Development of Robust PEBAX-Based Angiographic Catheter: Design and In Vitro Study

BACKGROUND

Keeping in mind the unceasingly escalating prevalence of coronary disease worldwide, the mortality rate is also expected to rise with a staggering increase in healthcare costs. Angiography is the gold standard for diagnosing these blockages that trigger these diseases. Amides and urethanes are the common catheter construction material used for angiography. However, the experimental evidence verifying the use of PEBAX® and comparing its performance with that of commercially available catheters for angiography is not published despite it being well recognized for its excellent flexural modulus, mechanical properties, and biocompatibility and its potential to reduce the incidence of vascular spasm during intravascular diagnostic and interventional procedures. Therefore, the aim of this study was to develop a PEBAX®-based angiographic catheter and evaluate its performance in comparison with three commercially available nylon- and polyurethane-based angiographic catheters.

METHODOLOGY

A PEBAX®-based angiographic catheter was developed for this purpose. This study analyzes and reports the performance and behavior of PEBAX®-, nylon-, and polyurethane-based catheters. The catheter's performance and arterial forces' endurance nature were mapped out by evaluating pushability (advancement force) and selective bench tests outlined in the applicable regulatory standard.

CONCLUSIONS

The PEBAX®-based catheter exhibited the least bond-flexural rigidity (180.4 g), which was approximately one-third of that shown by all six French catheters and which exhibited the least advancement force (510.4 g), which was approximately 50% less than that of the nylon- and polyurethane-based catheters when traversing through the mock arterial system. Bench testing was carried out as per the applicable regulatory standard; the differences obtained between individual catheters were discussed in detail. Based on this extensive in vitro assessment, it was concluded that the PEBAX®-based catheters outperformed the nylon- and polyurethane-based catheters, exhibiting an exceptionally minimal advancement force of 510.4 g. This leads to the inference that this catheter can inject more radiopaque material (because of the enhanced flow rate) to the coronary arteries and can play a significant role in minimizing vascular spasms during a diagnostic procedure.

Investigating Balloon-Vessel Contact Pressure Patterns in Angioplasty: In Silico Insights for Drug-Coated Balloons

Drug-Coated Balloons have shown promising results as a minimally invasive approach to treat stenotic arteries, but recent animal studies have revealed limited, non-uniform coating transfer onto the arterial lumen. In vitro data suggested that local coating transfer tracks the local Contact Pressure (CP) between the balloon and the endothelium. Therefore, this work aimed to investigate in silico how different interventional and device parameters may affect the spatial distribution of CP during the inflation of an angioplasty balloon within idealized vessels that resemble healthy femoral arteries in size and compliance. An angioplasty balloon computational model was developed, considering longitudinal non-uniform wall thickness, due to its forming process, and the folding procedure of the balloon. To identify the conditions leading to non-uniform CP, sensitivity finite element analyses were performed comparing different values for balloon working length, longitudinally varying wall thickness, friction coefficient on the balloon-vessel interface, vessel wall stiffness and thickness, and balloon-to-vessel diameter ratio. Findings indicate a significant irregularity of contact between the balloon and the vessel, mainly affected by the balloon's unfolding and longitudinal thickness variation. Mirroring published data on coating transfer distribution in animal studies, the interfacial CP distribution was maximal at the middle of the balloon treatment site, while exhibiting a circumferential pattern of linear peaks as a consequence of the particular balloon-vessel interaction during unfolding. A high ratio of balloon-to-vessel diameter, higher vessel stiffness, and thickness was found to increase significantly the amplitude and spatial distribution of the CP, while a higher friction coefficient at the balloon-to-vessel interface further exacerbated the non-uniformity of CP. Evaluation of balloon design effects revealed that the thicker tapered part caused CP reduction in the areas that interacted with the extremities of the balloon, whereas total length only weakly impacted the CP. Taken together, this study offers a deeper understanding of the factors influencing the irregularity of balloon-tissue contact, a key step toward uniformity in drug-coating transfer and potential clinical effectiveness.

Simulation and Experimental Investigation of Balloon Folding and Inserting Performance for Angioplasty: A Comparison of Two Materials, Polyamide-12 and Pebax

BACKGROUND

A balloon dilatation catheter is a vital tool in percutaneous transluminal angioplasty. Various factors, including the material used, influence the ability of different types of balloons to navigate through lesions during delivery.

OBJECTIVE

Thus far, numerical simulation studies comparing the impacts of different materials on the trackability of balloon catheters has been limited. This project seeks to unveil the underlying patterns more effectively by utilizing a highly realistic balloon-folding simulation method to compare the trackability of balloons made from different materials.

METHODS

Two materials, nylon-12 and Pebax, were examined for their insertion forces via a bench test and a numerical simulation. The simulation built a model identical to the bench test's groove and simulated the balloon's folding process prior to insertion to better replicate the experimental conditions.

RESULTS

In the bench test, nylon-12 demonstrated the highest insertion force, peaking at 0.866 N, significantly outstripping the 0.156 N force exhibited by the Pebax balloon. In the simulation, nylon-12 experienced a higher level of stress after folding, while Pebax had demonstrated a higher effective strain and surface energy density. In terms of insertion force, nylon-12 was higher than Pebax in specific areas.

CONCLUSION

nylon-12 exerts greater pressure on the vessel wall in curved pathways when compared to Pebax. The simulated insertion forces of nylon-12 align with the experimental results. However, when using the same friction coefficient, the difference in insertion forces between the two materials is minimal. The numerical simulation method used in this study can be used for relevant research. This method can assess the performance of balloons made from diverse materials navigating curved paths and can yield more precise and detailed data feedback compared to benchtop experiments.

Insight Into Solventless Production of Hydrophobically Modified Ethoxylated Urethanes (HEURs): The Role of Moisture Concentration, Reaction Temperature, and Mixing Efficiency

In this work, we report for the first time on the influence of the quality of reactants and reaction conditions on the production of hydrophobically modified ethoxylated urethanes (HEURs) and selected prepolymers without the use of solvents. We show that the polyol water concentration is detrimental to the progress of the main urethane forming reaction, confirming the necessity of carefully drying the reactants below 1000 ppm to suppress the consumption of diisocyanate toward urea during HEUR synthesis. Increasing the mixing speed (≈30 to 750 rpm), reaction temperature (80-110 °C), and catalyst concentration (0.035-2.1 wt % bismuth carboxylate) can significantly increase the rate of molecular weight buildup, but their effect decreases with time as the bulk viscosity increases and mixing limitations eventually take over, leading to the Weissenberg effect and chain growth termination. Consequently, for the selected formulation, the maximum product molecular weight attained lies in the range of ≈20 000-22 000 g/mol, irrespective of the specific process conditions applied.