CHRONIC MITRAL INSUFFICIENCY
Two valves, called atrioventricular valves, separate the ventricles from the atria: the tricuspid valve.
On the right side and the mitral valve on the left.
The mitral apparatus
The Mitral valve is made of a fibrous ring from 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 find the mast (pillar), the ropes that connect the sail to the structures and the sail itself (the mitral sheet).
The two leafletsare attached around the fibrous ring. The free edges of these sheets are not smooth. Real robes are formed from the rim and attach to the muscular pillars at the bottom of the left ventricle.
This configuration allows the valves to be sealed.
Contraction of the ventricles closes the mitral valve
The heart’s electrical system ensures a contraction of the ventricles. The pressure generated by contraction of the left ventricle pushes the blood from the bottom to the top and consequently closes the mitral valve.
Normal closing of the mitral valve
When the mitral valve closes normally, the edges of each leaflet attach to each other.
The ropes hold the leaflets in place 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.
Strong pressure is applied on the mitral valve
Normal tension on the mitral valve is very important. It is even 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 flowsor, in other words, has lost its seal and allows the blood of the ventricle to return to the left atrium, we have what is called mitral insufficiency.
This situation can be acute (sudden) or chronic (progressive).
CHRONIC MITRAL INSUFFICIENCY
Chronic mitral insufficiency is the most common cardiac valve disease.
Over time, an anomaly in the mitral apparatus’ structure causes an insufficiency.
Often found by luck
The mild form is symptomless and is often found by luck during a cardiac ultrasound or after hearing a murmur at the heart level.
The most common cause is mitral prolapse. Other causes include damage to the muscular pillars after a stroke, endocarditis, left heart failure and now very rarely, rheumatic fever.
Even without the rupture of a pillar following a stroke, the repairing process following the stroke can distort it, moving it away from the mitral valve. The pillar is retreated. The ropes are attached to this pillar and the pull the mitral leaflet, creating an opening on it.
Transitory mitral insufficiency
A temporary lack of oxygen in the muscle pillar, such as during an angina attack, can cause a temporary mitral leak known as angina pectoris.
This form of angina happens when the artery that brings the oxygenated blood to the pillar’s muscle has animportant shrinkagelimiting its oxygen supply during effort.
With this lack of oxygen, the muscle of the pillar does not contract as well. The leaflet attached to these ropes can fall back into the atrium and cause a temporary leak.
An important shortage of breath with or without chest discomfort will ring a bell in the cardiologist.
Mitral valve infection
Endocarditis is the infection of the ropes and leaflets. It is usually treatedeasily. Once resolved, it leaves scars and deformations on the valve, consequently causing the loss of the leaflet sealson the mitral valve.
Consequences on the left ventricle
Chronic mitral regurgitation leads to chronic fatigue of the heart muscle, which progresses towards the dilation of the left ventricle.
Stretching of the left ventricle muscle causes the mitral ring to dilate. The mitral valve leaflets that are attached to this ring no longer connect, creating an opening that is responsible for the mitral leak.
The importance of the leak is proportional to the dilation of the ring.
The chicken or the egg
We have just seen that chronic mitral insufficiency can cause left ventricular dilatation but a left ventricular dilatation secondary to another disease such as heart failure with decreasedventricular ejection fraction can cause mitral leakage.
This dilation of the left ventricle has an impact on the geometry of the mitral apparatus.
By increasing the size of the left ventricle "by dilation", the muscle pillars move away from their original positions, the ropes are now "too short" and the leaflets retained by these shortened ropes do not meet anymore. The valve is no longer waterproof and it leaks.
In fact, the importance of the leak is proportional to the relative distance of the pillars and to the changes on the valve ring.
Very variable symptoms
The symptoms of chronic mitral insufficiency are multiple and vary according to the severity of the mitral insufficiency and its impact on the heart itself or, in other words, how the heart behaves with this sick valve.
In the most severe form, the patient has shortness of breath at the slightest effort and even at rest. There may be palpitations, fatigue and swollen legs.
The long-term consequences of severe mitral regurgitation, even in the absence of symptoms, may justify corrective surgery. Rigorous medical monitoring of this condition is therefore necessary.
Medical check-ups allow you to learn about the evolution of symptoms and / or the appearance of new symptoms.
The frequency of these visits is based on the importance of mitral insufficiency, how the heart works with this sick valve, and the implications for the patient's daily activities.
In addition to a medical examination done by the professional, a periodic ECG and a follow-up by echocardiography is requested.
In the event that palpitations are perceived, a holter is requested to clarify their nature.
The doctor may request a coronary angiography if a valve reparation or replacement is considered.
Repair of an insufficient mitral valve.
Repair or mitral repair or mitral valve replacement is done depending on the evolution of the disease and the patient.
This repair is indicated only when the patient is limited in these activities by his condition or the left ventricle shows signs of weakness as it dilates.
We speak of "timing" of the surgery because, just as in all other procedures, involves risks.
The mitral reconstruction surgery involves repairing the sick valve.
The best surgical options
This is the best option with the lowest mortality risk.
A mitral valve repair usually does not require the patient to take anticoagulants for the rest of his life unless other medical conditions such as chronic arrhythmias are present.
This procedure, which is now applicable in the vast majority of cases of mitral regurgitation, is available in specialized valvular surgery centers. Nearly all patients referred to an experienced cardiac surgeon benefit from this type of repair.
Several conditions must be met in order to benefit from such a procedure. These conditions are verified with the passing of an echocardiography.
The replacement of the mitral valve
The replacement of the mitral valve consists of solving a problem by creating another.
A METAL VALVE
Metal valves, used mainly in patients younger than 70 years of age, need to "clear up" the blood for life.
Promotes blood clot formation
These metal valves tend to cause clots that can either block the valve (thrombosis) or escape into the circulation and cause significant blockages of important arteries (emboli) to the brain or elsewhere.
Good for life
If the metal valve does not become infected and does not thrombose, it should last the patient's entire life.
"Diluting" the blood alone carries the risk of bleeding.
Biological valves are made from animal tissues such as pork or beef.
Anticoagulants for a short time
They require the use of anticoagulants only for the first months after surgery.
Once this period is complete, a biological mitral valve usually does not require the patient to take anticoagulants for the rest of his life unless other medical conditions such as chronic arrhythmias are present.
Can work very well for many years
These valves can be efficient for 15-20 years if used in patients over 70 years old.
The right choice of valve
The choice of the type of valve will depend on several factors and should be discussed in detail by the patient, the surgeon and the cardiologist.
That's why we talk about "timing" for a mitral valve replacement and solving one problem with another.
Delaying the surgery as much as possible while ensuring that the heart goes well ensures that the benefits to this surgery will outweigh the risks associated with this procedure.
Coronarography to be done
Just before proceeding with mitral valve replacement surgery, a coronary angiography is required.
This examination is done in order to check if certain coronary arteries are to be repaired once the surgeon is on task.
Non-pharmacological therapy equally important
The therapy also has a very important nonmedical component.
It is recommended to do regular cardiovascular exercise, quit smoking, have a balanced diet, target the healthy weight and apply the restrictions in liquid and salt if necessary.
Good oral hygiene is also important.
In the event where mitral insufficiency is secondary to cardiac failure with lowered ejection fraction, the same recommendations for cardiac failure apply.
It is important to mention all types of mitral valve repairs to dentists or any other health professional.
It is recommended to take antibiotics as a preventive measure before dental procedures or in the case of certain surgeries or endoscopic examinations (gastroscopy, colonoscopy).