Quantitative Evaluation of Left Ventricular Wall Motion in Patient with Coronary Artery Bypass Grafting Using Magnetic Resonance Tagging Technique

Abstract

The left ventricular wall motion during systole was investigated from a mechanical point of view by using a magnetic resonance tagging technique. Subjects were seven patients with coronary artery bypass grafting (CABG). At first, in order to evaluate the cardiac contractility in each patient, the circumferential strain in myocardial wall was analyzed. It was found from there results that the circumferential strain in four patients decreased compared with that in healthy humans. Next, the paradoxical wall motion in patients with CABG was quantitatively described by calculating the displacement. The results showed that the radial displacement of septal wall in the patients was smaller than that in healthy humans, and the radial displacement of lateral wall was larger. Furthermore, anterior wall and posterior wall moved toward septal wall. Such left ventricular wall motion was recognized in even the patients with normal cardiac contractility. Therefore, it was considered that the paradoxical wall motion in the patients with CABG was not caused by a drop of the cardiac contractility, but a rigid-body motion of the heart.