There are four heart valves in a human heart. Two on the right side - Tricuspid and Pulmonary and two on the left side - Mitral and Aortic. Valves ensure unidirectional blood flow in the heart and prevent backward leakage.


Abnormality of a heart valve thus could be leakage leading to backward flow or obstruction to the forward flow. The heart has an inbuilt capacity to compensate when the degree of leakage or obstruction is minimal. Excessive leakage or severe obstruction however may need surgical intervention. This is explained in detail below.


The Aortic and Mitral valves are commonly affected but due to back pressure the right side of the heart can also enlarge leading to leakage of the Tricuspid valve. When this happens, it may also need to be surgically repaired.


The Pulmonary valve is rarely involved in an adult; abnormalities are usually seen in the paediatric group.

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Aortic Valve

Aortic valve disease is one of the most common forms of heart valve abnormality seen in the UK. Over 5000 operations are performed annually in UK whereby the aortic valve is replaced with an artificial valve.


Aortic valve is an outlet valve between the aorta and the left ventricle (pumping chamber). 









Aortic Valve Structure

It is usually made of three leaflets or cusps, which open and close with every heart beat. In 10% of the population, the aortic valve may be made up of two leaflets referred to as a bicuspid aortic valve. A bicuspid aortic valve may be associated with a heart murmur.








Aortic Stenosis

Calcium gets deposited on to the cusps with age, making them rigid. This restricts the degree of their opening. The normal area of an open aortic valve resembles a 10 pence coin, allowing an unobstructed forward flow of blood; however, when stenosed, it resembles an area of a 5 Pence coin or less. This is called Aortic Stenosis. Valve replacement is the only option as repair is not possible.







Aortic Regurgitation

When the aortic cusps close, they prevent leakage. But whent there is an abnormality in the cusps or their attachement thereby preventing complete closure or a gap, it leads to leakage into the pumping chamber. When this leakage is large and long standing, it  leads to dilatation of the pumping chamber and needs surgical treatment in the form of an aortic valve repalcement. Aortic valve repair may be possible in select few patients.





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Mitral valve

Degenerative Mitral valve disease is the second commonest form of heart disease in the UK. Historically it was the commonest form when rheumatic heart disease was prevalent in UK. 

 

The Mitral valve lies between the collecting chamber i.e. left atrium and the pumping chamber i.e. left ventricle. 









Mitral Valve Structure

It is made up of two leaflets, a large anterior and a crescentic posterior leaflet. The Mitral valve resembles a sail or a parachute. Thus, the leaflets are attached to the muscle of the pumping chamber with strands called papillary muscles and chordae.




 




Mitral Regurgiation

When the left ventricle pumps blood into the aorta, the Mitral valve closes to prevent backward flow into the atrium. When the closure of the leaflets is imperfect due to either abnormality in the leaflets or in the chordae, it leads to leakage. 


When Mitral valve leakage is significant, it can need surgical treatment. Unlike the Aortic valve, the Mitral valve can be repaired in the majority of the cases. When the valve is not repairable, it can be replaced with an artificial valve.





Mitral Stenosis

It is a common manifestation of rheumatic heart disease and hence not commonly seen in UK. The leaflets are thickened, calcified and deformed. Hence majority of the cases are treated with valve replacement.





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