subject: MITRAL STENOSIS Aetiology and clinical features [print this page] Although a rare congenital form exists, mitral stenosis isalmost always a consequence of rheumatic heart disease,and is the commonest valvular manifestation of thedisease. The two valve cusps become adherent along theircommissures, producing progressive stenosis with a 'fishmouth' orifice. Initially the cusps remain fairly pliable, but become increasingly rigid with time and eventually calcify.The increasing degree of stenosis produces a rise in leftatrial pressure and left atrial dilatation. The raised pulmonaryvenous pressure can induce pulmonary oedemaand lead to progressive pulmonary hypertension, with secondary incompetence of the tricuspid valve.
Clinical features
Mitral stenosis, which is commoner in women, may remain asymptomatic for many years with little limitation of exercise tolerance. However, an additional load on the heart,such as pregnancy, exertion, emotional stress or intercurrentchest infection (which is more common in patientswith mitral valve disease because of the pulmonary vascular congestion), may produce the first symptoms of left heart failure. The onset of fast AF in middle age is acommon presentation, often leading to left heart failure,and thrombus formation with the risk of embolism. Rightheart failure eventually develops as a consequence of pulmonary hypertension.
SymptomsOf left heart failure
The symptoms of left heart failure are shortnessof breath on exertion, orthopnoea, paroxysmal nocturnal dyspnoea, pulmonary oedema, and haemoptysis of fresh blood occurring from rupture of a congested bronchial or pulmonary vein (uncommon with other causes of left heart failure). Haemoptysis may also be due to pulmonary infarction,which is more common in mitral valve disease.Due to atrial fibrillationThe raised left atrial pressure may lead to AF, sometimes paroxysmal at first, but then sustained. The loss of atrial contraction and the shortened diastolic filling period canchange an asymptomatic patient into one severely disabled by breathlessness, and may convert a quiescent stenosisinto a life-threatening condition.Systemic embolism. Thrombus can form in the enlargedleft atrium and give rise to systemic emboli. A hemiplegiamay occur and embolism to other sites is frequent. The patient in sinus rhythm is also at risk from embolism, but to a lesser extent. The greatest risk is in the patient who,having been in AF, reverts to sinus rhythm, as the return of coordinated atrial contraction can dislodge clot.Due to a raised left atrial pressure Long-standing raised left atrial pressure often leads to constriction of pulmonary arterioles and thickening of the capillary basement membranes. There is increased resistance to flow through the lungs, and hence pulmonaryhypertension.Right ventricular hypertrophy compensates for theincreased load on the right ventricle. When pulmonaryhypertension is severe, right ventricular failure follows,usually (but not always) associated with left heart failure. Right ventricular dilatation may lead to tricuspid regurgitation,with its attendant symptoms and signs . Lessfrequently, tricuspid valve disease (regurgitation morefrequently than stenosis) occurs through direct involvement in rheumatic fever.Massive enlargement of the left atrium can lead to hoarseness from pressure on the recurrent laryngeal nerve,dysphagia from oesophageal compression, and bronchiectasis from distortion of the left main bronchus.SignsThe main signs of mitral stenosis are listed in Summary box7. Pure mitral stenosis in sinus rhythm without pulmonary hypertension is relatively uncommon. The signs are then purely auscultatory, as cardiac output is maintained and there is no significant right ventricular hypertrophy.
Management
Management of mitral stenosis consists of three phases:
Monitoring the asymptomatic patient with mild diseasewho does not require any treatment, with an eventualdecision on anticoagulation;
Medical management of the symptomatic patient with adecision on surgery;
Surgical management of the patient with more severe disease.
