Causes and risk factors
The primary cause of mitral stenosis is rheumatic fever (acute joint rheumatism) related to a streptococcal infection. Rheumatic fever, which has become rare in Italy but is still present in developing countries, can result in severe alterations of the mitral valve. Causes of mitral stenosis include:
- Rheumatic fever
- Calcium metabolism abnormalities
- Congenital valve defects
- Chest radiotherapy
- Autoimmune diseases such as lupus erythematosus
Risk factors include: a history of rheumatic fever and untreated streptococcal infection.
If left untreated, mitral stenosis leads to serious consequences such as:
Heart failure and pulmonary edema: increased pressure within the left atrium results in fluid accumulation within the lungs leading to the appearance of exertional dyspnea and, in severe cases, pulmonary edema. If this process progresses, there is an increase in pressures in the pulmonary circulation as well (pulmonary hypertension), which in the long run also affects the right ventricle and tricuspid valve.
Dilation of the left atrium and occurrence of atrial fibrillation, an arrhythmia generated by dilation and stretching of the atrial wall. Presence of atrial fibrillation together with mitral stenosis involves a significant risk of thrombus formation within the left atrium, with consequent risk of stroke and peripheral embolization.
In the presence of mitral stenosis, it is necessary to carry out cardiological evaluation, including instrumental examinations such as echocardiography to establish the clinical conditions (symptoms and their severity) and assess possible reparability.
Which are the symptoms?
Mitral stenosis can run asymptomatic or with mild symptoms even for decades. Its evolution is slow in most casesi. Mitral stenosis is also classified into mild, moderate, and severe. Symptoms that may appear and determine the need for a cardiologic checkup are as follows:
Symptoms can appear or worsen any time the heart rate increases (such as in exertion) and can be triggered by pregnancy or infection. Symptoms usually appear between the ages of 15 and 40, but can occur at any age.
- Legs and feet swelling
- Dizziness or fainting
How is it diagnosed?
Mitral stenosis is diagnosed with a colordoppler echocardiogram.
How is it treated?
The goal of treatment is to improve heart function, reduce symptoms and/or avoid possible future complications.
In the early stages of the disease, especially in patients with mild to moderate mitral stenosis and modest symptoms, periodic clinical checks are recommended.
Although drugs cannot treat the valve defect, medical therapy may be indicated to treat symptoms or prevent complications.
Medical therapy may include: diuretics to reduce fluid buildup in the lungs, antithrombotic drugs (anticoagulants) to prevent thrombus formation, beta blockers to reduce heart rate and promote filling of the heart, antiarrhythmics to treat atrial fibrillation or other rhythm disorders, antibiotics to prevent recurrence of rheumatic fever if this is the cause of the valvulopathy.
Surgery for the treatment of mitral stenosis may be repair or replacement.
Both repair and replacement surgery are performed with cardiac arrest and extracorporeal circulation.
Surgical options include:
Commissurotomy. Surgical procedures may include: a) removal of calcifications that usually alter the profile and thickness of the flaps, occupy the annular tissue, and are responsible for the fusion of the areas where the flaps meet or commissure; b) mobilization of the flaps and subvalvular apparatus; c) eventual reinforcement of the ring (annulus) surrounding the valve by implanting an artificial ring (annuloplasty).
Valve replacement. In case the commissurotomy is not possible or does not guarantee an optimal and lasting result (valve apparatus extremely calcified in all its components), the replacement of the mitral valve with a prosthesis is indicated:
mechanical, robust and durable enough to be considered a permanent solution. The metal materials comprising it require the patient to follow an anticoagulant therapy for life to prevent the formation of clots (embolism).
biological, composed of material of animal origin. This feature, on the one hand, does not require the patient to follow an anticoagulant therapy, but on the other hand, exposes the prosthesis to wear with the possible need for a reoperation.
The surgical approaches that can be used are different based on the degree of invasiveness:
the traditional intervention is the one that is performed with total sternotomy,
the so-called minimally invasive approach can be:
the minimally invasive right anterior minithoracotomy intervention: it is the most commonly used approach. Access is through the third or fourth intercostal space, with a skin incision of about 5-6 cm, without damaging any bony structure (sternum and ribs).
the minimally invasive intervention in partial sternotomy: it is a technique not commonly used that provides shorter skin incisions and allows to leave intact a part of the sternum.
The minimally invasive surgery of mini-thoracotomy, compared to total sternotomy, has shown advantages for the patient such as better clinical results, especially on the reduction of postoperative bleeding, reduction of time spent in intensive care and overall hospital stay, with consequent reduction of convalescence time and resumption of normal life after surgery. For minimally invasive mitral valve surgery, it is always critical to refer to a center of excellence.
Non-surgical intervention: percutaneous mitral valvuloplasty: In selected cases (absence of significant calcification of the mitral leaflets, absence of associated significant mitral insufficiency) the technique of percutaneous mitral valvuloplasty can be used. The procedure is completely percutaneous and transcatheter and involves the introduction, through the femoral vein, of a catheter equipped with an inflatable balloon at its end. The catheter is pushed until it reaches the stenotic valve, and the valve is opened by inflating the balloon. In well-selected cases, the procedure is extremely effective in reducing the extent of stenosis and improving symptoms.
All possible options and aspects related to each individual patient, however, must be discussed and deepened with the cardiac surgeon before the operation.