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ACEP Now: Vol 34 – No 02 – February 2015

(click for larger image) Figure 2: Anatomical description of coronary perfusion in the A) PLAX, B) PSAX, and C) A4C.

condensed into a modified three-area evaluation that corresponds roughly to the major coronary artery perfusion territories of the left ventricle. This is based on American Society of Echocardiography guidelines and cardiac magnetic resonance imaging data of patients with acute coronary ischemia and has been successfully utilized in prior ED studies.^12–14 Visualization of the left ventricle in PLAX, PSAX, and A4C can roughly display RWMAs of the three major coronary arteries: left anterior descending (LAD), circumflex (Cx), and right coronary artery (RCA) (see Figure 2). Thus an anterior RWMA corresponds with an occlusion of the LAD, a lateral RWMA corresponds with an occlusion of the Cx artery, and an inferior RWMA corresponds with an occlusion of the RCA.

Findings

Left ventricular RWMA is described as a hypokinesis, dyskinesis, or akinesis of a segment when compared to the other contracting segments of the chamber. This can be visualized sonographically as a blunting of the typical symmetric myocardial thickening during contraction as compared to other cardiac wall segments. This abnormal movement of the wall segment is highly suspicious for an associated coronary thrombus.

(click for larger image) Figure 3: Echocardiogram images with outlined regional wall motion abnormality territories of A) PSLAX B) PSAX, and C) A4C.

The anterior wall is supplied by the LAD, whereas the lateral wall is supplied by the Cx, and the inferior wall is supplied by the RCA (PLAX view, see Figure 3a). In our opinion, the PSAX at the level of the papillary muscles is often the best ultrasound view to appreciate RWMAs (see Figure 3b). In the A4C view, the proximal intraventricular septum is supplied by the RCA, while the rest of the visualized myocardium is supplied by the LAD (see Figure 3c). All three major vessels are roughly equally distributed over the left ventricle. However, some variation is to be expected.

ECG Correlation

Correlation of the ECG and POC echo images is helpful when attempting to determine the presence of RWMAs (see Figure 4). An anterior RWMA (LAD distribution) should correlate with ECG changes in V1 and V2. A lateral RWMA (Cx distribution) should correlate with ECG changes in V5, V6, I, and aVL. An inferior RWMA (RCA distribution) should correlate with ECG changes in II, III, and aVF.

Next Steps in Management

An identified RWMA can often suggest a moderate-sized coronary thrombus in the chest pain patient. While the initiation of invasive strategies based solely on a RWMA remains controversial, cardiologic consultation, consultative echocardiography, and serial biomarker testing may be prudent. Echocardiographic evaluation of RWMAs, in conjunction with ECG and a targeted history, can be useful in the risk stratification of the ED chest pain patient.