Tag Archives: aorta

Long-Term Experience With Endovascular Aortic Repair For Trauma

For decades, the treatment of blunt injury to the thoracic aorta was open repair. The big debate at the time was use of cardiac bypass vs fast clamp and sew. But starting in 1997 with the introduction of thoracic endovascular aortic repair (TEVAR) of this injury, we have rapidly moved to the point where most traumatic aortic injuries are repaired using this technique.

A report that was written nearly a decade ago indicated a relatively high complication rate for the procedure. Graft complications were reported in 18% of patients, with 14% showing endoleaks. Stroke and left arm ischemia were also reported.

The diagram above shows insertion for management of an aneurysm, but the technique is similar for trauma. Blunt aortic injury occurs closer to the left subclavian artery and care must be taken to place the endograft closer to but not covering its orifice.

As the insertion systems and stents improved, short term events have been on the decline. Unfortunately, long term followup data has been hard to come by.

Until now. An article that is not yet in print reports 11 years of experience and followup with patient undergoing TEVAR at the ShockTrauma center in Baltimore.

Here are the factoids:

  • 88 patients underwent TEVAR during the study period, all from blunt trauma
  • Average ISS was 38, showing these patients were severely injured
  • Overall mortality was 7%, but none was due to the TEVAR procedure
  • TEVAR-related complication rate was 9% Endoleaks at the ends of the graft occurred in 4 patients, and all required repair. There were 4 other minor leaks that resolved on their own.
  • 26 had all or part of the left subclavian orifice covered at initial operation. None developed ischemia, although 2 had a prophylactic carotid-subclavian bypass before TEVAR.
  • The longest followup imaging occurred 8 years after the procedure. No long-term complications were noted.

Bottom line: TEVAR has essentially replaced open repair of the aorta, except in special cases. We continue to learn from our experience, and the complication rate is still falling. Other than endoleaks recognized in the postop period, most other complications rarely occur. Long term followup is poor, but in the patients who do return, there were no complications. But remember, this is an expected sampling bias. If the patient had major problems and/or died, they would just be lost to followup. We would never know.

EAST Guidelines: Blunt Traumatic Aortic Injury

The Eastern Association for the Surgery of Trauma (EAST) has been helping trauma professionals through the publication of practice guidelines for more than 15 years. Members of EAST donate their time to review reams of literature, good and bad, to try to determine the answers to common or puzzling clinical questions.

Why follow a practice guideline? Quite simply, if properly developed, a guideline represents our best understanding of the “correct” answer to the question posed. And as many of you who follow this blog already know, things that “seem to make sense” frequently are totally wrong. Your own experience is poignant, but the pooled experience of the many others who contributed to research on the topic in question is much more significant.

So on the the practice guideline for blunt traumatic aortic injury (BTAI). This one answers three questions. I will list each, followed by the conclusions reached through the literature review.

1. In patients with suspected BTAI, which diagnostic modality should be chosen: CT angiography of the chest, or conventional catheter angiography?

  – Catheter angiography was the standard for decades. When the first EAST guideline on this topic was released 15 years ago, CT angiography was only a level III recommendation because experience with it was lacking. CT technology has advanced rapidly, with multiple detectors, helical scanning, and incredible computing power. Although the quality of the evidence is somewhat low, the panel strongly recommends the use of CT angiography due to its ready availability, speed, low invasiveness, and ability to detect and define other injuries.

2. Should endovascular or open repair be selected in order to minimize stroke, renal failure, paraplegia, and death?

  – Once again, the quality of available data is so so. However, it was possible to detect differences in outcome in comparative studies. The panel strongly recommends the use of endovascular repair in patients who do not have contraindications due to its lower blood loss, mortality, and paraplegia, and equivalent risk of stroke. Furthermore, it is performed more frequently now than open repair, and experience is thus greater at many institutions, further reducing complications.

3. Should the repair be performed immediately or delayed in order to minimize stroke, renal failure, paraplegia, and death?

  – Literature review revealed that the incidence of renal failure and paraplegia were lower with delayed repair, while renal failure was the same in patients with significant associated injuries. There was benefit to delaying repair until resuscitation was achieved and any other life threatening injuries were addressed. The panel recommends that delayed repair be carried out once these other conditions have been corrected. The procedure should not be delayed until the next morning for the convenience of the surgeons.

Related posts:

Reference: Evaluation and management of blunt traumatic aortic injury: a practice guideline from the Eastern Association for the Surgery of Trauma. 78(1):136-146, 2015.

When To Image The Aorta In Blunt Trauma

Blunt injury to the thoracic aorta is one of those potentially devastating ones that you (and your patient) can’t afford to miss. Quite a bit has been written about the findings and mechanisms. But how do you put it all together and decide when to order a screening CT?

There are a number of high risk findings associated with blunt aortic injury. Recognize that they are associated with the injury, but are still not very common. They are:

  • Fractures of the sternum or first rib
  • Wide mediastinum
  • Displacements of mediastinal structures (left mainstem down, trachea right, esophagus right)
  • Loss of the aortopulmonary window
  • Apical cap over the left lung

Here’s a sensible method for screening for blunt aortic injury, using CT scan:

  • Reasonable mechanism (fall from greater than 20 feet, pedestrian struck, motorcycle crash, car crash at “highway speed”) PLUS any one of the high risk findings above.
  • Extreme mechanism alone (e.g. car crash with closing velocity at greater than highway speed, torso crush)

Note on torso crush: I have seen three aortic injuries from torso crush in my career, one from a load of plywood falling onto the patient’s chest, one from dirt crushing someone when the trench they were digging collapsed, and one whose chest was run over by a car.

What Is A Wide Mediastinum Anyway?

Trauma professionals are always on the lookout for injuries that can kill you. Thoracic aortic injury from blunt trauma is one of those injuries. Thankfully, it is uncommon, but it can certainly be deadly.

One of the screening tests used to detect aortic injury is the old-fashioned chest xray. This test is said to be about 50% sensitive, with a negative predictive value of about 80%. However, the sensitivity is probably decreasing and the negative predictive value increasing due to the rapidly increasing number of obese patients that we see.

A wide mediastinum is defined as being > 8cm in width. In this day and age of digital imaging, you will need to use the measurement tool on your workstation to figure this out.

Unfortunately, it seems like most chest xrays show wide mediastinum these days. What are the most common causes for this?

  • Technique. The standard xray technique used to reduce magnification of the anterior mediastinum (where the aortic arch lives) is a tube distance of 72 inches from the patient, shot back to front. We can’t do this for trauma patients because we can’t stand them up and are reluctant to prone them. The standard trauma room technique is 36 inches from the patient shot front to back. This serves to magnify the mediastinal image and make it look wide.
  • Obesity. The more fat in the mediastinum, the wider it looks. The more fat on the back, the further the mediastinum is from the xray plate and the greater the magnification.
  • Other mediastinal blood. Major blunt trauma to the chest can cause bleeding from small veins in the mediastinum, making it look wide.
  • Thymus. Only in kids, though.
  • Aortic injury. Last but not least. Only a few percent of people with wide mediastinum will actually have the injury.

If you encounter a wide mediastinum on chest xray in a patient with a significant mechanism for aortic injury, then they should be screened using helical CT.

Related post:

Blunt Aortic Injury And New Cars

Car crashes are a significant cause of trauma death worldwide. Aortic injury is the cause of death in somewhere between 16% and 35% of these crashes (in the US). Over the years, automobile safety through engineering improvements has been rising. A recent poster presented at EAST 2012 looked at the effect of these improvements on mortality from aortic injury.

The authors analyzed the National Automotive Sampling System – Crashworthiness Data System database (NASS-CDS) for car model years dating from 1994 to 2010. They included any front seat occupants age 16 or more. Over 70,000 cases were reviewed.

Interesting findings:

  • Overall mortality from aortic injury was 89%
  • 75% of deaths occurred prior to arrival at a hospital
  • Risk for suffering an aortic injury was statistically associated with age >=60, being male, being the front seat passenger, position further back from the steering wheel, and ejection from the vehicle
  • The injury was more likely to occur when speed was >= 60mph, impact occurred with a fixed object, and in SUV vs pickup truck crashes
  • Newer cars protected occupants from aortic injury in side-impact crashes, but the incidence actually increased in frontal-impact crashes

Bottom line: Aortic injury will remain a problem as long as we find ways to move faster than we can walk. Engineers will continue to make cars safer, but the increase in aortic injury in frontal impact in late model cars is puzzling. This phenomenon needs further analysis so that safety can be improved further. Trauma professionals need to keep this injury in mind in any high energy mechanism and order a screening chest CT appropriately.

Related posts:

Reference: Aortic injuries in new vehicles. Ryb et al, University of Maryland and Johns Hopkins. Poster presented at EAST Annual Meeting, January 2012.