Restrictive cardiomyopathy
Other names: Obliterative cardiomyopathy, infiltrative cardiomyopathy, constrictive cardiomyopathy[1]
Micrograph ofcardiac amyloidosis, a cause of restrictive cardiomyopathy.Congo red stain.
Specialty	Cardiology
Symptoms	Decreased ability to exercise,palpitations,shortness of breath, leg swelling[2][3]
Complications	Liver failure,blood clots[2]
Causes	Amyloidosis,sarcoidosis,hemochromatosis,Loeffler endocarditis,storage diseases, diabetes, scleroderma,radiation therapy, certain medications, cancer[2]
Diagnostic method	Electrocardiogram (ECG),ultrasound of the heart,endomyocardial biopsy[2]
Differential diagnosis	Constrictive pericarditis,hypertensive heart disease,hypertrophic cardiomyopathy[2]
Treatment	Based on symptoms and the underlying cause[2]
Prognosis	Life expectancy 2 to 5 years[2]
Frequency	Rare[2]

Restrictive cardiomyopathy (RCM) is adisease of heart muscle in which theventricles do not appropriatelyrelax and fill despite relatively normalcontraction.^[4][3] Symptoms may vary from a decreased ability to exercise, to new onsetatrial fibrillation, toheart failure.^[2] In somesudden cardiac arrest is the first indication of the disease.^[2] Other complications may includeliver failure andblood clots.^[2]

The most common causes areamyloidosis,sarcoidosis,hemochromatosis, andLoeffler endocarditis.^[2] Other causes includestorage diseases,diabetes,scleroderma,radiation therapy, certain medications, andcancer.^[2] Diagnosis may be supported byelectrocardiogram (ECG),ultrasound of the heart, andendomyocardial biopsy.^[2]

There is no cure.^[2] Treatment involves addressing the underlying cause and measures to improve heart failure.^[2] Heart failure may be treated withdiuretics such asfurosemide,calcium channel blockers, orbeta blockers.^[2] For sarcoidosis,antiarrhythmics andimmunosuppressants are also commonly used.^[2] Hemochromatosis may be treated withremoval of blood.^[2] In certain cases aheart transplant may be an option.^[2]

Restrictive cardiomyopathy is relatively rare.^[2] It represents about 5% of cardiomyopathy cases with thehypertrophic anddilated types being more common.^[2] Life expectancy follow diagnosis is generally 2 to 5 years.^[2] Cases of RCM were described in the the 1930s.^[5] Cardiomyopathy; however, was not divided into its three main groups until 1961.^[1]

Signs and symptoms

Those with RCM will experience decreased exercise tolerance, fatigue, jugular venous distention,peripheral edema, andascites.^[6] Arrhythmias and conduction blocks are common.

Causes

RCM can be caused by genetic or non-genetic factors.^[7][8][9] Thus causes can be divide into primary and secondary.^[10] It can also be organized into infiltrative, storage diseases, non-infiltrative, and endomyocardial causes.^[11] The most common cause of restrictive cardiomyopathy isamyloidosis.^[6]

• Infiltrative
  • Amyloidosis
  • Sarcoidosis
  • Primary hyperoxaluria
• Storage diseases
  • Fabry disease
  • Gaucher disease
  • Hereditary hemochromatosis
  • Glycogen storage disease
  • Mucopolysaccharidosis type I (Hurler syndrome)
  • Mucopolysaccharidosis type II (Hunter syndrome)
  • Niemann-Pick disease
• Non-infiltrative
  • Idiopathic
  • Diabetic cardiomyopathy
  • Scleroderma
  • Myofibrillar myopathies
  • Pseudoxanthoma elasticum
  • Sarcomeric protein disorders
  • Werner's syndrome
• Endomyocardial
  • Carcinoid heart disease
  • Endomyocardial fibrosis
  • Idiopathic
  • Hypereosinophilic syndrome
  • Chronic eosinophilic leukemia
  • Drugs (serotonin, methysergide, ergotamine, mercurial agents, busulfan)
  • Endocardial fibroelastosis
  • Consequence ofcancer or cancer therapy
  • Metastatic cancer
  • Drugs (anthracyclines)
  • Radiation

Mechanism

Rhythmicity andcontractility of the heart may be normal, but the stiff walls of the heart chambers (atria andventricles) keep them from adequately filling, reducingpreload andend-diastolic volume. Thus, blood flow is reduced, and blood volume that would normally enter the heart is backed up in the circulatory system. In time, restrictive cardiomyopathy patients develop diastolic dysfunction and eventuallyheart failure.

Diagnosis

Diagnosis is typically made via echocardiography. Patients will demonstrate normal systolic function, diastolic dysfunction, and a restrictive filling pattern.^[11] 2-dimensional and Doppler studies are necessary to distinguish RCM from constrictive pericarditis. Cardiac MRI and transvenousendomyocardial biopsy may also be necessary in some cases.^[6][11] ReducedQRS voltage onEKG may be an indicator of amyloidosis-induced restrictive cardiomyopathy.^[11]

Untreated hearts with RCM often develop the following characteristics:^{[citation needed]}

• M or W configuration in an invasive hemodynamic pressure tracing of the RA
• Square root sign of part of the invasive hemodynamic pressure tracing Of The LV
• Biatrial enlargement
• Thickened LV walls (with normal chamber size)
• Thickened RV free wall (with normal chamber size)
• Elevated right atrial pressure (>12mmHg),
• Moderatepulmonary hypertension,
• Normal systolic function,
• Poor diastolic function, typically Grade III - IVDiastolic heart failure.

Treatment

Treatment of restrictive cardiomyopathy should focus on management of causative conditions (for example, using corticosteroids if the cause is sarcoidosis), and slowing the progression of cardiomyopathy.^[11] Salt-restriction,diuretics,angiotensin-converting enzyme inhibitors, and anticoagulation may be indicated for managing restrictive cardiomyopathy.^[12]

Calcium channel blockers are generally contraindicated due to their negative inotropic effect, particularly in cardiomyopathy caused by amyloidosis.^[13][14] Digoxin, calcium channel blocking drugs and beta-adrenergic blocking agents provide little benefit, except in the subgroup of restrictive cardiomyopathy with atrial fibrillation.^[15] Vasodilators are also typically ineffective because systolic function is usually preserved in cases of RCM.^[6]

Heart failure resulting from restrictive cardiomyopathy will usually eventually have to be treated bycardiac transplantation orleft ventricular assist device.^[12]

Epidemiology

Endomyocardial fibrosis is generally limited to the tropics and sub-saharan Africa.^[11] The highest incidence of death caused by cardiac sarcoidosis is found in Japan.^[16]

References

External links

• OverviewArchived 2011-10-04 at theWayback Machine atMerck Manual

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• Cardiomyopathy
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