An upgrade of the guidelines for chamber quantification recently has been published. The primary purpose of this guideline document is to set standard measurements, labels, and orientations so that there is better communication and standardization among all echocardiography laboratories both in the United States and in Europe. An apparent secondary goal is to integrate echocardiographic chamber quantification with other cardiovascular imaging modalities. This secondary goal is in recognition of an increasing trend toward making echocardiography a part of noninvasive cardiovascular imaging. To highlight this trend, there are now numerous multimodality imaging journals, and the European Association of Echocardiography has been renamed the European Association of Cardiovascular Imaging. As with all changes or “advances,” there are likely to be unexpected or unintended consequences.
An early effort at improving communication between echocardiography and nuclear cardiology was to change echocardiography’s standard 16-segment wall motion scoring system by adding a 17th segment at the apex. This wall motion diagram would then be compatible with nuclear apical perfusion and multiple gated acquisition scan apical motion. The echocardiography representatives agreed to make the change. However, the apex moves outward during isovolumic contraction (the apical impulse on palpation). During left ventricular ejection, the apex is in a neutral position. The apical motion frequently seen on echocardiography is due to recording a foreshortened apex, and multiple gated acquisition scan apical motion is an artifact due to the lack of detectable isotope at the normal apex during systole. The 17th segment, however, is correct for perfusion because there is normal apical perfusion. The message is that wall motion and perfusion are different. Fortunately, we realized our error, and the latest chamber guideline document states, “When using the 17-segment model to assess wall motion or regional strain, the 17th segment (the apical cap) should not be included.” I am not certain the statement is correct about apical strain. Even though there is no effective wall motion, there does appear to be apical strain.
A second effort to enhance communication between echocardiography and nuclear cardiology resulted in changing the standard echocardiographic segmentation labels and orientation so that they are similar to those used in nuclear perfusion. Unfortunately, the manner in which echocardiograms and nuclear images are acquired and displayed is quite different. As seen in Figure 1 , the right ventricle is anterior and to the right of the left ventricle in the echocardiographic short-axis view. The comparable nuclear view displays the right ventricle only on the right of the left ventricle. In addition, the spatial resolution is vastly different. The papillary muscles are clearly visible on the echocardiogram and are not seen on the nuclear image. The two views are sufficiently different that there probably never should have been an effort to make one set of labels and orientation fit both modalities. Figure 2 shows the regional wall motion diagram on current Synapse Cardiovascular reporting software compared with the current guidelines orientation and labels. Figure 3 shows a similar comparison between the GE strain “bull’s-eye” diagram orientation and labels compared with those of a guideline diagram in which the papillary muscles are arranged vertically rather than horizontally. The back wall of the left ventricle has been labeled “posterior” ( Figures 2 and 3 ) since the very beginning of echocardiography. It is now being labeled “inferior lateral” to make it compatible with nuclear cardiology. In my judgment, we again need to admit that we made a mistake in changing our segmentation labels and orientation, just as we did with apical motion, and go back to the original more commonly used echocardiographic labels and orientation.
