Preoperative 3D-reconstructions of ultrafast-CT images for the planning of minimally invasive direct coronary artery bypass operation (MIDCAB).

BACKGROUND

The direct left internal mammary artery (LIMA) bypass to the left anterior descending (LAD) without the use of extracorporal circulation through a small anterolateral thoracotomy has become established among the minimally invasive techniques in cardiac surgery. Technical difficulties may occur in patients with an enlarged left ventricle and subsequent lateral positioning of the LAD, a small LAD, or a small LIMA. We used electron beam tomography (EBT) for preoperative visualization of the topographical structures to seek out patients with potential technical difficulties.

METHODS

Eighteen patients, mean age 62 +/- 13 years, were entered in this study; in all cases the indication for revascularization was a significant stenosis of the LAD. Preoperatively an ECG-triggered EBT was performed. Following the image acquisition, a three-dimensional reconstruction of the data was performed. The LIMA, LAD, first diagonal branch, and chest wall were stained different colors for better visualization. Surgery was performed using a left anterolateral mini-thoracotomy and through this access, the LIMA was dissected and anastomosed using a stabilizer without the use of extracorporal circulation.

RESULTS

In all but one of the 18 patients who had a preoperative EBT, the minimally invasive direct coronary artery bypass (MIDCAB) procedure was successfully performed using an anterolateral mini-thoracotomy. Based on the results of the EBT, the 5 centimeter incision was done parasternally in six patients, and more laterally (2-4 cm parasternally) in the other eleven cases. In 13 patients the access penetrated the fourth intercostal space; in four cases the fifth intercostal space was used. In one patient EBT revealed a very laterally positioned and diffusely arteriosclerotic LAD so the patient was operated using a median sternotomy, but without the use of extracorporal circulation. In all 18 patients the preoperatively acquired information of the anatomical topography was confirmed intraoperatively. One case without a preoperative EBT had to be converted to a conventional procedure due to a small, intramyocardial LAD and a very small LIMA. Postoperative angiography revealed patent LIMA grafts and uneventful anastomoses.

CONCLUSIONS

For minimally invasive direct coronary artery bypass (MIDCAB) the topography of the LIMA, LAD and intercostal spaces is of major importance. Using the ECG-triggered EBT with subsequent three-dimensional reconstruction these relationships can be visualized. This enables an individual planning of the operation and a minimalization of the skin incision.