Design of a Coupled Thermoresponsive Hydrogel and Robotic System for Postinfarct Biomaterial Injection Therapy - Robotics Institute Carnegie Mellon University

Design of a Coupled Thermoresponsive Hydrogel and Robotic System for Postinfarct Biomaterial Injection Therapy

Yang Zhu, Nathan A. Wood, Kevin Fok, Tomo Yoshizumi, Daewoo Park, Hongbin Jiang, David S. Schwartzman, Marco A. Zenati, Takafumi Uchibori, William R. Wagner, and Cameron N. Riviere
Journal Article, Annals of Thoracic Surgery, Vol. 102, No. 3, pp. 780 - 786, September, 2016

Abstract

Background — In preclinical testing, ventricular wall injection of hydrogels has been shown to be effective in modulating ventricular remodeling and preserving cardiac function. For some approaches, early-stage clinical trials are under way. The hydrogel delivery method varies, with minimally invasive approaches being preferred. Endocardial injections carry a risk of hydrogel regurgitation into the circulation, and precise injection patterning is a challenge. An epicardial approach with a thermally gelling hydrogel through the subxiphoid pathway overcomes these disadvantages.

Methods — A relatively stiff, thermally responsive, injectable hydrogel based on n-isopropylacrylamide and n-vinylpyrrolidone (VP gel) was synthesized and characterized. VP gel
thermal behavior was tuned to couple with a transepicardial injection robot, incorporating a cooling feature to achieve injectability. Ventricular wall injections of the optimized VP gel have been performed ex vivo and on beating porcine hearts.

Results — Thermal transition temperature, viscosity, and gelling time for the VP gel were manipulated by altering n-vinylpyrrolidone content. The target parameters for cooling in the robotic system were chosen by thermal modeling to support smooth, repeated injections on an ex vivo heart. Injections at predefined locations and depth were confirmed in an infarcted porcine model.

Conclusions — A coupled thermoresponsive hydrogel and robotic injection system incorporating a temperature-controlled injectate line was capable of targeted injections and amenable to use with a subxiphoid transepicardial approach for hydrogel injection after myocardial infarction. The confirmation of precise location and depth injections would facilitate a patient-specific planning strategy to optimize injection patterning to maximize the mechanical benefits of hydrogel placement.

BibTeX

@article{Riviere-2016-106345,
author = {Yang Zhu and Nathan A. Wood and Kevin Fok and Tomo Yoshizumi and Daewoo Park and Hongbin Jiang and David S. Schwartzman and Marco A. Zenati and Takafumi Uchibori and William R. Wagner and Cameron N. Riviere},
title = {Design of a Coupled Thermoresponsive Hydrogel and Robotic System for Postinfarct Biomaterial Injection Therapy},
journal = {Annals of Thoracic Surgery},
year = {2016},
month = {September},
volume = {102},
number = {3},
pages = {780 - 786},
keywords = {minimally invasive surgery, cardiac surgery, heart, beating heart, medical robotics},
}