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.