Table 18.1 Nomenclature of bone tumors
Cardiomyopathies are a group of diseases primarily involving the myocardium and characterized by myocardial dysfunction that is not the result of hypertension, coronary atherosclerosis, valvular dysfunction, or pericardial abnormalities. Restrictive cardiomyopathies are characterized by decreased ventricular compliance, usually secondary to infiltration of the myocardium.
EPIDEMIOLOGY & DEMOGRAPHICS
Relatively uncommon cardiomyopathy that is most frequently caused by amyloidosis, myocardial fibrosis (after open heart surgery), and radiation
PHYSICAL FINDINGS & CLINICAL PRESENTATION
• Edema, ascites, hepatomegaly, distended neck veins
• Fatigue, weakness (secondary to low output)
• Kussmaul’s sign: may be present
• Regurgitant murmurs
• Possible prominent apical impulse
Impairment of ventricular filling gives rise to a volume and pressure overload in the atria. As a result, the atria are moderately to severely dilated. This is why symptoms of right-sided heart failure are dominant in most restrictive cardiomyopathies (Tab. 31). Dyspnea on exertion and orthopnea may also occur, however. Chest pain or discomfort may be the initial symptom of amyloidosis. Again, the principal findings are referable to rightsided heart failure. Auscultation often reveals a third and/or fourth heart sound and regurgitant murmurs indicating mitral and tricuspid insufficiency.
• Infiltrative and storage disorders (glycogen storage disease, amyloidosis, sarcoidosis, hemochromatosis)
• Endocardial fibroelastosis
• Endomyocardial fibrosis
• Toxic effects of anthracycline
• Carcinoid heart disease, metastatic cancers
• Diabetic cardiomyopathy
• Eosinophilic cardiomyopathy (Löffler’s endocarditis)
• Chronic lung disease
• Psychogenic dyspnea
• Pericardial abnormalities
Table 31 Symptoms and signs of restrictive cardiomyopathy
Etiology and Pathogenesis
In restrictive cardiomyopathy, the disease of the myocardium or endocardium leads to the impaired filling of one or both ventricles (see Fig. 52). Most cases show no cardiac dilatation or hypertrophy. Systolic function is usually intact, at least at the start of the disease.
Restrictive cardiomyopathy is most frequently caused by infiltrative diseases and storage diseases (see Tab. 29). The most important causative diseases are amyloidosis, prior radiotherapy, sarcoidosis, hemochromatosis, and Fabry disease. Idiopathic restrictive cardiomyopathy is very rare. Restrictive cardiomyopathy may also result from scarring of the endomyocardium, which usually affects both ventricles. The mitral and tricuspid valves are usually involved as well. The principal diseases that cause this obliterative form of restrictive cardiomyopathy are endomyocardial fibrosis and eosinophilic parietal endocarditis (Loffler endocarditis).
• Chest x-ray examination, ECG, echocardiogram
• Cardiac catheterization, MRI (selected cases)
• Chest x-ray examination:
1. Moderate cardiomegaly
2. Possible evidence of CHF (pulmonary vascular congestion, pleural effusion)
1. Low voltage with ST-T wave changes
2. Possible frequent arrhythmias, left axis deviation, and atrial fibrillation
• Echocardiogram: increased wall thickness and thickened cardiac valves (especially in patients with amyloidosis)
• Cardiac catheterization to distinguish restrictive cardiomyopathy from constrictive pericarditis
1. Constrictive pericarditis: usually involves both ventricles and produces a plateau of elevated filling pressures
2. Restrictive cardiomyopathy: impairs the left ventricle more than the right (PCWP > RAP, PASP >50 mm Hg)
• MRI may also be useful to distinguish restrictive cardiomyopathy from constrictive pericarditis (thickness of the pericardium >5 mm in the latter)
Control CHF by restricting salt.
ACUTE GENERAL Rx
• Cardiomyopathy caused by hemochromatosis may respond to repeated phlebotomies to decrease iron deposition in the heart.
• Sarcoidosis may respond to corticosteroid therapy.
• Corticosteroid and cytotoxic drugs may improve survival in patients with eosinophilic cardiomyopathy.
• There is no effective therapy for other causes of restrictive cardiomyopathy.
Death usually results from CHF or arrhythmias; therefore therapy should be aimed at controlling CHF by restricting salt, administering diuretics, and treating potentially fatal arrhythmias.
Prognosis varies with the etiology of the cardiomyopathy.
Fig. 52 Schematic representation of cardiomyopathies.
a Normal heart
b Dilated cardiomyopathy
c Hypertrophic cardiomyopathy with left ventricular hypertrophy and asymmetrical septal hypertrophy (ASH). The systolic anterior motion (SAM) of the mitral valve leaflet leads to mitral insufficiency.
d Restrictive cardiomyopathy with dilatation of the both atria.
e Obliterative form of restrictive cardiomyopathy with involvement of the tricuspid and mitral valves.
f Arrhythmogenic right ventricular cardiomyopathy (explained further in the text).
Table 29 Classification of cardiomyopathies by specific etiology