Overview
Definition:
The brachiocephalic trunk (BCT), also known as the innominate artery, is the first and largest branch of the aortic arch, supplying blood to the right side of the head, neck, and right arm
Exposure of the BCT during sternotomy is crucial for various cardiac and vascular surgical procedures
Adjuncts refer to specific techniques, instruments, or maneuvers employed to optimize visualization and safe access to this vital vessel, particularly in challenging anatomical situations or during complex reconstructions.
Epidemiology:
While variations in the origin and branching pattern of the brachiocephalic trunk are not uncommon (e.g., common origin with left common carotid artery), direct surgical intervention on the trunk itself or its branches is typically indicated for specific pathologies
The frequency of procedures requiring BCT exposure correlates with the prevalence of conditions like aortic aneurysms, dissections, atherosclerotic disease, and congenital anomalies affecting the great vessels.
Clinical Significance:
Adequate exposure of the brachiocephalic trunk is paramount for the successful execution of a wide range of surgical interventions
These include aortic arch replacement, carotid-subclavian bypass, debranching procedures for thoracoabdominal aortic aneurysms, repair of brachiocephalic arteriovenous fistulas, and management of traumatic injuries
Suboptimal exposure can lead to increased operative time, risk of injury to adjacent structures (recurrent laryngeal nerve, vagus nerve, azygos vein), and compromised surgical outcomes
Mastering these adjuncts is essential for residents preparing for DNB and NEET SS examinations in surgery.
Indications For Exposure
Aortic Arch Surgery:
Aortic arch aneurysm or dissection requiring replacement, often involving debranching of supra-aortic vessels including the BCT.
Supra Aortic Artery Disease:
Surgical revascularization for severe atherosclerotic stenosis or occlusion of the BCT or its branches, such as carotid-subclavian bypass.
Congenital Anomalies:
Repair of complex congenital heart disease involving the aortic arch and its branches, or anomalies like right-sided aortic arch with aberrant BCT origin.
Traumatic Injuries:
Management of penetrating or blunt trauma to the great vessels originating from the aortic arch.
Reconstructive Procedures:
Grafting or endarterectomy procedures requiring direct cannulation or proximal control of the BCT.
Sternotomy Adjuncts For Exposure
Instrumentation:
Use of specialized retractors (e.g., sternal spreaders with longer blades, custom-designed aortic arch retractors)
Introduction of a longer sternal saw for more proximal sternal division if needed, to improve superior access
Application of delicate vascular clamps or snares for temporary occlusion.
Patient Positioning:
Slight reverse Trendelenburg position can help in cephalad retraction of abdominal contents, facilitating better superior exposure of the mediastinum
Neck extension should be carefully managed to avoid excessive stretching of the recurrent laryngeal nerves.
Anatomical Dissection Techniques:
Meticulous dissection along the anatomical planes
Identification and preservation of the left recurrent laryngeal nerve (usually located anterior to the ligamentum arteriosum) and the right recurrent laryngeal nerve (loops around the subclavian artery)
Careful mobilization of the azygos vein
Dissection of the pleura to gain wider access superiorly.
Surgical Maneuvers:
Cautious upward retraction of the innominate vein (if encountered and uncrossed) or mobilization of the thymus can improve exposure
Sometimes, division of the left innominate vein may be necessary for enhanced visualization, but this carries its own risks and is usually avoided if possible
Use of a cardiac surgeon-assisted retracting system for consistent and stable retraction.
Imaging Guidance:
Intraoperative transesophageal echocardiography (TEE) can be invaluable for assessing great vessel anatomy, flow, and identifying potential collateral circulation or complications during exposure and manipulation
Intraoperative fluoroscopy might be used for guidewire placement in endovascular adjuncts.
Challenges And Solutions
Challenges:
Short sternal incision, obese patients, previous mediastinal surgery (adhesions), tortuous great vessels, calcification, presence of mediastinal masses or lymphadenopathy.
Solutions:
Extended median sternotomy (manubriotomy extension)
Careful use of electrocautery and blunt dissection to release adhesions
Proximal division of the sternum can be achieved with specialized saws
Use of flexible guidewires and advanced imaging for navigating tortuous vessels
Careful palpation and identification of arterial pulsations
Judicious use of vasodilators to reduce aortic pressure and facilitate proximal control.
Complications Of Exposure
Early Complications:
Hemorrhage from arterial or venous injury
Injury to adjacent nerves (recurrent laryngeal, vagus)
Air embolism
Myocardial stunning from aortic manipulation
Stroke due to embolization.
Late Complications:
Graft infection
Pseudoaneurysm formation at the anastomosis
Chronic pain
Persistent neurological deficits.
Prevention Strategies:
Meticulous surgical technique
Maintaining excellent visualization
Careful handling of instruments
Adequate systemic heparinization and reversal
Prophylactic antibiotics
Intraoperative monitoring of neurological function and hemodynamics
Careful selection of patients and techniques based on pre-operative imaging.
Key Points
Exam Focus:
Understanding the anatomical relationships of the brachiocephalic trunk to the trachea, esophagus, vagus nerve, and recurrent laryngeal nerve is critical for DNB/NEET SS
Know the indications for supra-aortic vessel exposure and the specific adjuncts used in aortic arch surgery.
Clinical Pearls:
Always identify the innominate vein before dissecting superiorly
The right recurrent laryngeal nerve is more vulnerable during BCT dissection
Consider the sequence of clamping and cannulation carefully, especially in complex aortic arch reconstructions
Flow-volume loops can sometimes be useful in assessing central airway obstruction from extrinsic compression related to BCT pathology.
Common Mistakes:
Inadequate sternal exposure leading to blind dissection
Accidental injury to the vagus or recurrent laryngeal nerves
Inadvertent damage to the innominate vein
Incomplete mobilization leading to tension on grafts
Failure to control proximal aorta adequately.