What is the role of echocardiography in the workup of dilated cardiomyopathy?

Updated: Nov 28, 2018
  • Author: Vinh Q Nguyen, MD; Chief Editor: Gyanendra K Sharma, MD, FACC, FASE  more...
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Answer

Echocardiography has become one of the most useful and most efficient diagnostic modalities in attaining a diagnosis and classification of cardiomyopathy. Echocardiography may be indicated in the ED when a patient has findings suggestive of failure (eg, jugular venous distention) but the diagnosis is unclear.

In this setting, the differential diagnosis may include pulmonary embolism or cardiac tamponade. On echocardiography, secondary findings associated with pulmonary embolism such as right ventricular distention or pericardial effusion with tamponade may be seen. Pericardial effusion can be easily excluded or characterized using this imaging modality.

Different forms of echocardiography offer different information. Two-dimensional echocardiography allows for assessment of overall function.

M-mode assists in measurement of chamber sizes (end-diastolic left ventricular dimensions are usually greater than 65 mm in patients with dilated cardiomyopathy) and wall thickness. Hypertrophy is defined as and LV mass index greater than 115 g/m2 in men, or over 95 g/m2 in women. Doppler echocardiography facilitates the measurement and assessment of flow and valvular pathologies. It also allows for measurements of diastolic and systolic dynamics.

The physician must assess the E wave–to–A wave ratio (E/A) when evaluating left ventricular filling and pulmonary venous flow by Doppler echocardiography during left atrial filling. This provides important information on diastolic function and left atrial pressure. For example, a pattern with an E:A ratio above 2:1 and a short mitral deceleration time suggest a restrictive physiology with elevated left atrial pressure.

Tissue Doppler interrogation measures the velocity of portions of the heart wall, most often the left ventricular basilar annular area. Just as in the blood velocity parameters of E and A amplitudes, similar measurements of wall velocity—E' and A'—are made. Reversal of the E'/A' amplitude signifies likely diastolic dysfunction.

Segmental wall motion abnormalities may suggest an ischemic etiology for the cardiomyopathy. While ischemic cardiomyopathy is a common cause of such abnormalities, however, they can often be observed in association with other forms of cardiomyopathy, as well.

Echocardiography is used to help differentiate dilated cardiomyopathy from restrictive and hypertrophic cardiomyopathy. Dilated chambers and thin walls are the most prominent features of dilated cardiomyopathy.


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