The Apical Two-Chamber View
©Walter Rasmussen, R.D.C.S.
The apical two-chamber view of the left ventricle is acquired by rotating the transducer counter-clockwise from the apical four-chamber view approximately 90 degrees.
While the Apical four-chamber view depicts the left ventricular lateral and septal walls, the apical two-chamber view isolates the anterior and inferior walls. Particular effort should be made to image as much of the endocardial border as possible in order to accurately assess left ventricular wall motion, myocardial thickness and chamber volume.
Imaging the apical two-chamber view is generally easier than the apical four-chamber view because the sector axis is more parallel to the axis of the intercostal space where the transducer is placed. Respiratory maneuvers, (including hyper-inspiration or expiration with suspension where the image is clearest), can make a dramatic improvement when image quality is sub-optimal.
Because the left ventricular apex tends to curve posteriorly, the two-chamber view depicts the true left ventricular apex more easily than the four-chamber view and can help determine whether or not the four-chamber view was foreshortened. The apical two-chamber view can be foreshortened, just as can happen with the apical four-chamber view. To eliminate foreshortening, the same techniques for depicting the true left ventricular apex in the apical four-chamber view apply to the apical two-chamber view, as outlined in the prior section, “Avoiding a Foreshortened or “Truncated” Apical View“.
The apical two-chamber view provides unique images of the mitral valve or a mitral prosthesis and the sonographer should make certain they are clearly seen though controls mentioned in prior topics such as focusing and TGC. Recordings should be made featuring any anomalies observed. Color Doppler is used to help determine the severity of mitral regurgitation in this view and it may be necessary to modify the axis or angulation of the transducer in order to follow the full length of a long, narrow, MR jet.
As with all of the apical views, the sonographer should investigate the apical region for evidence of left ventricular thrombus in those patients who have apical dilatation, thinning, or akinesis. For better thrombus detection, the focal zone should be moved to the apex.
The left atrium is also evaluated in the apical 2 chamber view, allowing the tracing of its borders for the estimation of left atrial volume and the assessment of any anomalies. If necessary, the focus can be adjusted to the level of the left atrium for better wall definition. It is often the case that the left atrial area may be under-estimated when the image is specifically recorded for best images of the left ventricle. The sonographer should therefore record a separate apical two chamber view with an emphasis on maximizing the left atrial area without regard for rendering a perfect view of the left ventricle, when necessary. The left atrial appendage is often well-visualized in the apical two-chamber view, particularly when dilated.