2D Echocardiography Case Review : Cardiac Amyloidosis

NATIONAL HEART INSTITUTE OF MALAYSIA

2D ECHOCARDIOGRAPHY

CASE REVIEW

RESTRICTIVE CARDIOMYOPATHY

CARDIAC AMYLOIDOSIS

Myocardial infiltration by amyloid fibrils can occur in primary, familial, secondary, and senile amyloidosis. The degree of involvement is variable depending upon the type of amyloidosis. Two dimensional echocardiography remains the ideal method for identifying and following individuals with cardiac amyloidosis.

Characteristic two dimensional and Doppler echocardiographic features have been described in individuals with cardiac amyloidosis. Two dimensional features include thickening of the LV walls, increased reflectivity of these walls (the ‘‘speckled’’ or ‘‘granular’’ myocardium), biatrial enlargement, thickening of the interatrial septum, thickening and regurgitation of the mitral and tricuspid valves, and the presence of a small pericardial effusion.

Transmitral Doppler flow patterns in patients with amyloidosis exhibit evidence of diastolic dysfunction. Characteristic transmitral Doppler patterns representative of early impaired relaxation and later restrictive filling have been demonstrated in this population. An increase in both the pulmonary venous Doppler atrial reversal duration and the ratio of this atrial reversal duration to the transmitral A wave duration have been observed in these patients and reflect increased LA pressure.

Cardiac amyloidosis should be considered in individuals in whom several of these echocardiographic features are observed. The coexistence of increased thickening of the LV walls on echocardiography yet low voltage on electrocardiography is highly suggestive of amyloid infiltration of the myocardium.

Differentiating cardiac amyloidosis from hypertrophic cardiomyopathy can be difficult on echocardiography. Asymmetric septal thickening can result from focal amyloid deposition and can mimic hypertrophic cardiomyopathy. The presence of decreased LV function would argue strongly against hypertrophic cardiomyopathy. The presence of highly reflective myocardium can also be seen in individuals with primary and secondary causes of LV hypertrophy, ventricular fibrosis, and other infiltrative processes.

The integration of clinical, echocardiographic, and electrocardiographic data is essential when making the diagnosis of cardiac amyloidosis. While the long term prognosis is substantially worse inmpatients with primary amyloidosis, the echocardiographic distinction between familial, primary, and secondary amyloidosis can be difficult.

Impaired LV systolic function is more common in primary amyloidosis than in the other forms. Doppler tissue echocardiography is helpful in differentiating amyloid patients from those with similar two dimensional echocardiographic features but without amyloidosis. Abnormally low tissue Doppler diastolic velocities are present in individuals with cardiac amyloid compared with control patients.