Aortic Dissection – A Covert Killer

Aortic dissections are insidious killers that are often undetectable by history and physical exam alone. Obviously, providers must have a high index of suspicion for these as their presentations are highly variable. CT angiography, and less often, transesophageal echocardiography are classically the diagnostic modalities that providers use to identify this rare, deadly diagnosis. However, getting a patient over to CT can sometimes be delayed whether it is for transportation, or stabilizing the patient before CT scan.

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Case:

A 73 year old lady with only a past medical history of hypertension that presented to our emergency department with intermittent focal left upper extremity numbness and weakness, and bilateral lower extremity pain. She presented hypotensive and tachycardic. The astute clinician had a high index of suspicion of dissection and while the patient was getting prepared to go to CT scan obtained the following clip of the parasternal long axis of the heart:

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It is obvious here that the aortic outflow tract is dilated (usually, it should be the size of the left atrium).

Then the physician obtained a suprasternal view of the aortic arch and obtained the following clip:

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Then, given the focal neurologic symptoms, she got the following images of the right carotid, in which you can see an intimal flap and also more distally, a blood clot in the carotid:

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To investigate the distal extension of the clot, the following views were obtained of the abdominal aorta with an actual intimal flap:

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Finally, at the level of the bifurcation, extension of the dissection into the bilateral iliacs is visualized

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CT surgery was notified before the CT scan and the patient was taken directly from the CT scanner (which revealed the image below) to the OR..

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Tips on POCUS for aortic dissection:

  1. A parasternal long axis view can be helpful to visualize a dilated aortic root and/or a pericardial effusion in the setting of a suspected dissection
  2. Evaluating carotid arteries, the distal aorta, or the iliac arteries can help diagnose an extensive dissection.
  3. Point of care ultrasound should be used to quickly make a diagnosis, speed further imaging, or get a consultant involved expeditiously. Similar to much of what we do with point of care ultrasound, this tool should be used to rule in a diagnosis, rather than to rule out a diagnosis.
  4. Point of care ultrasound can be used to make a quick diagnosis at the bedside before more consultative imaging, making it an invaluable tool in identifying this covert killer.

 

Aneurysm screening

Sweep through large AAA from Sinai EM Ultrasound on Vimeo.

Abdominal aortic aneurysm (AAA) affects 5-10% of males age 65-79, and among males over 55 years of age represents the 14th leading cause of death. Ruptured aortic aneurysm is associated with a very high mortality rate. Up to 80% of patients die by the time they reach the hospital, and half die during emergent operative repair.

Evaluation of the abdominal aorta by emergency physicians using point-of-care sonography has been a core indication since ACEP’s first ultrasound guidelines were published in 2001. Several studies have demonstrated sensitivity and specificity for aneurysm which approach those of Radiology Department performed ultrasounds, and even CT scans.

While many providers have adopted a point-of-care assessment strategy in patients where AAA is suspected, it is debatable whether emergency physicians should engage in screening asymptomatic patients for AAA. Several ED-based studies have found aneurysms in 5-7% of asymptomatic male patients over the age of 65. Screening has been shown to reduce mortality from AAA, and is recommended by the U.S. Preventive Services Task Force. A single screening examination for asymptomatic males over age 65 is covered by many insurers in the United States including Medicare (Medicare requires that you have smoked over 100 cigarettes or have a family history of AAA to qualify for coverage).

So there is evidence that emergency physicians are capable of screening for aneurysm, and there is evidence to support that someone should be screening selected elder patients. Whether emergency physicians should engage in screening will depend on ED resources available. Many departments across the country have screening programs for HIV, abuse, and other pathology. There is a balance between using limited resources to diagnose and treat acute illness and deploying resources to impact the long-term health of a population which might otherwise be lost to follow up.

So you decide!

Further reading:

  • Tayal VS, Graf CD, Gibbs MA. Prospective study of accuracy and outcome of emergency ultrasound for abdominal aortic aneurysm over two years. Acad Emerg Med 2003 (PMID: 12896888)
  • Costantino TG, Bruno EC, Handly N, Dean AJ. Accuracy of emergency medicine ultrasound in the evaluation of abdominal aortic aneurysm. J Emerg Med 2005 (PMID: 16243207)
  • Knaut AL, Kendall JL, Patten R, Ray C. Ultrasonographic measurement of aortic diameter by emergency physicians approximates results obtained by computed tomography. J Emerg Med 2005 (PMID: 15707804)
  • Salen P, Melanson S, Buro D. ED screening to identify abdominal aortic aneurysms in asymptomatic geriatric patients. Am J Emerg Med 2003 (PMID: 12671815)
  • Moore CL, Holiday RS, Hwang JQ, Osborne MR. Screening for abdominal aortic aneurysm in asymptomatic at-risk patients using emergency ultrasound. Am J Emerg Med 2008 (PMID: 18926345)
  • Cosford PA, Leng GC. Screening for abdominal aortic aneurysm. Cochrane Database Syst Rev. 2007 (PMID: 17443519)
  • Hoffmann B, Um P, Bessman ES, Ding R, Kelen GD, McCarthy ML. Routine screening for asymptomatic abdominal aortic aneurysm in high-risk patients is not recommended in emergency departments that are frequently crowded. Acad Emerg Med. 2009 (PMID: 20053243)