PLAX view: Orientation
The parasternal long axis view or the PLAX is obtained by placing the transducer to the left of the sternum in 3rd or 4th intercostal space with the orientation marker toward patient’s right shoulder or 10 o’ clock position, which is essentially the ‘long axis’ of the heart. For a better understanding of the scanning technique, watch my video 3 (~19:33) and video 8 (~5:22).
The following figures demonstrate the plane in which we are slicing the heart to obtain PLAX view.
Normal sonographic anatomy of the PLAX view:
In a technically ‘good’ PLAX view, both the mitral valve and the aortic valve will be clearly seen and will be roughly in the center of the image, stacked on top of each other. The base of the left ventricle (LV), but not the apex, will be visible. The right ventricular outflow tract (RVOT) will be seen on the top of the image. Note that the right ventricle has noticeably thinner and smaller walls compared to the LV. The right atrium (RA) is not visible in this view. On the right, the left atrium (LA), aorta and RVOT each should roughly take up one-third of the image. Pericardium appears as a bright border and the descending thoracic aorta is visible at the bottom of the image, as a circle outside the LA.