Page 48 - Medicine and Surgery

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44 Chapter 2: Cardiovascular system

Mitral stenosis On auscultation there is a loud S 1 as the mitral valve
only closes when the ventricle contracts. There is an
Definition
opening snap after S 2 caused by the stiff mitral valve,
An abnormal narrowing of the mitral valve.
followed by a mid to late diastolic rumbling murmur
due to turbulent flow through the stenosed valve. If the
Incidence patient is in sinus rhythm there is a pre-systolic increase
Declining in the Western world due to the decline of in the volume of the murmur due to increased flow dur-
rheumatic fever. ing atrial contraction. Pulmonary hypertension may re-
sult in pulmonary regurgitation with an early-diastolic
Sex murmur (Graham–Steell murmur).
2F:1M
Complications
Complications are frequent:
Aetiology
Atrial fibrillation (AF) due to atrial dilation and hy-
Almostallmitralstenosisissecondarytorheumaticheart
pertrophy.
disease; it is also the most common valve to be affected
Risk of stroke or systemic embolisation with mitral
by rheumatic fever. All other causes are rare, but include
stenosis and AF is high.
rheumatoid arthritis, systemic lupus erythematosus and
Pulmonary hypertension and right-sided heart fail-
congenital valve narrowing.
ure.
Ifthestiffvalvealsofailstocloseproperly,mixedmitral

Pathophysiology
stenosis and regurgitation.
The pathological process of rheumatic fever results in
fibrous scarring and fusion of the valve cusps with cal-
Investigations
cium deposition. The valve becomes stiff, failing to open Chest X-ray shows selective enlargement of the left
2
fully. When the normal opening of 5 cm is reduced to1 atrium (bulge on the left heart border). Calcification
2
cm the mitral stenosis is severe. The pressure within the within the mitral valve may be visible and there may
left atrium rises and left atrial hypertrophy occurs. As a be signs of pulmonary hypertension and oedema.
consequence of this the pressure in the pulmonary circu- In sinus rhythm, the ECG may show a bifid P wave due
lation rises and eventually right atrial pressure will rise to delayed leftatrial activation; however, atrial fibril-
leading to right-sided heart failure. The cardiac output lation is common. Signs of right ventricular hyper-
falls with little increase possible on exertion. trophy such as right axis deviation, right ventricular
hypertrophy or right bundle branch block may also be
Clinical features seen.
The condition is asymptomatic until the valve is nar- Echocardiography is diagnostic showing the narrow-
rowedbyaround 50%. The initial symptoms are due ing and immobility of the valve. Doppler studies can
to pulmonary venous hypertension and the resultant assess the degree of stenosis and any concomitant mi-
oedema, with dyspnoea, orthopnoea and paroxysmal tral regurgitation. If there is tricuspid regurgitation
nocturnal dyspnoea. Atrial arrhythmias are common pulmonary pressures can also be calculated.
and may cause palpatations. A cough productive of Cardiac catheterisation is used if Doppler is inconclu-
frothy,blood-tingedsputummayoccur(frankhaemopt- sive and to assess for coronary artery disease if valve
ysisisrare).Progressionleadstosymptomsofright-sided replacement is contemplated.
heart failure (weakness, fatigue and peripheral oedema).
On examination the patient may have mitral facies (bi- Management
lateral, dusky cyanotic discoloration of the face). In se- The course of mitral stenosis is gradual with interven-
vere mitral stenosis atrial fibrillation is very common. tionbasedonsymptomatology.Associatedatrialfibrilla-
The apex beat is tapping in nature due to a palpable first tion is treated with digoxin and anticoagulation. Cardiac
heart sound. failure may also require treatment. Prophylaxis against