General information
The mitral valve consists of two leaflet, an anterior and a posterior leaflet. Both leaflets are attached to a ring of connective tissue. The free edges of the leaflets are attached to the papillary muscles with tendon threads (chordae) on the heart muscle, preventing the leaflets from turning over into the atrium while the left ventricle pumps blood into the circulation. In terms of its structure, the mitral valve resembles a two-part parachute.
Mitral valve disease
On the one hand, diseases of the mitral valve can lead to the valve leaflets no longer opening properly. The valve leaflets are then thickened and calcified. This is called mitral valve stenosis. On the other hand, it can also happen that the mitral valve no longer closes completely; this is called mitral valve regurgitation. A combination of lack of closure and restricted valve opening may also be present. This is called a combined mitral valve defect.
Mitral valve stenosis
Mitral valve stenosis occurs when the opening of the mitral valve is severely narrowed. It is difficult for the blood to flow from the left atrium to the left ventricle, causing the atrium to expand over time. As a result, atrial fibrillation can develop, which in turn can severely limit the patient’s quality of life. The permanently high pressure in the left atrium also increases the pressure in the pulmonary circulation. Pulmonary hypertension (high pressure in the lungs) develops.
Today, mitral valve stenosis is rarely found in industrialised countries because the most common cause of stenosis is rheumatic fever, which is hardly ever found in these regions. The Department of Cardiovascular Surgery at the German Heart Centre Munich enjoys an excellent international reputation and treats patients from all over the world. The expertise in the treatment of mitral valve stenosis is therefore very high.
The treatment of mitral valve stenosis is based on international guidelines and is primarily minimally invasive. A balloon catheter is advanced through the inguinal vessels to the mitral valve and dilated. This mechanically widens the opening of the mitral valve. This procedure is also known as mitral valvuloplasty. If a minimally invasive procedure is not applicable, the mitral valve defect is treated by open heart surgery. This involves replacing the mitral valve with a biological or mechanical prosthesis. For surgical mitral valve replacement, the minimally invasive approach via a small incision below the right breast is favoured at the German Heart Centre Munich. The heart-lung machine needed for this is then connected via the groin vessels.
Mitral valve regurgitation (leakage)
Mitral valve regurgitation is the most common disease of the mitral valve. It is caused by an inability of the mitral valve leaflets to close due to changes in the mitral valve apparatus. This inability to close causes blood to flow from the left ventricle back into the left atrium during systole. In order to maintain adequate circulation, the left ventricle has to do more, which in the long run leads to excessive strain and eventually to a reduction in the function of the left ventricle. Blood flowing back into the left atrium with each heartbeat (pendulum volume) causes the left atrium to enlarge. Atrial fibrillation develops. If the disease remains untreated, the pressure in the pulmonary circulation eventually increases. Pulmonary hypertension develops. The most common clinical symptom is dyspnoea (shortness of breath) on exertion. However, patients with severe mitral valve regurgitation can often be asymptomatic.
The diagnosis is made by means of ultrasound monitoring (echocardiography) of the heart. In addition to the degree of leakage of the mitral valve, this examination also evaluates the cause of the valve’s inability to close. It is also determined whether and to what extent the cardiac output is limited, how large the heart chambers are and whether other heart valves, such as the tricuspid valve, are also affected.
Mitral valve regurgitation can occur in two ways. As a rule, one speaks of primary mitral valve regurgitation when the valve or the valve apparatus itself has become diseased due to degenerative processes. An example of this is mitral valve prolapse, which is often accompanied by a rupture of the chordae. However, if there is an inability to close for other reasons and although the valve is intact, for example because the heart is enlarged as a result of heart failure, this is called secondary mitral valve regurgitation.
