Assessing radiocephalic wrist arteriovenous fistulas of obtuse anastomosis using computational fluid dynamics and clinical application.

INTRODUCTION: A radiocephalic arteriovenous fistula (AVF) is the best choice for achieving vascular access (VA) for hemodialysis, but this AVF has high rates of early failure due to juxta-anastomotic stenosis, making it impossible to use for dialysis. Low hemodynamic shear stress contributes to the pathophysiology of VA failure due to secondary thrombosis, stenosis, and re-occlusion after percutaneous intervention. METHODS: We used a computational fluid dynamics (CFDs) approach to evaluate the shear stress distribution and minimize its effects under various conditions including changes in the anastomosis angle. A three-dimensional computational domain was designed for arteriovenous end-to-side anastomosis based on anastomosis angles of 45°, 90° and including 135° angle of an obtuse anastomosis using three-dimensional design software. COMSOL Multiphysics® simulation software was used to identify the hemodynamic factors influencing wall shear stress at the anastomosis site using a low Reynolds number k-ε turbulence model that included non-Newtonian blood flow characteristics, the complete cardiac pulse cycle, and distention of blood vessels. In preliminary clinical study, all 201 patients who received a radiocephalic wrist AVF from January 2009 to February 2014 were divided into classic and obtuse angle groups. RESULTS: The CFD results showed that the largest anastomosis angle (135°) resulted in lower shear stress, which would help reduce AVF failures. This obtuse angle was preferred, as it minimized the development of anastomotic stenosis and tended to favor primary and primary-assisted patency in clinical study. CONCLUSIONS: An obtuse radiocephalic wrist AVF shows more favorable patency compared to a classic radiocephalic AVF. Surgeons establishing a radiocephalic wrist AVF would be better to consider an AVF with an obtuse anastomosis.

Ruptured aneurysm of the external iliac vein.

Primary iliac venous aneurysm is an extremely rare vascular abnormality that is associated with the likelihood of rupture, embolism, and thrombosis. In this report, we describe the case of a ruptured aneurysm of the external iliac vein in a 63-year-old woman who was admitted to the emergency department and diagnosed by computed tomography. Computed tomography indicated a 4 × 5-cm ruptured aneurysm in the right external iliac vein that was surrounded by hematoma in the right side of the pelvis. The aneurysm was successfully treated by tangential aneurysmectomy and lateral venorrhaphy.

Prevalence of the Factor XIII Val34Leu Polymorphism in Korean Patients with Deep Vein Thrombosis.

OBJECTIVE: According to recent reports, a common polymorphism resulting in Val to Leu substitution, located 3 amino acids (Val34Leu) upstream of the thrombin cleavage site of FXIII A, has been related to a lower incidence of deep vein thrombosis (DVT). And, a different expression pattern has been shown across nations and races. However, the frequency of FXIII polymorphism expression in Koreans has not been reported in normal individuals or DVT-patient groups. DESIGN: Case-control study in Korean population. METHODS: We investigated the distribution of factor XIII Val34Leu polymorphisms in Korean patients of DVT (50 cases) and Korean healthy controls (100 cases), using real-time polymerase chain reaction for single nucleotide polymorphism genotyping. RESULTS: With regard to the frequency of the FXIII polymorphism in DVT patients and in the general control group, all 50 cases in the patient group and 100 cases in the control group were found to be Val34 homozygotes. CONCLUSIONS: The Val34Leu polymorphism of FXIII was not found in Korean people, and compared with Caucasians, a noticeably low incidence of DVT was shown. Thus, the preventive effect of the Val34 allele of FXIII on the formation of thrombi was shown.

Predictors of postoperative mortality of ruptured abdominal aortic aneurysm: a retrospective clinical study.

PURPOSE: Despite significant improvements in surgery, anesthesia, and postoperative critical care, the postoperative mortality rate of ruptured abdominal aortic aneurysm (RAAA) has remained at 40% to 50% for several decades. Therefore, we evaluated factors associated with the postoperative mortality of RAAA. MATERIALS AND METHODS: From January 1999 to December 2008, a retrospective study was performed with 34 patients who underwent open repair of RAAA. The preoperative factors included age, sex, smoking, comorbidities, serum creatinine, hemoglobin, shock, pulse rate, and time from emergency room to operation room. The intraoperative factors included blood loss, transfusion, aortic clamping site and time, aneurysmal characteristics, rupture type, graft type, hourly urine output (HUO), and operative time. The postoperative factors included inotropic support, renal replacement therapy (RRT), reoperation, bowel ischemia, multiple organ failure (MOF), and intensive care unit stay. The 2-day and the 30-day mortality rates were analyzed separately. RESULTS: The 2-day and the 30-day mortality rates were 14.7% and 41.2%, respectively. On univariate analysis, shock, transfusion, HUO, inotropic support and MOF for the 2-day mortality and serum creatinine, transfusion, aortic clamping site, HUO, inotropic support, RRT and MOF for the 30-day mortality were statistically significant. On multivariate analysis, shock, inotropic support and MOF for the 2-day mortality and aortic clamping site, RRT and MOF for the 30-day mortality were statistically significant. CONCLUSION: To decrease the postoperative mortality rate of RAAA, prevention of massive hemorrhage and acute renal failure with infrarenal aortic clamping, as well as prompt operative control of bleeding and maintenance of systemic perfusion are important.

Popliteal vein aneurysm as a source of pulmonary embolism: report of a case and review of the world literature.

Although popliteal vein aneurysms are uncommon, they are potentially fatal because they can cause a pulmonary embolism. One-third of patients have further embolic events despite therapeutic anticoagulation. We report the case of a 67-year-old man who presented with dyspnea, rapid respirations, and dull, left pleuritic chest pain of 3-day duration. Computed tomography scanning of chest confirmed the diagnosis of multiple bilateral pulmonary emboli. Color duplex scanning followed by ascending venography confirmed a 3 × 4 cm(2) right saccular aneurysm of above-knee popliteal vein--containing thrombus. Aneurysm was treated with open tangential aneurysmectomy and lateral venorrhaphy.