Mitral prolapse

Content

Introduction

Introduction

The mitral valve prolapse (PVM) or mitral valve prolapse it consists of a malfunction in the closure of the valve which controls, allowing or preventing its passage, the flow of blood which from the left atrium, when the heart contracts (systole), passes into the left ventricle.

During contraction, the mitral valve closes hermetically, blocking the passage of blood backwards and preventing it from rising from the ventricle towards the atrium.

The closure is hermetic, guaranteeing optimal operation, when all the parts of which the valve is made are intact:

  • ring, circular structure of connective tissue that surrounds the opening and connects the two flaps to the wall of the heart cavities at the point of union between the atrium and the ventricle
  • orifice, open structure approximately 30 millimeters in diameter
  • two flaps called cusps (for this reason the valve is called bicuspid) anchored, at the top, to the ring, at the bottom of the walls of the left ventricle by means of the tendon cords. Consisting of connective tissue rich in elastic fibers and collagen, the flaps join together perfectly to block the passage of blood also thanks to the welding of their edges at the point where they meet: the so-called commissures, similar to the corners of the mouth
  • papillary muscles, prolongations of the musculature of the ventricle
  • tendon cords, which join the flaps to the papillary muscles from which they are supported, are similar to splints that bind the flaps to the walls of the ventricle, preventing their overturning backwards (towards the atrium) at the time of closure

In perfect functioning conditions, in order for the valve to close, the flaps meet until they fit perfectly under the (imaginary) plane that separates the atrium from the ventricle.

When, in the majority of cases due to a genetic defect, the connective tissue, of which the valve is largely constituted, is damaged, all its components can be damaged in a chain (dilation of the ring, elongation of the tendon cords, growth and dilation of the flaps).

It follows that the union between the two flaps, no longer stretched downwards but swollen upwards, no longer occurs under the ideal plane but increasingly closer to it, causing an imperfect closure of the valve and determining a condition called billowing (fluctuating, first stage of the disease).

If, on the other hand, they go beyond the plane, barely touching each other, a definite condition is determined prolapse (alteration from its natural location, second phase of the disease).

The most serious situation is represented by the rupture of the tendon cords (even just one) which determines the loss of the ability of the flaps to join together, causing a condition called flail (uncontrolled activity, third stage of the disease).

The more significant the malfunction, the greater the amount of blood flowing back into the left atrium (blood regurgitation) and the more severe the degree of the disease.

If the "echocardiogram (reference examination for this pathology) were a routine examination, it would highlight in more than 20% of the people subjected to it a condition of billowing. However, this does not mean that all cases found over time turn into a real prolapse or the most serious condition (flail).

PVM is one of the most frequent heart valve problems: about 5-10% of the total population is affected.

Symptoms

Symptoms

In the context of mitral valve prolapse (PVM) there are many conditions, from those that can be considered simple variants of the norm, up to those with a high risk of serious complications.

As long as the flaps, even if dilated, are able to close and the valve is still able to perform its function of controlling blood flow, no problem arises and the condition can be considered a benign anomaly or even a characteristic valve physics that does not affect the quality of life in any way.

The actual condition of prolapse may include moderate to severe cases in which various disorders (symptoms) may occur, also related to the various complications that may arise.

When the tendon cords break and the flaps overturn upwards and no longer touch each other, more or less serious conditions arise.

The most frequent disorders of PVM are:

  • shortness of breath (dyspnea), first only after physical exertion then also at rest
  • heart pounding (heartbeat)
  • lack of strength (asthenia)
  • chest pain
  • flooding of fluid in the lungs (pulmonary edema)
Causes

Causes

The main cause of mitral prolapse (PVM) is myxomatous degeneration (due to myxoma, a benign tumor) of the valve: the collagen fibers that make up the connective tissue of which the valve is largely made up stretch and thin, therefore the ring dilates, the tendon cords stretch, the flaps swell.

Over time, the thinning of the fibers could cause the rupture of one of the cords and the detachment of the flaps which at this point would begin to float in the atrium, completely losing the ability to unite (the valve is no longer able to close) and to block the ascent of blood from the ventricle to the atrium (regurgitation). In this case we speak of primary PVM.

PVM can also be found in association with:

  • diseases that damage connective tissue
  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • adult polycystic kidney disease
  • osteogenesis imperfecta
  • elastic pseudoxanthoma
  • systemic lupus erythematosus
  • polyarteritis nodosa
  • muscular dystrophies

or as a secondary manifestation (in this case it is defined secondary PVM) to:

  • heart disease with imbalance between left ventricular volume and valve anatomy
  • heart disease characterized by a low ability to contract in the left ventricle (myocarditis, rheumatic endocarditis, Wolff-Parkinson-White syndrome, dilated cardiomyopathy)
  • ischemic heart disease, which includes all conditions in which there is an insufficient blood supply to the heart
Diagnosis

Diagnosis

The characteristic signs of mitral valve prolapse (PVM) are a particular noise (click) or a murmur in the final phase of the heart's contraction (end-systolic murmur), detectable during a simple visit to your doctor or a cardiologist; the instrumental examination to confirm the suspicion of mitral valve prolapse is the "echocardiogram.

Other tests may be required in relation to the presence of disorders (symptoms) that suggest the association of PVM with other conditions.

Therapy

Therapy

The most suitable therapy is chosen by the doctor based on the severity of mitral valve prolapse, general health conditions, family history.

If the prolapse is:

  • mild, any type of medication may not be required
  • moderate or severe, β-blocking drugs and other specific medicines may be needed to prevent any complications and, in some cases, even surgery

In case of rupture of the tendon cords it is advisable to resort to surgery to avoid the risk of serious alterations in the heartbeat (arrhythmias); the intervention is also indicated in the case of atrial fibrillation.

Today, in most cases, it is possible to repair the valve without replacing it with a prosthesis.

The repair can be done with:

  • traditional plastic, performed with an open heart with the opening of the chest and extracorporeal circulation
  • mitralclip implant, i.e. positioning of a clip (button) between the two flaps of the valve. The mitralclip is delivered to the heart through a catheter passed into the femoral vein
  • Neochord technique, implantation of new cords through an instrument that reaches the valve through a small cut in the chest
  • Cardioband system, consisting in the "insertion of a device through the femoral vein and the positioning of a ring that regulates the size of the mitral ring, often performed also to complete the implantation of new cords

The techniques used as an alternative to the more traditional intervention are defined minimally invasive and represent an advantageous alternative for everyone but, above all, for those who would take important risks with open-heart surgery.

Prevention

Prevention

Since a genetic defect is the main cause of mitral valve prolapse (PVM) in most cases, there is no prevention of any kind to avoid this condition.

After having ascertained (diagnosed) its presence, it is advisable to follow the instructions of the treating physician regarding the therapies and checks to be carried out to assess the evolution of PVM and avoid worsening of the conditions.

Complications

Complications

The most frequent complication of mitral valve prolapse ismitral insufficiency.
Prolapse with mitral insufficiency can cause heart failure, infective endocarditis, and atrial fibrillation with thromboembolism.

It is still being investigated whether mitral valve prolapse, without necessarily being accompanied by mitral insufficiency and atrial fibrillation, can cause stroke or endocarditis.

Living with

Living with

In the context of mitral valve prolapse (PVM) or mitral valve prolapse, it is possible to identify many conditions, from those considered simple variants of the norm, up to those with a high risk of serious complications.

Each of them constitutes a case in itself to be evaluated in the vision of a more general and familiar picture, however, in the majority of cases, PVM is considered a benign anomaly or, even, a physical characteristic of the valve that does not affect in any way. on the quality of life.

In the absence of disorders (symptoms), especially in the case of adults with no other cases in the family, for whom there will hardly be an evolution towards an aggravation of the conditions, one could limit oneself to periodic ultrasound checks, without any type of therapy.

Especially for young people with other cases of prolapse in the family, already in the first stage of the disease (billowing) or even more so in the case of real prolapse, even if with slight insufficiency, it is advisable to carry out ultrasound checks to constantly check the situation, evaluate the speed of variation of the conditions over time and, in case of aggravation, evaluate the opportunity for surgery.

Mitral valve prolapse (PVM) in athletes

In high-level sports (competitive), the evaluation of PVM for the purposes of sporting fitness is conditioned by two elements: the degree of valve dysfunction and the association with other conditions.

For all cases in which it can be considered a simple variation of the standard, there is no restriction.

In cases of myxomatous and redundant PVM of the flaps but with mild blood regurgitation, the competitive fitness may be issued only for some sports with the mandatory need for complete cardiological checks at least every 6 months, considering that over time it could worsen.

There may be a restrictive attitude in the release of sports fitness if mitral valve prolapse is associated with arrhythmias, particularly if favored by effort.

Competitive fitness is denied to athletes who have had episodes of unexplained syncope, who have had family members who died suddenly at a young age, who have moderate to severe mitral valve insufficiency; who have repeated supraventricular tachyarrhythmias or complex ventricular arrhythmias both at rest and from exertion.

The exams scheduled for athletes with PVM are:

  • echocardiogram
  • ergometric test
  • cardiac holter, including a training session (under stress)
Bibliography

Bibliography

NHS. Mitral valve problems (English)

Niguarda Hospital. What is mitral valve prolapse?

In-depth link

In-depth link

American Heart Association (AHA) - American Stroke Association (ASA). Problem: Mitral Valve Prolapse (English)

Monza Polyclinic. The Evolution of Mitral Valve Surgery

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