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THE VALVES

HOW THE HEART'S VALVES WORK

Valves keep blood flowing in one direction through the heart, ventricles relax {diastole), the pressure within them decreases. The and tricuspid valves are pushed open, allowing blood to flow from the atria to the ventricles. The aortic and pulmonary valves are pushed shut, preventing the return of blood that was pumped out on the preceding beat. During contraction (systole), the pressure pushes the aortic and pulmonary valves open, and the mitral and tricuspid valves are p shut and prevent back flow of blood.

DISEASES OF THE VALVES

Diseases of the valves may cause them to become too narrow, restricting blood flow (valve stenosis). They can also become "leaky," allowing blood to flow backward (valve regurgitation).

Diastole (relaxation). A narrowed (stenotic) mitral valve impedes blood flow from the left atrium to the left ventricle. A leaky (regurgitant) aortic valve allows blood to flow back from the aorta to the left ventricle when the ventricle relaxes.

Systole (contraction). A narrowed (stenotic) aortic valve reduces efficient blood flow from the left ventricle to the aorta. A leaky (regurgitant) mitral valve allows blood to flow back from the left ventricle to the left atrium when the ventricle contracts.

Regurgitant aortic valve damaged by infection (infective endocarditis).

Mitral valve stenosis as a result of rheumatic fever.

Stenosis of a bicuspid aortic valve caused by deposits of calcium preventing adequate opening of the valve.

Regurgitant mitral valve due to breakage (arrows) of the chordae tendineae that tether the valve leaflets.

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Cardio & Blood-holesterol




DISEASES OF THE BLOOD VESSELS & THE PERICARDIUM
PACEMAKERS AND DEFIBRILLATORS
ELECTROPHYSIOLOGY CATHETERS
THE CONDUCTION SYSTEM
RESTORING CORONARY BLOOD FLOW
CORONARY ARTERIES
THE VALVES
HEART TRANSPLANTS
THE MYOCARDIUM (HEART MUSCLE): THE STRUCTURE & THE CELLS OF HEART MUSCLE
THE HEART MUSCLE