eMedicine Specialties > Emergency Medicine > Cardiovascular
Cardiomyopathy, Restrictive
Updated: Jul 3, 2008
Introduction
Background
Restrictive cardiomyopathy is the least common of the 3 clinically recognized and described cardiomyopathies. Its principal abnormality is diastolic dysfunction, specifically restricted ventricular filling. Differentiation from constrictive pericarditis, a clinically similar entity, is difficult but important because the treatment options and prognosis differ drastically.
Pathophysiology
Restrictive cardiomyopathy can be idiopathic or secondary to a heart muscle disease that manifests as restrictive physiology. The common hemodynamic disturbance is impairment of ventricular filling due to the thickening and increased rigidity of the endocardium and myocardium secondary to infiltration by amyloid tissue or by fibrosis. Ventricular diastolic pressures are elevated and may inscribe a "dip and plateau" or "square root" pattern, both similar to constrictive pericarditis. Systolic function remains normal or near normal until late stages.
Frequency
United States
Occurrence of restrictive cardiomyopathy is rare with no quantifiable incidence.
International
Endomyocardial fibrosis (EMF), an etiologic factor of idiopathic restrictive cardiomyopathy, is a progressive disease of unknown cause that occurs most commonly in children and young adults in tropical and subtropical Africa, primarily in Uganda and Nigeria. EMF may account for up to one fourth of deaths due to cardiac disease in those areas.
Mortality/Morbidity
The natural history of restrictive cardiomyopathy is especially poor in children with heart failure. Adults experience a prolonged course of heart failure and may have complications of cardiac cirrhosis and thromboembolism. Patients who are refractory to supportive therapy usually die of low-output cardiac failure unless cardiac transplantation is an option.
Race
Natives of Africa, South America, and India are predisposed to EMF.
Age
EMF is most common in children and young adults.
Clinical
History
- Patients often present at an advanced stage of disease with pronounced cardiopulmonary symptoms. The patient's history may reveal the following:
- Angina (uncommonly)
- Dyspnea, orthopnea, or dyspnea on exertion
- Paroxysmal nocturnal dyspnea
- Peripheral edema
- Abdominal discomfort, liver tenderness
- Increased abdominal girth, ascites
Physical
- In addition to the findings listed below, a careful general physical examination must be conducted to search for extracardiac manifestations of a systemic disorder that may cause secondary restrictive cardiomyopathy (eg, hemochromatosis, amyloidosis, sarcoidosis, scleroderma).
- Elevated jugular venous pulse, Kussmaul sign
- y descent blunted relative to x
- S3 and/or S4
- Occasional mitral or tricuspid regurgitation murmur
- Distant heart sounds
- Pulmonary rales
- Peripheral edema
- Pulsus paradoxus - As the restrictive process progresses, no change in blood pressure occurs with inspiration.
Causes
- According to guidelines of the World Health Organization, cardiomyopathy refers to the disease of the myocardium secondary to an idiopathic cause (ie, primary cardiomyopathies). However, secondary infiltrative myocardial diseases, which are actually cardiac manifestations of systemic diseases, often are grouped together with cardiomyopathies.
- Idiopathic restrictive cardiomyopathy
- EMF
- Loeffler eosinophilic endomyocardial disease
- Secondary restrictive cardiomyopathy
- Hemochromatosis
- Amyloidosis
- Sarcoidosis
- Progressive systemic sclerosis (scleroderma)
- Carcinoid heart disease
- Glycogen storage disease of the heart
- Radiation
- Metastatic malignancy
- Anthracycline toxicity
Differential Diagnoses
Cardiomyopathy, Dilated
Congestive Heart Failure and Pulmonary
Edema
Pericarditis and Cardiac Tamponade
Pericarditis, Constrictive
Sarcoidosis
Workup
Laboratory Studies
- CBC: An elevated eosinophil count may indicate eosinophilic endomyocardial disease.
Imaging Studies
- Chest radiography
- Absence of cardiomegaly, normal cardiac silhouette, no pericardial calcification (seen in constrictive pericarditis)
- Manifestations of pulmonary venous hypertension and pulmonary congestion
- Echocardiography
- Normal to symmetrically thickened walls
- Rapid early-diastolic filling, slow late-diastolic filling
- Normal or slightly reduced ventricular volume and systolic function
- Minimal to no respiratory variation in Doppler flow velocities
- No pericardial thickening
- CT and MR imaging may help in differentiating from constrictive pericarditis.
Other Tests
- Endomyocardial biopsy
- May detect typical eosinophil infiltration in the inflammatory stage
- May detect myocardial fibrosis in later-stage cases
- Negative findings do not exclude diagnosis
- Risk of embolism may be due to dislodgement of recent ventricular thrombus
- Electrocardiography
Procedures
- Cardiac catheterization
- Elevated and equalized ventricular diastolic filling pressures
- Dip and plateau or square root configuration of the diastolic portion of the ventricular pressure pulse
- Normal to slightly decreased ejection fraction
- Prominent a wave and x and y descent
- Pulmonary artery pressure often greater than 40 mm Hg
- Little to no variation in systolic pressure between the right and left ventricle with inspiration
Treatment
Emergency Department Care
With the possible exception of chelation therapy for hemochromatosis and corticoidsteroid therapy for sarcoidosis, restrictive cardiomyopathy has no specific treatment. ED care is symptom directed. The mainstay of treatment options include diuretics, vasodilators, angiotensin-converting enzyme inhibitors as indicated, as well as anticoagulation (if not contraindicated).
Consultations
Cardiology consultation is suggested in order to optimize management and establish a definitive diagnosis.
Medication
As mentioned above, treatment of restrictive cardiomyopathy is symptomatic. Treatment goals include decreasing systemic and pulmonary congestion, lowering ventricular filling pressure, augmenting systolic pump function, and reducing risk for embolism.
Loop diuretics
Diuretics are used to reduce pulmonary and systemic congestion. Initiate therapy with a low dosage because relatively high levels of ventricular filling pressure must be maintained for adequate diastolic filling.
Furosemide (Lasix)
Increases excretion of water by interfering with chloride-binding cotransport system resulting from inhibition of reabsorption of sodium and chloride in ascending loop of Henle and distal renal tubule.
Dosing
Adult
40-160 mg/d IV/IM
Pediatric
1 mg/kg IV/IM; increase by 1 mg/kg/dose q6-12h; not to exceed 6 mg/kg
Interactions
Metformin decreases concentrations; interferes with hypoglycemic effect of antidiabetic agents and antagonizes muscle-relaxing effect of tubocurarine; concurrent aminoglycosides may increase auditory toxicity—hearing loss of varying degrees may occur; may enhance anticoagulant activity of warfarin; may increase plasma levels and toxicity of lithium
Contraindications
Documented hypersensitivity; hepatic coma; anuria; severe electrolyte depletion
Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Measure serum electrolytes, CO2, glucose, creatinine, uric acid, calcium, and BUN frequently during first few months of therapy and periodically thereafter
Inotropic agents
Digitalis and other positive inotropic agents generally are not indicated unless systolic pump function and contractility are impaired. Digitalis must be used with caution in patients with amyloid cardiomyopathy as they may be digoxin sensitive (arrhythmogenic) because of amyloid fibril binding of digoxin.
Digoxin (Lanoxin)
Added to regimen to enhance myocardial contractility. Cardiac glycoside with direct inotropic effects in addition to indirect effects on cardiovascular system.
Dosing
Adult
0.125-0.375 mg PO qd
Pediatric
<10 years: Not established
>10 years: 10-15 mcg/kg PO
Maintenance dosing: 25-35% of loading dose
Interactions
Medications that may increase digoxin levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, oral amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil
Medications that may decrease serum digoxin levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, oral colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (including carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid
Contraindications
Documented hypersensitivity; beriberi; heart disease; idiopathic hypertrophic subaortic stenosis; constrictive pericarditis; carotid sinus syndrome
Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Hypokalemia may reduce positive inotropic effect; IV calcium may produce arrhythmias in digitalized patients; hypercalcemia predisposes patient to digitalis toxicity, and hypocalcemia can make digoxin ineffective until serum calcium levels normal; magnesium replacement therapy must be instituted in patients with hypomagnesemia to prevent digitalis toxicity; patients diagnosed with incomplete AV block may progress to complete block when treated with digoxin; exercise caution in hypothyroidism, hypoxia, and acute myocarditis
Vasodilators
These agents are used to reduce ventricular filling pressure. Avoid excessive decrease in preload and diastolic filling.
Hydralazine (Apresoline)
Decreases systemic resistance through direct vasodilation of arterioles.
Dosing
Adult
10-20 mg/dose IV q4-6h prn initially; increase to 40 mg/dose prn; change to PO therapy as soon as possible
Pediatric
0.1-0.2 mg/kg/dose IV q4-6h prn; not to exceed 20 mg or 1.7-3.5 mg/kg/d divided in 4-6 doses
Interactions
MAOIs and beta-blockers may increase toxicity; indomethacin may decrease pharmacologic effects
Contraindications
Documented hypersensitivity; mitral valve rheumatic heart disease
Precautions
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Has been implicated in myocardial infarction; caution in suspected coronary artery disease
Isosorbide dinitrate and hydralazine (BiDil)
Fixed-dose combination of isosorbide dinitrate (20 mg/tab), a vasodilator with effects on both arteries and veins, and hydralazine (37.5 mg/tab), a predominantly arterial vasodilator. Indicated for heart failure in blacks, based in part on results from African American Heart Failure Trial. Two previous trials in the general population of patients with severe heart failure found no benefit but suggested benefit in patients who are black. Compared with placebo, blacks showed 43% reduction in mortality rate, 39% decrease in hospitalization rate, and decrease in symptoms from heart failure.
Dosing
Adult
1 tab PO tid; may titrate upward, not to exceed 2 tab tid
Pediatric
Not established
Interactions
Hydralazine may increase propranolol, metoprolol, and lisinopril AUC and Cmax; isosorbide dinitrate may cause additive vasodilating effects with other vasodilators (eg, sildenafil [Viagra], vardenafil [Levitra]), especially when coadministered with alcohol
Contraindications
Documented hypersensitivity; allergy to organic nitrates
Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
May cause symptomatic hypotension even with small doses; careful hemodynamic monitoring required if administered in patients with acute MI
Hydralazine: May cause SLE-like symptoms, including glomerulonephritis, tachycardia, hypotension, and peripheral neuritis (pyridoxine therapy may be required)
Isosorbide dinitrate: If hypotension exists, may aggravate angina associated with hypertrophic cardiomyopathy
Anticoagulants
These agents are used to prevent embolism from ventricular thrombus.
Warfarin (Coumadin)
Interferes with hepatic synthesis of vitamin K–dependent coagulation factors. Used for prophylaxis and treatment of venous thrombosis, pulmonary embolism, and thromboembolic disorders.
Dosing
Adult
5-15 mg/d PO qd for 2-5 d; adjust dose according to desired INR
Pediatric
0.05-0.34 mg/kg/d PO; adjust dose according to desired INR
Infants may require doses at, or near, high end of this range
Interactions
Drugs that may decrease anticoagulant effects include griseofulvin, carbamazepine, glutethimide, estrogens, nafcillin, phenytoin, rifampin, barbiturates, cholestyramine, colestipol, vitamin K, spironolactone, oral contraceptives, and sucralfate
Medications that may increase anticoagulant effects include oral antibiotics, phenylbutazone, salicylates, sulfonamides, chloral hydrate, clofibrate, diazoxide, anabolic steroids, ketoconazole, ethacrynic acid, miconazole, nalidixic acid, sulfonylureas, allopurinol, chloramphenicol, cimetidine, disulfiram, metronidazole, phenylbutazone, phenytoin, propoxyphene, sulfonamides, gemfibrozil, acetaminophen, and sulindac
Contraindications
Documented hypersensitivity; severe liver or kidney disease; open wounds; GI ulcers
Precautions
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Do not switch brands after achieving satisfactory therapeutic response; caution in active tuberculosis or diabetes and in patients with protein C or S deficiency (they are at risk of developing skin necrosis)
Heparin
Augments activity of antithrombin III and prevents conversion of fibrinogen to fibrin. Does not actively lyse but is able to inhibit further thrombogenesis. Prevents reaccumulation of clot after spontaneous fibrinolysis.
Dosing
Adult
Loading dose: 40-170 U/kg IV
Maintenance dose: 15-25 U/kg/h IV; increase dose by 5 U/kg/h IV q4h prn as indicated by aPTT results
Pediatric
Loading dose: 50 U/kg IV
Maintenance dose: 15-25 U/kg/h IV; increase dose by 2-4 U/kg/h IV q6-8h prn as indicated by aPTT results
Interactions
Digoxin, nicotine, tetracycline, and antihistamines may decrease effects; NSAIDs, aspirin, dextran, dipyridamole, and hydroxychloroquine may increase toxicity
Contraindications
Documented hypersensitivity; subacute bacterial endocarditis; active bleeding; history of heparin-induced thrombocytopenia
Precautions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
In neonates, preservative-free heparin recommended to avoid possible toxic reaction (gasping syndrome) to benzyl alcohol, which is used as preservative; caution in severe hypotension and shock
Follow-up
Complications
- Thromboembolism
- Dysrhythmias
- Cardiac cirrhosis
- Progressive deterioration of cardiac function
Prognosis
- Prognosis generally is poor in the adult population, with progressive deterioration.
- The outlook is especially bad in children with heart failure.
- Surgical treatment (cardiac transplantation) is potentially helpful. It is contraindicated in amyloidosis.
Miscellaneous
Medicolegal Pitfalls
- Differentiation from constrictive pericarditis is difficult but important. While restrictive cardiomyopathy has no specific therapy, constrictive pericarditis is potentially curable with surgery.
References
Braunwald E, Abelmann WH. Atlas of Heart Diseases. Vol 2. 1994:53-61.
Davies MJ, Mann JM. Systemic pathology. In: The Cardiovascular System. Vol 10. 1995:1409-16.
Goldstein JA. Differentiation of constrictive pericarditis and restrictive cardiomyopathy. ACC Ed Highlights. 1998;Fall:14-22.
Higano ST, Azrak E, Tahirkheli NK, Kern MJ. Hemodynamic rounds series II: hemodynamics of constrictive physiology: influence of respiratory dynamics on ventricular pressures. Catheter Cardiovasc Interv. Apr 1999;46(4):473-86. [Medline].
Kasper DL, Braunwald E, Fauci AS, eds. Harrison's Principles of Internal Medicine. McGraw-Hill; 2005:chap 221.
Kushwaha SS, Fallon JT, Fuster V. Restrictive cardiomyopathy. N Engl J Med. Jan 23 1997;336(4):267-76. [Medline].
Schlant RC, Alexander RW, eds. The Heart. McGraw-Hill; 1994:1637-45.
Tintinalli JE, Kelen GD, Stapczynski JS, eds. Emergency Medicine: A Comprehensive Study Guide. McGraw-Hill;2004:381.
Wald DS, Gray HH. Restrictive cardiomyopathy in systemic amyloidosis. QJM. May 2003;96(5):380-2. [Medline].
Willerson JT, Cohn JN, ed. Cardiovascular Medicine. Churchill Livingstone; 1995:871-86.
Keywords
diastolic dysfunction, restrictive cardiomyopathy, endomyocardial fibrosis, EMF, dip and plateau configuration, dip and plateau pattern, square root pattern, square root configuration, heart failure, cardiac cirrhosis, thromboembolism, low-output cardiac failure
Contributor Information and Disclosures
Author
Paul J Kaloudis, MD, Clinical Assistant Professor, Department of Emergency Medicine, Stony Brook School of Medicine; Physician Lead, Department of Information Technology, Stony Brook University Hospital
Disclosure: Nothing to disclose.
Coauthor(s)
Asa William (Peter) Viccellio, MD, Professor, Vice-Chair, Department of Emergency Medicine, State University of New York at Stony Brook
Asa William (Peter) Viccellio, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Emergency Physicians, American Medical Association, Medical Society of the State of New York, National Association of EMS Physicians, New York Academy of Medicine, New York Academy of Sciences, and New York County Medical Society
Disclosure: Nothing to disclose.
Robert Fan, MD, Attending Staff, Department of Emergency Medicine, Kaiser Permanente Medical Center at Hayward
Disclosure: Nothing to disclose.
Medical Editor
David FM Brown, MD, Assistant Professor, Department of Medicine, Division of Emergency Medicine, Harvard Medical School; Associate-Chief, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital
David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Pharmacy Editor
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Managing Editor
A Antoine Kazzi, MD, Chair and Medical Director, Department of Emergency Medicine, American University of Beirut, Lebanon
A Antoine Kazzi, MD is a member of the following medical societies: American Academy of Emergency Medicine
Disclosure: Nothing to disclose.
CME Editor
John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Chief Editor
Jonathan Adler, MD, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital; Division of Emergency Medicine, Harvard Medical School
Jonathan Adler, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
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