Cardiac Valve Prostheses an itroduction

Introduction

The first clinical use of cardiac valvular prosthesis took place in 1952, when Dr. Charls Hufnagel implanted the first artificial caged ball valve for aortic insufficiency. The Plexiglas cage contained a ball occluder and was inserted into the descending aorta without the need for cardiopulmonary bypass. It did not cure the underlying disease, but it did relieve regurgitation from the lower two-thirds of the body.

The first implant of a replacement valve in the anatomical position took place in 1960, with the advent of cardiopulmonary bypass. Since then, the achievements in valve design and the success of artificial heart valves, as replacements have been remarkable. [Roberts, 1976]. More than 50 different cardiac valves have been introduced over the past 35 years. Unfortunately, after many years of experience and success, problems associated with heart valve prostheses have not been eliminated. The most serious problems and complications are:

*Thrombosis and thromboembolism

*Anticoagulation-related haemorrhage

*Tissue overgrowth

*Infection

*Paravalvular leaks due to healing defects

*Valve failure due to material fatigue or chemical change.

[Bodnar 1992] [Roberts 1976]

New valve designs continue to be developed. Yet, to understand the future of valve replacement, it is important to understand their history.

History of Heart Valve Prostheses

This section highlights a relatively small number of the many various types, which have been made. However, those that have been included are either the most commonly used or those, which have made a noticeable advancement of replacement heart valves.

Mechanical Valves

The use of the caged-ball valve in the descending aorta became obsolete with the development in 1960 of what is referred to as the Starr-Edwards ball-and-cage valve. It was designed to be inserted in place of the existing diseased natural valve. This form of intracardiac valve replacement was used in the mitral position and for aortic and...