All patients who reach the hospital alive following penetrating thoracic aortic trauma will require repair. Historically, the indication for surgery for BTAI has also been the presence of an injury. However, with advances in imaging and the widespread application of MDCT in the emergency department, more minor intimal injuries are being diagnosed. A number of grading systems have been proposed to assess the need for and urgency of repair. We favor the grading system adopted by the Society for Vascular Surgery and published as clinical practice guidelines, although there is still debate regarding the relative significance of stable intramural hematomas and small pseudoaneurysms (Fig. 24.1).

Grade I injuries have a high probability of healing and are generally treated with impulse control using intravenous (IV) beta blockade with esmolol, labetalol, or metoprolol to maintain heart rate (HR) below 80 beats per minute and systolic blood pressure (BP) less than 120 mm Hg (or mean arterial pressure [MAP] less than 80 mm Hg). An IV vasodilator such as nicardipine or nipride is added if BP control is inadequate with beta blockade alone. Aggressive pain management is another critical component of HR and BP control. Repeat CTA in 72 hours, or sooner if chest or back pain occurs, should be done to assess for progression or dissection. An additional CTA should be obtained 6 weeks later to assure healing or stability.

Grade II and III injuries should be repaired during the index hospitalization, and the remaining question is one of timing and technique. With adequate impulse control, associated injuries should be managed first. Indeed, numerous reports have found improved survival and, more recently, improved neurologic outcomes when a delayed repair (>24 hours after admission) strategy is used, despite longer ICU stays.

Grade IV injuries require emergency repair as soon as other life-threatening injuries have been addressed. Intra-abdominal injuries or hemorrhage should be controlled at laparotomy. Hemorrhage from long bone or pelvic fractures should be controlled with appropriate embolization or fixation.

Most centers favor thoracic endovascular aortic repair (TEVAR) over open repair for BTAI. The advantages of TEVAR include avoidance of thoracotomy and single-lung ventilation, reduced risk of spinal cord injury, and decreased mortality. However, since TEVAR is not available at all centers both open and endovascular surgical techniques will be described below.

There are few absolute contraindications to repair following BTAI aside from uncontrolled hemorrhage or evidence of brain death. Other sources of bleeding should be controlled prior to aortic repair. Severe pulmonary contusions limit the ability to perform open surgical repair with single-lung ventilation, therefore, TEVAR and/or delayed repair should be considered.

A well timed contrast-enhanced CT scan of the aorta from thoracic inlet to bifurcation will provide all the information needed to plan open repair. It is critical to examine the entire aorta. While multiple injuries are uncommon they can occur, and the extent of intramural hematoma or dissection must be defined to achieve complete repair.

Concomitant injuries must be identified and active bleeding from other sources controlled prior to aortic repair. Traumatic brain injury (TBI) should be identified by CT and the relative risk of morbidity or death from aortic versus brain injury considered. Vertebral fractures threatening the spinal cord can also be identified by CT scan and facilitate appropriate planning for stabilization of the spine. Once all concomitant injuries are defined and life-threatening injuries are controlled, aortic repair may proceed.

Preoperative planning is critical for procedural success in TEVAR. Software programs allow for the review of multiplanar reconstructions (MPRs), centerline (orthogonal) measurements, and three-dimensional representations of the aorta using the data obtained during CTA. This allows the surgeon to determine the exact location and extent of the injury, the presence of suitable landing zones proximally and distally, the configuration and size of the rest of the aorta, and the size and calcium burden of the iliofemoral vessels with regard to vascular access and sheath or device placement. A proximal landing zone of 2 cm is preferred and the landing zone may be increased with intentional coverage of the left subclavian artery (LSA). For this reason the arterial BP line should be placed in the right radial artery. In addition, attention should be paid to the relative sizes of the vertebral arteries or an anomalous vertebral artery origin off of the arch. In the presence of a patent left internal mammary graft from prior coronary artery bypass grafting, the LSA cannot be covered and open repair may be necessary if the landing zone is otherwise inadequate.

Patients treated for BTAI tend to be younger than those for whom stent grafts were developed for aneurysmal disease, and as such their aortas and iliofemoral vessels are often smaller and may be outside the range of commercially available thoracic aortic stent grafts. Devices with a specific indication from the United States Food and Drug Administration (FDA) to treat TAI include the Gore Conformable TAG and the Medtronic Valiant stent grafts. This allows for the treatment of aortas ranging in size from 16 to 44 mm. The Cook Zenith TX2 graft and the Bolton Relay Plus (Sunrise, FL) are approved by the FDA but their use for trauma would be considered off-label. Abdominal cuffs or iliac extension limbs may be placed in smaller aortas but their delivery systems are shorter and may require retroperitoneal iliac or distal aortic access.

The debate regarding the “clamp and sew” technique versus various methods of distal aortic perfusion has largely been settled. The rate of spinal card injury has reliably been decreased with the adjunct of bypass to provide continuous perfusion of the distal aorta
and hence the distal spinal cord. We favor partial left heart bypass using a heparin-bonded circuit to minimize heparinization. With this circuit partial bypass may be safely performed with an activated clotting time (ACT) >250 seconds.