Assessment of mechanical and biocompatible performance of ultra-large nitinol endovascular devices fabricated via a low-energy laser joining process

Abstract

Nitinol is an excellent candidate material for developing various self-expanding endovascular devices due to its unique properties such as superelasticity, biocompatibility and shape memory effect. A low-energy laser joining technique suggests a high potential to create various large diameter Nitinol endovascular devices that contain complex geometries. The primary purpose of the study is to investigate the effects of laser joining process parameters with regard to the mechanical and biocompatible performance of Nitinol stents. Both the chemical composition and the microstructure of the laser-welded joints were evaluated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In vitro study results on cytotoxicity demonstrated that the joining condition of 8 Hz frequency and 1 kW laser power showed the highest degree of endothelial cell viability after thermal annealing in 500°C for 30 min. Also, in vitro study results showed the highest oxygen content at 0.9 kW laser power, 8 Hz frequency, and 0.3 mm spot size after the thermal annealing. Mechanical performance test results showed that the optimal condition for the highest disconnecting force was found at 1 Hz frequency and 1 kW power with 0.6 mm spot size. Two new endovascular devices have been fabricated using the optimized laser joining parameters, which have demonstrated successful device delivery and retrieval, as well as acute biocompatibility.

A Novel Low-Profile Self-Expanding Biodegradable Percutaneous Heart Valve Frame That Grows with a Child

“…Typical values of adult nitinol heart valve frames' radial force are in a range between 9 and 54 N [44]. The Acurate neo S (ANS; Symetis, Switzerland) shows the smallest radial force, lower than 9N, but two other CoreValve devices (CV 23, CV26, Medtronic, Minneapolis, MN, USA) show higher forces with an increased deployed diameter [44]. This comparison study's results show the relationship between the deployed diameter and radial force.…”

“…As a reference, commercial adult heart valve frames made of nitinol can be compared for validating the radial force produced in the experiment. Typical values of adult nitinol heart valve frames' radial force are in a range between 9 and 54 N [44]. The Acurate neo S (ANS; Symetis, Switzerland) shows the smallest radial force, lower than 9N, but two other CoreValve devices (CV 23, CV26, Medtronic, Minneapolis, MN, USA) show higher forces with an increased deployed diameter [44].…”

In vitro and In vivo assessment of a novel organ perfusion stent for successful flow separation in donation after cardiac death

“…A prototype OPS used in in vivo porcine studies was created via a microlaser welding, thermal shape setting and polymer covering process with optimized parameters used in aortic endovascular devices. 21 The perfusion outlet was distal to the heart and a 10 Fr sheath was used for perfusion to maximize the delivered oxygenated blood. 20 Figure 12(a) shows the baseline angiography of a branched segment of aorta without the device placement.…”

“…The perfusion sheath is inserted through a docking zone, which is designed to be collapsible, as shown in Figure 2(b). The welding parameters were exploited from the previous studies, 21 where both mechanical and biocompatible properties were optimized for use in endovascular devices. The parameters used in the laser joining process were spot size of 700 μm, power of 1.4 Kw, time duration of 1.2 ms and frequency of 3 Hz.…”

Impresión 4D empleando polímeros y aleaciones con memoria de forma para una nueva generación de dispositivos médicos inteligentes

“…Ejemplos de este tipo de aleaciones incluyen aleaciones como FeMnSi, CuZnAl, CuAlNi, pero sobre todo, NiTi, más popularmente conocido como nitinol. Las aleaciones de nitinol son biocompatibles gracias a la capa protectora de óxido de titanio que se forma en su superficie [24], y puede encontrase en varios dispositivos, sobre todo en aplicaciones cardiovasculares, pero también en ortopedia y ortodoncia [25].…”