Assessment of the magnitude of the SF, systolic excursion and PSS at the septum in different cardiac views in patients with RV pacing. The left upper panel shows parasternal long-axis view of the heart in a patient with RV pacing and normal LV function. The left lower panel shows an M-mode image of the septum demonstrating a minimal SF (thick white arrow), normal systolic excursion (thick yellow arrow), and no PSS. The middle upper panel shows parasternal short-axis view of the heart in a patient with RV pacing and mildly reduced LV function (EF 46%). The middle lower panel shows an M-mode image of the septum demonstrating a slightly greater SF, reduced systolic excursion, and PSS (thin white arrow). The right upper panel shows apical four-chamber view of the heart in a patient with RV pacing and severly reduced LV function (EF 35%). A pacemaker lead can be appreciated in the RV (red arrow). The right lower panel shows an M-mode image of the septum demonstrating a large SF, PSS, and no systolic excursion. PM, pacemaker; PSS, post-systolic shortening; SE, systolic excursion; SF, septal flash.