Mechanism of Paradoxical Ventricular Septal Motion After Coronary Artery Bypass Grafting

Paradoxical septal motion is commonly noted on echocardiography after coronary artery bypass grafting (CABG), but its mechanism is unclear. Cardiac magnetic resonance imaging was performed before and 3 months after CABG in 23 patients. On a mid–left ventricular short-axis cine image, the motion of myocardial landmarks during the cardiac cycle was ascertained relative to a stationary anterior reference point. Before CABG, the movement of the ventricular septum in systole was either posterior or neutral (median −2 mm) in 19 patients, whereas after CABG, the septum moved anteriorly in all 23 patients (+4 mm; p