Incidence of SBI
The incidence rate of SBI was 14.9% in patients who underwent MICS with retrograde perfusion. According numbers of previous study, SBI is common in cardiac surgeries or catheterization 10. Compared to previous reports about SBI after median sternotomy, the incidence of SBI in this study was low. In the study of Sun et al., the incidence rate of SBI after median sternotomy was 29% (5). A detailed review of this report revealed that the incidence rates were 45% after on-pump coronary artery bypass grafting (CABG) 8, 47% after valve surgery 11, 31% after off-pump CABG12, 22% after catheterization of aortic valves13, 10.2% after coronary angiography14, 29% after coronary angiography and percutaneous coronary intervention 7, and 34.7% after urgent percutaneous coronary intervention 15.
The two possible causes for the low incidence of SBI in our institution were as follows: First, our criteria for femoral cannulation might have affected the incidence of SBI. At our institution, all patients underwent whole-body contrast-enhanced CT scan before surgery, and vascular properties were evaluated using our criteria. Because retrograde perfusion is not used in patients with poor vascular properties, only those with comparatively good vascular properties were included in this analysis. The second cause for the low incidence of SBI is that the thoracic cavity was filled with CO2 at the time of surgery. However, measures were taken to ensure that air does not enter the blood, and air removal was performed using left atrioventricular vent and route vent. Thus, the effect of air embolism was reduced.