Soft robotic steerable micro-catheter for the endovascular treatment of cerebral disorders

Catheters used for endovascular navigation in interventional procedures lack dexterity at the distal tip. Neurointerventionists, in particular, encounter challenges in up to 25% of aneurysm cases largely due to the inability to steer and navigate the tip of the micro-catheters through tortuous vasculature to access aneurysms. We overcome this problem with sub-millimeter diameter, hydraulically-actuated hyperelastic polymer devices at the distal tip of micro-catheters to enable active steerability. Controlled by hand, the devices offer complete 3D orientation of the tip. Using pressures up to 400 kPa (4 atm) we demonstrate guidewire-free navigation, access, and coil deployment in vivo, offering safety, ease of use, and design flexibility absent in other approaches to endovascular intervention. We demonstrate the ability of our device to navigate through vessels and to deliver embolization coils to the cerebral vessels in a live porcine model. This indicates the potential for microhydraulic soft robotics to solve difficult access and treatment problems in endovascular intervention.

Comparison Study on the Effect of Traction Speed on the GAE and Traditional Extrusion Forming of Four-Lumen Plastic Micro-Catheter

In this paper, the effect of traction speed on the four-lumen plastic micro-catheter (FLPMC) was numerically studied. Moreover, the numerical simulations of FLPMC based on two kinds of extrusions, i.e., traditional extrusion and gas-assisted extrusion were performed and compared. Numerical results show that with the increase of traction speed, the sizes of FLPMC for both extrusions all decrease. The sizes of FLPMC based on gas-assisted extrusion are sightly larger than those of the traditional extrusion. To ascertain the reasons, the flow velocities, pressure, shear stress and first normal stress difference distributions of melt based on both extrusions under two different traction speeds were obtained and compared. Results show that with the increase of traction speed under the fixed volume inlet flow rate, the radial flow velocities of melt at the outlet of die decrease but the axial flow velocities increase, which results in the decrease of the die swell at the outlet of die and the size shrinkage of exit face for the FLPMC based on both extrusions. However, for the gas-assisted extrusion, the axial velocities are larger, and the pressure, shear stress and first normal stress difference are far less than those of traditional extrusion, which results in the larger unit volume flow rate, then the sizes of cross-section face are larger than those of the traditional extrusion.

Balloon occluded TACE (B-TACE) vs DEM-TACE for HCC: a single center retrospective case control study

Background To compare oncological results and safety profile of balloon micro-catheter trans-arterial chemoembolization (b-TACE) and drug-eluting-microsphere (DEM-TACE) in patients with hepatocellular-carcinoma (HCC). Methods This is a case–control, retrospective, single-center study. Between January-2015/March-2019, 149 patients (131 males [87.9%]) with 226 HCC were treated, 22 patients (35 HCC; 19 [86.4%] males) with b-TACE and 127 with DEM-TACE (191 HCC, 112 [88.2%] males). Embolization protocol was standardized (sequential 100 ± 25 and 200 ± 25 μm microspheres). Results were evaluated by modified-response-evaluation-criteria-in-solid-tumor [mRECIST] at 1, 3–6 and 9–12 months and time to recurrence after complete response [TTR] at 1 years. Cox’s regression weighted with tumor dimensions was performed. Adverse events (AEs) were recorded. Results mRECIST oncological response at all time points (1, 3–6 and 9–12 months) for both treatments were similar, with the exception of Objective response rate at 9-12 months. Objective response at 1 and 3–6 months between b-TACE vs DEM-TACE [23/35 (65.7%) vs 119/191 (62.3%), 21/29 (72.4%) vs 78/136 (57.4%) (p > 0.05), respectively]. On the contrary, at 9–12 months, it was significantly higher in b-TACE subgroup than DEM-TACE (15/19 [78.9%] vs 48/89 [53.9%], p = 0.05). TTR for complete response at 1 year had a better trend for b-TACE vs DEM-TACE (278.0 days [196.0–342.0] vs 219.0 days [161.0–238.0], OR 0.68 [0.4–1.0], p = 0.10). The use of balloon micro-catheter reduced the relative risk of the event of recurrence by 0.63 [CI95% 0.38–1.04]; p = 0.07). No significant differences were found in AEs rate. Conclusion b-TACE showed a trend of better oncological response over DEM-TACE with and longer TTR with a similar adverse events rate, in patients presenting with larger tumors.

COILUMICA: coil embolization of a coronary artery to pulmonary artery fistula via novel dual lumen micro catheter technique

Background Management of coronary artery fistula (CAF) is based on obliterating the fistula communication between the cardiac arteries and other thoracic vessels. Case presentation We describe the presentation of an 85-year-old female with progressive exertional dyspnea on a background of a long standing left anterior descending diagonal to pulmonary artery fistula. We utilized neuro-interventional techniques to perform coil embolization via use of a Scepter XC dual lumen micro catheter. Conclusions Dual lumen balloon catheters allow for super-selective artery interrogation, stability of balloon positioning, with less trauma to vessel architecture and accurate embolization. There were no complications and the patient reported improvement of symptoms on review.

Balloon Occluded TACE (B-TACE) vs DEM-TACE for HCC. A Single Center Retrospective Case Control Study.

Background To compare oncological results and safety profile of balloon micro-catheter trans-arterial chemoembolization (b-TACE) and drug-eluting-microsphere (DEM-TACE) in patients with hepatocellular-carcinoma (HCC).Methods This is a case-control, retrospective, single-center study. Between January-2015/March-2019, 149 patients (131 males [87.9%]) with 226 HCC were treated, 22 patients (35 HCC; 19 [86.4%] males) with b-TACE and 127 with DEM-TACE (191 HCC, 112 [88.2%] males). Embolization protocol was standardized (sequential 100±25 and 200±25 μm microspheres). Results were evaluated by modified-response-evaluation-criteria-in-solid-tumor [mRECIST] at 1, 3-6 and 9-12 months and time to recurrence after complete response [TTR] at 1 years. Cox’s regression weighted with tumor dimensions was performed. Adverse events (AEs) were recorded.Results mRECIST oncological response at all time points (1, 3-6 and 9-12 months) for both treatments were similar, with the exception of Objective response rate at 9-12months. Objective response at 1 and 3-6 months between b-TACE vs DEM-TACE [23/35 (65.7%) vs 119/191 (62.3%), 21/29 (72.4%) vs 78/136 (57.4%) (p>0.05), respectively]. On the contrary, at 9-12 months, it was significantly higher in b-TACE subgroup than DEM-TACE (15/19 [78.9%] vs 48/89 [53.9%], p=0.05). TTR for complete response at 1 year had a better trend for b-TACE vs DEM-TACE (278.0 days [196.0-342.0] vs 219.0 days [161.0-238.0], OR 0.68 [0.4-1.0], p=0.10). The use of balloon micro-catheter reduced the relative risk of the event of recurrence by 0.63 [CI95% 0.38-1.04]; p=0.07). No significant differences were found in AEs rate. Conclusion b-TACE showed a trend of better oncological response over DEM-TACE with and longer TTR with a similar adverse events rate, in patients presenting with larger tumors.

Liquid embolic agent Fe3O4-EVOH for endovascular arteriovenous malformation embolisation: Preliminary evaluation in an in vivo swine rete mirabile model

Aim Arteriovenous malformation (AVM) embolisation is in peril after the ARUBA trial. Advancements that are needed to reduce procedural risk are better control and visualisation during micro-catheter injection of liquid embolic material. The injectability, radiographic visualisation, mechanical stability and biocompatibility of the embolic agent Fe3O4-EVOH was evaluated in an in vivo swine AVM model. Methods The swine AVM model is the rete mirabile (RM). Nine swine AVM models were embolised with the embolic agent Fe3O4-EVOH by using a 1.5 F micro-catheter. Procedure times, embolisation success (defined as complete embolisation of the nidus), volume of embolic agent and histopathology were assessed. Results Six swine underwent embolisation of one side rete, and three underwent embolisation of both sides. We did not experience any technical complication during embolisation of each rete. The micro-catheter was easy to retrieve. Fluoroscopic visualisation of the Fe3O4-EVOH cast was adequate. The mean embolisation time for each RM was 7.5 minutes. The median volume of the embolic agent for each RM was 0.52 mL. At one, four and eight weeks following injection, microscopic and histological analysis demonstrated minimal inflammatory changes in the perivascular tissues and permanent occlusion of the embolised vasculature. Conclusion Fe3O4-EVOH embolic agent is an effective endovascular occlusion material, providing the initial in vivo characteristics of stability and biocompatibility.

Gastric Artery Embolization: Studying Effects of Catheter Type and Injection Method on Bead Distributions within a Benchtop Arterial Model

Aims: To investigate the effect of catheter type and injection method on microsphere distributions, specifically vessel targeting accuracy. Materials and Methods: The study utilized three catheter types (a standard micro-catheter, a Surefire anti-reflux catheter, and an Endobar occlusion balloon catheter) and both manual and computer-controlled injection schemes. A closed-loop, dynamically pressurized surrogate arterial system was assembled to replicate arterial flow for bariatric embolization procedures. Four vessel branches immediately distal to the injection site were targeted for embolization. Embolic microspheres were injected into the model using three catheter types (a standard micro-catheter, a Surefire anti-reflux catheter, and an Endobar occlusion balloon catheter) and both manual and computer-controlled injections. Results: Across all injection methods, the catheter effect on the proportion of microspheres to target vessels (vs. non-target vessels) was significant (p=0.005). The catheter effect on the number of non-target vessels embolized was significant (p=0.059). Across all catheter types, the injection method effect was not statistically significant for either of two outcome measures (percent microspheres to target vessels: p=0.265, number of non-target vessels embolized: p=0.148). Conclusion: Catheter type had a significant effect on targeting accuracy across all injection methods. The Endobar catheter exhibited a higher targeting accuracy in pairwise comparisons with the other two injection catheters across all injection schemes and when considering the Endobar catheter with the manifold injection method vs. each of the catheters with the manual injection method; the differences were significant in 3 of 4 analyses. The injection method effect was not statistically significant across all catheter types and when considering the Endobar catheter/Endobar manifold combination vs. Endobar catheter injections with manual and pressure-replicated methods.