Characterization of main pulmonary artery and valve annulus region of piglets using echocardiography, uniaxial tensile testing, and a novel non-destructive technique

Characterization of cardiovascular tissue geometry and mechanical properties of large animal models is essential when developing cardiovascular devices such as heart valve replacements. These datasets are especially critical when designing devices for pediatric patient populations, as there is often limited data for guidance. Here, we present a previously unavailable dataset capturing anatomical measurements and mechanical properties of juvenile Yorkshire (YO) and Yucatan (YU) porcine main pulmonary artery (PA) and pulmonary valve (PV) tissue regions that will inform pediatric heart valve design requirements for preclinical animal studies. In addition, we developed a novel radial balloon catheter-based method to measure tissue stiffness and validated it against a traditional uniaxial tensile testing method. YU piglets, which were significantly lower weight than YO counterparts despite similar age, had smaller PA and PV diameters (7.6–9.9 mm vs. 10.1–12.8 mm). Young’s modulus (stiffness) was measured for the PA and the PV region using both the radial and uniaxial testing methods. There was no significant difference between the two breeds for Young’s modulus measured in the elastic (YU PA 84.7 ± 37.3 kPa, YO PA 79.3 ± 15.7 kPa) and fibrous regimes (YU PA 308.6 ± 59.4 kPa, YO PA 355.7 ± 68.9 kPa) of the stress-strain curves. The two testing techniques also produced similar stiffness measurements for the PA and PV region, although PV data showed greater variation between techniques. Overall, YU and YO piglets had similar PA and PV diameters and tissue stiffness to previously reported infant pediatric patients. These results provide a previously unavailable age-specific juvenile porcine tissue geometry and stiffness dataset critical to the development of pediatric cardiovascular prostheses. Additionally, the data demonstrates the efficacy of a novel balloon catheter-based technique that could be adapted to non-destructively measure tissue stiffness in situ.

Time of Dropout From the Liver Transplant List in Patients With Hepatocellular Carcinoma: Clinical Behavior According to Tumor Characteristics and Severity of Liver Disease

BACKGROUND

Prolonged time on the waiting list affects post-transplant survival of patients with hepatocellular carcinoma (HCC). However, it is not yet known which patients will be at higher risk for early dropout from the list. We investigate specific risk factors for early waiting list dropout in patients with HCC.

METHODS

This was a single-center, intention-to-treat analysis of adults with HCC, within the Milan criteria, from July 2006 through September 2013. Patients were divided into groups according to waiting list time. The main end point was dropout from the list.

RESULTS

The dropout rates of the study cohort at 3, 6, and 12-months were 6.4%, 12.4%, and 17.7%, respectively. Patients who dropped out from the list tended to be older, with blood types A and O, and with higher Child-Pugh and Model for End-Stage Liver Disease (MELD) scores. They also had larger nodules, responded poorly to trans-arterial chemo-embolization (TACE), and had a higher alpha-fetoprotein. Those with blood types B and AB appeared to be protected for dropout (odds ratio [OR] = 0.21, P = .02). Patients who responded to TACE were also protected (OR = 0.22, P < .001). When we looked into time to dropout, the only baseline characteristic that stood out was a higher MELD score (13 for those dropping out up to 90 days vs 10 for those dropping out after 180 days, P = .0025).

CONCLUSIONS

We conclude that patients who drop out early from the list are primarily driven by the severity of liver disease. Patients who had progressive HCC had a high tumor load and poor response to loco-regional therapies, dropping out from the list after 180 days of inclusion.

Diagnostic Accuracy of Transient Elastography for Detecting Liver Fibrosis After Liver Trannsplantation: A Specific Cut-Off Value Is Really Needed?

INTRODUCTION

Liver transplant recipients often perform liver biopsy (LB), specially in the context of potentially recurring diseases, such as hepatitis C infection. However, the LB has risks of complications, despite being the gold standard. Transient elastography (TE) is a noninvasive method comparable to the LB to evaluate liver fibrosis in various settings, but its accuracy among transplant recipients is not fully understood.

OBJECTIVE

To determine the accuracy of TE in liver transplant recipients compared with LB to successfully predict liver fibrosis.

PATIENTS AND METHODS

Patients who underwent liver transplantation at Hospital Israelita Albert Einstein from 2010 to 2012 and presented with LB indication were also subjected to TE at the time of LB. The medium value of ten successful measurements was kept as a representative of the liver stiffness. The definition of cut-off points was made to ensure specificity of ≥90 % for all fibrosis stages (F0-F4).

RESULTS

LB was performed in 267 patients. TE was not analyzed in only 8 (3 %) due to an elevated body mass index. The optimal liver stiffness cut-off value and diagnostic performance were 8.1 kPa for F ≥ 1, 12.3 kPa for F ≥ 2, 15.1 for F ≥ 3, and 16.7 for F = 4 for all patients and were 8.1 kPa for F ≥ 1, 12.3 kPa for F ≥ 2, 16.5 for F ≥ 3, and 17.6 for F = 4 for patients with hepatitis C.

CONCLUSIONS

TE demonstrated good performance in defining cut-off points for fibrosis on liver histology observed in transplant recipients. The TE can be considered an alternative to LB in post-liver transplantation.

List and liver transplant survival according to waiting time in patients with hepatocellular carcinoma

The time that patients with hepatocellular carcinoma (HCC) can safely remain on the waiting list for liver transplantation (LT) is unknown. We investigated whether waiting time on the list impacts transplant survival of HCC candidates and transplant recipients. This is a single-center retrospective study of 283 adults with HCC. Patients were divided in groups according to waiting-list time. The main endpoint was survival. The median waiting time for LT was 4.9 months. The dropout rates at 3-, 6-, and 12-months were 6.4%, 12.4%, and 17.7%, respectively. Mortality on the list was 4.8%, but varied depending of the time on the list. Patients who waited less than 3-months had an inferior overall survival when compared to the other groups (p = 0.027). Prolonged time on the list significantly reduced mortality in this analysis (p = 0.02, HR = 0.28). Model for End Stage Liver Disease (MELD) score at transplantation did also independently impact overall survival (p = 0.03, HR = 1.06). MELD was the only factor that independently impacted posttransplant survival (p = 0.048, HR = 1.05). We conclude that waiting time had no relation with posttransplant survival. It is beneficial to prolong the waiting list time for HCC candidates without having a negative impact in posttransplant survival.

Clinical profile and liver explant findings in patients with and without pretransplant downstaging for hepatocellular carcinoma

INTRODUCTION

Since August 2010, The Brazilian National Transplantation System has allowed performance of liver transplantation (OLT) for patients with hepatocellular carcinoma (HCC) beyond the Milan criteria (MC) who have been successfully treated with preoperative downstaging (DS). Herein we sought to compare the clinical profiles and liver explant findings among patients with versus without preoperative DS.

METHODOLOGY

Prospective cohort of patients with HCC within and beyond the MC undergoing OLT. Patients were considered for DS if they were beyond the MC without evidence of vascular invasion or extrahepatic disease. Transcatheter arterial chemoembolization was used for DS, which was considered to be successful if the MC were achieved at any moment during the follow-up.

RESULTS

Between May 2006 and May 2010, we performed 130 OLTs in HCC patients, among whom 10 received preoperative DS. Both groups were comparable for gender, age, viral etiology, serum levels of alpha fetoprotein, and Child-Pugh and Model for End-Stage Liver Disease (MELD) scores (P > .05). The liver explants were within the MC in 80% of patients with preoperative DS and 90% of those without preoperative DS. They were comparable for the number of HCC nodules, total tumor size, histologic grade, and presence of microvascular invasion. Patients with pretransplant DS showed larger HCC nodules (33.3 ± 9.65 vs 26.3 ± 9.62 mm; P .029) and more frequent macrovascular invasion (1 vs 1 patient, P = .024).

CONCLUSION

Preoperative DS for unresectable HCC may provide a curative treatment for patients who would otherwise be candidates for palliative therapy only. The baseline characteristics and liver explant findings were similar in both groups. We have yet to determine whether the differences observed regarding the size of the largest nodule and the higher frequency of macrovascular invasion have an impact on outcome.

Antibody-mediated rejection: hyperacute rejection reality in liver transplantation? A case report

Hyperacute rejection is rare among ABO-compatible liver transplantations. The mechanism is donor preformed antibodies causing graft loss within a few days. Herein, we have described a case of an ABO-compatible liver transplantation that underwent hyperacute rejection, needing retransplantation for treatment. A 27-year-old man of blood group A positive who displayed fulminant hepatic failure due to hepatitis B (in agreement with the O'Grady criteria), received an ABO-compatible graft. He developed significant asthenia, fever, hypotension, oliguria, and coagulopathy. Ultrasonography revealed total thrombosis of the portal vein and absence of dilatation of bile ducts. The patient was priorized for retransplantation and underwent a good subsequent evolution. On anatomopathologic exam the explant revealed thrombosis of the intrahepatic branches of the portal vein with venous and ischemic infarcts compatible with a diagnosis of hyperacute rejection. The clinical findings of hyperacute rejection were characterized by progressive elevation of bilirubin and thrombocytopenia associated with signs of hepatic failure during the first days after transplantation. In this case, the histological exam was compatible with hyperacute rejection, excluding the diagnoses of hepatic artery thrombosis or biliary obstruction, despite the negative test for anti-HLA antibodies. The diagnosis of hyperacute rejection could be made associated with a short ischemic time and a good response after retransplantation.

Twenty Years of Liver Transplantation in Brazil

This paper summarizes the 20 years of liver transplantation in Brazil, in the context of the Western world scenario. More than 5000 liver transplantations have been performed in the country since September 1, 1985. The living-donor liver transplantation, one of the landmarks in liver transplantation, was first described by our team in 1989. Brazil is the seventh country in number of liver transplants in the Western world and the first in Latin America. Almost 1000 procedures were performed in 2004, 19% of them involving living donors.

An investigation on the ecology of Triatoma vitticeps (Stal, 1859) and its possible role in the transmission of Trypanosoma cruzi, in the locality of Triunfo, Santa Maria Madalena municipal district, state of Rio de Janeiro, Brazil

From January 1989 to April 1995, 465 specimens of Triatoma vitticeps were collected in the locality of Triunfo, 2nd District of Santa Maria Madalena municipal district, State of Rio de Janeiro. The bugs were found indoors by local residents with predominance of adults. The flight activity was high in hot months when the incidence in the domicile also increased. Two hundred and two bugs (111 alive and 91 dead) were examined for Trypanosoma cruzi infection. This was detected in 31 of the dead bugs (34%) and 88 (79%) of the live bugs examined. With a view to investigate the possible vertebrate hosts of the T. cruzi isolates, the blood of 122 mammals was examined through Giemsa-stained smears, hemocultures and xenodiagnosis. T. cruzi was detected in three specimens of Didelphis marsupialis and T. (M.) theileri was detected in one specimen of Bos taurus. The parasites were isolated from triatomine feces, xenoculture and hemoculture. No evidence of human infection was detected in 58 inhabitants examined, as evaluated by indirect imunofluorescence technique using T. cruzi epimastigotes as antigens. These results show that T. vitticeps is still a sylvatic species although nymphs have been found inside the domicile. Thus, an epidemiological vigilance is necessary to know the behaviour of this species following the continuous modifications promoted by the presence of man.