What is Aortic Valve.

According to the Wikipedia, a valve is a device for controlling flow of fluid through a pipe or a duct, especially an automatic device allowing movement in one direction only.

The aortic valve, (and the other heart valves) is just that, in the sense that, it controls and allows flow of blood only from the left ventricle of heart into the aorta.

Where is the Aortic Valve.

The aortic valve is situated at the junction of the left ventricle and the aorta in the heart. To understand the aortic valve, it is necessary for you to read the anatomy of the heart first, which explains the four chambers of the heart and the four valves of the heart.

The left ventricle is the lower chamber of the left side of the heart. It is larger and thicker than the right ventricle because it contracts at each heart beat with a greater force as it has to pump blood to every part of the body. The left ventricle pumps pure oxygenated blood into the aorta through the aortic valve.

The aorta is the largest artery in the body which branches into the ascending aorta and descending aorta, which again go on to form a network of arteries, arterioles and the smallest sized capillaries. Through this network, blood supply is ensured to every tissue and cells of the body.

With this basic information of the left ventricle and the aorta, the importance of the aortic valve will be easier to understand.

Anatomy of Aortic Valve|Structure of the Aortic Valve.

 The aortic valve is made up of three strong but thin flaps of tissue called cusps or leaflets. The shape of the leaflets is semi lunar (like the half moon) and hence this valve is one of the semi lunar valves, the other being the pulmonary valve.

The cusps of the aortic valve are attached to a ring of fibrous tissue called the annulus which supports the aortic valve to keep it in place and maintain its shape. The annulus acts as a door frame while the aortic valve leaflets serve as door shutters. When the aortic valve shuts, the cusps close in perfect alignment allowing no passage of blood through it.

Picture of aortic valve position and structure.

Function of the Aortic Valve.

During the systole (contraction of the ventricles), the pressure in the left ventricle is more than the pressure in the aorta. This forces the aortic valve to open widely and allow blood to flow from the left ventricle into the aorta.

During the diastole  (relaxation of the ventricles), pressure in the left ventricle is less than that in the aorta. This higher pressure in the aorta forces the three cusps of the aortic valve to shut thereby allowing no backward passage of blood flow through it.

The aortic valve thus serves as a one way non return valve which allows passage of blood from the left ventricle to the aorta and prevents any flow of blood backwards from the aorta to the left ventricle. This ensures proper sequence of blood flow in the heart required for proper blood circulation.

Aortic Valve Diseases.

Bicuspid Aortic Valve.

This is the most common congenital anomaly of the aortic valve in which the aortic valve has only two unequal sized cusps instead of the normal equal sized three. This is found in about 1% to 2% of the population and exhibits a hereditary trait. This condition stays undetected till this disorder becomes symptomatic, usually between the age of 40 years to 50 years, when aortic stenosis develops.

Bicuspid aortic valve is associated with other conditions of the aorta such as dilatation of the aorta, dissection of the aorta and aortic aneurysm.

Bicuspid aortic valve has to be treated once symptoms occur, as else death occurs within 2 to 4 years.

Aortic Stenosis.

Aortic stenosis is narrowing of the aortic valve in which the valve does not open completely thereby causing obstruction to the flow of blood. Common causes of aortic stenosis are rheumatic fever, degenerative calcification and congenital bicuspid aortic valve.

Aortic Regurgitation (AR) or Aortic Insufficiency(AI).

Also called aortic incompetence, this is a condition in which there is incompetence of the aortic valve which results in improper closure of the aortic cusps when the valve closes. This causes regurgitation or leakage of blood backwards, that is from the aorta to the left ventricle. Common causes of AR are previous history of rheumatic fever, infective endocarditis, dilatation of the aorta, myxomatous degeneration of the aortic valve and Marfan’s syndrome.

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