All you need to know about Heart valves

Heart valves

The heart valves have tissue appendages that regulate blood flow within the heart. It is fibrous tissue, coated by endocardium, which controls the passage of blood through the orifices that connect the atria (the upper cavities of the heart) with the ventricles (the lower cavities) and the ventricles with the vessels adjacent to the heart such as the aorta and pulmonary artery.

What is a heart valve?

Heart valves are used to ensure that blood moves through the heart in one direction. There are four valves inside the heart:

-  tricuspid valve

- mitral valve

- pulmonary valve

- aortic valve

Healthy heart valves give blood unidirectional flow through the cavities of the heart and thus prevent the reflux of blood into the cavities. The valves are made up of thin but very resistant membranes, which open and close with each heartbeat in a coordinated manner, normally allowing the flow of blood to move in only one direction through the heart, preventing its reflux (or retrograde flow).

The tricuspid and mitral valves control the flow of blood between the chambers of the heart, while the pulmonary and aortic valves control the emission of blood from the heart. Each valve opens and closes with each heartbeat. They consist of a thin but extremely resistant tissue, attached to the heart muscle through a mechanism of the flexible hinge, called an annulus. 

The tricuspid valve is located between the atrium and the right ventricle and consists of three flaps.

In addition to the flaps, this valve is composed of a valve ring (or annulus) that connects the flaps to the heart and chords (or chordae) and papillary muscles that join the valve flaps to the heart muscle. 

The mitral valve is located between the atrium and the left ventricle and consists of two flaps. In addition to the flaps, this valve is composed of a valve ring that connects the flaps to the heart and papillary cords and muscles that connect the valve flaps to the heart muscle. 

The pulmonary valve can be found between the pulmonary trunk, the pulmonary trunk, and the right ventricle. The pulmonary artery carries oxygenated blood to the lung. The pulmonary valve is inserted directly on the muscle of the most distal part of the right ventricle. 

The aortic valve is located at the intersection of the left ventricle and the ascending aorta. The valve has three cusps, a tissue ring on which the cusps are inserted. The sinuses of Valsalva are bulges of the aortic wall in correspondence with the cusps.

How many heart valves are there in the body?

There are four heart valves

Tricuspid or tricuspid valve

An oval-shaped valve (physiological diameter of 40 mm) made up of three sheets, called cusps from which it takes its name. The tricuspid valve regulates blood flow between the atrium and the right ventricle.

The bicuspid or mitral valve

A slightly oval-shaped valve, so-called because of its similarity to the papal submachine gun. Left of the septum, called anterior or aortic cusp; the other, smaller, placed back and sideways, which corresponds to the posterior wall of the left ventricle and is called the posterior cusp. The anterior flap of the mitral is always smooth. It has a diameter of over 30 mm and regulates blood flow between the left atrium and the left ventricle.

Aortic valve with three semilunar cusps or aortic valve

It has a diameter of 20 mm and regulates blood flow from the heart to the circulatory system.

Pulmonary valve with three semilunar cusps

Called pulmonary semilunar valve or pulmonary valve. It has a diameter of 20 mm and regulates blood flow from the heart to the pulmonary circulation.

However, if these heart valves present narrowing problems (in the case of severe aortic stenosis, for example) or insufficient functioning (incontinent valves), it is possible to act promptly by means of valvuloplasty or replacement of an isolated heart valve. After a heart operation of this type, the patient faces a recovery of about 4-8 hours before regaining consciousness.

Which valves are used for valvuloplasty, and why?

The heart valves available to the valvuloplasty surgeon are of different types, but can be grouped into two large groups:

- mechanical valves, if they are built with artificial materials

- Biological valves, if they are made of natural tissues, such as pig valves (porcine valves) or bovine pericardium (bovine valves).

Given that the choice of one type of valve over another depends not only on the surgeon but also on the patient's condition even when it is open on the operating table, there are some general factors that must be kept in mind:

- The advantage of mechanical valves is that they are built with particularly resistant materials and have a limited life; their main disadvantage is the need to take anticoagulant drugs for life since the contact between the blood and the materials with which these valves are formed tend to cause thrombo-embolic phenomena.

- The advantage of biological valves is to be well tolerated in the human body, without the need for anticoagulation; the main disadvantage is that in general, their duration overtime is limited (on average 10-15 years in young patients, over 20 years in patients over seventy years of age), therefore in young patients it is also necessary to consider the degeneration of the valve itself and therefore the need to plan a new intervention in the long term. The further disadvantage may be to use them in patients who, for religious reasons, consider the pig an impure animal (Jews, Muslims) or the bovine a sacred animal (Hindus).

Although the constant improvement of the manufacturing techniques of the biological valves allows their duration to be even longer in younger patients, mechanical valves are generally recommended for these. There are particular situations to use instead in these same patients biological valves, such as for example a female patient of young age or who wants to undertake one or more pregnancies or in a young male patient the desire to be able to carry out a sports activity without running the risk of running into problems related to anticoagulant therapy, mandatory if you use mechanical valves.

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