Endovascular management of hemosuccus pancreaticus, a rare case report of gastrointestinal bleeding.

BACKGROUND: Hemorrhage from the pancreatic duct, or hemosuccus pancreaticus (HP), is an unusual cause of intermittent gastrointestinal bleeding. HP is most often diagnosed in patients with chronic pancreatitis, and is usually due to the rupture of an aneurysm in the splenic artery. The traditional treatment for HP is surgery, although most cases can be managed by angioembolization. CASE PRESENTATION: We present a case of HP in a patient with no history or evidence of chronic pancreatitis. Repeated endoscopy revealed fresh bleeding from the papilla of Vater. Angiography revealed an aneurysm of the splenic artery, which was the suspected cause of the intermittent bleeding from the pancreatic duct. Angiography demonstrated extravasation of contrast from the aneurysm. A peripheral Jostent stent-graft was hand-mounted on an angioplasty balloon and then inserted into the aneurysm. Arteriography revealed successful occlusion of the aneurysm with the stent-graft. No recurrent gastrointestinal bleeding was observed during the five years follow-up periods. CONCLUSION: HP should be included in the differential diagnosis of intermittent gastrointestinal bleeding in patients with histories of chronic alcoholism, even when they do not have a history of chronic pancreatitis. We recommend an interventional procedure with a metal stent for the initial treatment of HP.

Susceptibility-weighted imaging for stem cell visualization in a rat photothrombotic cerebral infarction model.

BACKGROUND: In cell therapy, magnetic resonance imaging (MRI) has been used to visualize superparamagnetic iron oxide (SPIO)-labeled stem cells homing to a lesion. Improving traceability is to utilize the sequence that maximizes sensitivity to the susceptibility effect of SPIO. PURPOSE: To explore the best method by comparing the MRI sequences to visualize mesenchymal stem cells (MSCs) labeled with SPIO. MATERIAL AND METHODS: Human bone marrow (hBM)-derived MSCs were labeled by internalization of SPIO nanoparticles. In vitro MRI was performed for the SPIO-labeled hBM-MSCs in tubes with T2-weighted (T2W), T2*-weighted (T2*W), and susceptibility-weighted images (SWI). Contrast-to-noise ratio (CNR) and volumes of dark signal of SPIO-labeled hBM-MSCs were obtained on images of each sequence. Photothrombotic cerebral infarction (PTCI) was induced in eight rats, and 2.5 × 10(5) SPIO-labeled hBM-MSCs were infused through the tail vein on the third day. In vivo MRI of the rat brain was performed using a 3.0 T MRI on the first, third, seventh, and 14th days. CNRspio was obtained on T2W imaging, T2*W imaging, and SWI. The dark signals were compared with the SPIO-positive cells of Prussian blue staining. RESULTS: In vitro MRI of 5 × 10(5) SPIO-labeled hBM-MSCs showed the CNR and volume of dark signal to be 63, 517 mm(3) in SWI, 41, 228 mm(3) in T2*W imaging, and 56, 41 mm(3) in T2W imaging, respectively. In vivo MRI showed a dark signal surrounding the high signal intensity of PTCI. Pathologically, the dark signals were matched with SPIO-labeled hBM-MSC in the corresponding rat. The dark signal was most prominent in SWI, then T2*W imaging, and finally in T2W imaging (P <0.05). In SWI, other causes of dark signals were matched with the veins and the choroid plexuses on histopathology. CONCLUSION: SWI can visualize SPIO-labeled hBM-MSCs more sensitively, earlier, and with larger size and greater contrast than T2W imaging and T2*W imaging.

Antiglycolytic therapy combined with an image-guided minimally invasive delivery strategy for the treatment of breast cancer.

PURPOSE: The antiglycolytic agent 3-bromopyruvate (3-BrPA) promotes anticancer effects in multiple tumor models. This study evaluated the therapeutic efficacy of ultrasound (US)-guided intratumoral delivery of 3-BrPA in an orthotopic tumor model of breast cancer. MATERIALS AND METHODS: Human breast cancer cell line MDA MB 231 was used for in vitro and in vivo studies. The anticancer effect of 3-BrPA was evaluated by viability assay, quantification of adenosine triphosphate (ATP) and lactate levels, and activity of matrix metalloproteinase (MMP)-9. In animal experiments, 15 nude mice with MDA MB 231 breast tumors were divided into three groups for US-guided intratumoral treatment with 1.75 mM 3-BrPA (group 1), 5 mM 3-BrPA (group 2), and saline solution (group 3). Tumor size was measured and subjected to histopathologic examination. RESULTS: In vitro, treatment with 3-BrPA resulted in a dose-dependent decrease in cell viability. A decrease in ATP and lactate levels, invasion, and MMP9 activity and expression was observed after treatment with concentrations of 3-BrPA that did not affect cell viability. In vivo, a significant difference in tumor volume was observed between 3-BrPA-treated and control animals. At the end of the study, tumor volumes in the 3-BrPA groups were 1,876 mm(3)±346 and 426 mm(3)±180 in the 1.75-mM and 5-mM 3-BrPA groups, respectively, versus 4,447 mm(3)±571 in the control group (P< .05). CONCLUSIONS: US-guided intratumoral injection of 3-BrPA effectively blocks breast cancer progression in an orthotopic mouse tumor model.

Design and characterisation of doxorubicin-releasing chitosan microspheres for anti-cancer chemoembolisation.

The aims of this study were to design and characterise doxorubicin-loaded chitosan microspheres for anti-cancer chemoembolisation. Doxorubicin-loaded chitosan microspheres were prepared by emulsification and cross-linking methods. Doxorubicin-chitosan solution was initially complexed with tripolyphosphate (TPP) to improve drug loading capabilities. Doxorubicin-loaded chitosan microspheres were highly spherical and had approximately diameters of 130-160 µm in size. Drug loading amount and loading efficiency were in the range 3.7-4.0% and 68.5-85.8%, respectively, and affected by TPP concentration, drug levels and cross-linking time. Doxorubicin release was affected by TPP complexation, cross-linking time and release medium. Especially, lysozyme in release media considerably increased drug release. Synergistic anti-cancer activities of doxorubicin-releasing chitosan microspheres were confirmed to VX2 cells in the rabbit auricle model compared with blank microspheres. Doxorubicin-loaded chitosan microspheres can efficiently be prepared by TPP gelation and cross-linking method and developed as multifunctional anti-cancer embolic material.

Glycol chitosan/heparin immobilized iron oxide nanoparticles with a tumor-targeting characteristic for magnetic resonance imaging.

We described the preparation of the glycol chitosan/heparin immobilized iron oxide nanoparticles (composite NPs) as a magnetic resonance imaging agent with a tumor-targeting characteristic. The iron oxide nanoseeds used clinically as a magnetic resonance imaging agent were immobilized into the glycol chitosan/heparin network to form the composite NPs. To induce the ionic interaction between the iron oxide nanoseeds and glycol chitosan, gold was deposited on the surface of iron oxide nanoseeds. After the immobilization of gold-deposited iron oxide NPs into the glycol chitosan network, the NPs were stabilized with heparin based on the ionic interaction between cationic glycol chitosan and anionic heparin. FE-SEM (field emission-scanning electron microscopy) and a particle size analyzer were used to observe the formation of the stabilized composite NPs, and a Jobin-Yvon Ultima-C inductively coupled plasma-atomic emission spectrometer (ICP-AES) was used to measure the contents (%) of formed iron oxide nanoseeds as a function of reaction temperature and formed gold deposited on the iron oxide nanoparticles. We also evaluated the time-dependent excretion profile, in vivo biodistribution, circulation time, and tumor-targeting ability of the composite NPs using a noninvasive NIR fluorescence imaging technology. To observe the MRI contrast characteristic, the composite NPs were injected into the tail veins of tumor-bearing mice to demonstrate their selective tumoral distribution. The MR images were collected with conventional T(2)-weighted spin echo acquisition parameters.

A radiofrequency electrode catheter-guide wire system for arterial occlusion.

PURPOSE: To describe the design of a radiofrequency (RF) electrode catheter/guide wire system to allow endovascular coagulation of vessels. MATERIALS AND METHODS: A circuit was created by modifying an ordinary microcatheter. An electrically conductive ring was placed at a microcatheter tip, and an extension lead at the hub site. They were each connected to an inherent coil mesh. The rings (ie, cathodes) were 1, 3, 5, 10, and 20 mm in length. In egg white, a coagulation study was performed by changing the length of the guide wire (ie, anode; 1, 3, 5, 10, 20, and 40 mm) in each cathode at 20 W. The coagulation time and site were analyzed. In rabbits, the renal artery was ablated with the use of a 20-mm cathode and 10-mm anode. RESULTS: In the egg white study, the coagulation time was proportionally increased and was dependent on the lengths of the cathode and anode (P < .05). Coagula developed at the anode to the 3-mm protrusion for the 1-mm cathode, to the 5-mm protrusion for the 3-mm cathode, to the 5-mm protrusion for the 5-mm cathode, to the 10-mm protrusion for the 10-mm cathode, and to the 20-mm protrusion for the 20-mm cathode. In rabbits, the renal artery was successfully occluded. Pathologic examination showed occlusion of the renal artery with organization, and the presence of a necrotic arterial wall with fibrosis, inflammation, and intact internal elastic lamina. CONCLUSIONS: The RF electrode catheter/guide wire system successfully coagulated egg white and occluded the rabbit renal artery.

In vivo tracking of mesenchymal stem cells labeled with a novel chitosan-coated superparamagnetic iron oxide nanoparticles using 3.0T MRI.

This study aimed to characterize and MRI track the mesenchymal stem cells labeled with chitosan-coated superparamagnetic iron oxide (Chitosan-SPIO). Chitosan-SPIO was synthesized from a mixture of FeCl(2) and FeCl(3). The human bone marrow derived mesenchymal stem cells (hBM-MSC) were labeled with 50 microg Fe/mL chitosan-SPIO and Resovist. The labeling efficiency was assessed by iron content, Prussian blue staining, electron microscopy and in vitro MR imaging. The labeled cells were also analyzed for cytotoxicity, phenotype and differentiation potential. Electron microscopic observations and Prussian blue staining revealed 100% of cells were labeled with iron particles. MR imaging was able to detect the labeled MSC successfully. Chitosan-SPIO did not show any cytotoxicity up to 200 microg Fe/mL concentration. The labeled stem cells did not exhibit any significant alterations in the surface markers expression or adipo/osteo/chondrogenic differentiation potential when compared to unlabeled control cells. After contralateral injection into rabbit ischemic brain, the iron labeled stem cells were tracked by periodical in vivo MR images. The migration of cells was also confirmed by histological studies. The novel chitosan-SPIO enables to label and track MSC for in vivo MRI without cellular alteration.

Highly spherical and deformable chitosan microspheres for arterial embolization.

The aim of this study was to fabricate deformable chitosan (CS) microspheres for arterial embolization. CS microspheres containing poly(ethylene glycol) (PEG) were prepared by ionotropic gelation; PEG was then removed from the CS microspheres to produce the highly porous structure to allow deformability. The porosity was controlled by blending ratios of CS/PEG polymers (CS/PEG=from 100/0 to 15/85) and the effect of porosity on microcatheter delivery was examined. The size range of porous microspheres was 500-600 mum with sphericity between 1.012-1.041. Scanning electron microscope observation confirmed that microporous networks were effectively obtained by PEG extraction proportional to the initial amount of PEG. Water retention capacities, indicative of internal porosities of microspheres, increased with increasing initial amounts of blended PEG. CS microspheres with water retention values of greater than 28% exhibited noticeable deformation and smooth passage through the microcatheter tip. Novel deformable microspheres are, therefore, expected to be clinically applicable for arterial embolization.

Metformin Ameliorates Lipotoxic ß-Cell Dysfunction through a Concentration-Dependent Dual Mechanism of Action.

BACKGROUND: Chronic exposure to elevated levels of free fatty acids contributes to pancreatic ß-cell dysfunction. Although it is well known that metformin induces cellular energy depletion and a concomitant activation of AMP-activated protein kinase (AMPK) through inhibition of the respiratory chain, previous studies have shown inconsistent results with regard to the action of metformin on pancreatic ß-cells. We therefore examined the effects of metformin on pancreatic ß-cells under lipotoxic stress. METHODS: NIT-1 cells and mouse islets were exposed to palmitate and treated with 0.05 and 0.5 mM metformin. Cell viability, glucose-stimulated insulin secretion, cellular adenosine triphosphate, reactive oxygen species (ROS) levels and Rho kinase (ROCK) activities were measured. The phosphorylation of AMPK was evaluated by Western blot analysis and mRNA levels of endoplasmic reticulum (ER) stress markers and NADPH oxidase (NOX) were measured by real-time quantitative polymerase chain reaction analysis. RESULTS: We found that metformin has protective effects on palmitate-induced ß-cell dysfunction. Metformin at a concentration of 0.05 mM inhibits NOX and suppresses the palmitate-induced elevation of ER stress markers and ROS levels in a AMPK-independent manner, whereas 0.5 mM metformin inhibits ROCK activity and activates AMPK. CONCLUSION: This study suggests that the action of metformin on ß-cell lipotoxicity was implemented by different molecular pathways depending on its concentration. Metformin at a usual therapeutic dose is supposed to alleviate lipotoxic ß-cell dysfunction through inhibition of oxidative stress and ER stress.

Retrievable biliary stent-graft in the treatment of benign biliary strictures.

PURPOSE: To investigate the technical and clinical efficacy of a retrievable stent-graft in the treatment of benign biliary strictures. MATERIALS AND METHODS: From February 2004 to December 2006, 29 patients with 32 benign biliary strictures (17 patients with 18 chronic cholangitis strictures and 12 with 14 postoperative strictures) were enrolled in this study. Twenty-four patients had 26 recurrent strictures despite prolonged catheter interposition after balloon dilation procedures. Five patients with six strictures had not previously undergone interventional treatment. A total of 36 stent-grafts were placed, and all stent-grafts were removed by means of a percutaneous route or via a T-tube 6.7 weeks (range, 2-10 weeks) after stent-graft placement. RESULTS: The retrievable stent-grafts were successfully placed and removed in all cases. Migration occurred in four of the 36 (11%) stent-grafts (11%). Immediately after stent-graft removal, all strictures were widened significantly. From 2 days to 8 weeks after removal, 29 of 32 lesions (91%) remained patent with or without recurrence of minimal strictures. During the mean follow-up of 27.9 months (range, 9-34 months), none of the 29 lesions had recurrence of clinically significant strictures. The primary patency rate was 90.6%. Three additional stent-graft placements for recurrent stricture were required in three lesions (9.4%). During a mean follow-up of 13.3 months (range, 9-16 months), two patients had no evidence of biliary obstruction. The secondary patency rate and clinical success rate was 97% (31 of 32 lesions). CONCLUSIONS: The placement and removal of a retrievable stent-graft in the treatment of benign biliary strictures is technically feasible and appears to be a clinically effective method.

Biliary stone removal through the percutaneous transhepatic biliary drainage route, focusing on the balloon sphincteroplasty flushing technique: a single center study with 916 patients.

PURPOSE: To present our experience in biliary stone removal (BSR) through the percutaneous transhepatic biliary drainage (PTBD) route in 916 patients, and discuss its clinical usefulness. MATERIALS AND METHODS: From 2001 to 2015, 916 patients (479 male patients and 437 female patients; age range, 22-92 years; mean age, 67 years) with 52 recurring cases, so a total of 968 cases, were enrolled in this study and retrospectively reviewed. PTBD was performed in all patients. BSR was performed using a combination of a balloon sphincteroplasty flushing technique, a pushing technique after sphincteroplasty, and classical extraction technique, decided case by case. RESULTS: A complete removal was achieved in 893 cases (92.3%) and the overall clinical success rate was 99.3%. Failure occurred in 7 cases (0.7%), and the causes of failure were stone impaction (n = 5) and intrahepatic bile duct stricture (n = 2). Sphincteroplasty was performed in 902 cases (93.2%). Balloon sphincteroplasty flushing technique was used in 829 (85.6%) cases. There was no major complication. Transient minor complications were seen in 86 cases (8.9%). CONCLUSIONS: BSR through the PTBD route using a combination of techniques, including balloon sphincteroplasty flushing, is a safe and effective treatment modality to remove biliary stones.

Preparation and magnetic resonance imaging effect of polyvinylpyrrolidone-coated iron oxide nanoparticles.

Polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles were prepared by the thermal decomposition of Fe(CO)(5) (iron pentacarbonyl) in one step. X-ray diffraction (XRD), transmission electron microscopy (TEM), electrophoretic light scattering (ELS), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) together with the variation of the molar ratio of PVP/Fe(CO)(5), solvent, and molecular weight of PVP, were used to characterize the PVP-coated iron oxide nanoparticles. Fifty to hundred nanometer-sized iron oxide nanoclusters with a spherical shape were formed in dimethylformamide (DMF), used as a solvent, and exhibited an enhanced stability in the aqueous media. Their magnetic properties were investigated by superconducting quantum interface device (SQUID). The in vitro cytotoxicity test revealed that the PVP-coated iron oxide nanoparticles exhibited excellent biocompatibility by MTT assay. Magnetic resonance imaging (MRI) effect was observed with the administration of PVP-coated iron oxide nanoparticles through the marginal vein of rabbit, resulting in improved detection of the liver lesions.

Sensitivity of susceptibility-weighted imaging in detecting superparamagnetic iron oxide-labeled mesenchymal stem cells: a comparative study.

BACKGROUND: Susceptibility-weighted imaging (SWI) is extremely sensitive in the detection of superparamagnetic iron oxide (SPIO) nanoparticle-labeled cells. However, no study has compared molecular imaging for stem cell detection using SWI and other MRI pulse sequences. OBJECTIVES: This study aims to assess the sensitivity of SWI in detecting SPIO nanoparticle-labeled, human bone marrow-derived mesenchymal stem cells (SPIO-hMSCs) compared with that of T2- and T2*-weighted imaging (T2WI and T2*WI, respectively) in a phantom and in vivo study in rats. MATERIALS AND METHODS: A phantom was prepared with various cell concentrations. In one normal rat, SPIO-hMSCs were implanted directly through burr holes into both caudate putamens, while in three rats without and six rats with photothrombotic infarction, 2.5 × 10(5)/ml SPIO-hMSCs were infused into the ipsilateral internal carotid artery (ICA). T2WI, T2*WI, and SWI findings were compared for dark regions representing SPIO-hMSCs. RESULTS: SWI and T2*WI detected 15 µL of 13 SPIO-hMSCs/µL and 15 µL of 27 SPIO-hMSCs/µL in the phantom, respectively and 3 µL of 333 SPIO-hMSCs/µL and 3 µL of 167 SPIO-hMSCs/µL in the normal rat brain (direct implantation). In the normal rat brain (ICA infusion), one of the three cases showed numerous foci of dark regions dispersed throughout the brain on T2*WI and SWI. Dark regions surrounded the infarcts in all six infracted rat brains. The dark region was most prominent on SWI, followed by T2*WI and T2WI in all six rats (P = 0.002). Implanted SPIO-hMSCs were confirmed using Prussian blue staining. CONCLUSIONS: SWI is the most sensitive in the detection of SPIO-hMSCs, with the dark regions representing SPIO-hMSCs being more prominent on SWI than on T2*WI and T2WI.

Evaluation of engraftment of superparamagnetic iron oxide-labeled mesenchymal stem cells using three-dimensional reconstruction of magnetic resonance imaging in photothrombotic cerebral infarction models of rats.

OBJECTIVE: To evaluate engraftment by visualizing the location of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) three-dimensionally in photothrombotic cerebral infarction (PTCI) models of rats. MATERIALS AND METHODS: Magnetic resonance imaging (MRI) of an agarose block containing superparamagnetic iron oxide (SPIO)-labeled hBM-MSCs was performed using a 3.0-T MRI, T2-(T2WI), T2(*)-(T2(*)WI), and susceptibility-weighted images (SWI). PTCI was induced in 6 rats, and 2.5 × 10(5) SPIO-labeled hBM-MSCs were infused through the ipsilateral internal carotid artery (ICA group) or tail vein (IV group). MRI was performed on days 1, 3, 7, and 14 after stem cell injection. Dark signal regions were confirmed using histology. Three-dimensional MRI reconstruction was performed using the clinical workflow solution to evaluate the engraftment of hBM-MSCs. Volumetric analysis of the engraftment was also performed. RESULTS: The volumes of SPIO-labeled hBM-MSCs in the phantom MRI were 129.3, 68.4, and 25.9 µL using SWI, T2(*)WI, and T2WI, respectively. SPIO-labeled hBM-MSCs appeared on day 1 after injection, encircling the cerebral infarction from the ventral side. Dark signal regions matched iron positive cells and human origin (positive) cells. The volume of the engraftment was larger in the ICA group on days 1, 3, and 7, after stem cell injection (p < 0.05 on SWI). SWI was the most sensitive MRI pulse sequence (p < 0.05). The volume of infarction decreased until day 14. CONCLUSION: The engraftment of SPIO-labeled hBM-MSCs can be visualized and evaluated three-dimensionally in PTCI models of rats. The engraftment volume was larger in the ICA group than IV group on early stage within one week.

Microfluidic-assisted fabrication of flexible and location traceable organo-motor.

In this paper, we fabricate a flexible and location traceable micromotor, called organo-motor, assisted by microfluidic devices and with high throughput. The organo-motors are composed of organic hydrogel material, poly (ethylene glycol) diacrylate (PEGDA), which can provide the flexibility of their structure. For spatial and temporal traceability of the organo-motors under magnetic resonance imaging (MRI), superparamagnetic iron oxide nanoparticles (SPION; Fe3O4) were incorporated into the PEGDA microhydrogels. Furthermore, a thin layer of platinum (Pt) was deposited onto one side of the SPION-PEGDA microhydrogels providing geometrical asymmetry and catalytic propulsion in aqueous fluids containing hydrogen peroxide solution, H2O2. Furthermore, the motion of the organo-motor was controlled by a small external magnet enabled by the presence of SPION in the motor architecture.

MRI traceability of superparamagnetic iron oxide nanoparticle-embedded chitosan microspheres as an embolic material in rabbit uterus.

PURPOSE: We aimed to compare polyvinyl alcohol (PVA) particles with calibrated superparamagnetic iron oxide (SPIO) nanoparticle-loaded chitosan microspheres in a rabbit model, specifically regarding the relative distribution of embolic agents within the uterus based on magnetic resonance imaging (MRI) and pathological evaluation. METHODS: Twelve New Zealand white rabbits underwent uterine artery embolization using either standard PVA particles (45-150 µm or 350-500 µm) or calibrated SPIO-embedded chitosan microspheres (45-150 µm or 300-500 µm). MRI and histopathological findings were compared one week after embolization. RESULTS: Calibrated SPIO-loaded chitosan microspheres 45-150 µm in size were detected on T2-weighted images. On histological analysis, calibrated SPIO-embedded chitosan microspheres were found in both myometrium and endometrium, whereas PVA particles were found only in the perimyometrium or extrauterine fat pads. A proportional relationship was noted between the calibrated SPIO-embedded chitosan microsphere size and the size of the occluded artery. CONCLUSION: Calibrated SPIO-embedded chitosan microspheres induced greater segmental arterial occlusion than PVA particles and showed great potential as a new embolic material. SPIO-embedded chitosan microspheres can be used to follow distribution of embolic particles through MRI studies.

Fixation methods for implantable port chamber: comparative study using glue, self-stabilizing leg and suture fixations in rabbits.

OBJECTIVE: To evaluate the fixation strength and tissue reaction of the glue fixation and self-stabilizing leg fixation methods and to compare the results with those of the conventional tagging suture fixation method. MATERIALS AND METHODS: Twelve healthy rabbits were selected and three different methods of implanting the port chamber were employed on the back of each rabbit. A total of thirty six port chambers were implanted with these three different methods, viz. the glue fixation method using tissue adhesive, the self-stabilizing leg method using a self-expandable stabilizing leg, and the suture fixation method. The fixation strength and the gross and histopathologic changes of each fixation method were evaluated at three days, one week, two weeks and four weeks after port implantation. RESULTS: The glue fixation method showed a good fixation strength, which was similar to that of the tagging suture method (p = 0.3486). Five of the six ports (83%) implanted with the glue fixation method which were examined after two weeks showed cracks on the external surface, but this had no adverse effects on their function. A large amount of granulation tissue reaction was found at the bottom of the chamber (p = 0.0025). The fixation with the self-stabilizing leg showed relatively lower fixation strength (p = 0.0043), but no turning-over of the chamber occurred. The fixation strength improved with time after the first week, and minimal granulation tissue reaction was observed with this method. CONCLUSION: The glue fixation method exhibited equal fixation strength compared to the suture fixation, but showed cracking and a large amount of granulation tissue, whereas the fixation with a self-stabilizing leg showed weaker fixation strength.

Mathematical modeling of radiofrequency ablation for varicose veins.

We present a three-dimensional mathematical model for the study of radiofrequency ablation (RFA) with blood flow for varicose vein. The model designed to analyze temperature distribution heated by radiofrequency energy and cooled by blood flow includes a cylindrically symmetric blood vessel with a homogeneous vein wall. The simulated blood velocity conditions are U = 0, 1, 2.5, 5, 10, 20, and 40 mm/s. The lower the blood velocity, the higher the temperature in the vein wall and the greater the tissue damage. The region that is influenced by temperature in the case of the stagnant flow occupies approximately 28.5% of the whole geometry, while the region that is influenced by temperature in the case of continuously moving electrode against the flow direction is about 50%. The generated RF energy induces a temperature rise of the blood in the lumen and leads to an occlusion of the blood vessel. The result of the study demonstrated that higher blood velocity led to smaller thermal region and lower ablation efficiency. Since the peak temperature along the venous wall depends on the blood velocity and pullback velocity, the temperature distribution in the model influences ablation efficiency. The vein wall absorbs more energy in the low pullback velocity than in the high one.