BMJ 2011;343:d4487 doi: 10.1136/bmj.d4487 Page 1 of 5 Practice PRACTICE EASILY MISSED? Acute aortic dissection Aaron M Ranasinghe Walport clinical lecturer 1 lecturer 2, Daniel Strong clinical fellow 3, Barry Boland consultant in emergency medicine 4, Robert S Bonser consultant cardiac surgeon 1 honorary professor 2 1 Department of Cardiac Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2TH, UK; 2 School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT; 3New Cross Hospital, Royal Wolverhampton Hospitals NHS Trust, Wolverhampton WV10 0QP, UK; 4Emergency Department, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2TH This is one of a series of occasional articles highlighting conditions that may be more common than many doctors realise or may be missed at first presentation. The series advisers are Anthony Harnden, university lecturer in general practice, Department of Primary Health Care, University of Oxford, and Richard Lehman, general practitioner, Banbury. To suggest a topic for this series, please email us at [email protected]. Acute aortic dissection is caused by an aortic intimal tear with propagation of a false channel in the media. Depending on the site and extent of the tear, it may cause chest, back, or abdominal pain, or collapse caused by rupture or malperfusion (transient or persistent ischaemia of any organ as a result of arterial branch obstruction). It is anatomically categorised according to involvement of the ascending aorta (type A, DeBakey type I/II) (fig 1); the categorisation dictates management. Why is aortic dissection missed? Although most patients present within two hours of onset of symptoms (usually to non-cardiac surgical centres), definitive diagnosis may be delayed by over 12 hours6 and half of patients do not have surgery until more than 24 hours have elapsed.7 Patients with dissection are commonly hypertensive men in their 60s, but all ages are affected (27% are aged 17-59 years, 40% aged 60-74 years, 33% aged >75 years),5 including young adults, some with connective tissue disorders, such as undiagnosed Marfan syndrome. In older patients, other conditions are more prevalent, and in the young, the diagnosis may not be considered. The clinical features at presentation (table ) may be sensitive but highly non-specific indicators and in some instances may include features of ischaemia from malperfusion (such as neurological deficits), which may confuse the clinical diagnosis.8 9 Electrocardiographic and troponin abnormalities resulting from coronary malperfusion are common and diagnostically misleading. Although changes in chest radiographs are common (89%), a normal chest radiograph does not exclude the diagnosis, and anterioposterior projections are unreliable. Guidelines for evaluating chest pain from the National Institute for Health and Clinical Excellence (NICE) concentrate on acute coronary syndrome (which is more common and less lethal). The need for chest radiographs, and their timing, is discretional and inquiry for transient neurological deficits is not mandatory.10 Why does this matter? For type A acute aortic dissection, untreated mortality is 1-2% per hour in the first day, with a 90% mortality at 30 days. With surgery, this can be converted to 75-90% survival, and no more than two patients need treatment to gain survival advantage.8 Rapid recognition and treatment (within hours) may prevent the survival attrition and maximise recovery of reversible malperfusion phenomena (including neurological deficit).11 Misdiagnosis as acute coronary syndrome may lead to inappropriate administration of anti-platelets and thrombolysis, complicating surgery. For all cases of acute aortic dissection, delayed diagnosis may delay antihypertensive treatment, allowing propagation and worsening of prognosis. How is acute aortic dissection diagnosed? Clinical A triad of symptoms—characteristic chest pain (usually abrupt and/or severe), a pulse deficit or blood pressure differential, and an abnormal chest radiograph—increases the likelihood of dissection but is present in only a third of patients. A pulse deficit is the unilateral absence or diminution of a pulse compared with contralateral palpation.4 To detect this, a full peripheral pulse examination is mandatory (radial, brachial, carotid, and femoral pulses). The blood pressure differential is defined as a difference in systolic blood pressure between both arms of >20 mm Hg.9 Correspondence to: R S Bonser [email protected] Reprints: http://journals.bmj.com/cgi/reprintform Subscribe: http://resources.bmj.com/bmj/subscribers/how-to-subscribe BMJ 2011;343:d4487 doi: 10.1136/bmj.d4487 Page 2 of 5 PRACTICE Case scenario A 64 year old hypertensive man presented to an emergency department with sudden onset, severe, sharp chest pain. Right arm blood pressure was 100/70 mm Hg and an electrocardiogram showed inferior ST segment depression. Troponin T was raised (0.2 ng/mL). Acute coronary syndrome was provisionally diagnosed, anti-platelet therapy administered, and coronary angiography planned. On later questioning, he described a left arm weakness that had resolved. Further examination noted left arm hypertension (155/90 mm Hg), a right carotid bruit, and diastolic murmur. Computed tomography showed a type A acute aortic dissection (see fig 2) for an example from another case) involving the right coronary ostium and brachiocephalic artery. He was transferred for emergency surgery. How common is acute aortic dissection? • The estimated annual incidence is 30-43 per million of the population2 and may be increasing3 • However, it is relatively uncommon, accounting for 1 in 300-350 emergency admissions for chest pain4 • For every emergency admission for dissection, there are 100 patients with acute myocardial infarction and 25 with pulmonary embolism5 Ask about any new neurological symptoms (transient or permanent) or symptoms of limb ischaemia, as these may highlight malperfusion phenomena and because focal neurological deficits occur in 17% of patients with type A dissection.12 In addition, for patients who are admitted with neurology or limb ischaemia, questioning about chest pain should be done to identify potential triggering causes of the presenting symptoms. The table outlines the key clinical features of both type A and B dissection. Investigations Patients with a suspected clinical diagnosis of acute aortic dissection should have basic investigations. These include electrocardiography, chest radiography, and blood tests for markers of myocardial ischaemia. Normality or abnormality of any of these does not exclude dissection; however, if further imaging rules out dissection, then they may be of use in future patient management. Once clinically suspected, a definitive diagnosis is made with cross sectional imaging (computed tomography of the aorta or magnetic resonance angiography) or transoesophageal echocardiography; each of these imaging techniques has high diagnostic accuracy. If computed tomography is done, images of the thoracic aorta should be obtained before injection of contrast to allow the detection of intramural haematoma (a condition that may progress to dissection). In the absence of trauma, computed tomography is not routine. Transthoracic echocardiography may be specific but is insensitive and operator dependent and does not exclude the diagnosis. Biomarkers may have a role: raised concentration of D-dimer is sensitive but non-specific, raising the suspicion for both dissection and the differential diagnosis of pulmonary embolus.13 14 manuscript. All authors have approved the final version. RSB is the guarantor. Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work. Provenance and peer review: Not commissioned; externally peer reviewed. Patient consent not required (patient anonymised, dead, or hypothetical). 1 2 3 4 5 6 7 8 9 10 Nienaber CA, Eagle KA. Aortic dissection: new frontiers in diagnosis and management. Part I: From etiology to diagnostic strategies. Circulation 2003;108:628-35. Meszaros I, Morocz J, Szlavi J, Schmidt J, Tornoci L, Nagy L, et al. Epidemiology and clinicopathology of aortic dissection. Chest 2000;117:1271-8. Olsson C, Thelin S, Stahle E, Ekbom A, Granath F. Thoracic aortic aneurysm and dissection: increasing prevalence and improved outcomes reported in a nationwide population-based study of more than 14 000 cases from 1987 to 2002. Circulation 2006;114:2611-8. Von Kodolitsch Y, Schwartz AG, Nienaber CA. Clinical prediction of acute aortic dissection. Arch Intern Med 2000;160:2977-82. Information Centre for Health Education and Social Care. Hospital epsiode statistics online. www.hesonline.nhs.uk. Raghupathy A, Nienaber CA, Harris KM, Myrmel T, Fattori R, Sechtem U, et al. Geographic differences in clinical presentation, treatment, and outcomes in type A acute aortic dissection (from the International Registry of Acute Aortic Dissection). Am J Cardiol 2008;102:1562-6. Sabik JF, Lytle BW, Blackstone EH, McCarthy PM, Loop FD, Cosgrove DM. Long-term effectiveness of operations for ascending aortic dissections. J Thorac Cardiovasc Surg 2000;119:946-62. Hagan PG, Nienaber CA, Isselbacher EM, Bruckman D, Karavite DJ, Russman PL, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA 2000;283:897-903. Bossone E, Rampoldi V, Nienaber CA, Trimarchi S, Ballotta A, Cooper JV, et al. Usefulness of pulse deficit to predict in-hospital complications and mortality in patients with acute type A aortic dissection. Am J Cardiol 2002;89:851-5. National Institute for Health and Clinical Excellence. Chest pain of recent onset: Assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin. (Clinical guideline 95.) 2010. www.nice.org.uk/guidance/CG95. Estrera AL, Garami Z, Miller CC, Porat EE, Achouh PE, Dhareshwar J, et al. Acute type A aortic dissection complicated by stroke: can immediate repair be performed safely? J Thorac Cardiovasc Surg 2006;132:1404-8. Collins JS, Evangelista A, Nienaber CA, Bossone E, Fang J, Cooper JV, et al. Differences in clinical presentation, management, and outcomes of acute type A aortic dissection in patients with and without previous cardiac surgery. Circulation 2004;110(11 suppl 1):II237-42. Suzuki T, Distante A, Zizza A, Trimarchi S, Villani M, Salerno Uriarte JA, et al. Diagnosis of acute aortic dissection by D-dimer: the International Registry of Acute Aortic Dissection Substudy on Biomarkers (IRAD-Bio) experience. Circulation 2009;119:2702-7. Sodeck G, Domanovits H, Schillinger M, Ehrlich MP, Endler G, Herkner H, et al. D-dimer in ruling out acute aortic dissection: a systematic review and prospective cohort study. Eur Heart J 2007;28:3067-75. Fattori R, Tsai TT, Myrmel T, Evangelista A, Cooper JV, Trimarchi S, et al. Complicated acute type B dissection: is surgery still the best option? A report from the International Registry of Acute Aortic Dissection. J Am Coll Cardiol Intv 2008;1:395-402. How is acute aortic dissection managed? 11 Administer analgesia for pain relief and control hypertension with intravenous β blockade, and refer all patients to cardiac surgical centres: (a) in patients with type A dissection, for emergency surgery to prevent intrapericardial rupture, restore true luminal flow and aortic valve competence, and to correct malperfusion; (b) in patients with type B dissection, for medical management and assessment for complications, which may require surgical or endovascular intervention.15 12 Contributors: AMR and RSB conceived the manuscript, interpreted the data from the literature, and drafted and revised the manuscript. DS and BB interpreted data from the literature and helped to revise the Accepted: 20 June 2011 Reprints: http://journals.bmj.com/cgi/reprintform Subscribe: http://resources.bmj.com/bmj/subscribers/how-to-subscribe 13 14 15 Cite this as: BMJ 2011;343:d4487 BMJ 2011;343:d4487 doi: 10.1136/bmj.d4487 Page 3 of 5 PRACTICE Key points • Consider acute aortic dissection in any patient with severe, sudden onset chest, back, or abdominal pain; although uncommon, dissection is commonly lethal, and rapid diagnosis and intervention may save life and treat morbidity from malperfusion • If clinical suspicion is raised by detailed history taking of the pain and high risk features on examination (pulse deficit or blood pressure differential; focal neurological deficits; murmur), confirm the diagnosis with imaging studies (such as computed tomography of the aorta, magnetic resonance angiography, transoesophageal echocardiography) • As malperfusion based symptoms may predominate, inquire about chest pain in patients presenting with neurological or peripheral ischaemic symptoms • A normal chest radiograph or abnormal electrocardiogram neither refutes nor confirms the diagnosis Reprints: http://journals.bmj.com/cgi/reprintform Subscribe: http://resources.bmj.com/bmj/subscribers/how-to-subscribe BMJ 2011;343:d4487 doi: 10.1136/bmj.d4487 Page 4 of 5 PRACTICE Table Table 1| Comparison of variables in patients presenting with acute type A and B aortic dissection. Values are percentages of patients except where stated otherwise. Data adapted from publications from the International Registry of Aortic Dissection’s database8 9 Patients with type A dissection Patients with type B dissection Patient characteristics Male 63 69 61 (14) 64 (13) Hypertension 69 77 Known occlusive vascular disease 24 42 Acute onset 85 84 Severe or worst ever 90 90 Anterior chest 71 44 Posterior chest 33 41 Abdomen 22 43 Back 47 64 Sharp 62 68 Tearing or ripping 49 52 Radiating 27 30 Painless 6 2 Aortic incompetence 44 12 Pulse deficit 30 9 Normal 31 32 Non-specific ST-T wave changes 43 43 Ischaemia 17 13 Left ventricular hypertrophy 25 32 11 16 Age (mean (SD)) (years) Pain Physical examination Electrocardiography Chest radiography Normal Wide mediastinum Abnormal aortic (or cardiac) contour 63 56 47 (27) 53 (24) 17 22 Pleural effusion Reprints: http://journals.bmj.com/cgi/reprintform Subscribe: http://resources.bmj.com/bmj/subscribers/how-to-subscribe BMJ 2011;343:d4487 doi: 10.1136/bmj.d4487 Page 5 of 5 PRACTICE Figures Fig 1 The two most common classifications of aortic dissection. The Stanford classification divides dissections into type A (involving the ascending aorta) and type B (no ascending involvement). The DeBakey classification subdivides Stanford type A into ascending and descending (type I) and ascending alone (type II). DeBakey type III is equivalent to Stanford type B. Stanford type A (DeBakey types I and II) dissection requires surgery, whereas most Stanford type B dissection is treated medically. DeBakey type I dissection has the greatest propensity for malperfusion. Neither classification reports the site of the intimal tear, and some dissections may propagate in a retrograde way. Adapted and reproduced with permission from Nienaber and Eagle1 Fig 2 Section of contrast enhanced computed tomogram at the level of the pulmonary artery bifurcation (labelled PA) showing an acute dissection. An intimal flap is seen within the ascending (AA) and descending aorta (DA). Black arrows indicate the intimal flap, and the true lumen is the smaller lumen. This therefore represents a Stanford type A (DeBakey type I) dissection, which requires surgical intervention Reprints: http://journals.bmj.com/cgi/reprintform Subscribe: http://resources.bmj.com/bmj/subscribers/how-to-subscribe
