TABLE OF CONTENTS The New York Times Abstract:
A unit of Pfizer Inc. has agreed to pay $10.75 million to settle Justice Department claims that the company lied to get Federal approval for a mechanical heart valve that has fractured, killing hundreds of patients worldwide. (Meier, 1994)
During the cardiac cycle, blood is transported from the atria to the ventricles, to the systemic and pulmonary circulation, and back again. Within the heart, blood flow is regulated by the four valves: the aortic, mitral, pulmonary, and tricuspid valves. Each valve is made up of a few thin folds of tissue, called leaflets or cusps, and keeps blood from flowing backward, or regurgitating, when closed.
A diseased valve may not open or close completely to regulate blood flow. Valvular disease may be congenital (present at birth) or may be caused by an infection that invades the tissue. It may also be caused by rheumatic fever, heart attack, stroke, or aging. Symptoms include dizziness, shortness of breath, fatigue, irregular heart rhythms, and fluid retention. The disease may be managed by drug therapy or, when severe, by surgical replacement.
A prosthetic replacement is necessary when stenosis or insufficiency occurs. During stenosis, the opening of the valve has decreased, causing the heart to work much harder to transport blood. During insufficiency, the valve is leaky, causing blood to flow backward. A prosthetic replacement may either be created from artificial materials or from animal or human cadaver tissue. Mechanical heart...
