Discussion
A previous study reported an in-hospital mortality of re-operative AVR after CABG of 6.4-17%1. Byrne et al. reported that the incidence of perioperative myocardial infarction, stroke, and ITA injury in re-operative AVR after CABG with single ITA is 7%, 11% and 6.8%, respectively2.
Full re-sternotomy and tissue detachment can increase the incidence of cardiac structural damage, bleeding, ITA injury, prolonged operative time, and massive transfusion and prolongs intensive care unit stay. ITA injury is associated with a mortality rate of 50% and perioperative myocardial infarction rate of 40%3.
Minimally invasive re-operative AVR (MIrAVR), via a partial sternotomy (upper, lower, or inverted T-shaped) and right mini thoracotomy is an alternative approach to the conventional strategy. Since minimally invasive access to the aortic valve was first reported in 1996, it has become the standard approach for aortic valve surgery4. The smaller surgical scar achieves early ventilator weaning, lesser wound pain, lesser bleeding, and shorter hospital stay compared with a full sternotomy5. Moreover, in patients with a high risk of postoperative mediastinitis, such as those with diabetes, chronic renal failure, frailty, and chronic obstructive pulmonary disease, the risk may be reduced by making the sternotomy as small as possible. For successfully achieving MIrAVR, preoperative evaluation of the graft routes, positional relationship between grafts and mediastinal structures, and extent of tissue adhesion using computed tomography is important. In this case, the ITA was located near the aorta; thus, it was determined that ITA identification was possible with minimal dissection of adhesions through a partial upper sternal incision. However, if graft dissection is difficult, surgery under hypothermic ventricular fibrillation, balloon occlusion of the ITA graft, or securing the ITA via a left axillary approach should be considered. However, hypothermia may increase bleeding due to prolonged extracorporeal circulation time, and the balloon may cause ITA injury 2,6,7.
Transcatheter aortic valve implantation (TAVI) is aggressively performed in high-risk patients, such as very elderly or frail patients, and those with hepatic cirrhosis, chronic obstructive pulmonary disease, and bleeding tendency8. A study comparing the outcomes of re-operative AVR after CABG and TAVI suggested that when transfemoral TAVI is not possible, it may be not the best option on behalf of re-operative AVR9. In this case, it was considered that TAVI would have worse outcomes than re-operative AVR due to ASO.