Accurate Imaging of Left Ventricular Geometry with Echocardiography
Avoiding a Foreshortened / Truncated Apical View
©Walter Rasmussen, R.D.C.S.
Normal left ventricular chambers have a wide base and a narrow apex but it is often the case that the easiest to obtain image depicts it as somewhat spherical in shape and this is one of the most difficult imaging challenges faced while performing an echocardiographic examination.
Image depicting the true left ventricular apex (7 cm in length).
The same patient with foreshortened left ventricle (6cm in length).
If the true left ventricular apex is not imaged, a diagnosis of spherical remodeling or the omission of apical myocardial thinning left ventricular hypertrophy, pseudoaneurysm or a missed apical thrombus may result.
An obvious sign that the transducer position may not be correct is when the left ventricle appears more spherical in shape, rather than elliptical and/or the left atrium appears to be as large as the left ventricle.
Normally, the apical cap of the left ventricle is slightly angled either toward the septum or posteriorly.
The apex may not be not fully visible from the easiest available intercostal space, and this often results in a foreshortened image.
The sonographer should be certain that a spherical appearance is not caused by incorrect transducer position. Briefly rotating the transducer to the apical two-chamber view can help to ascertain the actual shape of the left ventricular apex and whether it is truly spherical.
When the sonographer is faced with a difficult to image left ventricular apex, considerably more effort and special techniques for visualization are required.
Techniques for imaging the true left ventricular apex
Move the transducer down the chest wall one intercostal space, a little medially and if necessary, have the patient inhale until the left ventricle appears longer, narrower and more elliptical. This technique will in most cases, result in a dramatic improvement in the accuracy of the image. This imaging technique often decreases image resolution and may require adjustments to frequency, dynamic range, and compression in order to maintain good visibility of the endocardium.
Accurate rendering of the left ventricular chamber is very important because a spherical appearance raises the possibility of serious heart disease which may require additional tests and possibly unnecessary medications or procedures. Foreshortened views can also make the ventricle appear smaller than it actually is, thus affecting the calculations involving left ventricular volume and ejection fraction. When the left ventricular chamber is foreshortened, not all of the wall segments will be visualized.
If the patient has had a previous echo that did not image the true LV apex, obtain the view from which the left ventricle was previously imaged for the sake of an accurate comparison and explanation of the revised finding.
It is too often the case that previous echos are recorded in the easier to obtain foreshortened image of the left ventricle with an interpretation of spherical remodeling as a result. It is for this reason that careful imaging in order to obtain the truth about the left ventricular chamber geometry is very important.
The best transducer position for left ventrticular geometry is often not the best for imaging the heart valves. It is for this reason that a sonographer will shift between the two positions in order to obtain clear images of the valves.