Cardiovascular ImagingCardiomyopathy, amyloid
myocardial disease caused by
infiltration of amyloid. Primary amyloidosis is caused by an amyloid protein composed of portions of immunoglobulin light chain produced by monoclonal plasma cells, while the secondary form is due to overproduction of a nonimmunoglobulin protein. Senile amyloidosis is caused by a prealbumin protein.
Cardiac involvement is common in primary amyloidosis but clinically significant
cardiac involvement is uncommon in secondary amyloidosis.
Cardiac involvement may be unimportant or the cause of heart failure in the senile form. The most common manifestation of
cardiac amyloidosis is
restrictive cardiomyopathy. Systolic dysfunction dominates the
cardiac manifestation less frequently. Other abnormalities include orthostatic
hypotension, arrhythmias, conduction abnormalities and low ECG voltage. Also, see
amyloidosis.
Plain radiography shows pulmonary venous hypertension or oedema with little or no cardiomegaly in the restrictive form. Cardiomegaly may be present in the form with primarily systolic dysfunction. Echocardiography demonstrates thickened atrial walls, especially on the right side; thickened ventricular walls; small left ventricular volumes (LV); decreased ejection fraction; and diffuse hypokinesis. Echocardiography may reveal a distinctive "speckled" texture of the myocardium. Doppler echocardiography and blood pool LV scintigraphy show decreased left ventricular (LV) diastolic indices. Technetium 99m pyrophosphate scans may show intense myocardial uptake. MRI has become especially effective for demonstrating the thickening of the right atrial wall, interatrial septum and LV myocardium. A characteristic feature is enlarged atria in the presence of small ventricular cavities. Because of the diastolic dysfunction causing slow emptying of the atria, prominent intracavitary signal in the atria is evident on spin echo images. Cine MRI demonstrate diffuse hypokinesis of the LV and velocity-encoded cine MRI documents the depressed diastolic filling indices.
CBH