Biocompatibility tests of components of an implantable cardiac assist device

Abstract

A permanently implantable in-series left ventricular assist device, the dynamic aortic patch (DAP), has been tested in chronic animal experiments. The DAP replaces a section of the intrathoracic aortic wall. Hemothorax and hematocele at the implantation site have been complications in recent experiments. Primary postoperative hemorrhage was ruled out, and the biocompatibility of all components was therefore examined. Dacron velour, Teflon felt, conductive polyurethane, segmented polyether polyurethane, and Teflon-coated polyester fiber sutures were implanted in the pleural cavities of dogs and tested in vitro by culturing canine saphenous vein explants on them. In vivo experiments demonstrated that all components elicited mild to moderate inflammatory reactions, but hematocele occurred only when the components were implanted in the aorta with direct blood contact and exposed to arterial blood pressures. In vitro, cells were cultured on all components with no signs of toxic reactions. These results indicated that the host tolerated all implant components without major inflammatory responses. However, histological data indicated that chronic slow bleeding into or through the Dacron velour in contact with the arterial blood serum could account for hemothorax or hematocele formation. Therefore, a configuration of the assist device using materials impermeable to blood may obviate these difficulties.

In vitro chemotaxis and tissue remodeling assays quantitatively characterize foreign body reaction

“…In vivo studies have revealed a lower fibrous encapsulation and reactive inflammatory zone surrounding titanium implants compared to PTFE (Thomsen et al, 1986), copper (Suska et al, 2008), and stainless steel (Ungersböck et al, 1994). Formation of adherent fibrous tissue is reported for PTFE-aortic-patches in dogs (von Recum et al, 1978) as well as for vascular grafts in humans. Comparison of absolute weight reduction related to initial weight and collagen deposition with those in vivo studies, reveal a high consistency of developed fibrous tissue models to state-of-the-art scoring.…”

Vessel Wall Models for Studying Interaction Capabilities With Blood Platelets

“…Other noteworthy in vivo models, although not to be discussed in this review, are the pigeon spontaneous atherosclerosis model [1,100] and various implanted artificial channels for blood flow [167]. These include several biomaterials prostheses [169], some bearing cultures of endothelial cells [54,55,107] or other cell types [29,106,107] and additional devices [6,58,[135][136][137] implanted into the circulatory system with the objectives to establish biocompatibility and long-term host tolerance [6,20,[135][136][137]. Some of these models might also be classified as combination in vivo -ex vivo models since living cells are involved and maintained both inside and outside of the body at different times.…”

Overview on Biocompatibilities of Implantable Biomaterials

“…Tissue responses to PTFE are rather passivated. Hematocele occurred only when the components were implanted in the aorta with direct blood contact and exposed to arterial blood pressures [200]. An 8 cm long PTFE prosthesis was implanted into defects of the abdominal aorta of dogs, and the following changes were found: the blood flow through the vascular prosthesis induced a shortening of the blood clotting time and a slight increase in the prothrombin consumption.…”