What is it?
Mitral insufficiency (also known as mitral regurgitation) is the incomplete closure of the mitral valve during ventricular contraction (systole). This means that when the ventricle contracts, a portion of blood, instead of entering the aorta properly, flows back toward the left atrium. The result of this condition is that blood is not efficiently distributed to the rest of the body, resulting in a feeling of fatigue and breathlessness. This regurgitation, if left untreated, can lead to heart failure.
Mitral insufficiency can occur at any age and, after aortic stenosis, is the second most common valve disease.
Causes and risk factors
Mitral insufficiency can be caused by intrinsic valve problems or left ventricular disease. We speak of primary or degenerative mitral insufficiency if the pathology depends on the degeneration of the tissue of the mitral valve itself, and secondary or functional mitral insufficiency if instead it is due to dilatation of the left ventricle. Mitral insufficiency is classified into mild, moderate and severe.
Possible causes of degenerative mitral insufficiency include:
Mitral prolapse, a congenital defect in the shape and function of the valve leaflets that prevents proper valve closure.
Damage to the valvular chords, due to wear and tear over time or chest trauma. Over time, the chordae tendineae responsible for anchoring the mitral leaflets to the heart, can stretch or tear, causing the mitral valve to fail significantly and no longer close as it should.
Bacterial endocarditis: Infection of a layer of cardiac tissue that can also involve the valves.
Rheumatic disease: Complication of throat infection caused by Streptococcus which can result in significant damage to the mitral valve, and will lead to mitral insufficiency sooner or later.
Functional mitral insufficiency, on the other hand, is secondary to the post-infarct dilated heart disease: after acute myocardial infarction, which damages the heart muscle, there may be dilation of the left ventricle resulting in mitral insufficiency.
Idiopathic dilated cardiomyopathy: a condition that causes gradual dilation of the left ventricle. This "stretching" also affects the tissues surrounding the mitral valve causing the onset of mitral insufficiency.
Atrial fibrillation, a non-random cardiac arrhythmia that can be a cause or effect of mitral insufficiency.
Which are the symptoms?
Mitral insufficiency is in many cases mild and slowly progressing. Symptoms may not show up for years, leaving the patients completely unaware of their condition, while the disease continues to progress. In fact, the appearance of symptoms depends on the severity of the disease and the speed the condition develops with.
- Fatigue during exertion
- Shortness of breath (dyspnea) and fatigue, especially following physical activity
- Swelling of the feet and ankles (edema)
- Acute heart failure
How is it diagnosed?
The diagnosis of mitral insufficiency and its severity is made by colordoppler echocardiogram. Transesophageal echocardiogram is used in the planning phase of valvulopathy treatment, allowing an accurate and detailed evaluation of the valve anatomy.
How is it treated?
Treatment of mitral insufficiency depends on the severity of regurgitation, presence of symptoms, and worsening of the general clinical picture. In cases of severe mitral insufficiency, surgery may be required to repair or replace the valve. However, even patients without symptoms should undergo cardiologic evaluation to define whether early intervention would be useful. If left untreated, mitral insufficiency evolves unfavorably both in terms of worsening symptoms and in terms of progressively worsening conditions of the heart and lungs. Ideally, measures should be taken before heart function is irreversibly compromised. In fact, in case of late intervention, the function of the heart often does not recover; on the contrary, an early intervention involves a low surgical risk and allows the patient a quality and expectation of life not different from that of a healthy population.
The goal of surgical 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 failure, adherence to a healthy lifestyle and periodic clinical monitoring are recommended.
When mitral insufficiency is or becomes severe, surgery is always advisable. This indication is also appropriate in the absence of symptoms when it is possible to prevent the unfavorable evolution of the disease in terms of incidence of possible complications and increased probability of survival, and when there is a need for cardiac surgery for a concomitant cardiac pathology.
In case of isolated mitral insufficiency caused by degenerative disease (primary insufficiency), repair surgery with preservation of the native valve is usually feasible and recommended.
Repair: The surgeon can restore proper valve function (abolition of regurgitation) by reconstructing the valve leaflets (removal of excess tissue, widening of retracted leaflets, reattachment of detached elements), replacing or resizing or adding chordae tendineae, reinforcing the annulus surrounding the valve by implanting an artificial annulus (annuloplasty).
Replacement: In case repair is not possible or does not guarantee an optimal and lasting result (often in secondary mitral insufficiency), valve replacement is indicated with partial or total removal of the native valve and subsequent implantation of a prosthesis that can be:
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).
organic, 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 over the years.
Advantages of repair over replacement include improved survival, lower peri-operative mortality, and better preservation of left ventricular function, as evidenced by many scientific studies. Mitral valve repair surgery can be performed in more than 90% of patients referred for surgery, but as it is technically much more complex than replacement, the success of the procedure may vary depending on the degree of valve repairability and surgical experience. For this reason, it is of paramount importance to look for a center of excellence in both mitral valve and minimally invasive surgery. In centers of excellence and in experienced hands, the duration of a repair surgery can last on average and broadly speaking from three to four hours, and recovery times after minimally invasive repair range from three to four weeks.
The surgical approaches that can be used are different:
The traditional surgery is the one that is performed with total sternotomy, while the so-called minimally invasive approaches are:
mini-invasive with partial sternotomy: a technique not commonly used that provides shorter skin incisions and allows to leave intact a part of the sternum.
mini-invasive with right anterior minithoracotomy: access is through the third or fourth intercostal space, with a skin incision of about 4-5 cm, without damaging any bone structure (sternum and ribs). Mini-thoracotomy: compared with total sternotomy, it has demonstrated better clinical outcomes, especially on reduction in postoperative bleeding, reductionof staying in ICU and overall hospital stay times.
In some centers, mitral surgeries are performed with the technique of robotic surgery. For patients with degenerative mitral insufficiency who present a high surgical risk (because of age or comorbidities), a fully percutaneous technique of mitral valve repair is available. The procedure, called MitraClip, involves implanting a clip between the two mitral valve leaflets to reduce valve regurgitation. This method does not require opening of the chest or extracorporeal circulation and is performed through a small puncture of the femoral vein.
In well-selected patients, results are excellent and patients are discharged home two to three days after the procedure.
The same procedure can be performed in patients with functional mitral insufficiency, i.e. in cases in which mitral regurgitation is secondary to left ventricular dilatation and dysfunction. In these patients, the surgical risk is often too high, and the Mitraclip procedure has proven safe and effective.
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