Mitral valve disease

Mitral stenosis

Mitral stenosis signifies narrowing of the mitral valve ostium, which leads to an obstruction to the blood flow from the left atrium towards the left ventricle. The consequence is pressure overload of the left atrium, leading to an increase in its size. These changes cause an increase in the pressure in the lesser circulation, leading in time to pulmonary hypertension and right heart strain. Under these conditions, insufficiency of the tricuspid valve develops with dilatation of the right ventricle. The increase in the size of the left atrium is the cause of atrial fibrillation, an arrhythmia that often complicates the course of mitral stenosis.   

Mitral stenosis is usually due to rheumatic fever and occurs more often in women than in men. Rheumatic fever is endemic in third-world countries due to poor hygiene. In Western Europe, mitral stenosis is rare due to prompt antibiotic treatment of streptococcal infection. 

The predominant symptom is dyspnoea, which is caused by the lung congestion. Increasing stenosis of the mitral valve leads to orthopnoea and in extreme cases to pulmonary oedema. Since mitral stenosis is often accompanied by atrial fibrillation, thrombi can develop in the left auricle, leading to embolic complications of cerebral type (stroke) and/or peripheral ischaemia. Endocarditis is another complication that can arise due to infection of the stenosed mitral valve.

Mitral insufficiency

Mitral insufficiency occurs much more often than mitral stenosis. Men are most often affected. It is due to inability of the valve cusps to close. This develops because of damage to the cusps, the annulus, the suspensory apparatus (tendinous cords and papillary muscles) or a combination of these lesions.

The most common causes of such changes are connective tissue disorders, dilated cardiomyopathy, endocarditis and rheumatic fever. The clinical picture is determined by the speed at which the insufficiency develops. Patients with mild to moderate mitral insufficiency usually have no symptoms. Even severe mitral insufficiency can remain asymptomatic for many years. One of the first symptoms is a drop in energy level.

At an advanced stage of the disease, the clinical picture is characterised by signs of left heart strain, ranging from exertional dyspnoea to pulmonary oedema. An acute event can be caused by the onset of atrial fibrillation or rupture of a tendinous cord.