Mitral valve facts for kids
Quick facts for kids Mitral valve |
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| A front view of the opened heart. The white arrows show the normal direction of blood flow. The mitral valve is labeled in the center right. | |
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| The bottom chambers of the heart (ventricles) with the top chambers (atria) removed. The bicuspid (mitral) valve is at the bottom left. | |
| Latin | valva atrioventricularis sinistra, valva mitralis, valvula bicuspidalis |
The mitral valve is one of the four important valves in your heart. Think of it as a special one-way door with two flaps, called cusps. It is located between the heart's top left chamber (the left atrium) and the bottom left chamber (the left ventricle). It is also known as the bicuspid valve because it has two flaps.
The main job of the heart valves is to make sure blood flows in only one direction. The mitral valve opens to let blood move from the left atrium to the left ventricle when the heart relaxes. Then, it snaps shut when the ventricle pumps blood out to the rest of the body. This stops blood from flowing backward into the atrium.
Sometimes, the valve might not work perfectly. It could become leaky, letting blood flow backward, or it might become too narrow, making it harder for blood to pass through. The valve gets its name because its two flaps look like a mitre, a type of hat worn by a bishop.
Contents
How the Mitral Valve is Built
The mitral valve is a key part of the left side of the heart. It is made of a few important parts that work together.
Leaflets or Cusps
The "doors" of the valve are two flaps of tissue called leaflets or cusps. There is a front (anterior) leaflet and a back (posterior) leaflet. The front leaflet is a bit thicker and larger, covering about two-thirds of the valve opening when it's closed.
Chordae Tendineae
The valve leaflets are held in place by strong, string-like tissues called chordae tendineae. These connect the leaflets to small muscles inside the ventricle called papillary muscles.
When the ventricle pumps, these "heart strings" act like the strings of a parachute. They pull on the leaflets, holding them tightly shut and stopping them from bulging backward into the atrium. This ensures blood can only flow forward, out of the heart.
Annulus
The mitral annulus is a ring of tough, fibrous tissue that surrounds the valve. It acts like a frame for the valve's leaflets, holding them in place. This ring is flexible and changes shape as the heart beats. It tightens when the heart pumps, helping the leaflets close together completely.
What Does the Mitral Valve Do?
The mitral valve plays a vital role in the cardiac cycle, which is the process of the heart filling with and pumping out blood.
When the left ventricle relaxes, the pressure inside it drops. This signals the mitral valve to swing open. Blood that has collected in the left atrium then flows down into the left ventricle, filling it up for the next heartbeat. Most of this filling happens very quickly.
Just before the ventricle gets ready to pump, the left atrium gives a final little squeeze. This is sometimes called the "atrial kick," and it pushes the last bit of blood into the ventricle.
Once the ventricle is full, it begins to contract (squeeze) to pump blood to the rest of the body. This sudden increase in pressure forces the mitral valve to snap shut. This closing action prevents blood from leaking back into the left atrium.
When Things Go Wrong with the Valve
Sometimes, the mitral valve can have problems that affect how well it works. These are types of valvular heart disease.
Common Valve Problems
- Mitral stenosis: This is when the valve becomes stiff or narrowed. This makes it harder for blood to pass from the atrium to the ventricle, like trying to walk through a door that's only partly open.
- Mitral valve prolapse: This happens when the valve's flaps are floppy and don't close evenly. When the ventricle pumps, one or both flaps may bulge backward into the atrium.
- Mitral regurgitation: This means the valve leaks. When the valve doesn't close tightly, a small amount of blood can flow backward into the left atrium with each heartbeat. This is often caused by mitral valve prolapse.
These problems can sometimes be caused by conditions like rheumatic heart disease or can develop as a person gets older. In rare cases, some people are born with mitral valve problems.
How Doctors Check the Valve
Doctors have simple and painless ways to check on the mitral valve.
The first step is often listening to the heart with a stethoscope. The closing of the mitral valve helps make the first "lub" sound of the "lub-dub" heartbeat. Unusual sounds, like clicks or whooshing noises called murmurs, can tell a doctor if the valve might have a problem.
To get a better look, doctors use an ultrasound scan of the heart, called an echocardiogram. This test uses sound waves to create a moving picture of the heart. It can show the valve's shape, how the leaflets are moving, and whether any blood is leaking backward.
Fixing a Damaged Valve
If a mitral valve has a serious problem, doctors can help. In many cases, surgery can be done to repair the valve and help it work properly again. If the valve is too damaged to be repaired, it can be replaced with a new, artificial valve.
Where Does the Name Come From?
The word mitral comes from the Latin word for a mitre, which is the tall, pointed hat worn by a bishop. The two flaps of the valve look similar to the shape of this hat.
The valve is also called the bicuspid valve. This name comes from Latin words: bi- means "two," and cuspis means "point" or "flap." This name perfectly describes the valve's two-flap structure.
Additional images
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The human heart, viewed from the front. The mitral valve is visible on the right as the "bicuspid valve".
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The chest, showing the location of the heart (red) and its valves. The mitral valve is labeled "B" for Bicuspid.
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A real mitral valve, seen from inside the left atrium.
See also
- Heart
- Heart rhythm
- Electrocardiography
