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Figure 4 The upper panels represent the three apical views in systole in a patient with idiopathic dilated cardiomyopathy before implantation of a biventricular pacemaker. The majority of the lateral wall, anterior wall and posterior wall are gray, indicating a lack of systolic motion toward the apex. The mechanical function of the interventricular septum and inferior walls is abnormal, with a higher motion amplitude in the segment adjacent to the apex (arrows). The lower panels show corresponding views after one year of cardiac resynchronization therapy. At this time, systolic motion toward the apex is present in the entire left ventricle. In addition, the reverse distribution of motion amplitude in the septum and inferior wall has been normalized, with greater systolic performance at the base of the left ventricle.