A Retrospective Review of Patients with Aortic Trauma Ripal N. Shah August 5, 2003 Research Mentor: Renan Uflacker, MD Department of Radiology Division of Interventional Radiology
Overview of Purpose and Methods • To review several factors that influence the initial management of aortic injury including radiological studies, injuries to other systems, morphology of aortic injury, and status on arrival to the hospital. • Charts were reviewed for those patients brought to MUH with suspected vascular trauma. • The eventual objective of the review is to draw a correlation between initial patient treatment and management to the subsequent outcome. • Radiographic techniques were analyzed for specificity, sensitivity, and negative/positive predictive values. • Trends were identified and the statistics are presented.
Anatomy of Aorta • The aorta is the major artery that supplies blood to the entire body. • Acute injury to the aorta is a severe injury, and, left untreated, the patient may become hypoxic or hypovolemic. • Severe brain injury (anoxic encephalopathy) and ischemic damage to other viscera can result from untreated trauma. • As a result, timely, appropriate treatment is necessary to avoid further morbidity and mortality.
Causes of Aortic Injury • Overwhelmingly, the major cause of traumatic aortic rupture is a rapid deceleration type injury, such as in a motor vehicle accident involving anteroposterior force vectors. • In such cases, bony fragments of the osseous structures of the chest wall (sternum, manubrium, etc) resulting from blunt trauma can be retroplused into the mediastinum, rupturing the vasculature. • Other causes include: fall from a height, stab wounds, and gunshot wounds.
Morphology of Aortic Injury • Contained rupture (traumatic pseudoaneurysm): in such cases, an intimal flap is evident on CT, and a “double-barreled” aorta is seen at the level of the pseudoaneurysm (60% of cases) • Contained partial or total transection of the aorta. • Intramural hematoma • The most common site of aortic injury is the aortic isthmus, the region distal to the takeoff of the left subclavian and proximal to the intercostal arteries
How severe is it? • 80-90% of patients will not make it to the hospital. • Of those that do make it, 50% will die in 24 hours if they do not receive appropriate treatment. Mortality increases with amount of time left untreated. • For patients in which aortic injury is recognized and treated, 80% are stable upon initial discharge.
Radiological Modalities and their Role in Recognizing Aortic Injury • Chest X-Ray (CXR): initial study done on nearly all patients • signs on CXR suggestive of aortic injury include: widened mediastinum (>8 cm), indistinct aortic knob contour, depressed left main stem bronchus (>40 degrees below horizontal), loss of aortic pulmonary window, and deviation of nasogastric tube. • Pneumothorax and hemithorax are considered nonspecific findings. • One or more of these findings (particularly widened mediastinum) in patients with history of blunt chest trauma warrants additional work up. • Computed Tomography (CT): very useful tool in diagnosing aortic trauma. The standard of care for an abnormal CT with a conventional scanner is to follow up with angiography. Newer modalities such as helical and spiral CT scans have been shown to have a 100% negative predictive value (ie, no false negatives).
Modalities contd. • Angiography: long considered the “gold standard” in diagnosing vascular trauma • sensitivity and specificity approach 100% • drawbacks include expense, length of procedure, and invasiveness • Newer techniques include: intravascular ultrasound (IVUS) and transesophageal echocardiography (TEE) An example of an angiogram of the aortic arch showing the takeoff of the great vessels: bracheocephalic, left common carotid, and left subclavian arteries.
Review of MUH Patients • 48 patients were brought to MUH with the suspicion of vascular trauma at the scene of the accident • 23 patients were found to have aortic trauma upon CT, angiography and IVUS • Of the remaining 25 patients, 13 were found to have significant damage to other systems, but no vascular injury. 12 patients had only minor injuries.
Is age a factor? • The average age of the entire patient set (n=48) is 39±19 yrs, with the youngest being 5 and the oldest 80 years old • The average age of the patients with vascular trauma (n=23) is 36±19 yrs, with the youngest being 5 and the oldest 80 years old • These statistics show us that no certain age group is more likely to sustain aortic trauma than any other group.
Trends/Statistics • The 23 patients with aortic injury were retrospectively separated into two groups: Group 1 – patients with aortic injury and surgical repair; Group 2 – aortic injury but no surgery. • Of the entire set (n=23), 70% (n=16) underwent surgical repair, while 26% (n= 6) were treated conservatively, and one died prior to being taken to surgery • One false positive was identified on surgery. • Causes of trauma were as follows: 86% (n=20) MVA, 1 fall from height, 1 gunshot wound, and 1 stab wound • Of the MVAs, 4 were restrained, 6 unrestrained, 1 pedestrian vs. auto, 1 motorcycle vs. auto, 1 rollover, 1 ejection, and 6 of unknown restraint status. • Common associated injuries include neurological (closed-head injuries and spinal cord compromise), abdominal visceral, and orthopedic injuries.
Statistical Analysis • CXR showed at least one suggestive sign of aortic injury in 17 of 23 patients with vascular trauma (in most cases widened mediastinum) • CT done in 31 of 48 patients • NPV=79%, PPV=100%, Sn=80%, Sp=100% • 4 false negatives, 0 false positives • IVUS done in 43 of 48 cases • NPV=100%, PPV=95%, Sn=100%, Sp=96% • 0 false negatives, 1 false positive on surgery • Angiography done in 48 of 48 cases • NPV=90%, PPV=95%, Sn=87%, Sp=97% • 3 false negatives, 1 false positive on surgery • Notes: NPV/PPV are negative and positive predictive values, Sn is sensitivity and Sp is specificity; patients were considered positive for vascular injury if so indicated by angiography or IVUS; mediastinal hematoma on CT is not considered definitive of aortic injury
Diagnostic Studies • In most cases, patients underwent CT, Angiography and IVUS as part of the diagnostic work up after initial CXR. • Interestingly, in Group 1 (patients with surgical repair), not a single diagnostic study was negative. CXRs are not included since they are not considered conclusive. • However, of the 6 patients in Group 2, 87% (n=5) had at least one negative study and all patients had significant damage to other systems, in addition to the vascular trauma. • These findings indicate that although surgical repair is the preferred treatment of aortic trauma, conservative medical management is opted for unless aortic injury is clearly seen.
More trends • 74% (n=17) patients with vascular trauma had a pseudoaneurysm or contained vascular leak; 13% (n=3) had a partial or complete transection of the aorta; and 13% (n=3) had an intramural hematoma • The diagnosis of intramural hematoma is interesting because the only modality which can identify such trauma is IVUS. • This accounts for the 3 false negatives from aortography and 3 of the 4 false negatives from CT • 83% (n=19) had trauma in the proximal descending thoracic aorta (in the region of the aortic isthmus); one patient had pseudoaneurysm of the brachiocephalic artery, one had a left common carotid pseudoaneurysm, one had an aortic tear over the diaphragm, and one had a mid-thoracic aortic tear
Treatment Options • Surgical repair: • The treatment of choice is surgical repair. • Two options are “clamp and sew” and distal aortic perfusion techniques. Recent studies have found distal perfusion techniques to reduce ischemic injuries that may be seen with “clamp and sew” methods. • Endovascular stent-graft placement: • A minimally invasive approach to aortic repair. • A small incision is made in the femoral artery and with the aid of angiography and fluoroscopy, a self-expanding wall stent is placed in the region of trauma • A recent study found initial technical success to be 100%, with only one mortality post-op. No mortality of morbidity in the remaining patients at 17 month follow-up.
Medical Management • In some cases, such as when craniotomy or exploratory laparotomy is indicated, a more conservative course is pursued in the ICU. • In cases where surgical repair is not indicated, a pharmacological beta-blockade regimen is recommended to reduce heart rate and force of contraction and to control blood pressure. • Nitroprusside treatment can also be used to control blood pressure and prevent rupture of the contained aortic rupture and subsequent exsanguination
Further Study • Assess the impact of status at admission • Analyze discharge status and conduct retrospective patient outcome survey • Correlate outcome data with hospital course
Case Report • HPI: 21 y/o white male brought to MUH post-MVA. Patient was a restrained passenger in a single car MVA. Patient required 30 minute extraction time at scene of accident. • Physical Exam: • Glasgow Coma Scale of 8 • only responded to painful stimuli • visible fx of right femur and tibiofibular fx • intubated and sedated at scene • Injuries identified at admission: subarachnoid hemorrhage, aortic pseudoaneurysm, liver laceration, and serosal tears intra-abdominally
Radiographic studies for vascular injury • CXR: widened mediastinum, deviation of nasogastric tube to right, suggestive of vascular injury • CT chest: traumatic pseudoaneurysm of proximal descending thoracic aorta (2 cm cranio-caudally), mediastinal hematoma, hemithoraces (left>right) • Angiography: pseudoaneurysm at level of ligamentum arteriosum • IVUS: confirmed findings of angiography Aortogram indicating pseudoaneurysm at level of ligamentum arteriosum in this patient.
Hospital Course • After the diagnosis of aortic injury was made, the pt was not considered a candidate for surgical repair due to his other injuries. The pt was therefore put on beta blockade and his blood pressure was closely monitored. • Neurosurgery also opted for conservative management of the closed head injuries. • Exploratory laparotomy was performed on the day of admission, and the liver laceration and serosal tears were identified and repaired. • Pt also had orthopedic repair of femoral shaft fx same day
Course contd. • Once the patient was stabilized during his hospital course, informed consent was obtained to repair the injured aorta (~17 days after admission) • The aorta was repaired with a Hemashield graft with left atrial to distal aorta bypass using a posterolateral thoracotomy incision (through the latissimus dorsi muscle). • The remainder of the hospital course was remarkable for an infection that was effectively treated and a paralyzed left true vocal cord. • The patient was discharged to the Marines on day 32 with CT, neurosurgery, ENT, OT and PT follow ups scheduled.