Myocardial protection strategy for conventional aortic valve replacement following previous coronary surgery: should it be patient-specific?

Abstract

We read with great interest the recent article by Park et al. [1] regarding outcomes in patients who underwent isolated aortic valve replacement (AVR) in a redo setting with a patent internal thoracic artery (ITA). They further analysed the impact of ITA control on patient outcome, concluding that not impeding ITA blood flow and allowing thus myocardial perfusion was associated with improved outcomes. Myocardial territories at the borders of ITA distribution are traditionally considered prone to ischaemic changes due to an incomplete cardioplegic effect. Although ITA control aims at preventing cardioplegia ‘washout’ to achieve adequate cardioplegic arrest, this was early associated with a substantial risk of graft injury and associated mortality. A number of approaches have been developed to address myocardial protection in this anatomically complex group, including various on-pump beating heart approaches. These incorporate pure retrograde perfusion of normothermic oxygenated blood [2, 3] as well as simultaneous retrograde and antegrade blood perfusion, according to individual patient anatomy [4]. Furthermore, if previous revascularization provides sufficient perfusion of all myocardial territories, retrograde and/ or antegrade blood perfusion may be avoided entirely with safety [2, 5]. We have described a case of AVR in the presence of bilateral patent ITAs with the use of cross-clamp fibrillation [6]. Perfusion temperature ranged from 32°C to normothermia in these series. The authors used cold blood cardioplegia in all patients [1]. Retrograde and/or antegrade perfusion with oxygenated blood appears to provide myocardial protection and optimal conditions for performing conventional AVR in selected patients. From the technical standpoint, potential washout from the coronary ostia is easily manageable with simple measures, as already described in the literature. Appreciating the limitations of a retrospective study in this complex entity, we would like to enquire if the authors have modified their approach in recent years in regard to achieving myocardial protection. We commend the authors on their outstanding results.