Cardiac Involvement in Miscellaneous Systemic Diseases

The heart may be involved in a number of systemic syndromes. Many of these have been mentioned briefly in prior subsections of this chapter. The pericardium, myocardium, heart valves, and coronary arteries may be involved either singly or in various combinations. In most cases the cardiac manifestations are not the dominant feature, but in some it is the primary cause of symptoms and may be fatal.

The most common type of myocardial involvement is an infiltrative cardiomyopathy, such as systemic amyloidosis, sarcoidosis, hemochromatosis, or glycogen storage disease. Cardiac calcinosis can occur in hyperparathyroidism (usually the secondary form) and in primary oxalosis. A number of muscular dystrophies can cause a cardiomyopathic picture (particularly Duchenne's, less frequently myotonic dystrophy, and several rarer forms).

In addition to left ventricular dysfunction and heart failure, all of these conditions frequently cause conduction abnormalities, which may be the presenting or only feature.

The myocardium may also be involved in inflammatory and autoimmune diseases. It is commonly affected in polymyositis and dermatomyositis, but usually this is subclinical. Systemic lupus erythematosus, scleroderma, and mixed connective tissue disease may cause myocarditis, but these commonly also involve the pericardium, coronary arteries, or valves. Several endocrinopathies, including acromegaly, thyrotoxicosis, myxedema, and pheochromocytoma, can produce cardiomyopathies, though again they are usually not isolated features.

Pericardial involvement is quite common in many of the connective tissue diseases. Systemic lupus erythematosus may present with pericarditis, and pericardial involvement is not uncommon (but is less frequently symptomatic) in active rheumatoid arthritis, systemic sclerosis, and mixed connective tissue disease. Endocardial involvement takes the form of patchy fibrous - predominantly on the right side - or inflammatory or sclerotic changes of the heart valves. Carcinoid heart disease typically is manifested as tricuspid regurgitation, and the same may be the case in systemic lupus erythematosus. The hypereosinophilic syndromes involve the endocardium, leading to restrictive cardiomyopathy. A variety of arthritic syndromes are associated with aortic valvulitis or aortitis, including ankylosing spondylitis, rheumatoid arthritis, and Reiter's syndrome, as is tertiary syphilis also. Disorders of elastic tissue (Marfan's syndrome is the most frequent) often affect the ascending aorta, with resulting aneurysmal dilation and aortic regurgitation.

Almost any vasculitic syndrome can involve the coronary arteries, leading to myocardial infarction. This is most common with polyarteritis nodosa and systemic lupus erythematosus. Two vasculitic syndromes have a particular predilection for the coronary arteries - Kawasaki's disease and Takayasu's disease. In these, myocardial infarction may be the presenting symptom.