Heart valve

3D reconstruction of the heart as viewed from the apex towards the valves, image flipped 180° relative to illustration above. Pulmonary valve not visible, leaflets of the tricuspid and aortic valves only partly visible. To the left two images in 2D from the same dataset, showing tricuspid and mitral valves (above) and aortal and mitral valve (below).

In anatomy, the heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side. They are mechanically similar to reed valves.

There are four valves in the heart (not counting the valve of the coronary sinus, and the valve of the inferior vena cava):

The two atrioventricular (AV) valves between the atria and the ventricles.
The two semilunar (SL) valves, in the arteries leaving the heart.

Atrioventricular valves

This is an explanation of the echocardiogram above. MV: Mitral valve, TV: Tricuspid valve, AV: Aortic valve, Septum: Interventricular septum. Continuous lines demarkates septum and free wall seen in echocardiogrm, dotted line is a suggestion of where the free wall of the right ventricle should be. The red line represents where the upper left loop in the echocardiogram transects the 3D-loop, the blue line represents the lower loop.

An artificial heart valve may be used to surgically replace a patient's damaged valve.

These are small valves that prevent backflow from the ventricles into the atria during systole. They are anchored to the wall of the ventricle by chordae tendineae, that prevent the valve from inverting.

The chordae tendineae are attached to papillary muscles that cause tension to better hold the valve. Together, the papillary muscles and the chordae tendinae are known as the subvalvular apparatus. The function of the subvalvular apparatus is to keep the valves from prolapsing into the atria when they close. The subvalvular apparatus have no effect on the opening and closure of the valves, however. This is caused entirely by the pressure gradient across the valve.

The closure of the AV valves is heard as the first heart sound (S1).

Mitral valve

Also known as the bicuspid valve contains two flaps. The mitral valve gets its name from the resemblance to a bishop's mitre (a type of hat). It allows the blood to flow from the left atrium into the left ventricle. It is on the left side of the heart and has two cusps.

A common complication of rheumatic fever is thickening and stenosis of the mitral valve.

Tricuspid valve

The tricuspid valve is the three flapped valve on the right side of the heart, between the right atrium and the right ventricle which stops the backflow of blood between the two. It has three cusps.

Semilunar valves

These are located at the base of both the pulmonary trunk (pulmonary artery) and the aorta, the two arteries taking blood out of the ventricles. These valves permit blood to be forced into the arteries, but prevent backflow of blood from the arteries into the ventricles. ^[1] These valves do not have chordae tendinae, and are more similar to valves in veins than atrioventricular valves.

Aortic valve

The aortic valve lies between the left ventricle and the aorta. The aortic valve has three cusps. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the aortic pressure forces the aortic valve to close. The closure of the aortic valve contributes the A2 component of the second heart sound (S2).

The most common congenital abnormality of the heart is the bicuspid aortic valve. In this condition, instead of three cusps, the aortic valve has two cusps. This condition is often undiagnosed until the person develops calcific aortic stenosis. Aortic stenosis occurs in this condition usually in patients in their 40s or 50s, an average of over 10 years earlier than in people with normal aortic valves.

Pulmonary valve

The pulmonary valve lies between the right ventricle and the pulmonary artery and also has three cusps.

Notes

^ Pearson Custom Publishing

External links

Mitral Valve Repair at The Mount Sinai Hospital - "Mitral Valve Anatomy"
Adam's Heart Valve Surgery Blog - "Patient and caregiver information for heart valve replacement and heart valve repair operations"

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[1] Pearson Custom Publishing

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