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1.
Am J Clin Oncol ; 46(3): 94-100, 2023 03 01.
Article in English | MEDLINE | ID: mdl-36735530

ABSTRACT

OBJECTIVE: This study aimed to describe the clinical characteristics and outcomes of patients with venous thromboembolism (VTE) after Immune checkpoint inhibitors (ICI), focusing on patients with gastrointestinal (GI) immune-related adverse events (irAE). METHODS: In this retrospective, single-center study, we report the clinical outcomes of adult cancer patients who developed a VTE within 2 years of ICI initiation. Patients were excluded if alternate causes of VTE were present apart from malignancy and cancer therapy. The cohort was classified into those with GI-irAE, non-GI-irAE, and no irAE. A control group with ICI exposure without irAE and VTE was selected for comparative analysis. RESULTS: Of all ICI-treated patients, 1891 (17.2%) were diagnosed with VTE. In all, 501 (4.6%) had no etiology for VTE aside from malignancy and cancer therapy. Of these, 137 patients were included and classified as: 44 GI-irAE, 42 non-GI-irAE, and 51 no irAE. Chemotherapy within 6 months of ICI therapy was associated with increased VTE risk. There was no difference in the clinical course between those exposed to chemotherapy versus ICI therapy alone, time from ICI initiation to VTE, and VTE type, recurrence, or related hospitalization. While there was no difference in VTE-related mortality, the GI-irAE group was associated with lower all-cause mortality and superior overall survival. CONCLUSION: Combined ICI and chemotherapy use increased VTE risk. There is a similar disease course of VTE after ICI exposure, regardless of other irAEs. Co-existing GI-irAE with VTE is associated with superior overall survival. Prospective studies are needed to evaluate the relationship between ICI therapy and VTE and irAE impact on VTE outcomes.


Subject(s)
Antineoplastic Agents, Immunological , Neoplasms , Venous Thromboembolism , Adult , Humans , Immune Checkpoint Inhibitors/therapeutic use , Retrospective Studies , Antineoplastic Agents, Immunological/therapeutic use , Neoplasms/therapy
2.
Ann Gastroenterol ; 35(5): 522-531, 2022.
Article in English | MEDLINE | ID: mdl-36061160

ABSTRACT

Background: Immune checkpoint inhibitors (ICIs), used for the treatment of solid and hematologic malignancies, come with the risk of immune-related adverse events (irAEs). Opportunistic infections (e.g., cytomegalovirus [CMV]) mimic irAE symptoms and are understudied in this population. We aimed to describe the incidence, characteristics, treatment and outcomes of CMV infection in ICI-treated patients. Methods: We conducted a single-center retrospective review of all adult patients who were CMV-positive after ICI therapy between 06/2011 and 05/2020. A CMV-positive non-ICI cohort was matched to the ICI group based on age, sex and cancer type. Variables of interest were collected through electronic medical records. Results: The study population comprised 192 patients overall. CMV infection incidence was 7.7% in ICI patients and 12.9% in non-ICI patients (P<0.001). Rates of infection clearance (83% vs. 50%, P=0.002) and recurrence (20% vs. 3%, P=0.037) were higher in ICI patients with hematologic vs. solid tumors, despite similar treatments. All-cause mortality was higher in solid rather than hematologic malignancies in ICI patients (83% vs. 54%, P=0.009); CMV-related mortality was low (3-4%) in both groups. Conclusions: CMV infection occurred in about 7.7% of the ICI-treated cancer population. The infection can be disseminated in multiple organs and has a wide spectrum of clinical symptoms. ICI-treated patients with a hematologic malignancy had higher viral clearance and recurrence than those with solid tumors. In this study, CMV itself did not lead to high mortality in cancer patients. Further study is needed to investigate the role of CMV infection in patients' irAEs and cancer outcome.

3.
Case Rep Gastroenterol ; 16(2): 388-393, 2022.
Article in English | MEDLINE | ID: mdl-35949237

ABSTRACT

Encorafenib, a BRAF kinase inhibitor, in combination with binimetinib, a selective MEK inhibitor have known gastrointestinal adverse events; however, adverse colitis events have not been well studied. We report a case series of 4 patients with melanoma who developed inflammatory colitis after BRAF and MEK inhibition with encorafenib and binimetinib, respectively. In the setting of immune checkpoint inhibitor use, BRAF and MEK inhibitors can cause significant inflammatory colitis with endoscopic patterns of predominant right colon ulcerations. It can lead to significant morbidity and frequent interruption of cancer treatment. Early recognition and prompt intervention are critical to improving patient outcomes.

4.
J Gastroenterol Hepatol ; 37(10): 1983-1990, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35730192

ABSTRACT

BACKGROUND AND AIM: The diagnosis and treatment of gastrointestinal (GI) bleeding secondary to malignancy can be challenging. Endoscopy is the gold standard to diagnose and treat gastrointestinal bleeding but clinical characteristics and outcomes of patients with malignancy-related bleeding are not well understood. This study aims to look at clinical characteristics, endoscopic findings, safety and clinical outcomes of endoscopic interventions for GI malignancy-related bleeding. METHODS: We retrospectively reviewed outcomes of patients with confirmed GI malignancies who underwent endoscopy for GI bleeding at MD Anderson Cancer Center between 2010 and 2019. Cox hazard analysis was conducted to identify factors associated with survival. RESULTS: A total of 313 patients were included, with median age of 59 years; 74.8% were male. The stomach (30.0%) was the most common tumor location. Active bleeding was evident endoscopically in 47.3% of patients. Most patients (77.3%) did not receive endoscopic treatment. Of the patients who received endoscopic treatment, 57.7% had hemostasis. No endoscopy-related adverse events were recorded. Endoscopic treatment was associated with hemostasis (P < 0.001), but not decreased recurrent bleeding or mortality. Absence of active bleeding on endoscopy, stable hemodynamic status at presentation, lower cancer stage, and surgical intervention were associated with improved survival. CONCLUSIONS: This study indicates that endoscopy is a safe diagnostic tool in this patient population; while endoscopic treatments may help achieve hemostasis, it may not decrease the risk of recurrent bleeding or improve survival.


Subject(s)
Hemostasis, Endoscopic , Neoplasm Recurrence, Local , Endoscopy, Gastrointestinal , Female , Gastrointestinal Hemorrhage/diagnosis , Gastrointestinal Hemorrhage/etiology , Gastrointestinal Hemorrhage/therapy , Humans , Male , Middle Aged , Neoplasm Recurrence, Local/complications , Retrospective Studies
5.
Hepatol Commun ; 6(7): 1776-1785, 2022 07.
Article in English | MEDLINE | ID: mdl-35481940

ABSTRACT

The availability of immune checkpoint inhibitors (ICIs) for the management of advanced hepatocellular cancer (HCC) has changed the treatment paradigm. There are emerging questions regarding the efficacy of subsequent anticancer therapies. The primary aim of this retrospective, multicenter study was to examine the types of anticancer treatment received after ICIs and to assess the impact on post-ICI survival. We established an international consortium of 11 tertiary-care referral centers located in the USA (n = 249), Europe (n = 74), and Asia (n = 97), and described patterns of care following ICI therapy. The impact of subsequent therapy on overall survival (OS) was estimated using the Kaplan-Meier method and presented with a 95% confidence interval (CI). A total of 420 patients were treated with ICIs for advanced HCC after one line of systemic therapy (n = 371, 88.8%): 31 (8.8%) had died, 152 (36.2%) received best supportive care (BSC) following ICIs, and 163 patients (38.8%) received subsequent anticancer therapy. Tyrosine kinase inhibitors (TKIs, n = 132, 80.9%), in particular sorafenib (n = 49, 30.0%), were the most common post-ICI therapy followed by external beam radiotherapy (n = 28, 17.2%), further immunotherapy (n = 21, 12.9%), locoregional therapy (n = 23, 14.1%), chemotherapy (n = 9, 5.5%), and surgery (n = 6, 3.6%). Receipt of post-ICI therapy was associated with longer median OS compared with those who had received BSC (12.1 vs. 3.3 months; hazard ratio [HR]: 0.4 (95% CI: 2.7-5.0). No difference in OS was noted in those patients who received TKI before ICIs compared with those who received ICIs followed by TKI. Conclusion: Post-ICI therapy is associated with OS in excess of 12 months, suggesting a role for therapeutic sequencing. OS from TKI therapy was similar to that reported in registration studies, suggesting preserved efficacy following ICIs.


Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Carcinoma, Hepatocellular/drug therapy , Humans , Immune Checkpoint Inhibitors/therapeutic use , Liver Neoplasms/drug therapy , Retrospective Studies , Treatment Outcome
6.
Dig Dis Sci ; 67(9): 4509-4517, 2022 09.
Article in English | MEDLINE | ID: mdl-34981309

ABSTRACT

BACKGROUND: Gastric intestinal metaplasia (GIM) is a precursor to gastric adenocarcinoma, making it an attractive target for early detection by endoscopy. The aim of this study was to determine the prevalence, risk factors, and associated histologic findings of GIM among patients undergoing endoscopy in a diverse US population. METHODS: We conducted a retrospective, cross-sectional study of patients undergoing elective endoscopy with gastric biopsies at 6 academic and community centers in Houston, Texas. GIM prevalence was estimated with a 95% confidence interval (CI), and patient demographic and clinical characteristics were summarized using mean with standard deviation, or frequency with percentage. Generalized estimating equations (GEE) were used to compare characteristics between those with and without GIM. RESULTS: Our final cohort consisted of 2685 patients, including 216 cases with GIM and 2469 controls. The prevalence of GIM in our cohort was 8.04% (95% CI 7.07%, 9.14%). The mean age of GIM cases was higher than in the control group (59.8 vs 54.7 years, p < 0.0001). The prevalence of GIM in Asians, Hispanic, Black and Non-Hispanic Whites (NHW) was 14.7%, 11.7%, 9.8% and 5.8%, respectively. On multivariable analysis, factors associated with GIM include age (adj. OR 1.32 per 10 year increase, p < 0.0001), habitual smoking (adj. OR 1.68, p < 0.0001), and race (compared to NHW: Asian, adj. OR 2.34, p = 0.010; Hispanic, adj. OR 2.15, p < 0.001; Black, adj. OR 1.61, p < 0.001). CONCLUSION: Asians, Hispanics, and African Americans have higher rates of GIM than NHW. Ethnicity should be an important consideration on determining who to screen for GIM in the US.


Subject(s)
Helicobacter Infections , Helicobacter pylori , Precancerous Conditions , Stomach Neoplasms , Cross-Sectional Studies , Ethnicity , Gastroscopy , Helicobacter Infections/epidemiology , Humans , Metaplasia/diagnosis , Metaplasia/epidemiology , Middle Aged , Precancerous Conditions/pathology , Retrospective Studies , Stomach Neoplasms/diagnosis , Stomach Neoplasms/epidemiology
7.
Dig Dis Sci ; 67(7): 3244-3251, 2022 07.
Article in English | MEDLINE | ID: mdl-34350519

ABSTRACT

BACKGROUND/OBJECTIVES: Diffuse echogenicity of the pancreas, a commonly discovered finding on endoscopic ultrasound (EUS), is often of undetermined significance. The goal of this study was to characterize the clinical picture and pancreatic function in patients who incidentally present with this endosonographic finding. METHODS: This was a case-control study comparing consecutive adult patients with diffuse echogenicity of the pancreas found on EUS to those who did not have known pancreas disease. Demographic and clinical data were extracted from the electronic medical record. The primary endpoint was exocrine pancreatic insufficiency (EPI) defined as fecal elastase (FE-1) < 200 µg/g. RESULTS: A total of 166 patients were included in this study. There were 89 patients who had diffuse echogenicity of the pancreas on EUS and FE-1 testing. There were 77 control patients with chronic diarrhea who did not have known pancreas disease but did have FE-1 testing. EPI was significantly more likely in the fatty pancreas group compared to the control group (47% vs 6%, p < 0.001). There was also a significantly greater proportion of smokers in the fatty pancreas group compared to the control group (42% vs 17%, p = 0.002). There were no other differences in baseline characteristics between the two groups, including prevalence of chronic pancreatitis by Rosemont classification. On multiple logistic regression analysis controlling for multiple variables, smoking (OR 2.26, 95% CI 1.15-4.43) and NAFLD (OR 3.99, 95% CI 1.09-14.70) had significant associations with EPI. CONCLUSIONS: This study found a significantly greater amount of patients who had diffuse echogenicity of the pancreas on EUS to also have EPI. This is compared to a control group of patients without known pancreas disease. This prevalence was found in the absence of a significant association with chronic pancreatitis on EUS based on Rosemont classification. Future controlled studies are required to further investigate this relationship.


Subject(s)
Exocrine Pancreatic Insufficiency , Pancreatitis, Chronic , Adult , Case-Control Studies , Endosonography , Exocrine Pancreatic Insufficiency/complications , Exocrine Pancreatic Insufficiency/diagnostic imaging , Exocrine Pancreatic Insufficiency/epidemiology , Humans , Pancreas/diagnostic imaging , Pancreatitis, Chronic/complications , Pancreatitis, Chronic/diagnostic imaging
8.
Liver Cancer ; 10(6): 583-592, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34950181

ABSTRACT

BACKGROUND AND RATIONALE: Immune checkpoint inhibitor (ICI) therapy is an expanding therapeutic option for hepatocellular carcinoma (HCC). Antibiotics (ATB) taken prior to or early during ICI therapy can impact immunotherapy efficacy across indications; however, the effect of ATB is undefined in HCC. METHODS: In a large international cohort of 450 ICI recipients from Europe, North America, and Asia, we categorized patients according to timing of ATB focusing on exposure within -30 to +30 days from ICI (early immunotherapy period [EIOP]). EIOP was evaluated in association with overall survival (OS), progression-free survival (PFS), and best radiologic response using RECIST 1.1 criteria. RESULTS: Our study comprised mostly cirrhotic (329, 73.3%) males (355, 79.1%) with a Child-Turcotte Pugh class of A (332, 73.9%), receiving ICI after 1 therapy line (251, 55.9%) for HCC of Barcelona clinic liver cancer stage C (325, 72.4%). EIOP (n = 170, 37.9%) was independent of baseline clinicopathologic features of HCC and correlated with longer PFS (6.1 vs. 3.7 months, log-rank p = 0.0135). EIOP+ patients had similar OS, overall response, and disease control rates (DCRs) compared to EIOP. The effect of EIOP persisted in landmark time analyses and in multivariable models, confirming the independent predictive role of EIOP in influencing PFS following adjustment for covariates reflective of tumor burden, liver function, and ICI regimen administered. In patients receiving programmed cell death-1 receptor/ligand inhibitors monotherapy, EIOP was also associated with higher DCRs (61.4% vs. 50.9%, p = 0.0494). CONCLUSIONS: Unlike other oncological indications, ATB in the 30 days before or after ICI initiation is associated with improved benefit from immunotherapy, independent of disease and treatment-related features. Evaluation of the immune microbiologic determinants of response to ICI in HCC warrants further investigation.

9.
Eur J Cancer ; 157: 140-152, 2021 11.
Article in English | MEDLINE | ID: mdl-34508996

ABSTRACT

PURPOSE: The development of treatment-related adverse events (trAE) correlates favorably with clinical outcomes in multiple studies of patients receiving immune checkpoint inhibitors (ICI); however, this relationship is undefined in patients with hepatocellular carcinoma (HCC). PATIENTS AND METHODS: We derived a cohort of 406 patients with unresectable/advanced HCC receiving ICI therapy as part of international clinical trials submitted to the US Food and Drug Administration (FDA) in support of marketing applications. We tested whether the development of clinically significant trAE (i.e. graded ≥2, trAE2) predicted improved overall survival (OS), progression-free survival (PFS), and objective response rates (ORR) following ICI. We established an international consortium of 10 tertiary-care referral centres located in Europe (n = 67), United States (US, n = 248) and Asia (n = 42) to validate this association. RESULTS: In the FDA dataset of 406 patients, 325 (80%) with Barcelona Clinic Liver Cancer (BCLC) stage C HCC mostly treated with ICI monotherapy (n = 258, 64%), trAE2 were reported in 228 patients (56.1%). Development of trAE2 was associated with longer OS (16.7 versus 11.2 months) and PFS (5.5 versus 2.2 months) and persisted as an independent predictor of outcome after adjusting for viral aetiology, gender, Child-Pugh class, BCLC stage, AFP levels, ECOG-PS, ICI regimen (mono/combination therapy) and receipt of corticosteroid therapy. In a multi-institutional cohort of 357 patients with similar characteristics mostly treated with ICI monotherapy (n = 304, 85%), the development of trAE2 was associated with longer OS (23.3 versus 12.1 months) and PFS (9.6 versus 3.9 months). TrAE2 were confirmed predictors of improved OS (HR 0.43; 95% CI:0.25-0.75) and PFS (HR 0.48; 95% CI: 0.31-0.75), with multivariable analyses confirming their association with outcome independent of clinicopathologic features of interest. Additional time-varying multivariable analyses also indicated that trAEs were associated with a decreased risk of progression (HR 0.56, 95% CI: 0.46-0.67) in the FDA dataset and death (HR 0.55; 95% CI: 0.32-0.95) in the multi-institutional dataset. CONCLUSION: Development of trAE2 correlates with improved outcomes in patients with HCC receiving ICI in clinical trials and in routine practice. Prospective studies aimed at understanding the underlying immunologic foundations of such relationships are warranted to identify predictive biomarkers of toxicity and response.


Subject(s)
Carcinoma, Hepatocellular/drug therapy , Immune Checkpoint Inhibitors/adverse effects , Liver Neoplasms/drug therapy , Adolescent , Adult , Aged , Aged, 80 and over , Carcinoma, Hepatocellular/mortality , Clinical Trials as Topic , Female , Humans , Liver Neoplasms/mortality , Male , Middle Aged , Young Adult
10.
J Immunother Cancer ; 8(2)2020 10.
Article in English | MEDLINE | ID: mdl-33028690

ABSTRACT

The impact of corticosteroid therapy (CT) on efficacy of immune checkpoint inhibitors (ICI) is undefined in hepatocellular carcinoma (HCC). We evaluated whether CT administered at baseline (bCT) or concurrently with ICI (cCT) influences overall (OS), progression-free survival (PFS) and overall response rates (ORR) in 341 patients collected across 3 continents. Of 304 eligible patients, 78 (26%) received >10 mg prednisone equivalent daily either as bCT (n=14, 5%) or cCT (n=64, 21%). Indications for CT included procedure/prophylaxis (n=37, 47%), management of immune-related adverse event (n=27, 35%), cancer-related symptoms (n=8, 10%) or comorbidities (n=6, 8%). Neither overall CT, bCT nor cCT predicted for worse OS, PFS nor ORR in univariable and multivariable analyses (p>0.05). CT for cancer-related indications predicted for shorter PFS (p<0.001) and was associated with refractoriness to ICI (75% vs 33%, p=0.05) compared with cancer-unrelated indications. This is the first study to demonstrate that neither bCT nor cCT influence response and OS following ICI in HCC. Worse outcomes in CT recipients for cancer-related indications appear driven by the poor prognosis associated with symptomatic HCC.


Subject(s)
Adrenal Cortex Hormones/therapeutic use , Carcinoma, Hepatocellular/drug therapy , Immune Checkpoint Inhibitors/therapeutic use , Liver Neoplasms/drug therapy , Adrenal Cortex Hormones/pharmacology , Female , Humans , Immune Checkpoint Inhibitors/pharmacology , Male , Prospective Studies , Treatment Outcome
11.
J Immunother Cancer ; 8(2)2020 08.
Article in English | MEDLINE | ID: mdl-32868393

ABSTRACT

BACKGROUND: Nivolumab is Food and Drug Administration approved in sorafenib-experienced, advanced hepatocellular carcinoma (HCC). Post-registration data of treatment in a real-world setting is lacking. PATIENTS AND METHODS: We performed an international, multicenter observational study to confirm safety and efficacy of nivolumab in 233 patients treated outside clinical trials from eight centers in North America, Europe and Asia. RESULTS: Patients received nivolumab for Barcelona Clinic Liver Cancer stage C (n=191, 92.0%) and Child-Pugh (CP) A (n=158, 67.8%) or B (n=75, 32.2%) HCC as first (n=85, 36.5%) or second to fourth systemic therapy line (n=148, 63.5%). Objective response rate (ORR) was 22.4% and disease control rate was 52.1%. Median overall survival (OS) was 12.2 months (95% CI 8.4 to 16.0) and median progression-free survival was 10.1 months (95% CI 6.1 to 14.2). Treatment-related adverse events of grade >2 occurred in 26 patients (11.2%). Efficacy and safety were similar across CP classes and therapy line. OS was shorter in CP-B than A (7.3 months vs 16.3 months, p<0.001) and in post-first line use (10.4 months vs 16.3 months, p=0.05). Achievement of an objective response predicted for improved OS (25.4 months vs 13.2 months, p<0.001). CONCLUSIONS: This study confirms safety and efficacy of nivolumab in advanced HCC across various lines of therapy and degrees of liver dysfunction. Despite equal ORR and toxicity to nivolumab, patients with CP-B functional class have shorter survival than the patients with CP-A.


Subject(s)
Carcinoma, Hepatocellular/drug therapy , Liver Neoplasms/drug therapy , Nivolumab/therapeutic use , Aged , Carcinoma, Hepatocellular/pathology , Female , Humans , Liver Neoplasms/pathology , Male , Middle Aged , Nivolumab/pharmacology , Retrospective Studies
12.
Cancers (Basel) ; 12(7)2020 Jul 10.
Article in English | MEDLINE | ID: mdl-32664319

ABSTRACT

Immune checkpoint inhibitors (ICI) have shown positive results in patients with hepatocellular carcinoma (HCC). As liver function contributes to prognosis, its precise assessment is necessary for the safe prescribing and clinical development of ICI in HCC. We tested the accuracy of the albumin-bilirubin (ALBI) grade as an alternative prognostic biomarker to the Child-Turcotte-Pugh (CTP). In a prospectively maintained multi-centre dataset of HCC patients, we assessed safety and efficacy of ICI across varying levels of liver dysfunction described by CTP (A to C) and ALBI grade and evaluated uni- and multi-variable predictors of overall (OS) and post-immunotherapy survival (PIOS). We studied 341 patients treated with programmed-death pathway inhibitors (n = 290, 85%). Pre-treatment ALBI independently predicted for OS, with median OS of 22.5, 9.6, and 4.6 months across grades (p < 0.001). ALBI was superior to CTP in predicting 90-days mortality with area under the curve values of 0.65 (95% CI 0.57-0.74) versus 0.63 (95% CI 0.54-0.72). ALBI grade at ICI cessation independently predicted for PIOS (p < 0.001). Following adjustment for ICI regimen, neither ALBI nor CTP predicted for overall response rates or treatment-emerging adverse events (p > 0.05). ALBI grade identifies a subset of patients with prolonged survival prior to and after ICI therapy, lending itself as an optimal stratifying biomarker to optimise sequencing of systemic therapies in advanced HCC.

14.
Antimicrob Agents Chemother ; 60(8): 4600-9, 2016 08.
Article in English | MEDLINE | ID: mdl-27185807

ABSTRACT

Injury occurring on the surface of the rectal mucosal lining that causes defects in barrier function may result in increased risk for transmission of infection by HIV and other pathogens. Such injury could occur from microbicidal or other topical agents, mechanical trauma during consensual or nonconsensual intercourse, or inflammatory conditions. Tools for evaluation of rectal mucosal barrier function for assessing the mucosa under these conditions are lacking, particularly those that can provide in vivo structural and functional barrier integrity assessment and are adaptable to longitudinal imaging. We investigated confocal endomicroscopy (CE) as a means for in vivo imaging of the rectal epithelial barrier in the ovine model following spatially confined injury to the surface at a controlled site using a topical application of the microbicide test agent benzalkonium chloride. Topical and intravenous (i.v.) fluorescent probes were used with CE to provide subcellular resolution imaging of the mucosal surface and assessment of barrier function loss. A 3-point CE grading system based on cellular structure integrity and leakage of dye through the mucosa showed significant differences in score between untreated (1.19 ± 0.53) and treated (2.55 ± 0.75) tissue (P < 0.0001). Histological grading confirmed findings of barrier compromise. The results indicate that CE is an effective means for detecting epithelial injury and barrier loss following localized trauma in a large-animal model. CE is promising for real-time rectal mucosal evaluation after injury or trauma or topical application of emerging biomedical prevention strategies designed to combat HIV.


Subject(s)
HIV Infections/prevention & control , Intestinal Mucosa/cytology , Microscopy, Confocal/methods , Rectum/cytology , Animals , Disease Models, Animal , Intestinal Mucosa/metabolism , Sheep
15.
Biomed Eng Online ; 12: 103, 2013 Oct 12.
Article in English | MEDLINE | ID: mdl-24120254

ABSTRACT

BACKGROUND: Shape memory polymer (SMP) foams are being investigated as an alternative aneurysm treatment method to embolic coils. The goal of both techniques is the reduction of blood flow into the aneurysm and the subsequent formation of a stable thrombus, which prevents future aneurysm rupture. The purpose of this study is to experimentally determine the parameters, permeability and form factor, which are related to the flow resistance imposed by both media when subjected to a pressure gradient. METHODS: The porous media properties-permeability and form factor-of SMP foams and mock embolic coils (MECs) were measured with a pressure gradient method by means of an in vitro closed flow loop. We implemented the Forchheimer-Hazen-Dupuit-Darcy equation to calculate these properties. Mechanically-reticulated SMP foams were fabricated with average cell sizes of 0.7E-3 and 1.1E-3 m, while the MECs were arranged with volumetric packing densities of 11-28%. RESULTS: The permeability of the SMP foams was an order of magnitude lower than that of the MECs. The form factor differed by up to two orders of magnitude and was higher for the SMP foams in all cases. The maximum flow rate of all samples tested was within the inertial laminar flow regime, with Reynolds numbers ranging between 1 and 35. CONCLUSIONS: The SMP foams impose a greater resistance to fluid flow compared to MECs, which is a result of increased viscous and inertial losses. These results suggest that aneurysms treated with SMP foam will have flow conditions more favorable for blood stasis than those treated with embolic coils having packing densities ≤ 28%.


Subject(s)
Endovascular Procedures/instrumentation , Polymers , Hydrodynamics , Intracranial Aneurysm/surgery , Permeability , Porosity
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