https://orcid.org/0009-0005-6682-7670
Abstract
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.
Introduction
Perfusion during aortic arch surgery can present unique technical challenges in the presence of altered vascular anatomy. ACTA2-associated aortopathy is a form of familial thoracic aortic disease that commonly presents at young age and is often complicated by concomitant aneurysmal dilatation, aortic rupture, or dissection-related limb ischemia requiring surgical intervention [1]. We describe a case of compromised circulatory arrest due to atypical perfusion physiology arising from prior extra-anatomic bypass grafts in a patient with ACTA2 aortopathy undergoing mechanical aortic root replacement and arch replacement with frozen elephant trunk (FET).
Case report
A 40-year-old male with hypertension, known ACTA2 mutation (c.445C > T), and family history of aortic dissection and sudden death sustained a Stanford type B dissection at 15 years old managed with zone 3–5 thoracic endovascular aortic repair (TEVAR). The procedure was complicated by limb malperfusion, necessitating post-TEVAR right axillofemoral and femoral-femoralbypass grafting (Fig. 1A and B). He remained asymptomatic on anti-impulse therapy with nifedipine, losartan, and metoprolol without functional limitations. Twenty-five years later, surveillance computed tomography (CT) angiography demonstrated progressive aortic root enlargement with sinuses of Valsalva measuring 4.0 cm, sinotubular junction 4.8 cm, mid-ascending aorta 4.5 cm, and a 3.8 cm zone 3 outpouching with persistent false lumen perfusion, and interval growth of dissected infrarenal abdominal aortic aneurysm to 4.9 cm. Given his ACTA2 aortopathy, significant family history, and progressive aneurysmal dilatation, early surgical intervention was pursued to mitigate risk of aortic complications.
Extra-anatomic bypasses. Right axillofemoral bypass (A), femoral-femoral bypass (B), and left carotid-subclavian bypass grafting (C).
To facilitate distal arch repair, staged left subclavian-to-carotid artery bypass was performed (Fig. 1C). Thoracic aortic repair was subsequently pursued. Proximally, preoperative and intraoperative echocardiography demonstrated an asymmetric bicuspid aortic valve unfit for repair, and mechanical root replacement was indicated. Due to persistent false lumen perfusion at zone 3, total arch, and FET were deemed appropriate at a target hypothermic circulatory arrest temperature of 22°C. Given the presence of a right axillofemoral bypass, cardiopulmonary bypass was established via left axillary arterial cannulation. The sternum was opened, arch vessels dissected, pericardium opened, and central venous cannulation was performed before commencing cardiopulmonary bypass. The aorta was cross-clamped with myocardial protection achieved using antegrade and retrograde cardioplegia. The aortic root was dissected out with subsequent creation of coronary buttons. At the target systemic temperature, the supra-aortic arch vessels were clamped, and hypothermic circulatory arrest was initiated with antegrade cerebral perfusion (ACP) via the left axillary artery at a mean flow rate of 900 mL/min. Cerebral oximetry was monitored throughout circulatory arrest, with mean bilateral cerebral oxygen saturations (rSO2) maintained above 65%. Transcranial Doppler ultrasound was not used.
The aortic arch was transected at zone 2, exposing prior TEVAR stent, at which point significant operative field flooding was encountered. After brief troubleshooting, it became evident that blood was preferentially flowing from the left axillary cannulation site through an intact Circle of Willis, down the right axillary artery, through patent axillofemoral and femoral-femoral bypass grafts, and up the abdominal and descending thoracic aorta, ultimately flooding the operative field. Flooding was promptly controlled with manual right femoral artery compression to restore a bloodless field during circulatory arrest and to maintain optimal cerebral arterial perfusion, with stable bilateral cerebral oximetry throughout. A 30/40 mm Thoraflex Hybrid FET (Terumo Aortic, Inchinnan, UK) was deployed into the proximal descending thoracic aorta. Left common carotid and brachiocephalic arteries were reimplanted via end-to-end branch anastomoses. A mechanical aortic root replacement was performed using a 23 mm On-X valved conduit (Artivion On-X Life Technologies, Austin, TX) with coronary button reimplantation. Cardiopulmonary bypass, aortic cross-clamp, and circulatory arrest durations were 313, 268, and 20 min, respectively. The remaining operation was completed in standard fashion.
His postoperative course was complicated by anuric acute renal failure requiring continuous renal replacement therapy for 2 weeks, with gradual renal function recovery prior to discharge. His course was further prolonged by severe acute pancreatitis, paroxysmal atrial fibrillation, mild hoarseness, and transient left arm weakness without radiographic evidence of acute cerebral infarction. He was discharged in stable condition on postoperative day 42, and returned to his baseline functional status with stable repair on CT angiography at 4-month follow-up.
Discussion
ACTA2-associated aortopathy is characterized by early disease onset, accelerated aneurysmal progression, and increased risk of dissection or rupture at smaller aortic diameters [1]. The high incidence of ACTA2-associated dissections at aortic root or ascending diameters below 5.0 cm informs consensus recommendations for elective repair at ≥4.5 cm, with earlier intervention supported in family history of type A dissection [2]. In our patient, progressive aortic root enlargement to 4.8 cm, coupled with family history of dissection and sudden death, warranted early intervention despite being asymptomatic.
The presence of multiple prior extra-anatomic bypass grafts introduced unique and clinically consequential perfusion considerations during circulatory arrest. In unilateral ACP, vascular steal may occur when competing low-resistance pathways are present, a phenomenon commonly described with patent contralateral carotid runoff [3]. We describe a rare manifestation of altered perfusion physiology characterized by preferential flow diversion into right axillofemoral and femoral-femoral bypass grafts, forming a low-resistance parallel outflow tract during left axillary ACP. This configuration permitted systemic runoff with retrograde aortic filling, precluding a bloodless operative field, compromising cerebral protection and increasing technical complexity during circulatory arrest. Extra-anatomic bypasses may mimic steal-like physiology, influence cannulation strategy, and compromise effective circulatory arrest. Options for distal control include temporary manual compression, graft snaring, clamping, or balloon occlusion of peripheral conduits to reduce systemic runoff.
Patients with prior aortic or vascular interventions warrant preoperative assessment of peripheral bypasses that may alter perfusion patterns during circulatory arrest. Anticipation of atypical outflow circuits enables tailored cannulation strategies and, in case of compromised circulatory arrest, rapid identification and control of runoff, restoring a bloodless field while preserving cerebral perfusion.
Conflicts of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Data availability
Non-identifying information may be provided by the corresponding author upon reasonable request.
Ethical considerations
Our institution does not require ethics IRB approval for case reports.
Consent to participate
Patient provided written informed consent for use of information.
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Patient provided written informed consent for publication.
