Introduction

Traumatic aortic dissection (TAD) is an uncommon but frequently emphasized entity in trauma management in the emergency department (ED). Prognosis is poor without surgical treatment especially since most patients present with severe associated injuries.

Few cases have been published to date indicating Stanford Type-A dissection following trauma (₁,₂). Wilson and Hutchins reported a series of 204 autopsies of patients with aortic dissection and found only three cases with traumatic dissecting injury to the aorta (₃). Goarin et al reported the value of transesophageal echocardiography in 6 cases of aortic dissection in their series of 28 cases (₄). Another report involved a 65-year-old male presented with a descending aortic dissection developed 26 years after a blunt trauma (₅).

Case Report

A man in his 68 was brought in the University-based ED by local ambulance at 17:45. Crew reported that he was a pedestrian hit by a car that is learned to be cruising not very fast. There had been an amnestic period of several minutes. On arrival to the ED, the patient was hypertensive with 185 over 150 mm Hg, pulse 69 bpm, respiratory rate was 18 pm. Glasgow Coma Score (GCS) was calculated as E3 M6 V5. Detailed physical examination revealed a left frontal laceration of 1 cm, right periorbital hematoma and bilateral subconjunctival hemorrhage. Cardiac auscultation disclosed 2 to 3 / 6 diastolic murmur coupled with bilateral carotid bruit. Blood was detected in penile external meatus. Right pelvic instability and deformed right tibia with skin defect indicating open tibial fracture were recorded.

After cardiac monitoring, oxygen supplement and bilateral antecubital IV lines were instituted, blood type and cross-match, blood ethanol level together with complete blood count and trauma X-rays were ordered. Rapid infusion of 0.9% NaCl was started associated with tetanus vaccine and antibiotics. While the first unit of whole blood was transfused, bedside chest X-ray (Figure I) revealed an enlarged mediastinum which warranted a contrast-enhanced thoracoabdominal computerized tomography (CT).

Figure 1

Figure I. Bedside chest X-ray that depicted an enlarged mediastinum.

Right iliac and pubic fractures, right tibial and fibular proximal metaphyseal fractures were identified in pelvic and lower extremity X-rays, respectively. After the first two units of whole blood and 1000 ml of normal saline had been transfused, contrast-enhanced thoracoabdominal CT demonstrated Stanford Type-A aortic dissection from proximal aorta to iliac arteries (Figure II). Left subclavian artery and aortic arch were shown to have intimal flaps. An intimal flap that is characteristic for dissection divided the aortic channel into false and true lumens (Fig 3). The nurse informs that his blood pressure had declined to 72/45 mm Hg and pulse had risen to 80 bpm. Bedside echocardiography revealed mild aortic and moderate mitral insufficiency together with dissection flap in ascending aorta.

Orthopedic surgeons splinted the fractured tibia after suturing the skin defect. Another unit of blood had been transfused after which BP was restored to 110 over 70 mm Hg. Additional units of blood and fresh frozen plasma were ordered to be prepared in anticipation of operation.

Figure 2

Figure II. Contrast-enhanced thoracoabdominal CT demonstrated Type-B aortic dissection originated from proximal aorta to iliac arteries.

Complete blood count revealed a hemoglobin level of 13.5 gr/dl and hematocrit 41.7 % and 3 hours later corresponding levels were 11.5 and 34.5, respectively, after which cardiac surgeons were consulted. The patient was not a good candidate for the operation and was admitted to the surgical intensive care unit at midnight. By then, 3000 ml of crystalloids and 4 U of whole blood had infused. Blood pressure was 113/58 and pulse 80, GCS 14 while en route to the surgical intensive care unit. After four days of resuscitation and follow-up, he was operated on.

The patient suffered per-operational ventricular fibrillation repeatedly and was defibrillated. Hypotension persisted despite administration of positive inotropic agents and further resuscitation with fluids. The patient was declared dead and operation was ended.

Discussion

Dissection is a recognized finding after blunt trauma to the ascending and descending aorta. TAD is a life-threatening injury that prompts rapid diagnosis and treatment. Blunt thoracic aortic injury most often occurs beyond the left subclavian artery with subsequent transection and exsanguinations. Proximal aortic dissection is an extremely rare injury found in the setting of blunt trauma.

In this report we presented a case of a pedestrian involved in a motor vehicle crash who had a traumatic aortic dissection involving proximal aorta to distal iliac arteries. Numerous additional injuries sustained by the elderly patient complicated the situation by impairing circulatory status. This is one of the few cases indicating traumatic dissection of the aorta. Physicians' awareness of the possibility of these injuries may augment diagnostic and therapeutic measures.

A high index of suspicion should be maintained in case of a significant mechanism of blunt trauma and thus the diagnosis of aortic injury should be considered in the list of differential diagnoses. Gates et al reported a case with aortic dissection associated with compromised renal blood flow and recommended to consider the entity in the presence of anuria following chest trauma (2). A different scenario of the mechanism of the events is also possible. Dissection might have started very rapidly simulating heart attack. The accident may have been caused by a loss of consciousness due to the attack. But the lack of a relevant history and findings suggested that the dissection was due to the trauma itself.

Although general principles regarding treatment of acute aortic dissection also apply to this particular condition, replacement of sequestered blood volume by whole blood and other fluids including both crystalloids and colloids should take precedence before operative measures.

Vignon et al enrolled thirty-two trauma patients with suspected traumatic disruption of the aorta (₆). They concluded that transesophageal echocardiography should be considered the first-line imaging modality for the evaluation of trauma patients with suspected injuries of the thoracic aorta.

In this case, the emergency physicians also did pursue appropriate diagnostic measures leading to the diagnosis and immediately ordered thoracic CT evaluation following a suggestive X-ray finding. Then the patient was infused whole blood and crystalloids that helped restore the circulating blood volume and blood pressure. An interesting point is that the pulse had not risen above 80 pm until undergoing operation. This detail may have important implications for emergency medicine i.e., serious injuries and blood loss need not be associated with a tachycardia.

Conclusion

Stanford Type-A TAD may be seen in victims of blunt trauma and thus should always be kept in mind in the emergency evaluation and management of unstable trauma victims.

Correspondence to

Ozgur KARCIOGLU, MD Dept. of Emergency Medicine Dokuz Eylul University, School of Medicine Balcova 35340 Izmir, Turkey e-mail: ozgur.karcioglu@deu.edu.tr Mobile: +90.533.4105785 fax: 00-90-232-2590541