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.