Restrictive Cardiomyopathy: Amyloid, Diastolic Dysfunction, and Kussmaul’s Sign

Restrictive cardiomyopathy is the least common type of cardiomyopathy. The restriction refers primarily to diastolic dysfunction (ie: problems with relaxation of the heart); systolic function is generally well preserved. From a clinical perspective the restrictive cardiomyopathies present similarly to the hypertrophic cardiomyopathies.

There are two main causes of restriction: infiltration of the heart muscle with abnormal substances or scarring of the heart muscle. Each of these causes has many underlying etiologies, a few of which are listed below.

   (1) Infiltration
        (a) Amyloidosis
        (b) Sarcoidosis
        (c) Storage diseases
            (i) Hemochromatosis
            (ii) Glycogen storage diseases
   (2) Fibrosis and scarring
        (a) Post-radiation
        (b) Endomyocardial fibrosis

Regardless of the cause, the heart muscle gets "gunked up" with stuff that shouldn’t be there. The result is decreased contractile ability.

Signs and Symptoms

Patient’s with restrictive cardiomyopathy often present with signs and symptoms of diastolic dysfunction. Pulmonary edema (ie: fluid in the lungs) results in dyspnea (difficulty breathing), paroxysmal nocturnal dyspnea (waking up gasping for air), and orthopnea (inability to lay flat secondary to shortness of breath). Reduced cardiac output results in fatigue, dizziness, and weakness.

On physical exam, Kussmaul’s sign can sometimes be appreciated. Kussmaul’s sign occurs when you can see the jugular vein distend when a patient inspires (breathes in). Normally jugular venous distension decreases with inspiration as venous return to the heart increases due to decreased intrathoracic pressure. However, in restrictive cardiomyopathy the ventricle cannot accommodate the increased blood flow and it backs up into the jugular veins during inspiration, hence the paradoxical worsening.

In addition, signs of systemic volume overload can occur including hepatomegaly (ie: an enlarged liver), ascites (ie: fluid in the abdomen), and bilateral lower extremity edema (ie: leg swelling). Arrhythmias are also common because amyloid deposits can wreak havoc on the conduction system of the heart.

Diagnosis and Work-Up

It is important to distinguish restrictive cardiomypathy from restrictive pericarditis, which is treatable. The gold standard test is a myocardial biopsy, which will reveal infiltrating substances in restrictive cardiomyopathy. MRI and CT can show a thickened pericardium, which is more consistent with restrictive pericarditis.

Treatment and Prognosis

Treatment is aimed at the underlying cause. For example, chemotherapy for multiple myeloma or phlebotomy for hemochromatosis can slow disease progression. Since diastolic function is most affected, treatment is aimed at ensuring adequate filling time for the left ventricle. Diuretics should be used cautiously because patient’s are dependent on higher blood volumes to fill as much of the restricted ventricle as possible. Digoxin and vasodilator therapies are usually not helpful since systolic function is usually well-preserved.

Prognosis is generally poor unless treatment of the underlying condition is curative.


Restrictive cardiomyopathy is caused by infiltrative processes (most commonly amyloidosis). Physical exam reveals signs of diastolic dysfunction resulting in blood backing up in the lungs and body. The gold standard for diagnosis is myocardial biopsy, although this is not routinely performed in clinical practice. Treatment is aimed at the underlying cause, if identifiable. In addition, since diastolic dysfunction is present, treatments should be used that allow the heart adequate time to fill.

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