PORT-ACCESS BILATERAL INTERNAL MAMMARY ARTERY GRAFTING FOR LEFT MAIN CORONARY-ARTERY DISEASE - CANINE FEASIBILITY STUDY

Background: To extend the applications of minimal access cardiac surge ry, an endovascular cardiopulmonary bypass (CPB) system that allows ca rdioplegia delivery and cardiac venting was used to perform bilateral internal mammary artery (IMA) bypass grafting in six dogs. Methods: Th e left IMA (LIMA) was taken down thoracoscopically from three left lat eral chest ports, followed by the right IMA (RIMA) from the right side . One left-sided port was extended medially 5 cm with or without rib r esection, to expose the pericardium. Both IMAs were divided and exteri orized through the left anterior mediastinotomy. Flow and pedicle leng th were satisfactory in all cases. Femoral-femoral bypass was used and the heart arrested with antegrade delivery of cardioplegic solution v ia the central lumen of a balloon catheter inflated to occlude the asc ending aorta. All anastomoses were made through the mediastinotomy und er direct vision. In five studies the RIMA was attached to the left an terior descending artery (LAD) and the LIMA to the circumflex, and in one study the RIMA was tunneled through the transverse sinus to the ci rcumflex and the LIMA was anastomosed to the LAD. All animals were wea ned from CPB in sinus rhythm without inotropes. CPB duration was 108 /- 27 minutes (mean +/- SD) and the clamp duration was 54 +/- 10 minut es. Results: Preoperative and postoperative cardiac outputs were 2.9 /- 0.71/min and 2.4 +/- 0.31/min, respectively (p = NS), and correspon ding pulmonary artery occlusion pressures were 6 +/- 3 mmHg and 7 +/- 2 mmHg, respectively (p = NS). All 12 grafts were demonstrated to be f ully patent. Postmortem examination revealed well aligned pedicles and correctly grafted target vessels. Conclusion: This canine model demon strates the potential for a less invasive approach to the surgical man agement of left main coronary artery disease in humans.