Surgical Management of Acute Type A Aortic Dissection: Branch-First Technique

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Surgical Management of Acute Type A Aortic Dissection in Complicated Cases: Experience with Branch-First Aortic Arch Replacement Technique

Acute type A aortic dissection involving the aortic arch remains a life-threatening condition with high mortality rates if not promptly treated. Traditional surgical approaches, such as total arch replacement combined with stented elephant trunk implantation, have been recommended as standard therapies. However, these methods may not be suitable for all patients, particularly those with complex anatomical variations or severe complications. The branch-first aortic arch replacement technique has emerged as a viable alternative for managing these challenging cases. This article provides a comprehensive overview of this technique, its clinical application, and outcomes based on a study conducted at the Department of Thoracic and Cardiovascular Surgery, Nanjing First Hospital, Nanjing Medical University.

Background and Rationale

Acute type A aortic dissection is a medical emergency that requires immediate surgical intervention to prevent catastrophic outcomes. The involvement of the aortic arch further complicates the condition, necessitating intricate surgical strategies. Sun et al. proposed total arch replacement combined with stented elephant trunk implantation as a standard therapy for such cases. This approach involves cannulation of the right axillary artery for cardiopulmonary bypass (CPB) and selective cerebral perfusion. However, this method is not universally applicable, especially in patients with aberrant right subclavian arteries, severe involvement of the right subclavian or common carotid arteries, or acute pericardial tamponade. The branch-first aortic arch replacement technique was developed to address these limitations and has shown promising results in complex cases.

Study Design and Patient Characteristics

Between June 2017 and January 2019, 15 patients with acute type A aortic dissection underwent the branch-first aortic arch replacement technique at Nanjing First Hospital. The patient cohort included individuals with various complications: six patients presented with acute pericardial tamponade (systolic blood pressure <80 mmHg despite norepinephrine administration), four had an aberrant right subclavian artery, three had severe involvement of the right subclavian artery, and two had severe involvement of the right common carotid artery. Additionally, three patients experienced acute left or right lower limb ischemia, and two had acute bilateral lower limb ischemia. All patients underwent surgery within 24 hours of symptom onset.

Surgical Technique

The branch-first aortic arch replacement technique involves a meticulous step-by-step approach to ensure optimal outcomes. Key steps include:

  1. Monitoring and Incision: Continuous intraoperative monitoring of blood pressure in the left upper limb, left or right lower limb, and nasopharyngeal and bladder temperatures was performed. A midline sternotomy incision was made to access the thoracic cavity.

  2. Vessel Dissection and Cannulation: The innominate artery, left common carotid artery, and left subclavian artery were dissected extensively (5–6 cm). Simultaneously, the right femoral artery was exposed for cannulation. Heparinization was administered, and CPB was established via femoral artery and venous cannulation. In cases of acute pericardial tamponade, CPB was initiated immediately.

  3. Arterial Perfusion Setup: Two extracorporeal circulation arterial pump tubes were connected through a “Y” joint: one to the femoral artery and the other to a 10 mm perfusion branch of the four-branched aortic graft.

  4. Arch Branch Reconstruction: The main branch and three branches of the artificial vessel were clamped and vented. The pericardium was incised, and venous cannulation of the right atrium was performed to establish CPB. The left subclavian artery, left common carotid artery, and innominate artery were reconstructed via end-to-end anastomosis to the branches of the artificial vessel. The proximal parts of the arch branches were closed with locking clips, and the distal parts were anastomosed to the artificial vessel.

  5. Hypothermic Circulatory Arrest: When the bladder temperature reached 28°C, the ascending aorta was cross-clamped, and the heart was arrested using antegrade cold blood cardioplegia. The aortic arch was opened, and a frozen elephant trunk stent was implanted and anastomosed to the distal main trunk of the four-branched aortic graft. During this phase, lower body perfusion was halted, but whole cerebral perfusion was maintained. Cerebral oxygen saturation was monitored to adjust perfusion flow, ensuring it remained ≥70% of the pre-CPB baseline.

  6. Systemic Perfusion Restoration and Rewarming: After completing the distal anastomosis, systemic perfusion was restored, and the patient was gradually rewarmed. Proximal aortic anastomosis and other concomitant procedures were performed during the rewarming period, followed by restoration of coronary blood flow.

Concomitant Procedures and Intraoperative Data

In addition to the primary procedure, several concomitant operations were performed: one valve-sparing root replacement, three composite valve-graft root replacements, three partial aortic sinus replacements, one external shunt placement from the aorta to the right femoral artery, one closure of a patent foramen ovale, and one coronary artery bypass grafting (CABG) from the aorta to the saphenous vein to the right coronary artery (AO-SV-RCA). The mean CPB time was 133.4 ± 20.0 minutes, the mean aortic cross-clamp time was 68.1 ± 25.8 minutes, and the mean lower body circulatory arrest time was 18.3 ± 5.5 minutes (range: 14–25 minutes). The mean bladder temperature during hypothermic circulatory arrest was 27.8 ± 0.85°C (range: 26–29°C).

Outcomes and Follow-Up

All 15 patients recovered successfully and were discharged without significant permanent neurological deficits. The mean time to regain consciousness was 6 to 22 hours. One patient (6.7%) exhibited temporary neurologic dysfunction, characterized by paroxysmal mood abnormalities and confusion, which resolved before discharge. Thirteen patients (86.7%) were weaned from ventilator-assisted ventilation within 48 hours, with an intensive care unit stay of 2 to 5 days. Acute kidney injury occurred in three patients postoperatively: two showed a slight increase in serum creatinine with good urine output, and one required hemodialysis but recovered renal function before discharge.

Discussion

The branch-first aortic arch replacement technique offers several advantages over traditional methods, particularly in complex cases. It addresses challenges such as aberrant right subclavian arteries, severe involvement of arch branches, and acute pericardial tamponade. The technique ensures continuous cerebral perfusion during lower body circulatory arrest, reducing the risk of neurological complications. The mean lower body circulatory arrest time of 18.3 ± 5.5 minutes in this study was significantly shorter than that of classic total arch replacement techniques, contributing to improved outcomes.

Cerebral protection is a critical aspect of aortic arch surgery. The branch-first technique provides whole cerebral perfusion via bilateral common carotid arteries, bilateral vertebral arteries, and extracranial collaterals, minimizing the risk of stroke. The absence of permanent neurological deficits in this study underscores the effectiveness of this approach. Additionally, the reduced aortic cross-clamp time (68.1 ± 25.8 minutes) and reliance on cardioplegia further enhance patient safety and recovery.

The study also highlights the importance of timely intervention in cases of acute type A aortic dissection. Early restoration of lower limb perfusion, particularly within the “golden time” of 6 hours, maximizes functional recovery and avoids the need for additional shunting procedures. Femoral artery cannulation, used in this study, did not result in postoperative stroke, possibly due to the younger age of the patient cohort (mean age: 50.5 ± 10.2 years), which may reduce the risk of atherogenesis.

Limitations and Future Directions

This study has inherent limitations, including its retrospective design, small sample size, and potential single-surgeon bias. Further research involving larger, prospective studies and longer follow-up durations is necessary to validate the efficacy and safety of the branch-first aortic arch replacement technique. Additionally, standardized reporting of outcomes and higher levels of evidence will help establish this technique as a reliable option for managing complex cases of acute type A aortic dissection.

Conclusion

The branch-first aortic arch replacement technique represents a significant advancement in the surgical management of acute type A aortic dissection, particularly in complicated cases. It offers improved neurological outcomes, reduced mortality, and lower incidences of cerebral and other complications. The technique’s ability to address anatomical variations and severe complications makes it a valuable addition to the surgical arsenal for treating this life-threatening condition. As more centers adopt this approach and further evidence is gathered, the branch-first technique may become a standard option for aortic arch repair in patients with acute type A aortic dissection.

doi.org/10.1097/CM9.0000000000001436

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