Heart Valve
A heart valve is part of the heart separating the different chambers and prevent blood from flowing the wrong way.
The heart has four valves:
- The mitral valve between the atrium and left ventricle left;
- The tricuspid valve between the right atrium and right ventricle;
- The aortic valve between the left ventricle and aorta ;
- The pulmonary valve between the right ventricle and pulmonary artery
Summary |
Anatomy
These are elastic structures, not muscle, without innervation or blood supply, which have the same constitution as the articular cartilage. When closed, its seam is continent, preventing the passage of blood.
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Mitral Valve
It is composed of two layers, inserted on a ring (the mitral annulus or left atrioventricular ring) between the left atrium and left ventricle and connected to the ventricular muscle (pillars or papillary muscle) by chordae. The mitral valve thus has two parts called cusps (separated by a small commissure):
- the lateral cusp is called the small valve, it fits in the outer ring
- the septal cusp is called the large valve, it is inserted in the septum.
The series' ropes + pillars "is called sub-valvular apparatus. Its name comes from its form of "miter", ecclesiastical hat.
tricuspid valve
It is composed of three layers, inserted on a ring (ring tricuspid ring or right atrioventricular) separating the right atrium of the right ventricle.
The tricuspid valve is composed as its name suggests three cusps:
- cusp anterior or lateral;
- septal cusp against the interventricular septum;
- cusp inferior.
These three valves meet during the time of ventricular systole and away during atrial systole.
Aortic Valve
It is composed of three layers called cusps, or sigmoid valves:
- a dorsal valve
- a valve left anterolateral
- a valve right anterolateral
Pulmonary Valve
It is composed of three layers called cusps, or sigmoid valves:
- a valve anterior
- a valve left dorsolateral
- a valve dorsal-lateral right
Physiology
The opening and closing are completely passive. They depend on the pressure difference on either side of the valve: When the downstream pressure is lower than the pressure upstream of the valve is open. Otherwise, the valve is closed.
The closing of the valves provides the sounds of the heart , the first sound, called B1, corresponding to the closure of mitral and tricuspid valves and the second sound, B2, closure of aortic and pulmonary valves.
Overall, the systole is the time between mitral valve closure (and tricuspid) and aortic valve closure (and lung).
The diastole is the additional time (closure of the aortic valve closure to mitral valve).
Exploration
The valves are not normally visible on a radiograph. They are poorly visualized by CT or nuclear magnetic resonance , mainly because they are highly mobile structures and temporal resolution of these two tests is insufficient.
The investigation of choice is the ultrasound heart. It allows direct visualization of the valves and to analyze the movement. It is coupled with Doppler. The latter, by analyzing the blood velocity, allows to visualize and quantify leakage (reverse flow) and quantify shrinkage (increased flow remains in the right direction). The examination may be supplemented by an ultrasound by trans-esophageal to better view the details.
The angiogram can not directly visualize the valves. The injection of a contrast agent can view a leak (opacification of a cavity that should not be). Pressure measurements before and after a valve, coupled to the measurement of cardiac output, allows to estimate valve area.
Pathology valves
See detailed article valvular heart
A valve can be achieved in two ways:
- a lack of continence was closed causing a leak (also known deficiency)
- a narrowing of the valve (also called stenosis)
See also
| Pericardium epicardium myocardium Endocardium sinus node bundle of His Purkinje fibers heart valves aorta pulmonary artery | |
| See also: Heart |
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