Ascending Aortic Dissection
- A small sample size retrospective cohort analysis determined that POCUS performed by emergency physicians to evaluate the thoracic aorta in cases of confirmed ascending aortic dissection led to shorter time to diagnosis with decreased misdiagnosis rate compared with patients who did not receive POCUS.Median time to diagnosis in the EP POCUS group was 80 (interquartile range [IQR], 46-157) minutes vs 226 (IQR, 109-1449) minutes in the non–EP POCUS group (P = .023). Misdiagnosis was 0% (0/16) in the EP POCUS group vs 43.8% (7/16) in the non- POCUS group (P = .028). Pare JR, Liu R, Moore CL, Sherban T, Kelleher MS Jr, Thomas S, Taylor RA. Emergency physician focused cardiac ultrasound improves diagnosis of ascending aortic dissection. Am J Emerg Med. 2016 Mar;34(3):486-92. doi: 10.1016/j.ajem.2015.12.005. Epub 2015 Dec 12. PMID: 26782795.
- A prospective study of patients with suspected Type A aortic dissection (AD) was conducted to evaluate the accuracy of EP-performed POCUS for type A AD in patients presenting to the ED, and to evaluate its usefulness either to rule in or rule out AD as compared to the Aortic Dissection Detection Risk Score, a bedside tool for risk stratification proposed by the American Heart Association. Detection of direct signs (intimal flap or intramural hematoma) had a specificity of 94 % (95 % CI 90–97 %), while combination of ADD risk score >1 with detection of direct POCUS signs had a specificity of 98 % (95 % CI 96–99 %). Sensitivity, specificity, PPV, and NPV improved in the subgroup of patients with shock/hypotension (100 %, 54 % [95 % CI 25–81 %], 77 % [95 % CI 56–91 %] and 100 %, respectively). Nazerian P, Vanni S, Castelli M, Morello F, Tozzetti C, Zagli G, Giannazzo G, Vergara R, Grifoni S. Diagnostic performance of emergency transthoracic focus cardiac ultrasound in suspected acute type A aortic dissection. Intern Emerg Med. 2014 Sep;9(6):665-70. doi: 10.1007/s11739-014-1080-9. Epub 2014 May 29. PMID: 24871637.
- A retrospective analysis of cases of suspected dissection presenting to 21 EDs was conducted to determine if ascending aorta diameters measured by noncontrast CT allow for meaningful discrimination between patients with and without type A aortic dissection. A raw AscAo diameter of 34 mm and a normalized Z-score of 1.84 both yielded 100% sensitivity for TAAD, with respective specificities of 35% (95% CI = 29.6%–40.2%) and 67% (95% CI = 61.7%–72.2%). Sensitivity and specificity were optimized at a raw diameter of 42 mm and a Z-score of 2.95, with respective sensitivities of 93.5 and 91.0% and specificities of 89.2 and 91.0%. Mark DG, Davis JA, Hung YY, Vinson DR. Discriminatory Value of the Ascending Aorta Diameter in Suspected Acute Type A Aortic Dissection. Acad Emerg Med. 2019 Feb;26(2):217-225. doi: 10.1111/acem.13547. Epub 2018 Sep 17. PMID: 30091507.
- A review article discusses the risk factors and management of ascending aorta dilatation. Risk factors for dilatation include connective tissue disorders, hypertension, trauma, previous instrumentation, and inflammatory conditions such as Takeyasu or Giant Cell arteritis or infectious aortitis. The risk of dissection is related to aortic diameter. Diameters > 4.0 cm should prompt additional workup for risk factors, and diameters >4.5 cm require operative management. Cozijnsen L, Braam RL, Waalewijn RA, Schepens MA, Loeys BL, van Oosterhout MF, Barge-Schaapveld DQ, Mulder BJ. What is new in dilatation of the ascending aorta? Review of current literature and practical advice for the cardiologist. Circulation. 2011 Mar 1;123(8):924-8. doi: 10.1161/CIRCULATIONAHA.110.949131. PMID: 21357847.
Abdominal Aortic Aneurysm
- A systematic review and meta-analysis of 11 studies from 2001-2003 evaluated the sensitivity and specificity of non-radiologist performed ultrasonography in the diagnosis of abdominal aortic aneurysm. This was compared with AAA confirmed by radiology-performed ultrasound or intraoperative or autopsy findings. AAA was defined as maximal antero-posterior aortic diameter measurement of > 3 cm. Pooled sensitivity was 0.975 [95% confidence interval (CI), 0.942– 0.992] for AAA detection and pooled specificity was 0.989 (95% CI, 0.979– 0.995). While there was heterogeneity in the experience of ultrasonographers, this review did not find significant statistical heterogeneity. Concannon E, McHugh S, Healy DA, Kavanagh E, Burke P, Clarke Moloney M, Walsh SR. Diagnostic accuracy of non-radiologist performed ultrasound for abdominal aortic aneurysm: systematic review and meta-analysis. Int J Clin Pract. 2014 Sep;68(9):1122-9. doi: 10.1111/ijcp.12453. Epub 2014 May 18. PMID: 24837590.
- A systematic review of trials from 1965 to 2011 resulting in 7 studies was performed to evaluate if EP performed ultrasound has sufficient accuracy to rule out AAA in patients greater than 18 years of age with symptoms suggestive of AAA, defined as greater than 3 cm dilatation. The gold standard studies for comparison included formal ultrasound, CT, angiogram, MRI, and intraoperative or autopsy findings. Pooled sensitivity was 97.5% to 100%, specificity 94.1% to 100%, LR+ 10.8 to ∞, and LR– 0.00 to 0.025. Study authors therefore conclude that emergency physician bedside ultrasound can be used to rule in the need for emergent CT and/or vascular surgery consultation, and recommend screening patients > 50 with back or flank pain with POCUS. This evaluates for AAA only and is limited in cases of retroperitoneal AAA rupture, and conclusions may be limited by moderate statistical heterogeneity. Rubano E, Mehta N, Caputo W, Paladino L, Sinert R. Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. Acad Emerg Med. 2013 Feb;20(2):128-38. doi: 10.1111/acem.12080. PMID: 23406071.
Acute Aortic Syndromes (combined)
- This review article explains the role of TTE and other imaging modalities in early evaluation of cases of suspected acute aortic syndromes. TTE has a reported sensitivity of 59–83% and a specificity of 63–93% for the diagnosis of aortic dissection confirmed by dissection flap. High risk features of POCUS for Type A dissection include bicuspid aortic valve, AR, a dilated aortic root with associated pericardial effusion, or regional wall motion abnormality (especially inferior). POCUS may also be used to evaluate for other differential diagnoses including MI, PE, and pericardial effusion. The authors assert that TTE has poor diagnostic accuracy and therefore cannot rule out pathology but can be useful in the early assessment of unstable patients; gold standard would be formal transesophageal echocardiography, helical CT, and MRI which all have similar diagnostic accuracy. Meredith EL, Masani ND. Echocardiography in the emergency assessment of acute aortic syndromes. Eur J Echocardiogr. 2009 Jan;10(1):i31-9. doi: 10.1093/ejechocard/jen251. PMID: 19131497.
POCUS versus CT
- A retrospective pilot analysis compared the agreement, sensitivity, and specificity of POCUS for thoracic aortic dimensions, dilation, and aneurysm compared with CT angiography (CTA) for cases of acute aortic pathology. Sensitivity, specificity, and the observed kappa value (95% confidence interval [CI]) between POCUS and CTA for the presence of aortic dilation at the 40-mm cutoff were 0.77 (95% CI = 0.58 to 0.98), 0.95 (95% CI = 0.84 to 0.99), and 0.74 (95% CI = 0.58 to 0.90), respectively. POCUS demonstrated good agreement with CTA measurements of maximal thoracic aortic diameter, and appears to be specific for aortic dilation and aneurysm. Taylor RA, Oliva I, Van Tonder R, Elefteriades J, Dziura J, Moore CL. Point-of-care focused cardiac ultrasound for the assessment of thoracic aortic dimensions, dilation, and aneurysmal disease. Acad Emerg Med. 2012 Feb;19(2):244-7. doi: 10.1111/j.1553-2712.2011.01279.x. Epub 2012 Jan 30. PMID: 22288871.
- A prospective single center cohort study evaluated the diagnostic accuracy and interobserver variability of POCUS performed to estimate thoracic aortic dilation and aneurysm and compared with the results of computed tomography angiography (CTA). Sensitivity and specificity of POCUS were 78.6% (95% confidence interval [CI] = 65.6% to 88.4%) and 92.9% (95% CI = 85.1% to 97.3%), respectively, for ascending aorta dilation and 64.7% (95% CI = 46.5% to 80.2%) and 95.3% (95% CI = 89.3% to 98.4%), respectively, for ascending aorta aneurysm. Interobserver agreement of POCUS was k = 0.82. Nazerian P, Vanni S, Morello F, Castelli M, Ottaviani M, Casula C, Petrioli A, Bartolucci M, Grifoni S. Diagnostic performance of focused cardiac ultrasound performed by emergency physicians for the assessment of ascending aorta dilation and aneurysm. Acad Emerg Med. 2015 May;22(5):536-41. doi: 10.1111/acem.12650. Epub 2015 Apr 21. PMID: 25899650.