Table 4 - uploaded by Ahmet Yigit Goktay
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Source publication
This study sought to compare the most frequently used embolic particles in an animal model. In 16 New Zealand white rabbits, right renal arteries were embolized using four different embolic particles (polyvinyl alcohol [PVA] particles, 150-250 microm; PVA microspheres [PVAMs], 150-300 microm; Tris-acryl gelatin microspheres [TGMs], 100-300 microm;...
Citations
... We initially searched literature reviews, commentaries and comparative studies in order to collect information on the different studies available on particle characteristics affecting arterial distribution and occlusion. Studies by Sheth et al., 42 Golzarian and Weng et al., 20 Senturk et al., 41 and Wenxiao et al. 25 helped greatly in this process as they summarized the main embolic particles used and the various intrinsic and extrinsic characteristics affecting their behavior. As addressed in the following, several characteristics were identified in these studies: particle size, particle type/aggregation, compressibility/deformability, infusion rate, concentration/dilution, and hemodynamics/ arterial resistance, elastic recovery/viscous relaxation and particle density/constitution. ...
Embolization has tremendously evolved in recent years and has expanded to treatment of a variety of pathologic processes. There has been emerging evidence that the level of arterial occlusion and the distribution of embolic particles may play an important role in the clinical outcome. This is a comprehensive literature review to identify variables that play important role in determination of level of occlusion of blood vessels and distribution of embolic particles. The literature searches between 1996 to 2020 through PubMed and Ovid-MEDLINE yielded over 1030 articles of which 30 studies providing details on the level of occlusion are reviewed here. We divided the playing factors into characteristics of the particles, solution/injection and vascular bed. Accordingly, particle size, type and aggregation, compressibility/deformability, and biodegradability are categorized as the factors involving particles' behavioral nature. Infusion rate and concentration/dilution of the medium are related to the carrying solution. Hemodynamics and the arterial resistance are characteristics of the vascular bed that also play an important role in the distribution of embolic particles. Understanding and predicting the level of embolization is a complex multi-factor problem that requires more evidence, warranting further randomized controlled trials, and powered human and animal studies.
... Due to their non-uniform shape, PVA particles can aggregate and form plugs that result in premature embolisation proximal to the intended level [28]. Occlusion is completed by thrombus formation and moderate perivascular inflammatory change [29]. ...
... Alternatively, any calibrated microsphere particles (300-900 lm) can be used [6,30]. These particles are more uniform in size and in penetration characteristics than PVA, and their smooth hydrophilic coated surface is less prone to clumping within catheters [27,29,30]. ...
This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for performing bronchial artery embolisation to effectively treat haemoptysis. It has been developed by an expert writing group established by the CIRSE Standards of Practice Committee.
... By adopting a small value of q, the periodic micro-dripping can yield uniform droplets at a high frequency and with a size that is only one-tenth of the nozzle size. Therefore, the micro-dripping mode of electrospray can provide uniform microdroplet templates that has a narrower size distribution than traditional ''top-down" approaches such as phase separation or precipitation with a standard deviation about 50% (Bonomo et al., 2009;Ferrari, 2006;Laurent et al., 2008;Senturk et al., 2010;Zhao et al., 2013). It has also a reasonable production rate. ...
... Currently, search for biodegradable alternative embolic microspheres is eminent (Nitta et al., 2013;Ohta et al., 2009;Weng et al., 2013aWeng et al., , 2013b. These biodegradable particles may eliminate the concern of possible late inflammatory foreign-body response to the presence of non-degradable microspheres (Senturk et al., 2010). In addition, utilization of biodegradable particles might provide more possibilities in device design, such as device loaded with different drug types or with combinations of drugs for personalized therapy and device with adjustable drug release kinetics. ...
... Furthermore, we have previously demonstrated that the fluid dynamics within the target vascular system can influence the flow behaviour of suspended embolic beads [33] and, ultimately, determine the spatial location of vascular occlusion sites [34]. The spatial location of embolic events has been observed to further depend on bead size and concentration in the embolic suspension, which was previously postulated by others but only qualitatively [35]. ...
... Additionally, it has been shown that embolisation with hydrogel beads happened in the form of proximal multi-bead occlusion or distal single-bead occlusion, indicating distinct therapeutic implications [34,35]. Notably, single-bead occlusion is desired as it is associated with more efficient devascularisation [35] and generally generates confined tissue ischaemia. ...
... Additionally, it has been shown that embolisation with hydrogel beads happened in the form of proximal multi-bead occlusion or distal single-bead occlusion, indicating distinct therapeutic implications [34,35]. Notably, single-bead occlusion is desired as it is associated with more efficient devascularisation [35] and generally generates confined tissue ischaemia. Proximal vascular occlusion may instead result in non-targeted tissue ischaemia and off-target delivery of chemotherapeutic agents [36]. ...
Anticancer treatment using embolic drug-eluting beads (DEBs) has shown multifarious advantages compared to systemic chemotherapy. However, there is a growing need for a better understanding of the physical parameters governing drug-elution from embolic devices under physiologically relevant fluidic conditions. In the present study, we investigated the spatiotemporal dynamics of doxorubicin hydrochloride elution from drug-loaded hydrogel embolic beads within a microfluidic device consisting of a network of interconnected microchannels which replicates the architectural properties of microvascular systems. Drug-elution has been investigated experimentally at a single-bead level, using in-house developed microscopy- and spectrofluorimetry-based methods. Results demonstrated that the kinetics of drug-elution and the amount of eluted drug strongly depended on the location of the embolic event within the embolised channel (e.g. fractional amount of eluted drug after 3 hours was equal to ~0.2 and ~0.6 for completely-confined and partially-confined bead, respectively). Drug-elution from partially-confined bead showed a counterintuitive dependence on the local Reynolds number (and thus on the mean fluid velocity), as a result of dynamic changes in bead compressibility causing the displacement of the bead from the primary embolic site. Conversely, the kinetics of drug-elution from fully-confined bead was less affected by the local Reynolds number and bead displayed faster elution from the surface area exposed to the systemic flow, which was associated with the formation of fluid eddies nearby the bead post embolisation.
Copyright © 2015. Published by Elsevier B.V.
... While we know that the stable embolic particles that are currently on the market are markedly 'biocompatible,' [40] it is also known that inflammatory reactions can be invoked. For example, Senturk et al. [41] reported the occurrence of mild-to-moderate inflammatory reactions to polyvinyl alcohol embolic particles (irregular and microspheres) as well as to tris-acryl gelatin microspheres in a rabbit kidney model of embolization. Furthermore, slow and controlled biodegradation of the polymer carrier provides a mechanism to deliver the drug(s) locally and within the therapeutic window, during a prolonged time interval. ...
Biodegradable poly(D,L-lactic acid) drug-eluting microspheres containing anti-tumor drugs, cisplatin, and sorafenib tosylate have been prepared by the emulsion solvent evaporation method with diameter between 200 and 400 μm. Scanning electron microscopy showed that cisplatin microspheres had smooth surfaces, while sorafenib tosylate microspheres and cisplatin + sorafenib tosylate microspheres were porous at the surface and the pits of the latter were larger than those of the former. Notably, cisplatin + sorafenib tosylate microspheres had a fast drug release rate compared with microspheres containing one drug alone. In vitro cytotoxicity experiments and classical matrigel endothelial tube assay certificated the maintaining bioactivity of cisplatin and sorafenib tosylate released from the microspheres, respectively. This work provides a useful approach for the fabrication of drug-eluting beads used in transarterial chemoembolization.
... The purpose of this animal study is to explore the optimal injection technique, feasibility, and effectiveness of PIB nanogel in intravascular embolization. Using a rabbit kidney endovascular embolization model, a well-known and intensively investigated model for studying vascular embolization, [14][15][16][17] we first sought to determine an ideal embolization methodology by investigating the depth of penetration and distribution characteristics of PIB with various injection rates. We then observed the long-term tissue inflammatory reactions and the durability of embolization over 3 months. ...
... To avoid angiographic misinterpretation from early redistribution of PIB, we did not perform a postembolization renal arteriogram via the same Cobra catheter until after a waiting period of 10 minutes. 14,18 After the procedure, the catheter and sheath were removed and the femoral artery was tied. ...
... 13 Another frequent reason for recanalization is extravasation of the embolic material due to vessel wall destruction. This mechanism has been described in previous reports, including embolization of human AVMs with cyanoacrylates 25 or polyvinyl alcohol particles, 26 and embolization of the animal kidney 14,27 or uterus 20 with polyvinyl alcohol particles and various microspheres. Because no vessel wall damage was observed in our study, this also contributes to the observed results. ...
Background and purpose:
We have developed a new thermosensitive liquid embolic agent, PIB nanogel, that can be solidified at body temperature. We thus further investigated the distribution, durability of vascular occlusion, and inflammatory reactions of PIB in embolization of the renal artery of rabbits.
Materials and methods:
The bilateral renal arteries of 9 rabbits were first embolized with PIB at different injection rates. The distribution pattern of PIB was investigated by contact radiography and histology 1 hour after embolization. The right renal arteries of 20 rabbits were then embolized with PIB at the proper injection rate. Angiography and pathologic examination of the kidneys were performed at 1 week and 1, 2, and 3 months after embolization to evaluate the long-term outcomes.
Results:
With the injection rate increasing, PIB could reach the more distal branch of the renal artery. The proper injection rate was chosen as 0.10 mL/s due to the homogeneous distribution of PIB from the main renal artery to the precapillary level at this rate. During a 3-month follow-up observation period, no angiographic recanalization was observed. Histologically, we found no disruption of the vessel wall or subintimal bleeding, no extravasation of PIB, and no evidence of neovascularization. Moreover, there was only a mild inflammatory response, manifested by few lymphocytic and monocellular infiltration, without foreign body granuloma formation.
Conclusions:
Embolization of the renal artery with PIB was easy and controllable, which could lead to a homogeneous and persistent occlusion without severe inflammatory changes. PIB might be a suitable material for intravascular embolization.
... Most of the embolizing agents can be used in more than one setting [9]. In a number of experimental and clinical studies, these features have been explored to some extent; however, there is ongoing debate with regards to selection of ideal embolization agent [2,20,27,29]. Solid embolizing agents (coils and Amplatzer Vascular Plug) occlude vascular structures up to a diameter with 2-3 mm. Size of the coils used depend on the diameter of the target vessels, which coils should be 1-2 mm larger than the diameter of the target vessels to be embolized. ...
Purpose
Renal artery embolization (RAE) is a minimally invasive therapeutic technique that is utilized in a number of disorders. Ankaferd is a novel hemostatic agent with a new mechanism of action independent of clotting factors. We used Ankaferd for RAE in a sheep model.
Methods
Seven adult female sheep were included in the study. Selective renal arteriogram using 5-F diagnostic catheter was performed to make sure that each kidney was fed by a single renal artery and the animal had normal renal vasculature. Coaxial 2.7-F microcatheter was advanced to the distal main renal artery. Under fluoroscopic guidance, 2 mL of Ankaferd mixed with 2 mL of nonionic iodinated contrast agent was slowly injected. Fluoroscopy was used to observe the deceleration of flow and stagnation. Control renal angiograms were performed just after embolization. After the procedure, the animals were observed for 1 day and then sacrificed with intravenous sodium thiopental.
Results
The technical success was observed in seven of the seven animals.. After embolization procedure, none of the animals died or experienced a major systemic adverse event. On macroscopic examination of the embolized kidneys, thrombus at the level of main renal artery formed after Ankaferd embolization was more compact compared with the thrombi that was not Ankaferd-associated, which was observed elsewhere. Microscopically, majority of the renal tubular cells (80–90 %) were necrotic, and there was epithelial cell damage in a small portion of the cells (10–20 %).
Conclusions
RAE was safe and effective in the short-term with Ankaferd in studied animals. Further studies should be conducted to better delineate the embolizing potential of this novel hemostatic agent.
... In conclusion, OCL 503 was found to be safe and effective as an embolotherapeutic agent as tested. The localized tissue distribution observed with this product, coupled with its in situ degradation and absorption, suggests that OCL 503 may have a greater safety profile than many approved and marketed embolic devices, which can migrate to nontarget tissue or have been reported to extravasate from the target vasculature [3,14,15]. Additional work is warranted with this device. ...
This study evaluated the safety, effectiveness, and biodegradation of a new embolic agent, Occlusin™ 503 Artificial Embolization Device (OCL 503). The agent consists of biodegradable poly-lactic-co-glycolic acid microspheres (150-212 μm) coated with type I bovine collagen and was compared with Embosphere® Microspheres (300-500 μm) in this controlled study of uterine artery embolization (UAE) in sheep.
Unilateral UAE was performed in 32 adult ewes randomly assigned. Vessels were embolized to effective stasis. The cohort was divided into four groups, which were sacrificed at 1, 3, 6, and 12 months.
Both agents were 100% effective in achieving stasis. At 6 months, all OCL 503-treated arteries were occluded, the microspheres degraded with time, and at 12 months all four animals examined demonstrated recanalization. OCL 503 was found in the untreated uterine artery in one animal with no other evidence of non target embolization. In the Embosphere-treated group, all vessels remained occluded and microspheres were detected in the contralateral uterine artery in 6 of 15 examined vessels and in 10 vaginal, 2 ovarian, and 1 vesical artery. No procedural-related complications were seen in either group.
OCL 503 is as effective an embolic agent as Embosphere® Microspheres when embolizing ovine uterine arteries and resorbs with time, allowing recanalization of the treated arteries. No device-related issues or adverse events were observed.
