ACUTE MITRAL FAILURE

ACUTE MITRAL FAILURE

Acute mitral insufficiency is the result of a sudden break in the mitral apparatus, whether it is the rupture of a muscular pillar, the rupture of a mitral cord, or the rupture or breakage of a mitral leaflet.

 

Let's review some basic notions

There are two valves that separate the ventricles from the atriums. They are called atrioventricular valves.

The tricuspid valve in on the right side while the mitral valve is on the left.

 

 

The mitral apparatus

The Mitral valve is composed of a fibrous ring of the cardiac skeleton, two leaflets, ropes and muscle pillars found in the bottom of the left ventricle.

All these structures form the mitral apparatus.

 

Like a sailboat

We can compare the mitral apparatus to a sailboat. We have the mast (pillar), the ropes that connect the sail to the structures and the sail (the mitral leaflet) itself.

 

The two leaflets are attached all around the fibrous ring. The free edges of these leaflets are not smooth. From this rim are born real ropes which are attached to muscular pillars at the bottom of the left ventricle.

This configuration allows these valves to be sealed.

 

 

Contraction of the ventricles from the bottom to the top

The electrical system of the heart ensures a contraction of the ventricles. The pressure generated by these contractions of the left ventricle pushes the blood from the bottom to the top and in doing so closes the mitral valve.

 

Closure of the normal mitral valve

When the mitral valve closes normally, the edge of each leaflet attaches to each other.

 

The ropes retain the leaflets and prevent them from falling back into the left atrium. The mitral valve then forms a barrier, preventing the blood from returning to the atrium. The only possible way out for the blood is through the aortic valve, moving forward.

The normal tension on the mitral valve is very important. It is more so in the hypertensive patient. Imagine all the tension on the mitral apparatus in patients with a pressure that can exceed 200 mm Hg!

When the mitral valve flows, or in other words, has lost its seal, and allows the blood of the ventricle to return to the left atrium, mitral insufficiency occurs.

This situation can be acute (sudden) or chronic (progressive).

 

ACUTE MITRAL FAILURE

Acute mitral insufficiency is the result of a sudden break in the mitral apparatus.

The different components of the mitral apparatus may be responsible for this.

 

The rupture of the muscular pillar

The rupture of a muscular pillar is usually related to a stroke in the section of the heart including this muscular pillar. The prolonged lack of oxygen in the pillar causes the cells to die. The repair mechanisms following a stroke weaken the pillar which can then give away.

 

A sudden breakage of mitral rope

Mitral rope breakage is often associated with certain diseases leading to the degeneration of the ropes, in other words, the resistance of the ropes becomes deficient. They can break under the stress put on the mitral apparatus when the ventricle contracts.

We then experience "myxomatous" diseases.

 

Rupture of the mitral leaflets

The breakage or rupture of the mitral leaflet is often associated with a mitral valve infection called "bacterial endocarditis". This mitral valve infection caused by bacteria destroys the leaves of the mitral valve. One or more holes are formed in the leaflets, which make them fragile, permeable and less effective.

 

These various sudden breaks put the heart in difficulty

In all these breakages of the mitral apparatus, the impact on the health of the affected individual is important. The heart does not have the capacity to adapt to this sudden break of the mitral valve.

Suddenly, the valve is no longer waterproof. The valve is leaking. A large amount of blood is returning to the left atrium.

 

Pulmonary flood

All this extra blood causes congestion that affects the lungs.

Here is an example. An ice jam is formed in a river. Behind the ice jam, the water rises. The river leaves its bed and floods the surrounding land.

 

When the mitral valve suddenly loses its seal, part of the blood ejected by the left ventricle returns to the left atrium. Suddenly, the atrium is saturated and cannot take in any more blood.  More volume in a less accommodating cavity increases the pressure in this cavity.

This increase in pressure is communicated to the pulmonary veins that enter the left atrium. The pulmonary veins are therefore congested.

This congestion is communicated to the pulmonary capillaries, bringing an outflow of water into the surrounding tissues such as this river which floods the surrounding lands.

Water invades the alveoli and floods them. The blood then has more difficulty oxygenating itself. Carbon dioxide accumulates and the patient lacks air.  This is called pulmonary edema more commonly known as "water on the lungs".

 

A medical emergency

This is a medical emergency - 911.

Once the diagnosis is confirmed, the treatment of acute mitral insufficiency will consist of administrating drugs to remove the water accumulated in the lungs and then a restoration of the effectiveness of the valve either by repairing or replacing it.

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