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Mentions: Two experienced investigators (one observer with five years of experience in cardiac MR imaging, and the other observer with 12 years of experience in cardiac MR imaging) evaluated MR images by consensus. MR imaging data analysis for cine MRI, perfusion, and DE-MRI was performed using commercially available software on a commercially available workstation (View Forum, release 3.2, Cardiac Package; Philips Medical Systems). Presence or absence of a perfusion defect or delayed hyperenhancement in the septum was qualitatively assessed on follow-up images of stress perfusion and DE-MRI. Endocardial and epicardial contours seen on short-axis images of cine MRI were traced using the semi-automated border technique for quantitative evaluation of global and regional systolic functions, such as the ejection fraction, LV end-diastolic volume, LV end-systolic volume, regional wall thickening, and regional wall motion. Presence or absence of ASM on cine MRI was determined using qualitative visual and quantitative assessment, and the final diagnosis was made by consensus. Septal wall motion was expressed as endocardial inward movement (in millimeters) from the end-diastolic to the end-systolic phase on cine MRI (11). For qualitative analysis of the ASM, we calculated the average value of regional wall motion in the septal segments (Fig. 1).
Abnormal Motion of the Interventricular Septum after Coronary Artery Bypass Graft Surgery: Comprehensive Evaluation with MR Imaging
Bottom Line: Septal wall motion was compared in the ASM and non-ASM groups.Preoperative and postoperative results with regard to septal wall motion in the ASM group were also compared.We suggest that ASM might occur due to an increase in anterior cardiac mobility after incision of the pericardium.
Affiliation: Department of Radiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
Objective: To define the mechanism associated with abnormal septal motion (ASM) after coronary artery bypass graft surgery (CABG) using comprehensive MR imaging techniques.
Materials and methods: Eighteen patients (mean age, 58 ± 12 years; 15 males) were studied with comprehensive MR imaging using rest/stress perfusion, rest cine, and delayed enhancement (DE)-MR techniques before and after CABG. Myocardial tagging was also performed following CABG. Septal wall motion was compared in the ASM and non-ASM groups. Preoperative and postoperative results with regard to septal wall motion in the ASM group were also compared. We then analyzed circumferential strain after CABG in both the septal and lateral walls in the ASM group.
Results: All patients had normal septal wall motion and perfusion without evidence of non-viable myocardium prior to surgery. Postoperatively, ASM at rest and/or stress state was documented in 10 patients (56%). However, all of these had normal rest/stress perfusion and DE findings at the septum. Septal wall motion after CABG in the ASM group was significantly lower than that in the non-ASM group (2.1±5.3 mm vs. 14.9±4.7 mm in the non-ASM group; p < 0.001). In the ASM group, the degree of septal wall motion showed a significant decrease after CABG (preoperative vs. postoperative = 15.8±4.5 mm vs. 2.1±5.3 mm; p = 0.007). In the ASM group after CABG, circumferential shortening of the septum was even larger than that of the lateral wall (-20.89±5.41 vs. -15.41±3.7, p < 0.05)
Conclusion: Abnormal septal motion might not be caused by ischemic insult. We suggest that ASM might occur due to an increase in anterior cardiac mobility after incision of the pericardium.
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