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.