Case # 2: A Needle In the Haystack

A 40 year old male presented with 3 days of progressive dyspnea on exertion. He notes he was in a normal state of health prior to this and played basketball daily without issue but now he can no longer walk across the room without becoming winded. He has no chest pain, a normal chest x-ray and an ECG demonstrating sinus tachycardia

Vitals: HR 109 BP 110/72 RR 22 O2 96

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Answer and Learning Point

Answer

There is evidence of severe aortic regurgitation and aortic root dilation (~6 cm) on this parasternal long axis view. In a patient without any previous cardiac history with new aortic regurgitation this is concerning for acute aortic dissection. Cardiac surgery was consulted immediately and the patient was taken straight to CT scan for confirmation of type A aortic dissection. The patient was in the OR within 1 hour and had an excellent outcome.

Learning Point

Aortic dissection is quite uncommon (~5-30 per 1 million people per year) and is often seen in patients with chronic uncontrolled hypertension or other diseases such as bicuspid aortic valve, Marfan Syndrome or Ehlers-Danlos Syndrome. Unfortunately all the "classic" indicators of dissection are actually not that common [1].  Traditionally we are taught that patients with acute aortic dissection will arrive hypertensive, while in actuality up to 1 in 4 patients with Stanford Type A dissection will have a presenting systolic blood pressure below 100 mmHg. Additionally, it is taught that a dissection presents as a “ripping or tearing” pain going to the back.  Looking at the data, while over 90% of patients felt that it was the worst pain they had ever experienced, only 50% of subjects described their pain as ripping or tearing (62% described pain as sharp), only 35% had any posterior chest pain, and only 85.4% of patients described the onset of their pain as ‘acute.’ [1]

The varied presentation of this disease makes aortic dissection difficult to diagnose, and the clinician should have a high index of suspicion for this life-threatening disease process.  This is where ultrasound comes in. Anyone who has a concerning chest pain story, pain above and below the diaphragm, chest pain + a neurological symptom, or signs and symptoms of acute heart failure without any previous cardiac history, should have a bedside ultrasound performed.  While ultrasound cannot rule out aortic dissection, it can rapidly identify complications of dissection and expedite care in these patients whom time is of the essence.

The Approach

Perform standard abdominal aorta ultrasound evaluating for aneurysm or intimal flap. Be sure to evaluate from proximal aorta, in the epigastric region, distally to the iliac vessels. A normal aorta caliber is < 3 cm.

Obtain a parasternal long axis view:

Measure aortic root, this should be less than 4 cm. There are varying opinions on where the best place to take this measurement is, I suggest measuring the largest area you see as it is better to be on the conservative side.
Apply color doppler to evaluate for aortic regurgitation.
Assess global cardiac function. This is useful to see if a patient is compensated or decompensated as well as assist with fluid/pressor management if needed.
Evaluate for pericardial effusion. If there is evidence of effusion and concern for Type A aortic dissection, this suggests that there is communication with pericardial sac.
Evaluate descending thoracic aorta for intimal flap

References

  1. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): New Insights Into an Old Disease. JAMA. 2000;283(7):897-903. doi:10.1001/jama.283.7.897.
  2. Taylor RA, e. (2017). Point-of-care focused cardiac ultrasound for the assessment of thoracic aortic dimensions, dilation, and aneurysmal disease. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/?term=22288871
  3. C, K. (2017). Emergency department diagnosis of aortic dissection by bedside transabdominal ultrasound. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/19549013
  4. Lang R, Bierig M, Devereux R, et al. Recommendations for Chamber Quantification: A Report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Chamber Quantification Writing Group, Developed in Conjunction with the European Association of Echocardiography, a Branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005; 18: 1440-63.
  5. Rubano E, e. (2017). Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/?term=23406071

3 Replies to “Case # 2: A Needle In the Haystack”

  1. Mike,
    Often we can seen dissection in multiple areas, check the internal carotids, the femoral arteries for that telltale flap, along with diminished pulses on physical exam.. The great imitator is what it has been called, dissection presents in a variety of ways, its always best to consider it when somebody comes in sick. Sometimes it looks like arterial occlusion if the false lumen is large.. Great case!

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