Acute Aortic Syndrome
- This is a rare event, 3-5/100,000 cases per year but with a high mortality: 22% in type A; 1-2 % increase in mortality for every hour in delay to surgery.
- Average age is 63: 75% between 40-70 yrs; 65% male; 65-75% history of hypertension.
Two classification schemes:
- Type A: Involves ascending aorta +/- descending aorta (60% of dissections).
- Type B: Involves only the descending aorta.
- I – Ascending aorta which extends to at least the aortic arch +/- descending aorta.
- II – Only the ascending aorta.
- III – Only the descending aorta.
- American Heart Association (AHA, 2010) developed an aortic dissection risk score, however it is retrospective, not validated, sensitivity 91% & specificity 40%.
- AHA AD risk score sensitivity = 97% in very low risk patients, but specificity = 56%. Not useful in intermediate risk patients.
- Canadian Clinical Practice Guidelines (2020) developed a clinical decision aid for assessing pre-test probability and recommendations for investigations. See table below:
- Once the pretest probability score is determined based on the clinical decision aid it can then be used to determine further diagnostic steps. Score=0: Low risk and no further testing required. Score=1: Moderate risk. Next step is to obtain d-dimer. Negative d-dimer then investigate other possible causes. Positive d-dimer, then ECG-gated CT aorta should be ordered. Score=2: High Risk and ECG-gated CT aorta should be ordered.
- Widened mediastinum (> 6cm upright PA film or > 8cm supine AP).
- Up to 40-45% will be normal.
- Positive in 25%.
- 1-2% may have ST elevation.
- AHA 2010 guideline do not use d-dimer for pretest probability analysis.
- Canadian Clinical Practice Guidelines do incorporate d-dimer into pretest analysis.
- ACEP 2014: DO NOT rely on d-dimer alone to exclude AD.
- Transthoracic Ultrasound for aneurysmal dilatation of the aortic root Sensitivity: 60%, Specificity: 85% (Nazerian et al. 2019).
- Having either a thoracic or abdominal aneurysm is associated with acute aortic syndrome. Point of care US (POCUS) is accurate in the diagnosis of Abdominal aortic aneurysm (Bentz et al. 2006) and should be performed as part of the pre test probability analysis. (Ohle et al. 2020).
- ACEP 2014: CV surgical consult or immediate transfer to higher level of care if US positive for dissection.
- Gold standard.
- Aortic dissection may be missed if only ordering CT PE studies. If clinical suspicion, need to order Aortic Dissection specific CT protocol.
- Triple rule out CT angiography (Ayaram et al. 2013): insufficient data to rule out AD.
- Decrease the BP and pulse if they are elevated.
- European guidelines recommend SBP 100-120mmHg.
- Use labetolol 20mg IV, onset is within 5-10 minutes, q10 min to max of 300mg.
- May use a labetolol infusion at 2mg/min.
- Insert an arterial line if possible.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
- AHA dissection score: Not a validated clinical decision score.
- Canadian AAS Clinical decision Aid.
- Treatment: No specific targets have shown reduction in mortality and morbidity.
- Transthoracic Ultrasound: ACEP level B.
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Nov 28, 2020
Visit our website at https://www.bcemergencynetwork.ca
Add public comment…