Page 49 - Medicine and Surgery

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Chapter 2: Rheumatic fever and valve disease 45

infective endocarditis is required. Patients with refrac- On auscultation there is a high pitched early diastolic
tory pulmonary venous congestion or pulmonary hy- murmur running from the aortic component of the sec-
pertension are treated surgically by conservative surgery ond heart sound. There may be an accompanying mid-
or valve replacement (see page 30). systolic ejection murmur due to volume overload. An
Austin Flint murmur may also be heard. This is a mid-
diastolic rumbling murmur due to back flow of blood
Aortic regurgitation during diastole causing a partial closure of the mitral
valve.
Definition
Retrograde blood flow through the aortic valve from the
aorta into the left ventricle during diastole. Investigations
Chest X-ray shows an enlarged left ventricle and pos-

Aetiology/pathophysiology sibly dilation of the ascending aorta.
Aortic regurgitation is caused by incompetence of the ECG may show signs of progressive left ventricular
valve in diastole, allowing blood to leak back into the left hypertrophy.
ventricle. This may result from: Echocardiogram is diagnostic demonstrating abnor-
Inability of the valve cusps to close properly due to
mal valve movement. Doppler studies demonstrate
thickening, shrinkage, perforation or a tear in the and quantify the regurgitation. The best way to mon-
cusp. Causes include rheumatic heart disease (now itor the clinical effect of the valve lesion is to measure
rare in the United Kingdom), infective endocarditis the left ventricular dimension. An end systolic dimen-
occurring on a previously damaged or bicuspid aor- sion of over 5 cm indicates decompensation.
tic valve, and various arthritides such as Reiter’s syn-
drome, ankylosing spondylitis or rheumatoid arthri-
Management
tis. Any underlying causes such as infective endocardi-
Significant dilation of the aortic annulus such that the

tis should be treated. Antibiotic prophylaxis against
cusps are separated at the edges. Causes include se-
infective endocarditis should be administered when
vere hypertension, dissecting aneurysm and Marfan’s
appropriate.
syndrome. Symptomatic relief can be given by treatment of any
As a result of the volume overload, the left ventricle grad-
associated heart failure.
uallyenlargesandtheejectionfractionisincreased(Star- Refractory symptoms with evidence of increasing
ling’s mechanism). It is only when volume overload is
heart size or diminishing left ventricular function are
excessive and chronic that the left ventricle fails. The
indications for surgical intervention usually by valve
first sign of this decompensation is a reduction in the
replacement.
ejection fraction, leading to an increased end systolic
volume. There is also reduced coronary artery perfusion
with associated increased risk of myocardial ischaemia. Prognosis
Mild or moderate aortic regurgitation has a relatively
good prognosis and thus surgical intervention is not
Clinical features
required. However, it is important to perform surgical
Aortic regurgitation is asymptomatic until left ventricu-
correction before irreversible left ventricular failure
lar failure develops. Patients usually present with dysp-
develops.
noea,apoundingheartbeatandangina.Onexamination
there is a large volume pulse, which is collapsing in char-
acter (see page 27). The blood pressure has a wide pulse Aortic stenosis
pressure (high systolic and low diastolic pressure). The
apex is displaced laterally and downwards and is heaving Definition
in nature. Various signs of the high-velocity blood flow Aortic stenosis is a pathological narrowing of the aortic
have been described but are rare. valve.