Page 73 - Medicine and Surgery

P1: JYS
BLUK007-02 BLUK007-Kendall May 25, 2005 17:25 Char Count= 0

Chapter 2: Disorders of pericardium, myocardium and endocardium 69

Familial: 30% of cases have relatives with left ventric- The impaired cardiac output leads to failure to perfuse

ular dysfunction or enlargement. the kidneys and hence secondary renal failure.
There is an association with chronic infective, toxic or

immune myocarditis. Investigations
Many systemic diseases may cause the clinical features Chest X-ray shows cardiac enlargement with signs of
of dilated cardiomyopathy, e.g. ischaemic heart disease, pulmonary oedema including upper lobe vein diver-
amyloidosis, metabolic diseases, haemochromatosis and sion, Kerley B lines and may show pleural effusions.
systemic lupus erythematosus. ECG usually shows sinus tachycardia or atrial fibrilla-
tion, there may be non-specific T wave changes.
Pathophysiology Echo reveals ventricular dilation, poor contractility
The dilatation of the heart results in impaired contrac- and will demonstrate any valvular regurgitation.
tion especially affecting the left ventricle. Left ventricu- Cardiac catheterisation may be needed to exclude
lar failure causes an elevated end-diastolic pressure with coronary artery disease, as this may present similarly
resultant increase in pressure within the pulmonary cir- without any history of angina or myocardial infarct.
culation and eventually right-sided heart failure. The di- Patients should also have an ESR, creatine kinase, viral
latation also results in a functional regurgitation at the serology, U&Es, LFTs and calcium, iron studies and
tricuspid and/or mitral valves (valve ring dilation). thyroid function tests to help identify the underlying
cause.
Clinical features
Management
Symptoms are dependent upon the degree of cardiac

General measures include bed rest, fluid restriction
failure. Patients tend to present with dyspnoea and
and quitting alcohol.
orthopnoea, which may be acute or of more insidious
Treat arrhythmias (digoxin especially useful in atrial
onset.
fibrillation) and commence treatment for cardiac fail-
On examination, the JVP is raised possibly with a sys-

ure(seepage63)withcareasitmaycausehypotension.
tolic pressure wave (cv wave) due to tricuspid regur-
Patients with atrial fibrillation, a history of throm-
gitation, and the blood pressure is low. Tachycardia
boembolicdiseaseorapresenceofintracardiacthrom-
is common and low perfusion results in peripheral
bous should be anti-coagulated. Severe cases may
vascular shutdown (small thready pulse, cold extrem-
benefit from anti-coagulation without other risk fac-
itiesandperipheralcyanosis).Auscultationmayreveal
tors.
agallop rhythm (tachycardia with third heart sound
due to rapid ventricular filling) and the pansystolic
murmurs of mitral and tricuspid regurgitation. Ankle Prognosis
and/or sacral oedema, mild hepatomegaly and jaun- Theprognosisisverypoor.Youngpatientsmaybetreated
dice, due to hepatic congestion or tricuspid regurgita- with cardiac transplantation.
tion, and ascites are signs of right-sided heart failure.
Hypertrophic cardiomyopathy
Macroscopy/microscopy
The ventricles are dilated (left more than right), the Definition
chamber walls are thin and the muscle poorly contrac- Hypertrophicorhypertrophicobstructivecardiomyopa-
tile. Fibrosis tends to occur in the dilated myocardium thy (HOCM) is a condition of the myocardium with
with a cellular infiltration especially T lymphocytes. massive hypertrophy of the ventricular walls.
Complications Aetiology
Atrial fibrillation is common, particularly in alcoholic Half the cases are due to an autosomal dominant in-
cardiomyopathy, and bouts of ventricular tachycardia herited point mutation of the β myosin heavy chain,
may occur. Mural thrombosis may occur in either ven- which codes for a component of the cardiac muscle
tricle with the associated risk of systemic embolisation. fibre.