Atypical perfusion compromising circulatory arrest during mechanical root replacement and aortic arch replacement with frozen elephant trunk in ACTA2 aortopathy.

Perfusion during aortic arch surgery may be uniquely complicated by atypical vascular anatomy in patients with prior extra-anatomic bypass grafts. We describe a case of compromised circulatory arrest in a 40-year-old male with ACTA2 aortopathy who previously underwent thoracic endovascular aortic repair, complicated by limb ischemia requiring right axillofemoral and femoral-femoral bypass grafts. Twenty-five years later, progressive aortic root enlargement and zone 3 false lumen perfusion prompted staged left carotid-subclavian bypass, followed by mechanical aortic root and arch replacement with frozen elephant trunk. During circulatory arrest, parallel outflow via patent bypasses flooded the operative field, necessitating right femoral arterial control preserving cerebral perfusion and bloodless field. Extra-anatomic bypass grafts may form low-resistance circuits mimicking steal physiology, and distal control including manual compression, graft snaring, clamping, or balloon occlusion should be anticipated. Preoperative recognition of extra-anatomic bypasses therefore enables tailored perfusion strategies to optimize cerebral perfusion and operative conditions.