M-mode echocardiogram showing movements of the interventricular septum and posterior wall of the left ventricle (LV). Right ventricle (RV) is seen above the interventricular septum. This is an image from the parasternal view. In systole, the posterior wall contracts and moves slightly anteriorly. Normally the interventricular septum should contract and move towards the posterior wall. Here the septum moves away from the posterior wall in systole (paradoxical septal motion – arrow). This occurs in situations of right ventricular volume overload.
In this M-Mode echocardiogram, the vertical axis is the distance from the transducer and the horizontal axis is time.