Towards the design of mechanically superior tubular structures for microcatheters

Abstract

Cardiac catheterization (CC) procedures in children and adults, and especially within vasculature of small cross-section comes with the increased risk of complications due to acute occlusive arterial injuries and (or) thrombosis. Micro-catheters play a vital role in enabling CC procedures, however, to extend their functionality beyond large blood vessels and into pediatric wards, necessitates superior mechanical attributes that are fundamental to their structure. There exists a strong correlation between tool footprint and the risk of these injuries, nevertheless, changes in tool-size are impeded by mechanical constraints and manufacturing. In this paper, we propose pattern geometries for tubular structures that can be tuned to obtain desired mechanical characteristics, while retaining a minimum tool cross-section. We perform numerical simulations to systematically investigate the effect of pattern design parameters on the tube's properties, and present guidelines for obtaining the preferred behavior. The rounded re-entrant honeycomb (RRH) is introduced as the base structure for more responsive catheters, and is contrasted with the dog-bone geometry (DB), and the conventional slot. Notably, the RRH patterned tubes are highly compliant in bending yet strong in torsion while the DB tubes are strong in both torsion and bending. Therefore, our results indicate positively for a wide-range of tunable behavior in patterned tubes, with the RRH poised as a promising alternative for achieving the design goals that are introduced.