I read with interest that Mick Jagger, 75, was dancing in a video shortly after having a heart valve replacement surgery. Talk about having the Moves like Jagger after such a major surgery! What are heart valves?

Our heart has four chambers – two atria and two ventricles.

Blood is pumped from the body to the heart, and then to the lungs to fill it with oxygen, and then back to the heart again to pump it back to our body for a new cardiac cycle.

Separating the four chambers are two of the heart valves, while the two ventricles are separated from the arteries connected to them by the other two valves.

These are tissue paper-thin membranes that are attached to our heart wall.

They help determine when and where our blood flows to within our heart, and are the source of the sound of our heartbeat.

Valves are made to last a long time. They can do 80 million beats a year, and five to six billion beats per lifetime.

What are the four heart valves?

There is the mitral valve, which separates your left atrium from your left ventricle.

The tricuspid valve separates your right atrium from your right ventricle.

Then there are two valves that control blood flow out of your ventricles: the aortic valve and the pulmonary valve.

The aortic valve sits between your left ventricle and your aorta, which sends blood to the rest of the body from the heart.

The pulmonary valve sits bet-ween your right ventricle and your pulmonary artery, which pumps blood into your lungs to be reoxygenated.

Valves are made out of thin, but very strong pieces of tissue called leaflets or cusps.

They are supported and tethered to the heart muscles by tough fibrous strings and papillary muscles.

These strings and muscles keep the leaflets stable to prevent blood from flowing back into the chamber once it has passed through.

Valves work like this: The leaflets of the valve open to let blood flow through during the first half of a heartbeat.

Then they close to keep the blood from flowing backward during the second half of the heartbeat.

Which valve closes first and last?

Blood from the whole body first flows from your right atrium to your right ventricle through your open tricuspid valve, together with blood from the lungs from your left atrium to your left ventricle through your open mitral valve.

This happens when your atria are contracting.

When your right ventricle is full, your tricuspid valve closes and stops the blood from flowing backward into your right atrium.

Then, when your right ventricle contracts, the pressure of the blood forces open your pulmonary valve, allowing blood to be pumped into your lungs through your pulmonary artery.

The same thing happens to your left ventricle with the mitral valve.

And when your left ventricle contracts, your aortic valve is forced open, allowing blood to be pumped to your whole body through your aorta.

The moment your ventricles finish contracting, your pulmonary and aortic valves close to prevent blood from flowing back to the ventricles.

Imagine all this going on repeatedly in a space of a heartbeat.

Wow. Can heart valves get damaged then?

Of course. Heart valve disease happens when the heart valves don’t work properly.

There are two main types of heart valve disease:

● Valvular stenosis

This happens when a heart valve becomes stiff or its leaflets have fused.

The heart valve opening becomes narrowed and your heart will find it very difficult to pump blood through it. This can then lead to heart failure.

● Valvular regurgitation

This is also called a “leaky valve”. It happens when a valve does not close tightly, allowing blood to be leaked back into the heart chamber that it just left.

If this happens, you can imagine that less blood will flow to the rest of your body.

The name of the valve disease will depend on which valve is affected and what type of disease it is affected with, e.g. aortic stenosis and mitral regurgitation.

There is one more valvular condition called atresia.

This happens when the valve has not formed properly and remains just a solid sheet that blocks blood from being pumped from chamber to chamber.

It is a congenital condition, meaning that babies are born with it.

What causes valve disease?

A common cause is actually infection.

There is a type of condition called rheumatic fever, which may start with a mild infection like a sore throat.

Then, some time later, it leads to problems with your heart.

Another type of heart infection is endocarditis – an infection of the heart lining.

Diseases of the heart muscle (cardiomyopathy) can also lead to valve problems, as does damage to the heart muscle (commonly after a heart attack).

Simply getting older can also cause valves to malfunction.

Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health, computers and entertainment. For further information, email starhealth@thestar.com.my. The information contained in this column is for general educational purposes only. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.