Page 294 - Concise Pathology for Exam Preparation ( PDFDrive )

11 Disorders of the Heart 279

TABLE 11.7. Types of CMP—cont’d

Hypertrophic (obstructive) Restrictive/obliterative or
Features Dilated (congestive) CMP CMP infiltrative CMP
Causes • Familial or genetic: • Genetic; inherited muta- Idiopathic; or associated with
• Inheritance is mainly autosomal tions in sarcomere pro- amyloidosis, radiation in-
dominant teins (b-myosin heavy duced fibrosis, sarcoidosis,
• X-linked, autosomal recessive chain or troponin I and T, metastatic tumour or in-
or mitochondrial inheritance myosin binding protein C born errors of metabolism
less common and a-tropomyosin)
• Inherited mutations seen in pro-
teins like dystrophin, cardiac a
actin, desmin and nuclear pro-
teins like lamin A and C
• Acquired:
• Viral myocarditis (Enterovirus
and coxsackie virus implicated)
• Toxic damage from alcohol (di-
rect toxicity or beriberi heart
disease due to thiamine defi-
ciency), cobalt, chemotherapy
with doxorubicin and other an-
thracyclines
• Peripartum CMP
• Iron overload as in hereditary
haemochromatosis
• Excessive catecholamines as in
pheochromocytoma
• Supraphysiologic or extreme
psychological stress
Clinical fea- Slowly progressing heart failure, Usually asymptomatic; symp- Presentation dependent on
tures shortness of breath, easy fatigabil- tomatic on heavy physical specific type. May manifest
ity, poor exercise tolerance activity. May manifest with with dyspnoea, angina and
dyspnoea, angina and con- congestive cardiac failure
gestive cardiac failure or or sudden death
sudden death
Gross • Heart is enlarged, weight may in- • Heavy hypercontracting • Ventricles normal or
appearance crease up to 1000 g (‘flabby hypo- heart slightly enlarged
contracting heart’). • Asymmetric myocardial hy- • Cavities not dilated
• Dilatation of all four chambers giv- pertrophy (interventricular • Myocardium is firm
ing rise to a typical globular ap- septum more hypertrophied
pearance. than free walls of the ven-
• Endocardial thickening tricles)
• Presence of mural thrombi • Transverse section: banana-
like appearance
Microscopy • Hypertrophy of some myocardial • Myocardial cell disorganiza- Patchy or diffuse interstitial
fibres; atrophy of others. Intersti- tion in the ventricular septum fibrosis, which varies from
tial fibrosis with focal mononu- • Myocardial fibres are irregu- minimal to extensive
clear infiltrate. larly and haphazardly ar-
• Small subendocardial scars may ranged (normally parallel)
be seen • Interstitial fibrosis
• Individual muscle hypertro-
phy and presence of large
prominent nucleoli (trans-
verse diameter more than
40 cm)
Outcome Mitral regurgitation/arrhythmias may Medical treatment to relax Gradually progressive cardiac
be observed. Average survival ventricles and surgical re- failure
from onset to death is 5 years duction of septum can be
undertaken

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