Numerical analysis of blood flow distribution in 4- and 3-branch vascular grafts

Trifurcated arch grafts (3-branch grafts) are now being used to repair the thoracic aorta in addition to conventional arch grafts (4-branch grafts). The anatomical shape of the 3-branch graft is different from the original vessel, so it is necessary for clinical application to evaluate blood flow distribution in the graft to assess whether there is adequate blood flow to the target organs. To achieve this, we developed a computational fluid dynamics (CFD) method to evaluate blood flow distribution in the grafts. Aortic blood flow was measured by phase-contrast magnetic resonance imaging (PC-MRI), and flow distribution into the branched vessels was obtained. The MRI image was used to create a patient-specific image model that represents the geometry of the aortic arch. The CFD analysis method was employed to determine a boundary condition of the blood flow analysis in the aorta using a patient-specific image model. We also created simplified models of 4-branch and 3-branch grafts and used our CFD analysis method to compare blood flow distribution among simplified models. It was found that blood flow distribution in the descending aorta was 71.3 % for the 4-branch graft and 67.7 % for the 3-branch graft, indicating that a sum of branching flow in the 3-branch graft was almost the same as the one in the 4-branch graft. Therefore, there is no major concern about implanting a new 3-branch graft. Our CFD analysis method may be applied to estimate blood flow distribution of a newly developed vascular graft prior to its clinical use and provide useful information for safe use of the graft.     

Preliminary study on the development of a system dynamics model: the case of EVAHEART

The Japanese medical device industry’s stagnation over the years can be attributed to the uncertainty related to device development. The purpose of this study is to identify the major factors that impact development. We studied the ventricular assist device EVAHEART through interviews with the persons involved and created a development model using system dynamics. There are at least six stages in the device development process, including interactions with academia and the government. Through a simulation and comparison to Novacor, it was determined that the satisfaction of academia leads to government action in the subsequent measures. Our trial simulation of EVAHEART suggests that it has the potential to clarify unclear relationships in the development of devices.     

Pharmacokinetics of 4′-cyano-2′-deoxyguanosine,a novel nucleoside analog inhibitor of the resistant hepatitis B virus,in a rat model of chronic kidney disease

IntroductionThe novel nucleoside analog, 4′-cyano-2′-deoxyguanosine (CdG), possesses inhibitory activity against both the wild-type and resistant hepatitis B virus. Since the dosage of the currently available nucleoside analog preparations needs to be adjusted, depending on renal function, we investigated the effect of renal dysfunction on the pharmacokinetics of CdG in a rat model of chronic kidney disease (CKD).MethodsCKD model rats were either intravenously or orally administered CdG at a dose of 1 mg/kg. The concentration of CdG in plasma, organs (liver and kidney) and urine samples were determined by means of a UPLC system interfaced with a TOF-MS system.ResultsFollowing intravenous administration, the plasma retention of CdG was prolonged in CKD model rats compared to healthy rats. In addition, the clearance of CdG was well correlated with plasma creatinine levels in CKD model rats. Similar to the results for intravenous administration, the plasma concentration profiles of CdG after oral administration were also found to be much higher in CKD model rats than in healthy rats. However, the results for the organ distribution and urinary excretion of CdG, the profiles of which were similar to that of healthy rats, indicated that CdG did not accumulate to a significant extent in the body.ConclusionThe extent of renal dysfunction has a direct influence on the pharmacokinetics (plasma retention) of CdG without a significant accumulation, indicating that the dosage of CdG will be dependent on the extent of renal function. .     

Recent clinical features of Wilson’s disease with hepatic presentation

Background We carried out this study to evaluate recent clinical features of Wilsons disease (WD) with hepatic presentation, especially in terms of age, degree of liver injury, and association with hepatocellular carcinoma (HCC).Methods Sixteen patients with hepatic manifestations were diagnosed with WD in the period 1976–2003. We divided this period into two periods, past and recent. The diagnosis was based on the presence of Kayser-Fleisher rings, low serum copper levels, low serum ceruloplasmin levels, increased urinary copper concentrations before or after D-penicillamine challenge, and increased hepatic copper concentrations. This retrospective study was done at Ehime University Hospital.Results Four patients, including a pair of siblings, had a family history of WD. Four patients had parental consanguinity. There were 6 patients aged over 40 years in the recent period, whereas no patients in the past period were over 40. Four patients had neurological manifestations. Ten patients had liver cirrhosis and 5 had chronic hepatitis. Two had fatty liver without obesity. All patients in the past period had liver cirrhosis. Three patients with liver cirrhosis were found to have HCC during the follow up. All patients were treated with either D-penicillamine or trientine chloride, or both. However, four patients had to discontinue these agents due to the side effects.Conclusions Recently, the number of patients diagnosed with WD has been increasing, not only in terms of those with classical-type WD but also in terms of elderly patients or patients with non-cirrhotic liver injury such as fatty liver and chronic hepatitis. The various clinical features of WD should be recognized and particular attention should focus on HCC as a complication.     

Fatal eosinophilic heart disease in a child with neurofibromatosis-1 complicated by acute lymphoblastic leukemia

We present a pediatric case of neurofibromatosis-1 (NF-1) complicated by acute lymphoblastic leukemia and hypereosinophilia, which caused multiple end-organ damage. Although clinical symptoms such as fever and coughing were noted only 1 week before admission, the condition deteriorated rapidly with a fatal outcome prior to antileukemic therapy. A postmortem examination demonstrated extensive endomyocardial fibrosis with thrombotic occlusion and recanalization of the coronary arteries. Leukemic cell infiltration was not seen in the cardiac tissue. When eosinophilia is diagnosed in patients with NF-1, eosinophilic end-organ damage, particularly cardiac involvement, in addition to hematological malignancies, should be screened for in order to start medical treatment at the early stage of the disease.     

A technique for the measurement of visceral fat by ultrasonography: comparison of measurements by ultrasonography and computed tomography

OBJECTIVE: This study aims to create a method of calculating intra-abdominal visceral fat volume by using ultrasound (US). The visceral fat volume measured by US was evaluated by comparison with the volume measured by computed tomography (CT). METHODS: Eighty-seven patients (52 males and 35 females) were enrolled in this study. Both US and CT were performed, and the visceral fat volume was measured. Both the distance and thickness of the parameters in US were measured as follows: 1) the distance between the internal surface of the abdominal muscle and the splenic vein, 2) the distance between the internal surface of the abdominal muscle and the posterior wall of aorta on the umbilicus, and 3) the thickness of the fat layer of the posterior right renal wall. RESULTS: The equation was calculated as follows: [visceral fat volume]=-9.008+1.191x[distance between the internal surface of the abdominal muscle and the splenic vein (mm)]+0.987x[distance between the internal surface of the abdominal muscle and the posterior wall of the aorta on the umbilicus (mm)]+3.644x[thickness of the fat layer of the posterior right renal wall (mm)]. There was a good correlation between the visceral fat volume calculated by the above equation and the volume by CT described (r=0.860, p<0.0001). CONCLUSION: The measurement of the visceral fat volume using US provided results as effectively as CT, and it was proven to be a useful method.