Aortic arch replacement for degenerative aneurysms: advances during the last decade.

During the last decade, treatment paradigm for degenerative aortic arch aneurysms has been changed by a better understanding of the pathophysiology of brain complication and introduction of endovascular technologies. To avoid neurocognitive dysfunction, safe duration of deep hypothermic circulatory arrest is now considered <25 min, and retrograde cerebral perfusion became less frequently used. Selective cerebral perfusion (SCP) is not associated with neurocognitive decline unless profound hypothermia (<20 °C) is used, which may suggest profound hypothermic SCP is not advantageous but may be detrimental. Attempts have been made to use mild to moderate hypothermia during SCP, and safe duration of distal circulatory arrest seems <60 min at 28 °C to avoid ischemic spinal cord injury. Three-vessel perfusion seems advantageous to provide adequate brain and spinal cord protection. To avoid aortogenic brain atheroembolism in the high risk patients, we previously proposed the "isolation" technique, where SCP is established before systemic perfusion. This technique has subsequently been modified to use both axillary and left carotid arteries for systemic arterial return, so that aortogenic emboli may not enter the brain circulation. In the TEVAR (thoracic endovascular aortic repair) era, hybrid operations such as the frozen elephant trunk or TEVAR completion after the elephant trunk are increasingly performed for extensive or distal arch aneurysms. It should be noted, however, that the frozen elephant trunk operation for extensive aneurysms carries an increased risk of paraplegia, and for distal arch aneurysms its outcome is not better than that after the standard open repair in Japan.