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Figure 1 M-mode recording of LV septal long axis from a patient with HOCM before (left) and after (right) septal reduction along with ECG and phonocardiogram. Vertical line marks A2, second heart sound. Note the reduction of total amplitude of septal excursion and the marked postejection shortening (arrow) occurring during early diastole associating the development of RBBB. ECG = electrocardiogram; HOCM = hypertrophic obstructive cardiomyopathy; LV = left ventricular; RBBB = right bundle branch block.