Physical signs, course, Complications, Prognosis And Treatment Of Mitral Stenosis
In significant MS, the pulse is of low volume. Totally irregular pulse should suggest the presence of atrial fibrillation. Jugular venous pulse shows prominent ‘a’-wave in cases with pulmonary arterial hypertension and prominent ‘v’ wave in cases with tricuspid regurgitation. In patients with congestive heart failure, the mean jugular venous pressure (JVP) is elevated. Sign of right ventricular hypertrophy may be evident. The apex beat is characteristically tapping and it is usually felt in the normal position. A diastolic thrill may be palpable over the apex beat. This can be made more prominent by palpating in the left lateral position with the breath held in expiration. Exercise accentuates the thrill and murmur. The characteristic auscultatory features of MS are:
- Loud first heart sound;
- Mid-diastolic murmur with pre-systolic accentuation; and
- The opening snap.
The murmur is low-pitched, rough and rumbling in character, and it is preceded by the opening snap. The opening snap is a sharp sound (high pitched) which is best heard over the apex beat, but conducted widely over the precordium, especially towards the sternum. The duration of the murmur and the interval between the second heart sound and opening snap (A2-OS) correlate with the severity of MS. The loudness and sharpness of the first heart sound and the opening snap are lower in valves with severe fibrosis and/or calcification. When atrial fibrillation sets in, the presystolic accentuation of the murmur is generally lost in most cases. The pulmonary second sound is accentuated due to pulmonary arterial hypertension. Tricuspid regurgitation gives rise to a systolic murmur best audible in left lower sterna border. It’s hallmark is the accentuation with inspiration.
Radiology: Chest X-ray shows enlargement of the left atrium. Upper lobe veins show dilatation as an evidence of pulmonary venous hypertention. In cases with pulmonary arterial hypertension, the main pulmonary artery and its major divisions show dilatation. X-ray chest may reveal calcification of the mitral valve, detectable by careful examination. Fluoroscopy using image intensifiers brings out calcification better. In a small number of cases, the chest x-ray may even appear normal.
Electrocardiogram (ECG): The ECG reveals left atrial enlargement as shown by P mitrale, i.e, longer duration of the P-wave with bifid P, best seen in leads II and V1. Right axis deviation and right ventricular hypertrophy are demonstrable in cases with pulmonary arterial hypertension. In many cases the ECG may be normal.
Echocardiography: This study gives diagnostic information about the valve, its size, calcification and other features. More invasive investigations are reserved only for those cases where echocardiography does not give full information.
Mitral Valve Disease
Course And Prognosis
Course and Prognosis: This depends on the severity of the stenosis. Though mild cases are generally asymptomatic, heavy exertion may lead to acute pulmonary edema. In moderate and sever cases, the disability progressively increases. Pulmonary hypertension becomes established and progresses over 10 years leading to right ventricular hypertrophy and subsequently failure. Atrial fibrillation is a very frequent complication. Its presence leads to thromboembolic episodes. Surgical correction of the valve lesion causes reversal of pulmonary hypertension and left atrial enlargement in most cases.
Death is due to complications such as acute pulmonary edema, congestive cardiac failure, thromboembolic complications or infective endocarditis. Thromboembolism presents commonly as cerebral infarcts, gangrene of the extremities, intestinal or renal infarcts or as pulmonary infarcts. Infective endocarditis is rare in pure mitral stenosis.
General measures: As such, mitral stenosis does not resolve through medical treatment. In a considerable proportion of cases, however, several coexistent remediable factors aggravate the disability. These include anemia, pulmonary eosinophilia, systemic and respiratory infections, obesity, thyrotoxicosis and pregnancy. Proper management of these conditions may give considerable symptomatic relief.
Surgery is the definitive treatment for established MS. Closed transventricular valvotomy is the commonly adopted procedure for uncomplicated mitral stenosis in Asia. Presence of atrial fibrillation with atrial thrombi, significant calcification of mitral valve, or grossly fibrosed valve are indications for open valvotomy under cardio-pilmonary bypass. When the valve apparatus is grossly damaged or other coexistent lesions such as mitrial incompetence are present, valve replacement may be required.
Surgery should be advised early in all cases of established significant mitral stenosis since the risk of fatal acute pulmonary edema is present even in mildly symptomatic cases. Complications like congestive heart failure, respiratory infection, infective endocarditis, and thromboembolism are to be managed medically before the case is sent for surgery.
Pregnancy has to be avoided in patients with tight mitral stenosis, till then condition is corrected surgically. If mitral stenosis is diagnosed for the first time during the middle or late pregnancy, and it the patient develops acute pulmonary edema resistant to medical therapy, emergency mitral valvotomy may have to be undertaken.
© 2014 Funom Theophilus Makama