Restrictive cardiomyopathy
Restrictive cardiomyopathy: Excerpt from Professional Guide to Diseases (Eighth Edition)
Restrictive cardiomyopathy, a disorder of the myocardial musculature, is characterized by restricted ventricular filling (the result of left ventricular hypertrophy) and endocardial fibrosis and thickening. If severe, it’s irreversible. The average survival after diagnosis is 9 years.
Causes and incidence
An extremely rare disorder, primary restrictive cardiomyopathy is of unknown etiology. However, restrictive cardiomyopathy syndrome, a manifestation of amyloidosis, results from infiltration of amyloid into the intracellular spaces in the myocardium, endocardium, and subendocardium.
In both forms of restrictive cardiomyopathy, the myocardium becomes rigid, with poor distention during diastole, inhibiting complete ventricular filling, and fails to contract completely during systole, resulting in low cardiac output.
Restrictive cardiomyopathy is rare. It’s most common in children and young adults. Natives of Africa, South America, and India are at increased risk.
Signs and symptoms
Because it lowers cardiac output and leads to heart failure, restrictive cardiomyopathy produces fatigue, dyspnea, orthopnea, chest pain, generalized edema, liver engorgement, peripheral cyanosis, pallor, S3 or S4 gallop rhythms, and systolic murmurs of mitral and tricuspid insufficiency.
Diagnosis
❑ In advanced stages of this disease, chest X-ray shows massive cardiomegaly, affecting all four chambers of the heart; pericardial effusion; and pulmonary congestion.
❑ Echocardiography, computed tomography scan, or magnetic resonance imaging rules out constrictive pericarditis as the cause of restricted filling by detecting increased left ventricular muscle mass and differences in end-diastolic pressures between the ventricles.
❑ Electrocardiography may show low-voltage complexes, hypertrophy, atrioventricular conduction defects, or arrhythmias.
❑ Arterial pulsation reveals blunt carotid upstroke with small volume.
❑ Cardiac catheterization shows increased left ventricular end-diastolic pressure and rules out constrictive pericarditis as the cause of restricted filling.
Restrictive cardiomyopathy may be difficult to differentiate from constrictive pericarditis. A biopsy of heart muscle may be used to confirm the diagnosis. A cardiac catheterization procedure can also help differentiate the type of cardiomyopathy through simultaneous left- and right-heart catheterization. In some cases, surgical exploration and biopsies are the only means to distinguish the type of cardiomyopathy or to differentiate it from pericarditis.
Treatment
Although no therapy currently exists for restricted ventricular filling, cardiac glycosides, diuretics, and a restricted sodium diet are beneficial by easing the symptoms of heart failure.
Oral vasodilators — such as isosorbide dinitrate, prazosin, and hydralazine — may control intractable heart failure. Anticoagulant therapy may be necessary to prevent thrombophlebitis in the patient on prolonged bed rest. Steroids or chemotherapy may help with the underlying disease process. A heart transplant may be considered in those with poor myocardial functioning.
Special considerations
❑ In the acute phase, monitor heart rate and rhythm, blood pressure, urine output, and pulmonary artery pressure readings to help guide treatment.
❑ Give psychological support. Provide appropriate diversionary activities for the patient restricted to prolonged bed rest. Because a poor prognosis may cause profound anxiety and depression, be especially supportive and understanding, and encourage the patient to express his fears. Refer him for psychosocial counseling, as necessary, for assistance in coping with his restricted lifestyle. Be flexible with visiting hours whenever possible.
❑ Before discharge, teach the patient to watch for and report signs of digoxin toxicity (anorexia, nausea, vomiting, and yellow vision); to record and report weight gain; and, if sodium restriction is ordered, to avoid canned foods, pickles, smoked meats, and use of table salt.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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