Mitral prolapse: causes, symptoms and therapy

Mitral prolapse

What is mitral prolapse

With the term prolapse of the mitral it refers to an anomaly in which a flap or both flaps of the mitral valve move into left atrium during the systole. This condition does not compromise the operation of the valve.
Quickly reviewing the anatomy of the heart we must remember that the heart valves there are four: mitral valve, tricuspid valve, pulmonary valve and aortic valve, all have the function of giving unidirectional blood respecting its trajectory along the cardiac cycle marked by the alternation of systole and diastole and composed as follows:

  1. right atrium
  2. tricuspid valve
  3. right ventricle
  4. pulmonary valve
  5. lungs
  6. pulmonary arteries
  7. left atrium
  8. mitral valve
  9. left ventricle
  10. aorta
  11. body

It is essential that the blood respects this cycle to allow the correct supply of oxygen throughout our body.
More than a mitral valve it would be better to talk about the mitral apparatus, given the complexity of this heart valve formed by:

  • annulus, flexible structure consisting of fibrous and muscular tissue, which unites the atrium and left ventricle and on which the 2 valve flaps are inserted directly,
  • 2 valve flaps front and rear,
  • 2 cusps,
  • tendon cords which join the valve flaps to the 2 papillary muscles.
Mitral or mitral valve

Mitral valve. Author: Patrick J. Lynch and C. Carl Jaffe This file is licensed under the Creative Commons Attribution 2.5 Generic license.

In this image it is possible to see how in case of prolapse the flap tends to go towards the left atrium.

Mitral prolapse

Mitral prolapse: flap of the flaps in the left atrium.

Epidemiology of mitral prolapse

It is a very common valve disease (the prevalence is approximately 3%). There is an equal prevalence between males and females.

Classification of mitral prolapse

There are several classifications for prolapse mitral but the best known and most used are that of Carpentier, one of the best known and most respected cardiac surgeons expert in mitral valve in the world and that of Barlow.

The first classification is from 1980's Carpentier which, based on the mobility of the mitral flaps, distinguished the prolapse as follows:

  • TYPE I: Mild mitral insufficiency with normal flap mobility
  • TYPE II: mitral prolapse in which the movements of the flaps are accentuated
  • TYPE III: restrictive, the movements of the flaps are reduced

Classification of Barlow of 1985:

  • Billowing (protruded valve): valve flaps protrude slightly into the atrium;
  • True prolapse: the flaps move during systole and regurgitation appears;
  • Floppy valve (lit. Sagged valve): protrusion of the flaps in the left atrium much more pronounced;
  • Flail Valve (lit. Floating valve): the most serious case occurs if there is a rupture of the tendon cords, so the valve is no longer anchored to the papillary muscle.

Causes of mitral prolapse

There cause most common of mitral valve prolapse is the myxomatous degeneration, that is the anomalous accumulation of proteoglycans at the level of the valve flaps and the chordae tendons which leads to their thickening. Stretching of the tendon cords results in prolapse and loss of coaptation of the flaps and can cause mitral regurgitation. A thickening of the flaps> or equal to 5 mm is considered the classic MVP (Mitral Valve Prolapse).

Among the possible causes of mitral valve myxomatous prolapse there are two types of diseases:

  • Barlow syndrome or mitral valve prolapse syndrome, valvulopathy present mainly in younger patients: there is a dilation of the mitral ring and also redundancy and prolapse of several segments;
  • Fibroelastic deficiency, in older patients: usually affects the posterior flap and is associated with thinning and breaking of cords.

The congenital mitral prolapse or primary, which can cause the most complications, appears to have a genetic predisposition. A possible autosomal dominant inheritance model was also investigated.
Mitral valve prolapse can be considered as part of connective tissue diseases such as:

  • Marfan syndrome,
  • Ehlers-Danlos syndrome,
  • Elastic pseudoxanthoma,
  • Myotonic dystrophy

In secondary prolapse there are no alterations to the connective tissue but to the structures of the valve such as annulus, chordae tendons and flaps that lead to a disproportion with the ventricle and therefore to the consequent prolapse.
This type of prolapse mainly affects the young women. The normalization of this disproportion between the size of the flap and that of the cavity decreases with age, so the incidence decreases as the years progress.
Secondary prolapse usually has little clinical significance and may be associated with mild mitral regurgitation.

It can also associate with:

  • atrial septal defect,
  • hyperthyroidism,
  • emphysema,
  • hypertrophic cardiomyopathy.

Symptoms of mitral prolapse

What are the main symptoms of prolapse of the mitral valve? Mitral prolapse can be asymptomatic in most cases, the finding is occasional. In symptomatic patients it can give:

  • Palpitations;
  • Atypical chest pain;
  • Arrhythmias, including supraventricular, ventricular tachyarrhythmias and bradyarrhythmias; sudden cardiac death is a rare complication occurring in <2% of patients following long-term follow-up.

In the event that the prolapse leads to regurgitation it is possible that symptoms of valvular insufficiency such as dyspnea and pulmonary edema are present.

Signs of mitral prolapse

On inspection there is a high incidence of chest excavate (pectus excavatum, sternum inwards, towards the spine).

On the auscultatory level, on the other hand: mesodiastolic click associated with a systolic murmur if mitral regurgitation is also present. The click is caused by the sudden tension of the valve flap and the corresponding tendon cord being pulled back towards the atrium.

Hemodynamic changes caused by conditions that decrease the size of the left ventricle (decreased venous return, increased contractility or reduced systemic volume), lead to an early onset of prolapse, an earlier click than normal and an increased duration of the murmur. These changes can be felt through the Valsava maneuver or occur with dehydration and amyl nitrite intake.

Instead, the increase in size of the left ventricle (if venous return increases, contractility decreases) causes clicks and murmurs to appear later in systole. This can occur via squatting or phenylephrine infusion.
The presence of a click that responds to provocative maneuvers is sufficient for the diagnosis of prolapse, even if the echocardiogram is not diagnostic.

Complications of mitral prolapse

Among the various complications of mitral prolapse we can consider:

  • infective endocarditis;
  • arrhythmia;
  • breaking rope, the most fearful

Mitral Prolapse Diagnosis

Echocardiography

Echocardiography (echocardiogram or ultrasound of the heart) it is the diagnostic test par excellence.

In echocardiography 2D prolapse is defined as a> 2mm displacement of one or both flaps in the left atrium during systole in the parasternal and apical long axis projections; in case of primary prolapse it is possible to see an increased thickness of the flaps (> 5mm) and redundant flaps and cords. If mitral regurgitation is present, Doppler echocardiography will show us the presence and severity of the regurgitation.

In the videos we can see Doppler color echo images of a myxomatous mitral valve prolapse.

Other exams

Electrocardiogram (ECG) e Chest X-ray (chest x-ray) are usually normal.

Pregnancy and sports

Before tackling the prolapse therapy it is good to dwell on two situations in which we consider a heart with mitral prolapse that undergoes an overload of volume:

  • Mitral prolapse and pregnancy: a pregnant woman has more blood than normal in circulation, but this increase in volume does not affect the prolapse, as there is no causal relationship between the severity of the prolapse and increased cardiac output.
  • Mitral prolapse and sport: there is no contraindication to sports since it is not the increased effort that causes any worsening of the prolapse.

If you are in one of the two situations just mentioned, you only need to periodically perform cardiological checks to evaluate the evolution of the prolapse over time; obviously for a pregnant woman the checks will be closer.

Mitral prolapse therapy

There isn't one care unique, but it depends on the different situations. Most patients with MVP have a benign prognosis and only periodic follow-up should be followed.
Numerous studies have been conducted in recent years regarding the need for one prophylaxis for endocarditis and it has been seen that the risk of contracting endocarditis is lower than the risk of adverse events associated with taking an antibiotic.

In the guidelines, the indication for prophylaxis remains for those who have a mechanical or biological valve prosthesis.

Approximately 10-15% of patients, particularly with thickened and redundant flaps, may develop mitral regurgitation.

Patients with evidence of primary MVP should avoid situations that can increase stress on the rope, such as suddenly lifting heavy weights.

In patients who have in anamnesis TIA (transient ischemic attack) antiplatelet therapy is indicated (eg with aspirin, acetyl salicylic acid). The guidelines also recommend aspirin for patients with prolapse who have no evidence of mitral regurgitation, atrial fibrillation, thrombus in the left atrium, or echocardiographic evidence of thickening or redundancy of the valve leaflets.
In any case, a long anticoagulant therapy with warfarin is recommended if risk factors for cardiovascular disease are present.

In patients with palpitations abstaining from caffeine, alcohol and tobacco is recommended. Beta blockers are useful in cases of premature atrial and ventricular contractions and often relieve symptoms.

In case of persistent palpitations, continuous echocardiographic monitoring is recommended. There ventricular tachycardia is an indication to perform an electrophysiological test to assess the risk of sudden death and the possible implantation of a defibrilator.

It comes to a intervention of repair or replacement valve mitral are in the most severe cases of heart disease, in which the prolapse of the mitral valve leads to severe heart failure.

 

 

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