An investigation on the effects of chamber wall's elasticity on blood flow in a LVAD pump

Left Ventricular Assist Device (LVAD) is a pump that is designed to provide life support to patients with end stage heart failure. In an effort to ensure the safety of LVAD, the pumping mechanics must not exert excessive stress on the blood or hemolysis would occur. This study investigates the effects of chamber wall's elasticity (isotropic) from common materials on blood flow in a LVAD, especially the shear stress resulted therein. The materials considered are titanium, diamond-like carbon (DLC), 2-methacryloyloxy ethyl phosphorylcholine (MPC) polymer, segmented polyurethane (SPU), polyurethane (PEU), and a material with properties corresponding to blood vessels, which is used as the reference. The study employs a Fluid Structure Interaction (FSI) simulation software suite to couple Computational Fluid Dynamics (CFD) with mechanical simulation (ANSYS). The test system is a centrifugal pump based on a 2012-Jarvik Patent. The flow through the pump is driven by an impeller rotating at set speed to achieve a pre-set blood flowrate. The results show that there is no significant difference in turbulent dissipation rate among the different chamber-wall materials, with PEU giving closest figure to the blood vessels'. On the other hand, regarding wall shear stress which is an important factor in hemolysis, titanium, DLC and SPU result in similar maximum values, whereas MPC, PEU and blood vessel material give noticeably lower ones

Outcomes after oesophageal perforation: a retrospective cohort study of patients with different aetiologies

Introduction: The mortality rate after oesophageal perforation is high despite advances in operative and non-operative techniques. In this study, we sought to identify risk factors for hospital mortality after oesophageal perforation treatment. Methods: We retrospectively examined patients treated for oesophageal perforation in a university teaching hospital in Hong Kong between January 1997 and December 2013. Their demographic and clinical characteristics, aetiology, management strategies, and outcomes were recorded and analysed. Results: We identified a cohort of 43 patients treated for perforation of the oesophagus (28 men; median age, 66 years; age range, 30-98 years). Perforation was spontaneous in 22 (51.2%) patients (15 with Boerhaaveâ s syndrome and seven with malignant perforation), iatrogenic in 15 (34.9%), and provoked by foreign body ingestion in six (14.0%). Of the patients, 14 (32.6%) had pre-existing oesophageal disease. Perforation occurred in the intrathoracic oesophagus in 30 (69.8%) patients. Emergent surgery was undertaken in 23 patients: 16 underwent primary repair, six surgical drainage or exclusion, and one oesophagectomy. Twenty patients were managed non-operatively, 13 of whom underwent stenting. Two stented patients subsequently required oesophagectomy. Four patients had clinical signs of leak after primary repair: two were treated conservatively and two required oesophagectomy. Overall, six (14.0%) patients required oesophagectomy, one of whom died. Nine other patients also died in hospital; the hospital mortality rate was 23.3%. Pre-existing pulmonary and hepatic disease, and perforation associated with malignancy were significantly associated with hospital mortality (P=0.03, < 0.01, and < 0.01, respectively). Conclusions: Most oesophageal perforations were spontaneous. Mortality was substantial despite modern therapies. Presence of pre-existing pulmonary disease, hepatic disease, and perforation associated with malignancy were significantly associated with hospital mortality. Salvage oesophagectomy was successful in selected patients.published_or_final_versio

Resection of T4 hepatocellular carcinomas with adjacent structures, is it justified?

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Late recurrence of hepatocellular carcinoma after liver transplantation

Background: Long-term survival of patients with hepatocellular carcinoma (HCC) after liver transplantation is affected mainly by recurrence of HCC. There is the opinion that the chance of recurrence after 2 years post-transplantation is remote, and therefore lifelong surveillance is not justified because of limited resources. The aims of the present study were to determine the rate of late HCC recurrence (≥2 years after transplantation) and to compare the long-term patient survival outcomes between cases of early recurrence (<2 years after transplantation) and late recurrence. Patients: A total of 139 adult HCC patients having liver transplantation during the period from July 1994 to December 2007 were included in the analysis. The median follow-up period was 55 months. Thirty-two patients received deceased-donor grafts and 107 received living-donor grafts. Results: Hepatocellular carcinoma recurrence occurred in 24 (17.3%) patients, among them 22 (86%) had living-donor grafts and 7 (5%) developed late recurrence. Patients in the early recurrence group and patients in the late recurrence group had comparable demographics and disease pathology. The former group, when compared with the latter, had significantly worse overall survival at 3 years (13.3 versus 100%) and 5 years (6.67 versus 71.4%) (log-rank test; p < 0.001). Conclusions: Both early recurrence and late recurrence of HCC after liver transplantation were not uncommon, mostly detected at a subclinical stage. Regular and long-term surveillance with imaging and blood tests is essential for early detection. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

Management of recurrent hepatocellular carcinoma after liver transplant – a single center experience

Background: Hepatocellular carcinoma (HCC) recurs in 10-60% of patients after liver transplantation and carries very dismal prognosis. Optimal management of this condition has yet to be defined. Patients and Methods: All adult patients with HCC within the UCSF (University of California, San Francisco) criteria who underwent liver transplantation at Queen Mary Hospital during the period from July 1995 to September 2013 were reviewed. Two hundred and fifty-two patients were included in the analysis. They were divided into three groups for comparison: with intrahepatic recurrence (IR), with multiple or extrahepatic recurrence (MR), with no recurrence (NR). Results: HCC recurrence occurred in 35 (13.9%) patients, 3 with IR and 32 with MR. Patients in the IR and MR groups had a younger age (51 vs. 51 vs. 56 years; p=0.007), a higher pretransplant serum α-fetoprotein level (27 vs. 97.5 vs. 18 ng/mL; p=0.005), more tumor nodules (4 vs. 2 vs. 1; p=0.003) and a higher incidence of lymphovascular permeation (33% vs. 59% vs. 27%; p=0.001) than patients in the NR group. More patients in the IR and MR groups had tumors beyond the UCSF criteria on histopathology (67% vs. 56% vs. 17%) when compared with the NR group. Treatments for IR included hepatectomy, radiofrequency ablation and transarterial chemoembolization. One patient with IR remained alive 3 years after last treatment. Overall survival in the IR group was longer than that in the MR group (59 vs. 30.4 months; p<0.001). Time from transplant to recurrence was similar between the two groups (23.1 vs. 12 months; p=0.141). Conclusions: Recurrence of HCC after liver transplantation is not uncommon. Aggressive surgical treatment may prolong survival in patients with IR only. Prognosis for patients with MR is dismal. Effective systemic therapy is urgently needed.published_or_final_versio

Alternatives to colonoscopy for population-wide colorectal cancer screening

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Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma: magnifying endoscopy findings

Gastric mucosaâ associated lymphoid tissue lymphoma is uncommon and most patients have an indolent clinical course. The clinical presentation and endoscopic findings can be subtle and diagnosis can be missed on white light endoscopy. Magnifying endoscopy may help identify the abnormal microstructural and microvascular patterns, and target biopsies can be performed. We describe herein the case of a 64-year-old woman with Helicobacter pyloriâ negative gastric mucosaâ associated lymphoid tissue lymphoma diagnosed by screening magnification endoscopy. Helicobacter pyloriâ eradication therapy was given and she received biological therapy. She is in clinical remission after treatment. The use of magnification endoscopy in gastric mucosaâ associated lymphoid tissue lymphoma and its management are reviewed.published_or_final_versio

Survival advantage of primary liver transplantation for hepatocellular carcinoma within the up-to-7 criteria with microvascular invasion

PURPOSE: Microvascular invasion of hepatocellular carcinoma (HCC) is considered a poor prognostic factor of liver resection (LR) and liver transplantation (LT), but its significance for lesions within the up-to-7 criteria is unclear. This study investigated the survival benefit of primary LT against LR for HCC with microvascular invasion and within the up-to-7 criteria. METHODS: Adult patients who underwent LR or LT as the primary treatment for HCC were included for study. Patients with prior local ablation, neoadjuvant systemic chemotherapy, targeted therapy, positive resection margin, or metastatic spread were excluded. RESULTS: There were 471 LR patients and 95 LT recipients (70 with living donor, 25 with deceased donor). Seventy-seven (81.1%) LT recipients had HCC within the up-to-7 criteria. Twenty-five (26.3%) LT recipients had HCC with either macrovascular (n = 4) or microvascular (n = 21) invasion. The 5-year survival rate was 85.7% for LT recipients with HCC within the up-to-7 criteria, unaffected by the presence or absence of vascular invasion (88.2 vs. 85.1%). The rate was comparable with that of LR patients with HCC without vascular invasion (81.2%, p 0.227), but far superior to that of LR patients with lesions with vascular invasion (50.0%, p < 0.0001). Overall survivals were compromised by multiple tumors [odds ratio (OR) 1.902, confidence interval (CI) 1.374-2.633, p = 0.0001], vascular invasion (OR 2.678, CI 1.952-3.674, p < 0.0001), blood transfusion (OR 2.046, CI 1.337-3.131, p = 0.001), and being beyond the up-to-7 criteria (OR 1.457, CI 1.041-2.037, p = 0.028). LT was a favorable factor for survival (OR 0.243, CI 0.130-0.454, p < 0.0001). CONCLUSION: Primary LT for HCC with microvascular invasion and within the up-to-7 criteria doubled the chance of cure as compared with LR.published_or_final_versio

A case of laparoscopic hepatectomy for recurrent hepatocellular carcinoma

Conventional hepatectomy is an effective way to treat hepatocellular carcinoma. However, it is invasive and stressful. The use of laparoscopy in hepatectomy, while technically demanding, reduces surgical invasiveness and stressfulness but still achieves complete resection with adequate margins. Compared with conventional hepatectomy, laparoscopic hepatectomy provides a better chance and situation for further surgery in the case of recurrence of hepatocellular carcinoma. Even aged patients can successfully endure repeated hepatectomy using laparoscopy, as shown in the present report. This report presents a case of repeated laparoscopic hepatectomy treating hepatocellular carcinoma and its recurrence in an aged patient having cirrhosis, a disease causing extra difficulty for performing laparoscopic hepatectomy. The report also describes techniques of the operation and displays characteristic results of laparoscopic hepatectomy such as smaller wounds, less blood loss, less pain, less scars and adhesion, shorter postoperative hospital stay, and faster recovery. © 2010 Baishideng. All rights reserved.published_or_final_versio