Fig. 1.

Representative measurement of left atrial anteroposterior diameter (LAD) obtained from the parasternal long-axis view in a healthy dog. The LAD was measured at end-systole (a frame just before mitral valve opening), evaluating the widest distance, parallel to the mitral valve annulus, from the inner wall of the middle of interatrial septum to the inner wall of the posterior free wall. The distance from the blood-tissue interface to blood-tissue interface was used (white arrow). LV, left ventricle; RA right atrium