Comment
The number of patients who require aortic valve replacement (AVR) for severe aortic stenosis (AS) has been increasing.1 When performing re-do AVR after CABG, clamping bypass grafts through median sternotomy used to be performed for sufficient myocardial protection. However, this measure imposes high risk due to severe adhesion of the patent grafts, and graft injury occurs in 5 to 50% of cases, which leads to a poor prognosis.2.4 This makes redo-AVR challenging, with a surgical mortality rate of 6-16%.2.5 Kaneko et al.3 introduced the right intercostal approach for re-do AVR after CABG with the patent left ITA. Cardioplegia was not used to avoid incomplete cardiac arrest due to washout from patent ITAs. The blood supply was completely graft-dependent and the native coronary arteries were totally occluded, therefore, it was theoretically possible to operate under beating condition. However, considering the impaired ejection fraction due to coronary arterial disease, cardiac arrest was chosen, which provides more reliable myocardial protection. In addition, as the right ventricular branch was not adequately contrasted in the preoperative coronary angiography, deep hypothermia was induced at 19°C to minimize myocardial oxygen consumption in case of poor right ventricular perfusion. Deep hypothermia at 19 °C can achieve reduced myocardial oxygen consumption by 45% compared to at 28°C.7
TAVR might be an alternative option in patients with a history of CABG. However, the long-term results and the durability of the valve remains unclear. Surgical AVR is required after TAVR in some situations including structural valve degeneration, para-valvular leakage, and complications of TAVR. Fukuhara and his colleagues2reported that 1% of patients required TAVR explantation within eight years after TAVR, more than the number of patients who had redo TAVR. Therefore, we believe it is essential for surgeons to understand the strategy for surgical AVR as a therapeutic option in post CABG patients.