Cardiomyopathy, restrictive
Cardiomyopathy, restrictive: Excerpt from Handbook of Diseases
A disorder of the myocardial musculature, restrictive cardiomyopathy is characterized by restricted ventricular filling (the result of left ventricular hypertrophy) and endocardial fibrosis and thickening. If severe, it’s irreversible.
Causes
Primary restrictive cardiomyopathy is an extremely rare disorder of unknown cause. However, restrictive cardiomyopathy syndrome, a manifestation of amyloidosis, results from infiltration of amyloid into the intracellular spaces in the myocardium, endocardium, and subendocardium.
With both forms of restrictive cardiomyopathy, the myocardium becomes rigid, with poor distention during diastole, inhibiting complete ventricular filling. The myocardium also fails to contract completely during systole, resulting in low cardiac output.
UNDER STUDY: Researchers have identified a link between the sarcomere contractile protein gene and cardiac troponin I (TNNI3) — the gene that researchers believe causes restrictive cardiomyopathy when diseased. In genetic investigations, mutations of TNNI3 were identified in six of nine patients with restrictive cardiomyopathy. Investigations continue as to what this association means and its implications with restrctive cardiomyopathy.
Signs and symptoms
Restrictive cardiomyopathy lowers cardiac output and leads to heart failure, thereby producing 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
❑ Chest X-ray shows massive cardiomegaly in advanced stages of this disease, affecting all four chambers of the heart; pericardial effusion; and pulmonary congestion.
❑ Echocardiography is used to rule 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 demonstrates increased left ventricular end-diastolic pressure and rules out constrictive pericarditis as the cause of restricted filling.
Treatment
Although no therapy exists for restricted ventricular filling, a digitalis glycoside, a diuretic, and a restricted sodium diet ease the symptoms of heart failure.
An oral vasodilator —such as isosorbide dinitrate, prazosin, and hydralazine —may control intractable heart failure. Anticoagulant therapy may be necessary to prevent thrombophlebitis in a patient on prolonged bed rest.
Special considerations
❑ If the patient is 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. Because a poor prognosis can cause profound anxiety and depression, be especially supportive and understanding, and encourage the patient to express his fears.
Clinical tip Refer the patient for psychosocial counseling, as necessary, for help in coping with his restricted lifestyle. Be flexible with visiting hours.
❑ Before discharge, teach the patient to watch for and report signs and symptoms of digoxin toxicity (including anorexia, nausea, vomiting, and yellow vision), to record and report weight gain and, if sodium must be restricted, to avoid canned foods, pickles, smoked meats, and table salt.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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