Low disturbance pulsatile flow system

Abstract

A flow system device used for testing / creating fluid flow. The system comprises at least one fluid filled loop and a rotor stage for maintaining at least one rotor. The loop is positioned on the rotor. The device also includes a driving motor for rotating the rotor stage and a motion controller for controlling the speed and directional motion of the motor.

Description

BACKGROUND OF THE INVENTION[0001] The invention relates to the field of coronary implants, and in particular to a low disturbance, pulsatile, in vitro flow circuit for modeling coronary implant thrombosis.[0002] Biocompatibility has been a major issue in the ability to use prosthetic implants in clinical settings. One such set of applications includes vascular prosthesis such as endoluminal stents or grafts to allow blood to flow either through or past a previously stenosed vascular segment. When such a foreign structure comes into contact with tissue and blood, a variety of biological consequences ensue. These reactions, ranging from thrombosis, to inflammation, to restenosis, can result in acute or long-term device failure. Not only is coagulation responsible for the obvious occurrences of acute thrombotic events, but sub-clinical levels have also been implicated as a player in the pathophysiology of restenosis through the release of chemical mediators and by providing a scaffold ...

AI Technical Summary

Benefits of technology

[0012] A model has been created to observe the physiological, controllable flows in a manner to create a large thrombotic signal, while minimizing the effects of background noise. This is accomplished by minimizing the length and discontinuities of a tubing loop into which a prosthetic, such as a stent or a graft, is placed. The loop is then filled with the desired blood constituents and spun about its axis in a prescribed fashion. This spinning is controlled in such a way as to modulate the inertial flow of the contained fluid through transmitted shear forces from the tubing wall, thereby creating a low disturbance flow.

[0017] Another object is to provide an improved connecting device such that two opposing ends of a tube are held in near perfect axial alignment, minimizing luminal discontinuity.

Problems solved by technology

Biocompatibility has been a major issue in the ability to use prosthetic implants in clinical settings.

These reactions, ranging from thrombosis, to inflammation, to restenosis, can result in acute or long-term device failure.

The thrombotic reaction is one of the earliest responses to implantation and by virtue of its potential for rapid acceleration and complete luminal occlusion, one of the most devastating.

One difficulty that has limited the extensive examination of bioprosthetic thrombosis is the highly flow-dependent nature of thrombosis and lack of widely applicable flow models.

It is not ideal as a large air / blood interface can cause protein aggregation and denaturation, creating a significant departure from the physiological situation.

Furthermore, this method does not allow for arterial flow profiles to be obtained.

However this is not helpful when studying actual coronary prosthetic configurations as the chambers and flow rates are not arterial in nature.

However, there are several factors that reduce the potential of this system to study stent thrombosis.

One is the level of background noise that is created with the large surface area of peristaltic tubing and the roller pump's action.

Furthermore, placing the stent in a discontinuous 4 mm region not only increases system background noise, but substantially perturbs the flow over the stent.

Although some differences could be noted with certain stents, others were not significantly different than control runs, thus indicating the lack of sensitivity and that the flow rate was not controlled.

Additionally, bleeding a volunteer requires a substantially greater amount of blood than recirculant setups.

Although these have the ability to create physiological flows, they have a drawback in that there is a limit on the amount of control that is attainable in the system as parameter variation must be within life-sustaining margins.

Therefore, studying the coupled nature of thrombus formation is difficult because the components cannot be varied to the extent that they may in an in-vitro setup.

Many extraneous variables exist in in-vivo systems that could complicate the process being observed rendering unanalyzable results.

Also interspecimen variation can create noise, which if large enough, could obscure potential findings.

Another concern is that although observations may be made in one species, they may not be robust enough to occur in humans due to relative functional component differences.

Practically, there are other issues, from the expense to the ethics, that must also be taken into account when using such systems.

These carry with them many of the same problems as the animal studies.

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