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Trauma to the major vascular structures of the thoracic cavity is caused by either penetrating mechanisms or acceleration–deceleration forces that tear vascular structures that are fixed within the thoracic cavity. Less than 10% of blunt injuries and only 15% to 30% of penetrating injuries in the thoracic cavity will require thoracotomy.1 Traditionally, of the patients receiving thoracotomy, only 25% will have a thoracic vascular injury.2 While penetrating injuries may damage any thoracic vascular structure, blunt injuries typically only impact the thoracic aorta, innominate artery, and intercostal vessels. Both blunt and penetrating vascular trauma to the chest can be lethal. However, most thoracic vascular injuries will require only airway management and thoracostomy tube for the drainage of the resulting hemothorax.1
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THORACIC CAVITY ANATOMY
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The thoracic cavity is an articulating musculoskeletal framework that houses the aerodigestive tract, lungs, heart, and great vessels. Because this is a dynamic cavity designed for both active and passive ventilation, the position of the rib cage changes during the respiratory cycle. The greatest thoracic cavity mobility is noted between ribs 7 and 10. Therefore, it should be understood that this is where most fractures occur. The next most common fractures occur at ribs 4 to 6. Hence, these intercostal vessels are the most susceptible to injury and hemorrhage. The muscular covering of the thorax includes the pectoralis major and minor muscles anteriorly, the latissimus dorsi and serratus anterior muscles laterally, and the trapezius, levator scapulae, serratus posterior rhomboid major and minor, latissimus dorsi muscles posteriorly. These muscles provide a protective coat to the rib cage and help to define a very well-protected superior anterior and posterior section of the rib cage versus a less well-protected inferior anterior and lateral sections. This anatomical structure explains why most rib fractures will occur in the lateral or anterolateral section and less in the posterior section. Penetrating trauma occurring between the nipples and the clavicles and sternocostal margin or the “cardiac box” is particularly concerning because of the underlying great vessel and cardiac structures. Blunt trauma that arises from an acceleration–deceleration mechanism can produce the “ripping” force that tears the descending aorta between the ligamentum arteriosum and the left subclavian artery. These are the two major anatomical considerations for the most severe thoracic vascular injuries.
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Blunt trauma is the most common source of injury to thoracic vascular structures. Blunt trauma mechanisms causing thoracic vascular injuries are usually fall from heights, motor vehicle or motorcycle collisions, or sky accidents. The innominate artery origin, pulmonary veins, vena cava, and most commonly the descending thoracic aorta are particularly at risk from blunt trauma. The recognized mechanisms of blunt great vessel injury include the following: a) shear forces, b) compressive forces, and c) intraluminal hypertension at the time of the trauma. Shearing forces primarily cause injury due to the relative increased mobility of the thoracic ...