Essay on Blood and Vascular Grafts

Submitted By hemasai
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BIOMATERIALS IN CARDIOLOGY
P.HEMASAI KUMAR
V.VIGNESH

BRANCH: BIOMEDICAL ENGINEERING
YEAR: I

Department of Biomedical engineering

PSG COLLEGE OF TECHNOLOGY
(Autonomous institution)
COIMBATORE-641 004
Email id: hemasai1996@gmail.com
Mobile no: 9600467824

1.1 Introduction:
During the last decades, man–made materials and devices have been developed to the point at which they can be used to replace parts of living systems in the human body. These special materials, which are able to function in intimate contact with living tissue, with minimal adverse reaction or rejection by the body are called biomaterials. “Biomaterial is any substance (other than a drug) or combination of substances, synthetic or natural in origin, which can be used for a period of time, as a whole or as a part of a system which treats, augments, or replaces any tissue, organ or function in the body”. This paper will review the main outlines for choosing the polymeric material for the right application, and will focus mainly on biomaterials that are in use today in the cardiovascular area. Two main parameters have to be considered in choosing the biomaterial for a certain application:
1. In order to choose the right Standard design, some physical and mechanical features such as strength and deformation, fatigue and creep, friction and wear resistance, flow resistance and pressure drop, and other characteristics which may be engineered with the material, must be considered.
2. Compatibility, or biocompatibility, characterizes a set of material specifications and constraints which refer to the material–tissue interactions. These characteristics have to be specified according to the intended device application, and have to be tested and evaluated in a set of in–vitro and in–vivo experiments.

2.1 Biocompatibility evaluation:
In order to evaluate the material’s suitability for the cardiovascular application for long term implantation, the biocompatibility criteria have to include the following host reactions to the biomaterial which focus on toxicity, carcinogenicity and bio stability: Foreign body reaction, Inflammatory reaction, Thrombosis, Hemolysis, Adaptation, Infection and sterilization, Carcinogenesis, Hypersensitivity and systemic effects, Long term stability, and Fatigue tests.
3.1 Blood vessels:
The development of peripheral vascular reconstructive surgery has been closely associated with the development of prosthetic vascular grafts. The quest for an ideal vascular conduit began soon after Carrel and Guthrie demonstrated in a canine model that homologous and heterologous artery and vein segments could be used as arterial substitutes. Although, living, non rejectable arterial and venous autografts appear to be near–ideal vessel conduits, problems of procurement and size restrictions have prompted efforts to develop stable prosthetic materials. The characteristics of the ideal graft have to fit the following requirements which are divided into three main parts: mechanical, biocompatibility and handling:
It must be durable, withstanding after implantation the dual threats of biodegradation and mechanical fatigue.
The ideal graft should have and maintain the same compliance as a normal artery: It should be flexible, maintaining its contour and have kinking resistance, bending without partial occlusion–as it crosses joints.
The graft must not harm the host in anyway.
Its luminal surface must interact with blood elements in a minimally traumatic, non-thrombogenic fashion.
It should be resistant to infection.
It must be capable of sterilization without graft alteration. The ideal graft should have an optimal porosity, allowing for good incorporation without causing unmanageable bleeding following implantation. Finally, from the handling point of view, it must be readily available in multiple lengths and sizes, and its handling characteristics should include an ease of suturing and
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