Lessons learned from robotic-assisted coronary artery bypass surgery: risk factors for conversion to median sternotomy.

Objective: Robotic-assisted coronary artery bypass is a minimally invasive alternative to traditional coronary artery bypass surgery via median sternotomy with an associated learning curve. The purpose of this study was to investigate the reasons for conversion to sternotomy.

Methods: From October 2009 to June 2012, two surgeons at one US academic institution performed 271 consecutive robotic-assisted coronary artery bypass procedures. For all cases, isolated, off-pump left internal mammary artery (LIMA) to left anterior descending coronary artery grafting was planned via a 3- to 4-cm sternal-sparing thoracotomy after robotic internal mammary artery harvest and pericardiotomy.

Results: Conversion to sternotomy occurred in 15 of 271 (5.5%) patients. The most common reason was technical difficulty with the anastomosis, which occurred in 6 (40.0%) patients. Others included LIMA dissection, 2 (13.3%); wrong vessel grafted, 2 (13.3%); ventricular fibrillation and cardiac arrest, 1 (6.7%); equipment malfunction, 1 (6.7%); adhesions, 1 (6.7%); and other. Two underwent emergent conversion. Six underwent multivessel bypass after conversion instead of hybrid coronary revascularization. No mortality occurred among converted patients. Two patients had postoperative myocardial infarction and one had a superficial sternal wound infection. Conversion rate was relatively stable among the four different time quartiles (range, 3.0%-7.4%), although the reasons for conversion were different.

Conclusions: Conversion to sternotomy is an infrequent complication of robotic-assisted coronary artery bypass, most commonly because of technical difficulties during the LIMA harvest and the LIMA to left anterior descending anastomosis. Anatomic and patient variables as well as inherent technical problems with minimally invasive procedures make conversion unavoidable in some patients.