid swelling in five patients (1.24%), pain in the eye in three patients (0.74%), and an upper lid mass in one patient (0.25%). Endovascular treatments, including coil and Onyx embolization, have been effective in relieving clinical symptoms and arresting the progression of these symptoms. In conclusion, the common clinical features in CCFs usually underline proptosis, congestion, and diplopia, necessitating a comprehensiveneuro-ophthalmological review. Prompt identification of the symptoms of blurred vision is crucial to avoid permanent damage. Lid swelling, ocular pain, and an upper lid mass are less common but equally essential presentations for comprehensive evaluation. The recognition of these variable presentations is essential not only for timely intervention but also for the improvement in patient outcomes, thus emphasizing the role of clinician awareness in managing CCF cases.

Vasorelaxant effect of phenylpropanoids: Methyl eugenol and eugenol in human umbilical cord vein

Methyl-eugenol (ME) and eugenol (EUG) are phenylpropanoids with vasodilatory effects. While EUG's vasorelaxant effect in human umbilical artery (HUA) is known, their action in veins is unclear. This study aimed to evaluate ME and EUG in human umbilical vein (HUV). Isolated HUV underwent tension recordings. ME and EUG caused 100 % relaxation in HUV, with EC50 values corresponding to: 174.3 ± 7.3 and 217.3 ± 6.2 µM for ME and EUG respectively in presence of K+; 362.3 ± 5.4 and 227.7 ± 4.9 µM for ME and EUG respectively and in presence of serotonin (5-HT). It was observed that in presence of BaCl2 and CaCl2 evoked contractions, ME (800 and 1000 µM) and EUG (1000 and 1400 µM) prevent the contractions. In presence of K+ channel blockers it was observed that ME promoted relaxation compared to its control, except in presence of 4-AP, suggesting a possible Ca2+-dependent K+ channel activation for this molecule; EUG increased all EC50 in presence of the K+ blockers except in presence of TEA 1 mM. Greater pharmacological potency was observed for ME. This study highlights natural substances' effects on HUV contractile parameters, suggesting ME and EUG as potential vasodilators in maintaining fetal oxygenation and venous flow during gestational hypertensive syndromes.

Superior vena cava syndrome: presentation of 7 cases and literature review

Superior vena cava syndrome (SVCS) is the result of obstruction of venous flow through the SVC. Mortality due to SVCS is rare (0.3%); however, the median survival in patients with SVCS secondary to malignancy is 6 months. Extrinsic occlusion due to malignancy is the most common cause; however, intraluminal thrombosis secondary to central venous catheters and pacemaker wires represents 30% of cases. The SVC is the main drainage pathway for the head, neck, and upper torso region, so SVCS is characterized by facial and neck edema, dyspnea, and distension of the neck and chest veins. Symptoms vary depending on the severity, location, and speed of onset of the obstruction and the establishment of collateral veins. Diagnosis is based on clinical presentation and imaging studies such as chest angiotomography and digital subtraction venography (gold standard). Regarding treatment, radiation therapy and chemotherapy were considered first-line; however, nowadays endovascular therapy (ET) (angioplasty, stent placement, and catheter-directed thrombus extraction) has demonstrated higher success rates and lower recurrence rates. Surgical diversion is reserved for cases of extensive venous thrombosis or occlusion not amenable to ET. We conducted a literature review and described 7 cases of SVCS treated with successful ET and their main complications at the national cancer institute of Mexico. SVCS is a condition with a diagnostic challenge. Currently, the use of endovascular treatment through angioplasty and stent placement leads to immediate improvement in patients, thus establishing it as first-line treatment.

Serum Lactate Clearance as a Predictive Biomarker for Optimal Graft Perfusion in Living Donor Liver Transplantation

BackgroundThe optimal balance between the graft volume (GV) and portal venous flow (PVF) in living donor liver transplantation (LDLT) is unclear. As lactate is mainly metabolized in the liver, perioperative lactate levels are reportedly a useful biomarker for early graft dysfunction (EGD). The present study analyzed perioperative lactate levels according to the PVF. MethodsThe PVF/GV (mL/min per 100 g GV) of 97 recipients from 1996 to 2022 was retrospectively classified as low (LPVF; PVF/GV ≤ 100, N = 29), moderate (MPVF; PVF/GV 100–250, N = 40), or high (HPVF; PVF/GV > 250, N = 28). Lactate levels were obtained preoperatively (L0), immediately after graft reperfusion (L1), 4 h after reperfusion (L2), and on postoperative day 3 (L3). The lactate clearances were then calculated. ResultsThe lower the PVF/GV ratio, the younger the age at LDLT and the higher the graft-to-recipient weight ratio. The median L2 and L3 in the HPVF group were significantly higher than those in the other groups (p = 0.019 and p = 0.003, respectively). The median ΔL1 in the HPVF group was lower than that in the LPVF and MPVF groups (0.23 vs. 0.50, p < 0.0001 and 0.23 vs. 0.41, p = 0.011, respectively). ΔL1 was negatively correlated with the PVF/GV. Although no patient had EGD, three patients with HPVF with low ΔL1 developed small-for-size syndrome. ConclusionsGraft hyperperfusion may delay the recovery of the graft function and result in poor lactate clearance. The combination of the PVF/GV and lactate clearance may be useful as a prognostic marker for optimal graft perfusion in LDLT. Level of evidenceIV.

Reconstruction of Defects After Oral Cancer Surgery With the Superior Thyroid Artery Perforator Flap.

The superior thyroid artery perforator flap (STAPF) was previously presented as a type of locoregional pedicled flap for lateral facial and temple defects. In this study, we aimed to present our clinical experience with this flap for the reconstruction of soft tissue defects after oral cancer surgery. From February 2019 to December 2022, 24 patients with oral cancers at the School and Hospital of Stomatology,Peking University were included. Among these patients, 10 had cancers located in the tongue, five in the cheek inside the oral cavity, three in the lower gingiva, two in the upper gingiva, two in the floor of the mouth, and two in the palate. All patients were treated with extended tumor resection, neck dissection, and STAPFs to reconstruct the soft tissue defects. The details of the flap, including the flap size, venous flow, vascular pedicle length, the attatched muscle, and operation time were evaluated. The dimensions of the flap skin paddle ranged from 3 cm × 5 cm to 6 × 14 cm. Fourteen patients had a closely concomitant superior thyroid vein perforator. Ten patients had non-closely concomitant superior thyroid veins perforators which retrograde external jugular vein. The vascular pedicle length ranged from 5 to 9 cm. The infrahyoid muscle group or sternocleidomastoid muscle was included in the flaps in three patients. A total of 23/24 flaps were successful. The STAPF is a viable reconstructive option for patients with oral cancers. It has the advantages of being robust, being thin, short operation time, and minor donor site complications. 4 Laryngoscope, 2024.

DANTE-CAIPI Accelerated Contrast-Enhanced 3D T1: Deep Learning-Based Image Quality Improvement for Vessel Wall MRI.

Accelerated and blood-suppressed postcontrast 3D intracranial vessel wall MRI (IVW) enables high-resolution rapid scanning but is associated with low SNR. We hypothesized that a deep-learning (DL) denoising algorithm applied to accelerated, blood-suppressed postcontrast IVW can yield high-quality images with reduced artifacts and higher SNR in shorter scan times. Sixty-four consecutive patients underwent IVW, including conventional postcontrast 3D T1-sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) and delay alternating with nutation for tailored excitation (DANTE) blood-suppressed and CAIPIRINHIA-accelerated (CAIPI) 3D T1-weighted TSE postcontrast sequences (DANTE-CAIPI-SPACE). DANTE-CAIPI-SPACE acquisitions were then denoised by using an unrolled deep convolutional network (DANTE-CAIPI-SPACE+DL). SPACE, DANTE-CAIPI-SPACE, and DANTE-CAIPI-SPACE+DL images were compared for overall image quality, SNR, severity of artifacts, arterial and venous suppression, and lesion assessment by using 4-point or 5-point Likert scales. Quantitative evaluation of SNR and contrast-to-noise ratio (CNR) was performed. DANTE-CAIPI-SPACE+DL showed significantly reduced arterial (1 [1-1.75] versus 3 [3-4], P < .001) and venous flow artifacts (1 [1-2] versus 3 [3-4], P < .001) compared with SPACE. There was no significant difference between DANTE-CAIPI-SPACE+DL and SPACE in terms of image quality, SNR, artifact ratings, and lesion assessment. For SNR ratings, DANTE-CAIPI-SPACE+DL was significantly better compared with DANTE-CAIPI-SPACE (2 [1-2], versus 3 [2-3], P < .001). No statistically significant differences were found between DANTE-CAIPI-SPACE and DANTE-CAIPI-SPACE+DL for image quality, artifact, arterial blood and venous blood flow artifacts, and lesion assessment. Quantitative vessel wall SNR and CNR median values were significantly higher for DANTE-CAIPI-SPACE+DL (SNR: 9.71, CNR: 4.24) compared with DANTE-CAIPI-SPACE (SNR: 5.50, CNR: 2.64) (P < .001 for each), but there was no significant difference between SPACE (SNR: 10.82, CNR: 5.21) and DANTE-CAIPI-SPACE+DL. DL denoised postcontrast T1-weighted DANTE-CAIPI-SPACE accelerated and blood-suppressed IVW showed improved flow suppression with a shorter scan time and equivalent qualitative and quantitative SNR measures relative to conventional postcontrast IVW. It also improved SNR metrics relative to postcontrast DANTE-CAIPI-SPACE IVW. Implementing DL denoised DANTE-CAIPI-SPACE IVW has the potential to shorten protocol time while maintaining or improving the image quality of IVW.

The impact of ankle movements on venous return flow: A comparative study.

To compare the haemodynamic effects of different ankle movements combined ankle and toe movements on the femoral vein of the lower extremity. 28 healthy volunteers participated in the study. Doppler ultrasound was used to measure peak systolic velocity and time-averaged mean velocity of the common femoral vein during ankle dorsiflexion, ankle dorsiflexion with simultaneous toe extension, ankle plantarflexion, and ankle plantarflexion with simultaneous toe flexion. In comparison to the resting state, both ankle alone or ankle combined with toe movement showed statistically significant differences (p < .01). However, there were no significant difference in the velocity of the common femoral vein between ankle alone and ankle combined with toe movement (p > .05). It is noteworthy that dorsiflexion of the ankle resulted in the highest peak velocity of blood flow. The impact of ankle movement, with or without toe movement, the velocity of the common femoral vein is not significantly correlated.

Lobar and Segmental Atrophy of the Liver: Differential Diagnoses and Treatments

Segmental or lobar liver atrophy is a common but not well-understood clinical condition. Hepatic atrophy can be classified into hepatic atrophy secondary to other pathologies and primary segmental hepatic atrophy, which is a benign intrahepatic lesion (pseudotumor) not associated with any other pathology. The pathophysiological mechanisms underlying atrophy can be divided into three main situations: obstruction of biliary outflow, obstruction of the systemic venous outflow, and obstruction of incoming portal venous flow. For what may concern secondary hepatic atrophy, there are many pathologies that could underlie this condition, ranging from benign to intrahepatic malignancies, with particular reference to particularly hepatocellular carcinoma and biliary duct carcinoma. An accurate and prompt differential diagnosis between the various forms and causes of atrophy is important for early identification and adequate treatment of underlying pathologies. A comprehensive review of the literature on the etiology and the radiological and histological characteristics of different types of hepatic atrophy is currently unavailable. Therefore, the aim of this review is to summarize the primary and secondary causes of segmental or lobar liver atrophy (excluding forms involving the entire liver parenchyma) and to provide practical tools for clinical and radiological differential diagnosis.

Trauma patients have reduced ex vivo flow-dependent platelet hemostatic capacity in a microfluidic model of vessel injury.

Trauma is the leading cause of death in individuals up to 45 years of age. Alterations in platelet function are a critical component of trauma-induced coagulopathy (TIC), yet these changes and the potential resulting dysfunction is incompletely understood. The lack of clinical assays available to explore platelet function in this patient population has hindered detailed understanding of the role of platelets in TIC. The objective of this study was to assess trauma patient ex vivo flow-dependent platelet hemostatic capacity in a microfluidic model. We hypothesized that trauma patients would have flow-regime dependent alterations in platelet function. Blood was collected from trauma patients with level I activations (N = 34) within 60 min of hospital arrival, as well as healthy volunteer controls (N = 10). Samples were perfused through a microfluidic model of injury at venous and arterial shear rates, and a subset of experiments were performed after incubation with fluorescent anti-CD41 to quantify platelets. Complete blood counts were performed as well as plasma-based assays to quantify coagulation times, fibrinogen, and von Willebrand factor (VWF). Exploratory correlation analyses were employed to identify relationships with microfluidic hemostatic parameters. Trauma patients had increased microfluidic bleeding times compared to healthy controls. While trauma patient samples were able to deposit a substantial amount of clot in the model injury site, the platelet contribution to microfluidic hemostasis was attenuated. Trauma patients had largely normal hematology and plasma-based coagulation times, yet had elevated D-Dimer and VWF. Venous microfluidic bleeding time negatively correlated with VWF, D-Dimer, and mean platelet volume (MPV), while arterial microfluidic bleeding time positively correlated with oxygenation. Arterial clot growth rate negatively correlated with red cell count, and positively with mean corpuscular volume (MCV). We observed changes in clot composition in trauma patient samples reflected by significantly diminished platelet contribution, which resulted in reduced hemostatic function in a microfluidic model of vessel injury. We observed a reduction in platelet clot contribution under both venous and arterial flow ex vivo in trauma patient samples. While our population was heterogenous and had relatively mild injury severity, microfluidic hemostatic parameters correlated with different patient-specific data depending on the flow setting, indicating potentially differential mechanistic pathways contributing to platelet hemostatic capacity in the context of TIC. These data were generated with the goal of identifying key features of platelet dysfunction in bleeding trauma patients under conditions of flow and to determine if these features correlate with clinically available metrics, thus providing preliminary surrogate markers of physiological platelet dysfunction to be further studied across larger cohorts. Future studies will continue to explore those relationships and further define mechanisms of TIC and their relationship with patient outcomes.

Which one is the best in treating deep venous thrombosis —— percutaneous mechanical thrombectomy, catheter-directed thrombolysis or combination of them?

ObjectiveTo compare the treatment outcomes among percutaneous mechanical thrombectomy (PMT) with AngioJet, Catheter-directed thrombolysis (CDT), and a combination of both.MethodsOne hundred forty nine patients with acute or sub-acute iliac-femoral vein thrombosis accepting CDT and/or PMT were divided into three groups respectively: PMT group, CDT group, PMT + CDT group (PMT followed by CDT). The severity of thrombosis was evaluated by venographic scoring system. Technical success was defined as restored patent deep venous blood flow after CDT and/or PMT. Clinical follow-up were assessed by ultrasound or venography imaging. The primary endpoints were recurrence of DVT, and severity level of post-thrombotic syndrome (PTS) during the follow-up.ResultsTechnical success and immediate clinical improvements were achieved on all patients. The proportion of sub-acute DVT and the venographic scoring in PMT + CDT group were significantly higher than that in CDT group and PMT group (proportion of sub-acute DVT: p = 0.032 and p = 0.005, respectively; venographic scoring: p < 0.001, respectively). The proportion of May-Thurner Syndrome was lower in PMT group than that in CDT and PMT + CDT group (p = 0.026 and p = 0.005, respectively). The proportion of DVT recurrence/stent thrombosis was significantly higher in CDT group than that in PMT + CDT group (p = 0.04). The severity of PTS was the highest in CDT group ( χ2 = 14.459, p = 0.006) compared to PMT group (p = 0.029) and PMT + CDT group (p = 0.006).ConclusionPatients with sub-acute DVT, high SVS scoring and combined May-Thurner Syndrome were recommended to take PMT + CDT treatment and might have lower rate of DVT recurrence/stent thrombosis and severe PTS. Our study provided evidence detailing of PMT + CDT therapy.

An Interesting Case of COPD Exacerbation Presenting with Mixed Features of Intracranial Hypertension and Hypercapnic Encephalopathy

Background: Idiopathic intracranial hypertension (IIH or pseudotumor cerebri) has two major morbidities: papilledema with visual loss and disabling headache. Intracranial Venous Hypertension (IVH) is a fundamental mechanism of IIH. Although traditionally considered limiting to the central nervous system, evidence suggests IIH as a systemic disease associated with cardiorespiratory disorders, which has been far less comprehended. Case Report: A 60-year-old female with Chronic Obstructive Pulmonary Disease (COPD) was admitted for dyspnea and developed a coma with a pH of 7.01 and pCO2 of 158 mmHg. She was intubated and had persistent nuchal rigidity, a brief myoclonus episode with a negative electroencephalogram, and negative CT head studies. A Lumbar Puncture (LP) revealed elevated opening pressure (35 cmH2O) with normal Cerebral Spinal Fluid (CSF) studies. Her nuchal rigidity improved after the removal of 40 mL CSF. The ophthalmology examination the next day after her the large volume LP didn’t show visual loss or papilledema. The patient improved clinically and was extubated two days later. Her echocardiogram showed a dilated right ventricle with pulmonary hypertension. The patient was discharged home. Discussion: IIH is different from hypercapnic encephalopathy and characterized by increased intracranial pressure with papilledema, vision loss, and debilitating headache. Hypercapnia-induced increased intracranial venous flow and pulmonary hypertension-caused elevated central venous pressure with consequent outflow resistance lead to IVH. In hypercapnic encephalopathy, the presentation is mostly cognitive changes. In this case, nuchal rigidity with a negative CT head scan triggered the investigation of IIH. Conclusion: A deep understanding of the relationship between COPD and IIH is vital. There is insufficient evidence to recommend routine eye examinations in COPD patients for papilledema and to conduct a pulmonary function test for a newly diagnosed IIH patient. However, we highly suggest a timely ophthalmology exam prior to performing an LP in COPD patients with suspecting IIH to avoid unnecessary procedures and meanwhile improve clinical outcomes.

The human craniospinal venous system and its influence on postural intracranial pressure: a review.

The cerebral and spinal venous systems have similar functions but unique anatomical and physiological properties. CSF occupies space in the cranial and spinal vaults, is continuously produced, and has many roles, including maintaining a favorable environment for CNS structures. The influence of the cerebrospinal venous system on CSF dynamics has been theorized since the 1940s. Newer studies suggest venous outflow pattern alterations in response to changes in body position. However, the relationship of postural cerebrospinal venous outflow shifts with and their influence on CSF homeostasis is not well understood. The authors searched the published literature related to the anatomy and function of vertebral venous plexus (VVP), CSF, and positional cerebral venous flow characteristics. A comprehensive collection of literature was compiled and reviewed, and the relationship between cerebrospinal and venous system changes and alterations in body positions, with an emphasis on the craniocervical system, is discussed. The VVP is a network of valveless veins extending from the sacrum to the cranium that are interconnected with the cranial dural sinuses. The internal VVP occupies space within the extradural spinal canal and functions to return spinal venous blood to the heart, but it has additional properties, including the capability of bidirectional venous flow, an intraspinal dilatory capacity, and a role in cerebral venous outflow. When one rises to the upright position, CSF shifts toward the spinal canal and force vectors change, leading to reduced intracranial CSF pressure; simultaneously, cerebral venous outflow shifts from the jugular vein to the VVP outflow pathway. The venous outflow shift mechanism and its purpose are poorly understood. The authors review the known physiology of the system, identify gaps in knowledge to direct future research, and propose an interpretation of these data, concluding that position-dependent CSF and cerebrospinal venous shifts are part of a complementary positional craniospinal pressure regulation system that must be kept in balance for optimal CNS function. Current knowledge of the cerebrospinal venous anatomy, dynamic flow characteristics in response to gravity, and the venous system's influence on CSF suggests that the VVP plays a role in influencing CSF pressure, and the authors hypothesize that it plays a role in supporting intracranial pressure in the upright body posture. Further research is needed to better characterize the functional relationship of the VVP to CSF dynamics as well as identify potentially related disease states.

Quantifying and visualizing abdominal hemodynamics in patients with Fontan circulation by 4D phase-contrast flow magnetic resonance imaging at 1.5 T

BackgroundLiver fibrosis has been recognized as a long-term morbidity associated with Fontan circulation (Fontan-associated liver disease, FALD). The pathophysiology of FALD is not completely understood and abnormal flow dynamics may be associated with this condition. Liver hemodynamics can be quantitatively evaluated with four-dimensional phase-contrast flow magnetic resonance imaging (4D PC flow MRI). The study aimed to evaluate suitability of liver 4D PC flow MRI in Fontan patients and relate flow measurements to normal values and FALD severity. Patients and methodsTwenty-two Fontan patients were examined by 4D PC flow MRI at 1.5 Tesla to assess mesenteric, portal, splenic, and hepatic venous blood flow. Severity of FALD was graded based on routine screening, including abdominal ultrasound and laboratory tests. ResultsMedian age was 18.5 (interquartile range, IQR 15.5–20.2) years. FALD was graded as “none or mild” in 16 and as “moderate to severe” in six cases. Ten patients presented at least one feature of portal hypertension (ascites, splenomegaly, or thrombocytopenia). For the entire cohort, blood flow in the superior mesenteric, splenic, and portal vein was lower than reported in the literature. No significant differences were observed in relation to FALD severity. Features of portal hypertension were associated with a higher splenic vein blood flow (0.34 ± 0.17 vs. 0.20 ± 0.07 l/min, p = 0.046). Splenic vein blood flow was negatively correlated to platelet count (r = −0.590, p = 0.005). Conclusions4D PC flow MRI appears suitable to assess liver hemodynamics in Fontan patients and integration into clinical follow-up might help to improve our understanding of FALD.

Improvements in edema and microcirculation in chronic venous insufficiency with Pycnogenol® or elastic compression.

Chronic venous insufficiency (CVI) is the consequence of venous valve reflux and/or venous flow obstruction and resulting venous hypertension in the lower extremities. The aim of this prospective supplement registry study was to evaluate the efficacy of compression stockings or Pycnogenol® in controlling symptoms and edema in CVI and their efficacy on microcirculatory parameters. Two comparable groups of 30 subjects with CVI were observed for 4 months. Elastic compression was less tolerated than Pycnogenol® with 12 subjects being unable to follow the compression routine. No side effects due to supplementation were observed; tolerability of the supplementation was optimal. Ambulatory venous pressure (AVP) and refilling time (RT) at inclusion indicated a significant increase in venous pressure and reflux (refilling time <16 seconds). AVP and RT did not change after 4 months. Microcirculatory and clinical measurements were comparable at inclusion between the 2 groups. After 4 months, skin resting flux (RF) and skin PO<inf>2</inf>-PCO<inf>2</inf> were significantly improved with Pycnogenol® compared to compression (P<0.05). The significant increase in skin PO<inf>2</inf> and the decrease in PCO<inf>2</inf> after Pycnogenol® intake were ascribed to the decrease in the abnormally high skin resting flux, a sign of better perfusion and skin nutritional supply. Pycnogenol® reduced leg volume, on average by 18.3% in the evening compared to 4.4% of reduction with compression (P<0.05) showing an important effect on edema. The venous Clinical Severity Score (VCSS) and the composite symptom score (CSS) decreased significantly in the Pycnogenol® group compared to compression, indicating a better improvement in microcirculatory perfusion and nutritional supply produced by the supplementation of Pycnogenol® in comparison with compression. Pycnogenol® significantly improved microcirculation and clinical symptoms in comparison with compression. The decrease in local oxidative stress (OS) at the distal perimalleolar region with Pycnogenol® was significant in comparison with compression (P<0.05). A lower local OS is an important metabolic indication of a better capillary perfusion with better nutritional exchanges. At the end of the registry study, four small ulcerations and skin breaks in four limbs (between 3 and 5 mm of maximum diameters) were observed in the compression group. No ulcerations or skin breaks were observed in the Pycnogenol® group. Pycnogenol® relieved edema, improved microcirculation in CVI patients and reduced stationary, interstitial fluid in comparison with compression. Most symptoms of CVI are associated with interstitial water retention; the presence of extra fluid in limb tissues alters perfusion and nutrient supply. Pycnogenol® supplementation reduced water and fluid accumulation in CVI limbs and improved microcirculation and local oxidative stress thus showing important anti-edema effects.

Blunt Trauma Induced Closed Femoral Bone Fracture in a Rat Model: Are Vessels Safe to Use for Microsurgery? Further Insight into the Zone of Injury Concept.

The study aims to investigate the zone of injury for major vessels after high-velocity traumas, as it is unclear whether avoiding vascular structures is necessary during microvascular anastomosis or how long it takes for them to be used again. This study uses Doppler ultrasonography and a rat model to evaluate the histopathological changes and flow velocity of major vessels in the zone of injury after high-velocity trauma with closed femoral bone fracture. Osteosynthesis was performed using an intramedullary wire. Samples were collected from day 3 and week 3. The unaffected contralateral side is used as control. Results from arterial and venous flow assessments showed no evidence of ischemia in the extremities. Both arteries and veins were patent in both intervals and on the control side. The evaluation of the vessels showed arterial injury with a slightly reduced arterial flow on day 3 and week 3. The venous flow was slightly reduced on day 3 but not on week 3. Statistically, arterial endothelial injury was higher on day 3 than on week 3 (p = 0.006). Media inflammation was also higher on day 3 (p = 0.06). Arterial endothelization distribution was higher in week 3 (p = 0.006). No significant differences were found in arterial media irregularity, necrosis, platelet aggregation, bleeding, and wall rupture. Venous samples showed no significant differences in any parameter (p < 0.05). High-velocity trauma increases the risk of thrombosis in vessels. Intravascular repair can start on day 2 and continue till week 3 with significant endothelization. Although physiologic findings do not alter arterial or venous flow, histologic findings support vessel injuries leading to potential complications. Microsurgery should be considered out of the injury zone until adequate vessel healing is achieved.

Assessment of cerebrovascular alterations induced by inflammatory response and oxidative–nitrative stress after traumatic intracranial hypertension and a potential mitigation strategy

The rapid perfusion of cerebral arteries leads to a significant increase in intracranial blood volume, exposing patients with traumatic brain injury to the risk of diffuse brain swelling or malignant brain herniation during decompressive craniectomy. The microcirculation and venous system are also involved in this process, but the precise mechanisms remain unclear. A physiological model of extremely high intracranial pressure was created in rats. This development triggered the TNF-α/NF-κB/iNOS axis in microglia, and released many inflammatory factors and reactive oxygen species/reactive nitrogen species, generating an excessive amount of peroxynitrite. Subsequently, the capillary wall cells especially pericytes exhibited severe degeneration and injury, the blood–brain barrier was disrupted, and a large number of blood cells were deposited within the microcirculation, resulting in a significant delay in the recovery of the microcirculation and venous blood flow compared to arterial flow, and this still persisted after decompressive craniectomy. Infliximab is a monoclonal antibody bound to TNF-α that effectively reduces the activity of TNF-α/NF-κB/iNOS axis. Treatment with Infliximab resulted in downregulation of inflammatory and oxidative–nitrative stress related factors, attenuation of capillary wall cells injury, and relative reduction of capillary hemostasis. These improved the delay in recovery of microcirculation and venous blood flow.

Quantitative 2-Dimensionsal Digital Subtraction Venography for Venous Interventions: Validation in Phantom and In Vivo Porcine Models

PurposeTo determine the feasibility of using a 2-dimensional quantitative digital subtraction venography (qDSV) technique that employs a temporally modulated contrast medium injection to quantify blood velocity in phantom, normal, and stenotic porcine iliac vein models. Materials and MethodsBlood velocity was calculated using qDSV following temporally modulated pulsed injections of iodinated contrast medium and compared with Doppler ultrasound (US) measurements (phantom, in-line sensor; in vivo, diagnostic linear probe). Phantom evaluation was performed in a compliant polyethylene tube phantom with simulated venous flow. In vivo evaluation of qDSV was performed in normal (n = 7) and stenotic (n = 3) iliac vein models. Stenoses were created using endovenous radiofrequency ablation, and blood velocities were determined at baseline, after stenosis, after venoplasty, and after stent placement. ResultsIn the phantom model, qDSV-calculated blood velocities (12–50 cm/s) had very strong correlations with US-measured velocities (13–51 cm/s) across a range of baseline blood velocities and injection protocols (slope, 1.01–1.13; R2 = 0.96–0.99). qDSV velocities were similar to US velocities regardless of injection method: (a) custom injector, (b) commercial injector, or (c) hand injection. In the normal in vivo model, qDSV-calculated velocities (5–18 cm/s) had strong correlation (slope, 1.22; R2 = 0.90) with US-measured velocities (3–20 cm/s). In the stenosis model, blood velocities at baseline, after stenosis, after venoplasty, and after stent placement were similar on qDSV and US at all time points. ConclusionsVenous blood velocity was accurately quantified in a venous phantom and in vivo porcine models using qDSV. Intraprocedural changes in porcine iliac vein blood velocity were quantified with qDSV after creation of a stenosis and subsequently treating it with venoplasty and stent placement.