Korean J Radiol.  2010 Dec;11(6):627-631. 10.3348/kjr.2010.11.6.627.

Abnormal Motion of the Interventricular Septum after Coronary Artery Bypass Graft Surgery: Comprehensive Evaluation with MR Imaging

• Choi SH
• Choi SI
• Chun EJ
• Chang HJ
• Park KH
• Lim C
• Kim SJ
• Kang JW
• Lim TH

• KMID: 1119225
• DOI: http://doi.org/10.3348/kjr.2010.11.6.627

Abstract

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.

Keyword

Coronary artery disease; Coronary artery bypass surgery; Magnetic resonance (MR); Abnormal septal motion

MeSH Terms

Contrast Media/diagnostic use
*Coronary Artery Bypass
Coronary Disease/*surgery
Female
Gadolinium DTPA/diagnostic use
Humans
Image Interpretation, Computer-Assisted
Magnetic Resonance Imaging/*methods
Male
Middle Aged
Pericardium/surgery
Retrospective Studies
Statistics, Nonparametric
Ventricular Septum/*physiopathology

Figure

• 

  Fig. 1 Schematic measurement of abnormal septal motion during cardiac cycle after coronary artery bypass graft surgery (CABG). Predefined landmarks on heart were chosen for qualitative evaluation of wall motion on end-diastole (upper panel) and end-systole (lower panel) in same post-CABG patient. Distances were measured from stationary anterior reference point. Septal wall motion was calculated as endocardial inward movement (C-A in millimeters) from end-diastolic to end-systolic phase. Note that septal wall motion was markedly decreased compared to wall motion in lateral wall (B-D in millimeters), suggesting abnormal septal motion after CABG. ES = endocardial border of interventricular septum, EL = endocardial border of lateral wall, M = midpoint of left ventricular cavity.

• 

  Fig. 2 Bulls eye diagrams before (A) and after (B) coronary artery bypass graft surgery. Note decreased wall motion at septum, indicating abnormal septal motion (white arrows), compared with lateral wall.

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  Fig. 3 Regional circumferential shortening in patients with abnormal septal motion after coronary artery bypass graft surgery. Note that circumferential stain of septum was significantly larger than that of lateral wall throughout systole. A = anterior, AL = anterolateral, AS = anteroseptal, I = inferior, IL = inferolateral, IS = inferoseptal

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