LEFT SUBCLAVIAN ARTERY RUPTURE DUE TO BLUNT THORACIC TRAUMA: A CASE REPORT

Blunt thoracic trauma highest incidence is in adult, 20% to 50 % of the trauma cause death. Injuries to the vascular structures of the thoracic outlet, especially left subclavian artery, are rare and typically accompanied by massive hemorrhage. Close observation of vital sign and serial chest x-ray are very important. We describe an unusual presentation of a patient who suffered traumatic rupture ofleft subclavian artery. No clinical presentation of supraclavicular hematoma, unilateral absence of radial artery pulse and mediastinal widening in chest x-ray was found, but there is a massive hemothorax. Left posterolateral thoracotomy was performed, the source of bleeding was found in the apex of the lung, suspected a rupture of the left subclavian artery. The procedure continued with median sternotomy extended to left supraclavicular incision, a rupture was found in the left subclavian artery, 1,5 cm proximal to aortic arch. Primary repair was done with a good result.


Introduction
Blunt thoracic trauma is seen frequently and it is one of the major injuries resulting in death in young people.The most frequent cause of trauma is motor vehicle accident.If thoracic injury is suspected, treatment of potentially fatal injuries must be prioritized.Approximately 20% to 25% of traumatic deaths at the scene of accidentare causedby isolated thoracic trauma.Twenty-five of every 100.000trauma victims die following the trauma.Deaths are often due to airway obstruction, hemorrhage, flail chest, tensionpneumothorax, cardiac tamponade, and associated intra-abdominaland skeletal injuries.Injuries to the vascular structures of thoracic outlet, especially left subclavian artery, are rare, accounting for only 1% to 2%of all vascular traumaand are typically accompanied by massive hemorrhage. (1,2,3,4,5,6) Associated organ injuries raise mortality.Involvement of heart, lung and great vessels will increase mortality. Closed observation of vital signs and serial chest radiographs are essential in monitoring such patients. Sometimes tube thoracostomy maybe needed for effective treatment. Hemodynamically unstable patients with cardiac and great vessel injuries, massive intrathoracic haemorrhage,tracheobronchial or diaphragmatic rupture may need urgent surgical Emergency Thoracotomy (ET). (3,7,8) This procedure (ET) isadopted from the Advanced Trauma Life Support(ATLS) management of penetrating chest injuries and selected cases of blunt thoracic trauma. The objectives of ET are to release pericardial tamponade, prevent air embolism, control massive intrathoracic or intraabdominal haemorrhage, and provide access for open cardiac massage and descending thoracic aortic cross-clamping. Majority of the cases are hemodynamicallystable on the scene, or are resuscitated using the ATLS protocol. Emergency thoracotomy is a life saving procedure in critically injured patients who presents with no detectable pulse or blood pressure following chest trauma. (8) We present a caseof 35 year-old-man with blunt chest trauma, resulting in left traumatic subclavian artery rupture with an unusualclinical presentation, whom underwent successful primary repair.

Case Report
A 35-year-old man came to our emergency department unit, had a bajaj collision with a bus coming from the left opposite direction. The patient was conscious and well orientated on admission, with a normal Glasgow coma scale. On primary survey,shorteness of breath, asymmetrical movement of hemithorax, decreased left fremitus, and hypersonor percussion was found, tension pneumothorax was suspected. Needle thoracosintesis was performed, a large bore needle was inserted at the 2 nd intercostal space midclavicular line, followed byinsertion of chest tube with initial drainage of 200 ml blood and minor air leak. Despite these injuries, the patient respiratory status and blood pressure was remained stable. On secondary survey, no bruise or supraclavicular hematoma on anterior chestand unilateral absence of radial artery pulse was found.The patient complaint to felt pain on his left hip joint, there is adduction, flexion, endorotation, no shortening and neurovascular distal disturbance.Closed reduction and skin traction was done due to anterior hip joint displacement.
Left hemopneumothorax, 1 st and 2 nd ribs fractures in left hemithorax was demostrated on chest radiographs. No sign of mediastinal widening, scapular fracture and hematoma at the apex of the lung was found. Left acetabular fracture and left femoral head dislocation was seen in pelvic radiograph. Laboratory findings shows haemoglobinlevel of12,8 gr/dl, hematocryte 38%, leucocyte 27.700/l. On observation period, instability of haemodynamic happened. The patient wasresuscitated with crystalloid and colloid solution, 800 ml blood was drained from chest tube.Sign of massive hemothorax and on going bleeding intra thoracic cavity was found, haemoglobin level was decreased to 5,5 gr/dl. Emergency left posterolateral thoracotomywas performed, intra thoracic cavity was entered through 5 th intercostal space. About 500 ml ofblood clot was found at the basis of the lung, and was also found at the apex of the lung. Source of the bleeding was suspected in apex of the lung andrupture of the left subclavian artery. The procedure continued with median sternotomy extended to left supraclavicular incision. In exploration, aortic arch, innominate artery, right and left carotid artery was intact, but there wasa rupture with active bleeding from left subclavian artery, 1,5 cm proximal to aortic arch.Primary repair was done with a good result. Postoperative, the patient's condition improved dramatically. He was extubated on the 1 st postoperative day in Cardiothoracic ICU, and was discharged home on the 10 th postoperative day, with the chest radiograph showing good lung expansion.  There is no wound dehiscence.

Discussion
Trauma is the leading cause of death among people younger than 40 years of age. Blunt thoracic trauma is seen frequently in society and also one of the major injuries resulting in death in younger people. Road traffic accidents were the main cause of injury, followed by domestic falls and labour accidents. Outdoor falls and sport accidents accounted for a small number of injuries.The increasing incidence of high-speed road accidents has important repercussions on the number of thoracic injuries admitted to hospital. It is widely accepted that 25% of all traumaticdeaths are due to thoracic injuries and that significant chest trauma is present in 50% of fatal traffic accidents. In a review of the management of chest trauma, Adebonojolet all noted that 10% of patients with chest injury died at the site of the accident, and 5% died within 1 hour of arrival at the hospital. He also found a 5% rate of thoracotomy in such patients. (1,3,9,10,11) Table 3. Etiology of blunt thoracic trauma. The most commonetiology is traffic accidents. The most common organ injuries are lung and chest wall. The chest wall and the soft tissues are the locations most commonly affected by blunt traumas. Although most of the fractures of bony thorax are benign entities and can be treated without hospitalization, trauma limited to the thoracic cage itself may cause profound pathophysiological alterations, which may be fatal if not promptly treated. On the other hand, the accurate identification of patient at high risk for major chest trauma is essential for regulation of over and under triage within atrauma system. Chest pain and dyspnea were the most common symptoms at presentation whereas sensitivity over the chest wall, bone crepitation and subcutaneous emphysema were the most common findings on physical examination. Soft tissue trauma and rib fractures were the most common problems observed following blunt thoracic traumas. Non-penetrating chest injuries are seen frequently in civil populations. Rib fractures are reported as the most common pathologies associated with chest trauma (35-40%). (11) The presence of 1 st or 2 nd ribs, or more than two rib fractures is a marker of severe injury and is the most common type of injury in blunt chest trauma, and intrapleural collection is the most frequently associated pathology. Chest tube insertion has significant role as the single most important treatment modality for chest trauma.Mortalityrate was 0.2% in patients with no rib fractures versus 4.7% in patients with more than two rib fractures. Lee reported that mortality doubles (1.8% vs 3.9%) for patients with three or more rib fractures and those with no rib fractures. Poole reviewed all series of fractures of first and second ribs and found a 3% risk for aortic injury and a 4.5% risk for injury of brachiocephalic and subclavian vessels. Hospital mortality rate for isolated chest injuries were reported to range from 4-8%, and increased to 13-15% when another organ system was involved, and to 30-35% when more than one organ system was involved. Lee et all reported the mortality rate as 1.8% in all patients with blunt chest trauma. An ISS of 16 or more has been taken as the cut-off value defining major trauma.Death was also occured due to associated head injury. (9,11,12,13) Associated organ injuries such as heart injuries or ruptured of great vessel increase mortality.   (14) . The absence of physical signs of thoracic trauma, such as mediastinal widening in chest radiograph, doesn't mean that there is no internal thoracic injury. Pulmonary parenchymal injury following blunt thoracic trauma have several mechanisms; (1) deceleration effects on the unfixed structures in the chest; (2) bidirectional compression between the sternum and vertebral bodies; (3) indirect force from the abdomen which increases intrathoracic pressure and produces rupture; (4) laceration by fractured ribs and (5) blast forces. (10,14) Mechanisms of vascular injury of blunt thoracic trauma can include avulsion or traction injury from stretch or rotational stress, compression, or contusion from a direct blow, and laceration from fractures of adjacent ribs or clavicle (6) Most traumatic great vessel disruptions that present for repair occur at the aortic isthmus near the ligamentum arteriosum and just distal to the left subclavian artery.These injuries are best approached through a posterolateral thoracotomy in the 4 th intercostal space. (15) The patient in this case report had traffic accident, was concious and well oriented in admission, sustained bidirectional compression on his chest. The patienthad shorteness of breath, was confirmed as tension pneumothorax.Large bore needle was inserted,continued with insertion of chest tube to drain blood. This management was based on ATLS protocols. First and second rib fractures was found in chest radiograph, but no mediastinal widening was found. Respiratory status and blood pressure maintained stable. The mechanism of the trauma was the same as in the literature mentioned above.
This lethal injuries is due to combination of direct compression, indirect compression and deceleration forces, which typically cause a transverse disruption of all three layers of the great vessel wall and it's branch, especially left subclavian artery. The aortic isthmus (limited in its mobility by the ligamentum arteriosum, the paired intercostal arteries, and the left main stem bronchus) is the site of disruption in 93% to 95% of all blunt great vesselinjuries who was survived. In contrast, survival after disruption of the aortic arch is extremely rare. The majority of patients sustaining aortic great vessel injuries die at the scene of accident. Of approximately 15% of the patients who survive the initial injury, the leading cause of in-hospital mortality is exsanguinating great vessel rupture occurring in 20% of these patients. Survival depends upon prompt diagnosis and repair. (10) Blunt injuries to branches of the great vessels, which is subclavian artery, may be suspected clinically, are not unusual and must beconsidered in any patient surviving deceleration or crush injury. Hemodynamically stable patients should undergo a high resolution contrastcomputed tomography(CT) of the chest which is the initial method of choice. (15,16) Clinical presentation for patient with suspected of subclavian artery injuries are listed below (18) :  Bruishing over anterior chest  Limb ischemia  Thoracic outlet hematoma  Discrepancies in pulses and blood pressure between the two arms Sign of subclavian artery injuries or great vessel injuries in blunt thoracic trauma that can be found in chest radiographs are also listed below (18) : Such injury should always be suspected in major trauma where there are fractures of the first, second and third ribs. An early chest radiograph (antero-posterior view) is obtained in the receiving area inall victims of either blunt chest trauma or decelerating traumawith or without evidence of chest injury. Mediastinal widening is the most frequent manifestation ofgreat vessel injury,and is the key of diagnosis. Angiography is the next diagnostic modality to perform whenany mediastinal abnormality is seen on the chest radiograph. Angiography remains the gold standard for the diagnosis of stable patients with thoracic vascular injury. Angiography provides the detailed anatomic information necessary for planning the operative approach. However, they may remain undetected until the fatal rupture of the mediastinal hematoma occur. Clinical presentation such as absent of upper extremity pulses, sudden hemothorax, left supraclavicular swellingand persistent hypotensionare also an indication for immediate angiography. (17) Relative indications for angiographyinclude brachial plexus palsy, apical pleural hematoma, and fracture of1 st rib. (7) The use of angiographyis to delineatethe entire thoracic aorta; this will define the anatomy of the injury that may not always be made clear on computerised tomography. (5,7,13,16,18,19,20,21) Clinical presentation in our patient was not usual like stated in literature. The patient did not have bruising on anterior chest, limb ischemia, discrepancies in pulses and blood pressure between the two arms, or widening of the mediastinum on chest radiograph, but fractures of the first and secondribs on chest radiograph was found, presented with massive hemopneumothorax and was hemodynamically unstable. ET was performed without any suspicious of great vessel injury. Large amount of blood clot at the basis and at the apex of the lung was found, suspected left subclavian artery ruptured, continued with median sternotomy extended to left supraclavicular incision.
Angiography should have been done first before the surgery, if injuries to the great vessels is suspectedbased on clinical presentation in orderto make a good plan for the surgery.Since the patient had unusual clinical presentation and was hemodynamically unstable, it was decided to performed ET for live saving.
Therapyis given based on priority when an injuryappears to be life-threatening,such as in the event ofairway obstruction, external or intraabdominalhemorrhage, or continuing intracranial bleeding. (7,22) Medical therapy include intravenous infusion of vasodilator(usually nitroprusside), attempted limitation of intravenousadministration of fluids once the blood pressure exceeds 90mmHg, and the administration of ß-blocker whenthe pulse rate exceeds 85-90 beats/min. Medical managementis continued while diagnostic studies or other surgical proceduresperformed, or until the patient with proven rupturehas been placed on cardiopulmonary bypass. (22) Successful repair was performed with autogenous saphenous vein.A high degree of clinical suspicion is necessary to detect subclavian arterytransection from blunt trauma because of the location of thisinjury, lack of initial bleeding, and the rich collateral bloodsupply to the arm. (17) Although prevention and treatment of pulmonary damage have reduced the mortality of patients with severe blunt thoracic trauma, the mortality is still high when multiple severe injuries, pulmonary contusion, cardiovascular injury, diaphragmatic rupture and brain damage are present. (1) Blunt injury of the brachiocephalic artery pose diagnostic and management problems for trauma and thoracic surgeon. Patients were stabilized and underwent repair through a median sternotomy with extension of the incision anterior to the sternocleidomastoid muscle. Median sternotomy is the best approach of choice in both controlling hemorrhage and repairing the arterial injury. (23,24) All patients had restoration of flow to the subclavian and carotid arteries utilizing bypass grafts or primary repair. All patients survived leave the hospital with no complications related to the procedure. Patients with blunt injuries of the brachiocephalic artery should be stabilized, and circulation of the subclavian and carotid arteries should be restored with graft placement or primary repair. (23) Median sternotomy with extension of the left supraclavicular incision, anterior to the sternocleidomastoid muscle was performed on the patient in this case report, primary repair of the ruptured site is also done, as the literature mentioned above, with a good result.
Conclusion ;Clinical presentation in the patient presented in this case report was unsual as what is mentioned in the literature mentioned.The patient only hadfractures of the first and secondribs on chest radiograph, massive hemopneumothorax and was hemodynamically unstable. ET was performed for live saving without any suspicion of great vessel injury. Left subclavian artery ruptured then suspected, the procedure continued with median sternotomy extended to left supraclavicular incision with good result.
The key word of diagnosis for great vessel injuries in blunt thoracic trauma is mediastinal widening in chest radiograph. Angiography should be done first before the surgery if the patient was stable and if there is a suspicious of great vessel injuries.