In silico analyses of blood flow and oxygen transport in human micro-veins and valves

BACKGROUND: Almost 95% of the venous valves are micron scale found in veins smaller than 300μm diameter. The fluid dynamics of blood flow and transport through these micro venous valves and their contribution to thrombosis is not yet well understood or characterized due to difficulty in making direct measurements in murine models. OBJECTIVE: The unique flow patterns that may arise in physiological and pathological non-actuating micro venous valves are predicted. METHODS: Computational fluid and transport simulations are used to model blood flow and oxygen gradients in a microfluidic vein. RESULTS: The model successfully recreates the typical non-Newtonian vortical flow within the valve cusps seen in preclinical experimental models and in clinic. The analysis further reveals variation in the vortex strengths due to temporal changes in blood flow. The cusp oxygen is typically low from the main lumen, and it is regulated by systemic venous flow. CONCLUSIONS: The analysis leads to a clinically-relevant hypothesis that micro venous valves may not create a hypoxic environment needed for endothelial inflammation, which is one of the main causes of thrombosis. However, incompetent micro venous valves are still locations for complex fluid dynamics of blood leading to low shear regions that may contribute to thrombosis through other pathways.

A rare case of ovarian torsion in a pregnant patient

Torsion of the ovary is the total or partial rotation of the adnexa around its vascular axis or pedicle. It is an uncommon cause of acute abdominal pain in females, and it is a gynecologic emergency. The majority of the cases present in the pregnant (22.7%) than in non-pregnant (6.1%) women. Diagnostic delay can result in loss of the ovary. This twisting initially obstructs venous flow, which causes engorgement and edema. The engorgement can progress until arterial flow is also compromised, leading to ischemia and infarction. The increased use of ovarian stimulation and assisted reproductive technology has led to an increase in the risk of adnexal torsion, particularly in pregnant women or women with ovarian hyperstimulation syndrome (OHSS). The differential diagnosis of adnexal torsion is particularly difficult in combination with OHSS or pregnancy, as abdominal pain, nausea and vomiting can be presenting symptoms of hyperstimulation or pregnancy as well. Here, we report a case of ovarian torsion occurring in pregnancy in which diagnostic delay occurred due to confusion with OHSS leading to oophorectomy. Fertility conservation may have been possible in case of earlier diagnosis and prompt treatment.

Versatility of Vein Grafts in Hand Neurovascular Reconstruction – Clinical Cases and Literature Review

Injuries to the upper limb may determine unexpected simple or complex soft tissue defects, due to different types of underlying injury mechanism, clean cut/stabs, crushing, torsion, avulsion or mixed types, which pose a challenge for the reconstructive surgeon. Ideally, all arterial, venous and nervous lesions, in the distal upper limb should be repaired in an end-to-end technique, outside of injury zones, with healthy ends, in a tension free manner. However, situations arise where, either a tension-free repair is not possible, or a considerable defect is met, often representing a challenge to the surgeon. Therefore, a timely decision is imposed in order to find the most favorable approach to restore limb or segment perfusion, ensuring efficient venous return, as well as providing a sensate repair. Usage of vein grafts represents an essential tool comprised in the reconstructive surgeon’s armamentarium, with high versatility in nerve, arterial and venous reconstruction. Not only does it provide an ideal solution, with high adaptability to each case, but it also may enhance short- and long-term outcome, offering an optimal reconstructive option in any upper limb trauma situation, regardless of etiology. We aim to describe our therapeutic strategies in a series of challenging trauma cases involving digital structures from the upper limb. Interposed vein grafts were used to re-stablish sensate function in a patient with a collateral digital nerve defect, but also to bridge vital digit arterial defect in a torsion-avulsion thumb amputation, as well as re-establishing venous flow in patients with Urbaniak II finger degloving injury.

Predictors of Exercise Capacity in Dilated Cardiomyopathy with Focus on Pulmonary Venous Flow Recorded with Transesophageal Eco-Doppler

The aim of this study was to clarify the relative contribution of elevated left ventricle (LV) filling pressure (FP) estimated by pulmonary venous (PV) and mitral flow, transesophageal Doppler recording (TEE), and other extracardiac factors like obesity and renal insufficiency (KI) to exercise capacity (ExC) evaluated by cardiopulmonary exercise testing (CPX) in patients with dilated cardiomyopathy (DCM). During the CPX test, 119 patients (pts) with DCM underwent both peak VO2 consumption and then TEE with color-guided pulsed-wave Doppler recording of PVF and transmitral flow. In 78 patients (65%), peak VO2 was normal or mildly reduced (>14 mL/kg/min) (group 1) while it was markedly reduced (≤14 mL/kg/min) in 41 (group 2). In univariate analysis, systolic fraction (S Fract), a predictor of elevated pre-a LV diastolic FP, appeared to be the best diastolic parameter predicting a significantly reduced peak VO2. Logistic regression analysis identified five parameters yielding a unique, statistically significant contribution in predicting reduced ExC: creatinine clearance < 52 mL/min (odds ratio (OR) = 7.4, p = 0.007); female gender (OR = 7.1, p = 0.004); BMI > 28 (OR = 5.8, p = 0.029), age > 62 years (OR = 5.5, p = 0.03), S Fract < 59% (OR = 4.9, p = 0.02). Conclusion: KI was the strongest predictor of reduced ExC. The other modifiable factors were obesity and severe LV diastolic dysfunction expressed by blunted systolic venous flow. Contrarily, LV ejection fraction was not predictive, confirming other previous studies. This has important clinical implications.

MPL-Positive Essential Thrombocytosis Presenting as Budd-Chiari Syndrome in a Middle-Aged Woman with an Initially Normal Platelet Count

Budd-Chiari syndrome (BCS) results from an occlusion of the hepatic venous flow which in turn leads to portal hypertension causing ascites and other signs of liver dysfunction. Here, we present the case of a 43-year-old woman with recurrent ascites who was found to have BCS secondary to an inferior vena cava thrombosis extending into the hepatic veins. Although she had a normal platelet count on admission, additional laboratory investigations revealed an MPL mutation. She was discharged on anticoagulation with apixaban and later found to have thrombocytosis on repeat blood work, confirming the diagnosis of essential thrombocytosis, following which she was started on myelosuppressive therapy with hydroxyurea.

A Case of Budd-Chiari Syndrome Associated with Erythrocytosis and Homozygous MTHFR C677T Mutation

An erythrocytosis describes an increased erythrocyte, subclassified into relative due to hemoconcentration or absolute by an increase in erythrocyte mass, defined as an increase in hemoglobin concentration and/or hematocrit in the peripheral blood above the sex-specific normal range. Budd-Chiari Syndrome (BCS) is related to an obstruction of the hepatic venous flow leading to occlusion of hepatic veins and their tributaries. Genetic and environmental factors can interact for risk determination of venous thromboembolism. The risk associated with SNP 677C>T and 1298A>C of the methylenetetrahydrofolate reductase (MTHFR), 1691G>A of the Factor V Leiden (FVL) and 20210G>A of the prothrombin (FII) genes were investigated in many studies involving thrombosis. This case report describes the clinical, hematological and biochemistry data about a 48-year-old woman diagnosed with PV and a BCS associated, also carrying 677C>T SNP in homozygosity. The patient started therapy with phlebotomy, hydroxyurea and oral anticoagulant. Currently, she presents a better clinical and laboratory condition with normalized values of hematological and platelet indices. This case report aims to contribute with evidence of related comorbidities and makes it possible to report that genetic factors are involved since the patient's mother had already been diagnosed with absolute erythrocytosis in 2016 at 78 years old. For this main result, we understand that it is clear that a family genetic study can reveal clinical modifying factors in these patients, as there are different clinical severities in the family. Furthermore, we believe in the need for a greater number of randomized clinical trials to add better evidence to complement an ideal therapeutic approach in these patients.

Sinistral Portal Hypertension after Pancreaticoduodenectomy with Splenic Vein Resection: Pathogenesis and Its Prevention

To achieve curative resection for pancreatic cancer during pancreaticoduodenectomy (PD), extensive portal vein (PV) resection, including porto-mesenterico-splenic confluence (PMSC), may sometimes be necessary if the tumor is close to the portal venous system. Recently, this extended resection has been widely accepted in high-volume centers for pancreatic resection due to its favorable outcomes compared with non-operative treatment. However, in patients with long-term survival, sinistral portal hypertension (SPH) occurs as a late-onset postoperative complication. These patients present gastrointestinal varices due to congested venous flow from the spleen, which may cause critical variceal bleeding. Since the prognosis of patients with pancreatic cancer has improved, owing to the development of chemotherapy and surgical techniques, SPH is no longer a negligible matter in the field of pancreatic cancer surgery. This review clarifies the pathogenesis and frequency of SPH after PD through PMSC resection and discusses its prediction and prevention.

Suprabulbar Approach to Jugular Fossa Tumors: 2-Dimensional Operative Video

Owing to their scarcity, location, and intricate neurovascular associations, jugular fossa tumors are among the most challenging pathologies encountered by the neurosurgeon.1 While paragangliomas originate within and often occlude the jugular bulb, schwannomas and meningiomas are extra-bulbar and typically do not impede venous flow.2 Schwannomas typically arise from an extradural origin, expanding the jugular foramen.3-5 Meningiomas are intradural and cause hyperostosis of the jugular tubercle.6 We described and have been exposing and resecting jugular fossa tumors through a presigmoid suprabulbar infralabyrinthine window6 that has been detailed in cadaveric studies.7,8 This approach maintains the patency of the jugular bulb without breaching the labyrinths or manipulating the facial nerve. It is applicable to cases with partially impaired hearing and intact lower cranial nerves. The carotid artery can be identified by neuronavigation and micro-Doppler ultrasonography. This approach provides a direct lateral trajectory with a short distance to the jugular fossa and cerebellopontine angle. Early exposure and central debulking of the tumor minimize manipulation of the exquisitely sensitive lower cranial nerves. The distal aspect of these tumors can be removed with endoscopic assisted techniques.9 The first patient is a 49-yr-old woman with a previously irradiated schwannoma who presented with worsening neurologic deficits—an extradural suprabulbar approach was used to resect this tumor. The second patient is a 27-yr-old woman with an enlarging meningioma and associated neurological dysfunction; this tumor was resected using the suprabulbar approach with opening of the presigmoid dura. Both patients have consented to surgery and publication of images. Image at 2:27 and 6:38 reprinted from Arnautović et al, with permission from JNSPG. Image at 2:50 and 6:45 ©Ossama Al-Mefty 1997, reused with permission.