Mitral valve

The mitral valve or bicuspid valve ( valva atrioventricularis sinistra, valva or mitral valva bicuspidalis ) is one of the four valves of the heart. It is located between the left atrium and left ventricle (left ventricle ), where it prevents the backflow of blood from the left ventricle into the left atrium during the contraction of the chamber. Its shape resembles a miter ( bishop's cap ), hence the name. The term bicuspid valve is derived from the two sails (Latin cuspides ) that make up these sails flap.

Anatomy

The bicuspid valve ( valva bicuspidalis ) consists of two sails, the cusp anterior (front sail ) and the posterior cusp ( behind the sail ). In veterinary anatomy, they are as septal cusp ( septum constant sail ) and parietal cusp designated ( permanent wall sails ).

The sails are ( chordae tendineae ) by means of chordae to the papillary muscles ( mm. papillares subauricularis and subatrialis ) and thus in the ventricle ( ventriculus cordis sinister) secured to prevent turning of the valve leaflets in systole ( contraction).

Diseases

The two most important diseases are mitral stenosis and mitral regurgitation the.

Mitral stenosis

In mitral stenosis, the flow is due to a congenital malformation or acquired disease, such as calcification or scarring of the door, reduced. Quantification such stenosis on the one about the remaining open area, on the other hand on the pressure gradient that builds up over the flap. Congenital malformations that lead to mitral stenosis:

• The supravalvular mitral stenosis: above the mitral valve is a restriction, which is in the form of a ring or a fine membrane. The membrane was formed from additional connective tissue originating in the connective tissue of the mitral leaflets and settles like a blanket over the mitral valve leaflets. The flow of blood from the left atrium into the ventricle is difficult. The membrane may be so tender that they can only be detected with transesophageal echocardiography. A supravalvular mitral ring alone is a very rare diagnosis. Most cases, the mitral valve is abnormally formed underneath.
• The parachute mitral valve (. Parachute, English " parachute " ) during development just a papillary muscle ( instead of two) was formed and in addition, the tendinous cords (called chordae ), connect the valve leaflets to the papillary muscle, thickened and shortened. The blood flow from the left atrium into the ventricle is difficult because the blood has to flow as through a funnel. The term " parachute = parachute " is explained by the presentation to the examiner and surgeon as follows: the papillary muscle is the parachutist, the chordae and the leaflets the parachute ropes and the enlarged left atrium of the parachute.
• The Hammock Valve (. Hammock, English " hammock ") is the parachute flap similar: all mitral valve leaflets are considerably thickened and it lacks the chordae ( chordae ) of this thickened valve leaflets to the papillary muscles, so that the valve leaflets and papillary muscles are fused directly together. The free mobility of the valve leaflets is severely restricted. It comes to leakage ( insufficiency) and stenosis of the mitral valve. The term " hammock " is explained as follows: Looking at the door from above, one finds instead of two delicate mitral leaflets that form an opening in the left ventricle, an oval hollow, which acts like a hammock. However, the hammock Valve is an extremely rare malformation flaps, the parachute mitral valve flaps a typical malformation of Shone complex. Transitional forms between two forms occur.
• The Mitralklappenatresie is the complete closure or non - investment of the flap. It is part of Hypoplastic Left Heart Syndrome.

Mitral regurgitation

In mitral regurgitation, the valve does not close properly.

• This may be due, for example, demolition or relative shortening of the holding threads ( chordae ), perforation or overstretching of a valve leaflet and expansion of the valve ring. The degree of insufficiency is given in degrees of I ° ( mild) to IV ° ( heavy).
• The mitral valve prolapse as a congenital malformation can lead to a failure, but is often clinically insignificant.

In addition to the "pure" stenosis and insufficiency especially mixed forms with different weighting of the two factors occur.