Three dimensional computed tomographic imaging in planning the surgical approach for redo cardiac surgery after coronary revascularization.

OBJECTIVE: Reoperative cardiac surgery after previous coronary artery bypass grafting represents a surgical challenge due to the potential for injury to patent coronary grafts, aorta or right ventricle. Standard preoperative imaging using a coronary angiogram and chest radiograph (CXR) often results in inaccurate assessment of mediastinal anatomy. We aimed to evaluate 3D volume rendered computed tomographic imaging as an adjunct to standard preoperative assessment of patients requiring cardiac surgery in whom coronary artery revascularization had been performed in the past. METHODS: Between January 2003 and January 2004, 33 patients with previous coronary revascularization referred for reoperative cardiac surgery underwent preoperative 3D CT imaging in order to optimize the surgical approach. The mean age in this patient population was 72+/-8 years. The combined evaluation of CXR and conventional angiography offered incomplete insight into pertinent mediastinal topography in 85% of patients (28/33). RESULTS: The correlations for distances of the left internal mammary artery (LIMA) to left anterior descending artery (LAD) graft from the midline and posterior sternum obtained by CT angiography (CTA) and CXR were poor, R=0.56 and 0.49, respectively. The correlation coefficients for distances between the right ventricle and the aorta to the sternum obtained by the same methods were similarly marginal, 0.58 and 0.48, respectively. The correlation coefficients for distances between the LIMA to LAD, circumflex and right coronary artery grafts from the midline obtained by CTA and conventional angiography were 0.54, -0.13 and 0.43, respectively. In seven patients (21%) the surgical strategy was modified based on the location of patent grafts in the mediastinum. The hospital mortality was 17% (5/29). Intraoperative injuries to vital structures were encountered in two patients (7%). No injuries to patent LIMA or the aorta were encountered. CONCLUSIONS: The 3D CT imaging technique is useful in defining the optimal surgical strategy for reoperative cardiac surgery. We found that CTA is superior to CXR and conventional angiography in defining the position of patent grafts and vital structures in relation to the midline and posterior sternum. Preoperative mapping of patent coronary grafts and other vital mediastinal structures reduces the morbidity of the reoperation through modification of surgical approaches.