Page 46 - Medicine and Surgery

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42 Chapter 2: Cardiovascular system

Echocardiography is used to examine the function of Infective endocarditis may cause destruction of the

the cardiac valves and may be helpful in diagnosing valve cusps.
pancarditis. Idiopathic rupture of chordae tendinae.

Management Pathophysiology
Patients with a clinical diagnosis of rheumatic fever
Inacutemitralregurgitation,retrogradebloodflowfrom
should be treated with benzylpenicillin regardless of the left ventricle into the left atrium causes the left atrial
culture results. pressure to increase. There is an increase in the pul-
Pain, fever and inflammation are treated with high-
monary venous pressure and there may be pulmonary
dose aspirin. Carditis may be treated with a course of oedema. In longstanding mitral regurgitation there is a
high-dose corticosteroids. gradual enlargement of the left atrium. This allows the
Patients may require treatment for heart failure (see
increased volume of atrial blood to be compensated for
page 63) and chorea may respond to haloperidol. without a rise in the atrial pressure. The left ventricu-
Following recovery patients should receive prophy-
lar stroke volume increases due to volume overload and
lactic penicillin for at least 5 years after the last at- over time this results in left ventricular hypertrophy.
tack or until the age of 20 years, whichever is the
later. Clinical features
Acute mitral regurgitation (e.g. following rupture of the
chordae or papillary muscle dysfunction) presents with
Prognosis
acute left-sided heart failure and pulmonary oedema. In
Although symptomatic improvement occurs with treat-
most cases mitral regurgitation is chronic and is asymp-
ment, therapy does not appear to prevent subsequent
tomatic for many years. Patients may present with pal-
valve damage.
pitations or symptoms of left ventricular failure (dysp-
noea, orthopnoea, paroxysmal nocturnal dyspnoea). On
examination the pulse is normal volume, but may be ir-
Mitral regurgitation
regular due to atrial fibrillation. The apex is thrusting
Definition and becomes displaced downward and laterally. On aus-
Flow of blood from the left ventricle to the left atrium cultation the first heart sound is soft due to incomplete
during systole through an incompetent mitral valve. apposition of the valve cusps and there is a pansystolic
murmur best heard at the apex radiating to the axilla.
There may be a prominent third heart sound due to the
Aetiology
sudden rush of blood back into the dilated left ventricle
In developing countries rheumatic disease accounts for
in early diastole.
the majority of cases of mitral regurgitation, often ac-
companied by mitral stenosis as a form of mixed mitral
disease. In developed countries other causes predomi- Complications
nate: Patients develop left ventricular failure due to chronic
Prolapsing mitral valve.
volume overload. Atrial fibrillation is common due
Myocardial infarction may lead to papillary muscle
to atrial dilation, with an increased risk of throm-
dysfunction or rupture. boembolism. Other complications include pulmonary
Any disease that causes dilation of the left ventricle,
oedema and infective endocarditis.
such as dilated cardiomyopathy. Congestive heart fail-
ure may also cause mitral regurgitation due to down- Investigations
ward displacement of the papillary muscle. This leads The chest X-ray shows cardiomegaly due to left atrial
to a failure of the valve cusps to meet and regurgita- and left ventricular enlargement. Valve calcification
tion ranging in severity according to the degree of left may be seen in cases due to rheumatic fever. There
ventricular enlargement. may be evidence of pulmonary oedema.