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70 Chapter 2: Cardiovascular system

Infamilieswithahistoryofsuddencardiacdeathfrom Echocardiographyshowsasmallleftventricularcavity

HOCM, there is an association with the angiotensin with generalised or asymmetrical hypertrophy of the
converting enzyme (ACE) genotype DD. septum. Mitral valve movement is also characteristic.
Twenty-five per cent of patients have outflow tract
Pathophysiology obstruction.
There is marked hypertrophy of one or both ventricles MRI scanning is of particular value if echocardiog-
particularly affecting the ventricular septum. This may raphy cannot obtain adequate views particularly in
result in obstruction to the outflow of the left ventricle, apical hypertrophy.
which is made worse on contraction of the ventricle. The 24-hour ECG monitoring is used to detect episodes of
muscle fibres relax poorly and as a result there is poor ventricular tachycardia.
left ventricular filling and contraction, with disordered Exercise testing is helpful for risk assessment, i.e. loss
mitral valve movement. of rise in blood pressure or onset of arrhythmia during
exercisearehighriskfeaturesforsuddencardiacdeath.
Clinical features
Hypertrophic cardiomyopathy often presents similarly Management
to aortic stenosis with dyspnoea, angina, syncope, or β-blockade is the mainstay of treatment as this lowers
sudden death. Signs of heart failure are common but the pressures within the left ventricle.
occur at a late stage. Initially the pulse is jerky with a Arrhythmias: β-blockers and amiodarone are used to
rapid outflow due to hypertrophy, in the late stages ob- prevent ventricular arrhythmias and there is increas-
struction results in a slow rising pulse. The JVP shows ing use of automatic implantable cardiac defibrillators
an increase in the size of the ‘a’ wave (atrial contraction). (AICD). Atrial fibrillation is preferably treated with
Palpationrevealsaprominentthrustingapex,whichmay DC synchronised cardioversion. Refractory atrial fib-
be double (palpable atrial contraction). There may be a rillation is treated with digoxin.
systolic murmur (and thrill) due to ventricular outflow Surgical treatment: Occasionally resection of the hy-
obstruction maximal at the left sternal edge. This may pertrophied septal wall (myotomy/myectomy) is in-
be varied by dynamic maneouvres or drugs that can al- dicated with, where necessary, a mitral valve replace-
ter the degree of functional obstruction. A fourth heart ment. Surgical intervention is usually reserved for
sound is often heard caused by ventricular filling due to severely symptomatic patients.
atrial contraction. Septal ablation by selective alcohol injection into a
sizeable septal branch of the left anterior decending
Complications artery has been shown to achieve similar results to
Thrombosis and consequent systemic embolisation may surgery.
occur requiring anticoagulation. Prophylaxis is required If patients have angina nitrates should be avoided, and
againstinfectiveendocarditis.ItisassociatedwithWolff– diuretics should only be used with care as these in-
Parkinson–White Syndrome. Ventricular arrhythmias crease the degree of functional obstruction.
are common and may lead to sudden cardiac death.
Prognosis
Macroscopy/microscopy Factors suggesting a worse prognosis include young age
Hypertrophy is asymmetrically distributed. The increase orsyncopeatpresentationandafamilyhistoryofsudden
in thickness occurs particularly of the interventricu- death due to HOCM.
lar septum. Disorganised branching of abnormal, short,
thick muscle fibres, in which there are large nuclei.
Restrictive cardiomyopathy
Investigations Definition
ECG shows ST, and T wave changes with evidence of Restrictive or infiltrative cardiomyopathy is a rare disor-

hypertrophy (anterior Q wave, T wave inversion and der of cardiac muscle resulting in restricted ventricular
increased QRS voltage). filling.