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Dr. Manish Barman ,
A high index of suspicion is required for prompt diagnosis and treatment of deadly and relatively rare aortic dissection yet diagnosis is both elusive and challenging, with a diversity of manifestations, depending on where it occurs along the aorta. It will usually provoke a sudden sharp chest pain of high intensity at onset in a male in his 60s, but not only, as you will see here in a review of the symptoms, diagnosis, treatment and follow-up of aortic dissection here.
Aortic dissection is the separation of the aorta into two areas of blood flow, - the true and false lumen held apart by an arterial flap resulting from the tear. In the false lumen, interrupted blood flow can compromise blood flow in the true lumen due to compression, and when the two lumens communicate due to re-entry, blood flow is present in both but can cause aneurysmal degeneration. Rupture, extensive hemorrhage, aortic valve incompetence, coronary dissection, cardiac tamponade, stroke and malperfusion are likely complications of acute aortic dissection. Surgery will usually involve placing a Dacron graft; medication will be a combination of nitrates and beta-blockers.Symptoms can vary according to where the tear is localised, and where it migrates to. Tear in the ascending aorta would bring on pain in the anterior, midline chest. A tear in the aortic arch might bring on pain in the jaw or neck. Intra scapular back and abdominal pain are more common with the descending aorta. Intramural hematoma, symptomatic aortic ulcer, and symptomatic aneurysm syndrome together with acute aortic dissection traditionally make up the wider spectrum of aortic disease. However, intramural hematoma and hemorrhage, and aortic ulcers can be seen as signs of evolving dissections according to the 2001 ESC guidelines on aortic dissection, which offered 5 classes of aortic dissection according to that staging of the disease: 1) classical (intimal flap between true and false lumen), 2) medial disruption (with formation of intramural haemotoma), 3) subtle dissection (without haematoma, eccentric bulge at tear site) 4) rupture (leading to aortic ulceration, penetrating aortic atherosclerotic ulcer with surrounding haemoatoma usually sub adventitial), or 5) iatrogenic and traumatic.With onset of symptoms as reference point, aortic dissection is acute within two weeks; sub acute from 2 to 6 weeks and it is chronic beyond 6 weeks. Previous to the ESC's disease staging, two anatomic systems widely served to describe it: 1) The Stanford system involving the ascending artery (type A) or not (type B) and 2) the DeBakey system which refers to the original site of intimal tear: I - ascending aorta propagating to aortic arch and II - ascending arch only and III - descending aorta and extending distally or proximallyA third, descriptive classification refers to proximal aortic dissection: (Stanford type A or DeBakey Type I and II 2) or distal: Stanford Type B or DeBakey Type III. (Fig. 1)Cardiovascular morbidity and mortality associated with this condition are high. Hospital-based mortality rates are approximately 30%. Patients with type A aortic dissection who undergo surgical treatment have a 30% mortality rate; patients who receive medical treatment have a mortality rate of 60%. The annual incidence of aortic dissection - 5 to 30 per million is low compared to that of myocardial infarction which is 4,000 per million.
A sudden, painful, ripping sensation in the chest or back is the usual complaint. The severe, sharp or ‘tearing’ back pain follows a tear in the aortic intima. Anterior chest pain in dissection is related to the ascending aortic artery distal to the left subclavian artery. (1)Painless dissection is rare. Only 63 patients in the International Registry of Acute Aortic Dissection experienced no pain, which represent 6.3% of patients of the 977 patients of the Registry. (2)Diastolic murmur from aortic regurgitation and neurological deficits can occur. Distant heart sounds secondary to pericardial effusion may be noted if the dissection causes bleeding into the pericardium. Tamponade symptoms and signs may be seen in extreme cases.Symptoms suggestive of congestive heart failure, stroke, shock or loss of distal pulse can be noted - most often in the older population.
In ascending aortic dissection in particular, early diagnosis is critical: prompt intervention can reverse the mortality rate, which is estimated to increase by 1% to 1.4% in the first 48 hours.
A recent meta-analysis by Shiga et al (8) reviewed published studies of the diagnosis of aortic dissection by TEE, helical CT and MRI and observed that these tests have equal and reliable diagnostic value (9).
Fig. 1 Common classification systems of aortic dissections: Stanford and DeBackey.
Patients with suspected aortic dissection should be admitted to an intensive care unit as rapidly as possible for:
Predisposing conditions are:
Differential diagnosis should include myocardial infarction and ischemia, pericarditis, pulmonary embolus, aortic regurgitation without dissection, aortic aneurysm without dissection, musculoskeletal pain, mediastinal tumors, pleuritis, cholecystitis, atherosclerotic or cholesterol embolism, peptic ulcer disease or perforating ulcer and acute pancreatitis. Follow-up will aim to minimise aortic stress:
Approximately half of all observed cases of aortic dissections in women under 45 years of age have been reported to be related to pregnancy - pregnancy is considered to be an independent risk factor for aortic dissection. Acute aortic dissection represents a rare pathology in women younger than 45 years of age; however, it is associated with a high rate of sudden death. In pregnancy, acute aortic dissection has an overall incidence of 0.4 cases per 100,000 person years.We present a case of type A aortic dissection diagnosed in a 37-year-old non-pregnant woman. We want to show that aortic dissection is diverse in its manifestations, and not uncommon or impossible in a young healthy and previously asymptomatic female. A 37 year old woman was admitted with complaints of acute onset, non-exertional, severe and stabbing lower chest and epigastric pain that lasted the previous hour and is increased with each movement and deep inspiration.Nausea, one episode of vomiting and syncope were present at onset. There was no history of hypertension, diabetes or bronchial asthma in this mother of two children, the last of which was born 5 years prior. The patient had no known allergies. She is a nonsmoker and has no family history of congenital heart defects. On presentation the patient is afebrile with a temperature of 36.7°C, a blood pressure reading of 110/60 mmHg, a pulse rate of 50 beats/min and a respiratory rate of 18 breaths/min. The patient is alert and oriented. On physical examination, the patient' pupils are round, equal, and reactive to light and accommodation. There is no jugular venous distension or hepatojugular reflux. There are no carotid bruits. The chest wall is symmetric and there is no deviation of the trachea. There was good bilateral air entry with clear breath sounds. The point of maximal impulse is located in the left fifth intercostal space anterior axillary line. Heart sounds have a regular rate and rhythm, with a grade II/VI mid-systolic murmur located in aortic area. There are no audible gallop or clicks. Heart sounds were not muffled and there was no pulsus paradoxus. The second heart sound was physiologically split. The abdomen was obese with no visible pulsations. Bowel sounds were normoactive and there were no palpable masses; abdomen was soft and nontender. The patient's extremities were warm to the touch, with no pallor, finger clubbing or cyanosis. Pulses were symmetrical; there was neither radio femoral delay nor peripheral edema. There was no femoral bruit or focal neurological signs.Due to the systolic murmur noted on physical examination, the patient was referred to a cardiologist for evaluation. On evaluation, a detailed history directed at symptoms and risk factors for aortic dissection was taken but was noncontributory. Chest X ray was reported normal by radiologist. An electrocardiogram and echocardiogram were ordered as preliminary tests along with D dimer and cardiac markers. The electrocardiogram showed a normal sinus rhythm with a rate of 50 beats/min (Fig. 2).
Fig. 2 ECG showing sinus bradycardiaThe echocardiogram showed a dilated aortic root (5.3 cm) with intimal flap in the ascending aorta (Fig. 3).
Fig. 3 The intimal flap seen in echocardiogramD dimer was elevated 1.68 mg/l (normal <0.50 mg/l). Cardiac markers were within normal range. With regard to risk factors, the patient had no previous cardiac catheterisation, intra-aortic balloon pump or any cardiac surgery such as valve replacement.A diagnosis of acute aortic dissection was made and patient was immediately referred to the cardiovascular surgeon for further management. The patient was eventually taken up for emergency surgery and underwent a Bentall operation with valve replacement and aortic root replacement conduit and IABP and inotropic support post operatively. Patient was successfully weaned and recovered completely.
Preventive measures of before and after the events of aortic dissection are:
Open repair of aortic dissection is involves a median sternototomy and cardiopulmonary bypass offered only to candidates who will be able to withstand the stress of surgery. Perioperative death rates exceed 10%, a risk of paraplegia of 4% to 5%, and a long recovery from thoracotomy make this a weighty undertaking for surgeon and patient alike.Endovascular stent grafting of aneurysmal disease processes of the thoracic aorta is feasible and relatively safe (12).Surgical intervention may involve the placing of stents or grafts to the aorta but accurate assessment are essential first, as there may be entry, re-entry and multiple tears.
Guidance of aortic stent-graft implantation in type-B aortic dissection is improved by complimentary use of contrast fluoroscopy, multiplane TEE with Doppler flow interrogation, and IVUS. This imaging approach implies no additional risk and provides online visualisation. Nevertheless, pre interventional and post interventional computed tomography/magnetic resonance, as well as peri interventional ANGIO, will not be replaced. However, procedural complications with stent-graft implantation are likely to be avoided, because TEE and IVUS help navigate guide wires and catheters in the true lumen, which improves safety of stent-grafting and, thus, may eventually improve procedural outcomes.
Aortic aneurysm is usually a progressive disease that needs to be monitored closely or treated. As aneurysms grow in size, there is increased incidence of rupture, dissection and death. Ascending aortic aneurysms grow an average of 1 mm to 4 mm each year, but in patients with bicuspid aortic valves and Marfan syndrome, growth is more rapid. The cumulative risk of rupture was 20% after five years. Seventy-nine per cent of ruptures occurred in women (P=0.01). The five-year risk of rupture as a function of aneurysm size at recognition was 0% for aneurysms less than 4 cm in diameter, 16% for those between 4 cm and 5.9 cm, and 31% for aneurysms 6 cm or larger (13, 14, 15). Once ruptured, emergent repair is extremely challenging with an associated mortality in the mid 90% range. Overall survival for TAA has improved significantly in the past 15 years. Aortic rupture and older age were risk factors for operative mortality, but the only variable associated with long-term mortality was increasing age. The patients who underwent surgery had an actuarial survival at one, five and 10 years of 92%, 77% and 57%, respectively.
A sharp, tearing or gripping possibly migrating pain, worst at onset rather than crescendo-like- eventually migrating, known aortic disease or inherited diseases, diagnostic murmur, a high pressure amplitude, neurological abnormalities, pulse deficits, a history of hypertension, radiography findings are elements that might warrant the high index of suspicion necessary for this serious condition. Because acute aortic dissection may occur anywhere along the aorta, manifestations are diverse.An initial diagnosis by chest radiography showing mediastinal widening and EKG excluding another diagnosis on one hand and transesophageal echocardiography, computed tomography or magnetic resonance imaging, on the other will be required to confirm or rule out the diagnosis. Treatment will depend on type or class or stage of condition - necessitating surgery or not. Perhaps in the future, biomarkers for example might help with the diagnosis of this condition, but in the meantime, we need to be all the more alert, even in atypical cases and presentations.
1 - Braunwald’s Heart Disease. A Textbook of Cardiovascular Medicine 9thed. Bonow RO, Mann DL, Zipes DP, Libby P. Elsevier saunders Publisher. 2012:1319-31. 2- Long-term survival in patients presenting with type A acute aortic dissection: Insights from the International Registry of Acute Aortic Dissection (IRAD) Tsai TT, Evangelista A, Nienaber CA, et al. Circulation. 2006; 114(1 Suppl):I350–6. 3 - Diagnostic imaging in the evaluation of suspected aortic dissection. Old standards and new directions. Cigarroa JE, Isselbacher EM, DeSanctis RW, Eagle KA. N Engl J Med. 1993; 328:35–43.4 - Echocardiography in diagnosis of aortic dissection. Erbel R, Engberding R, Daniel W, Roelandt J, Visser C, Rennollet H. Lancet. 1989; 1:457–61. 5 - Frequency and explanation of false negative diagnosis of aortic dissection by aortography and transesophageal echocardiography. Bansal RC, Chandrasekaran K, Ayala K, Smith DC. J Am Coll Cardiol.1995; 25:1393–401. 6 - Noninvasive evaluation of suspected thoracic aortic disease by contrast-enhanced computed tomography. White RD, Lipton MJ, Higgins CB, et al. Am J Cardiol. 1986; 57:282–90. 7 - The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. Nienaber CA, von Kodolitsch Y, Nicolas V, et al. N Engl J Med. 1993; 328:1–9. 8 - Diagnostic accuracy of Trans esophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection. Symptomatic review and meta-analysis. Shiga T, Wajma Z, Aptel CC, Inove T, Ohe Y. Arch Intern Med. 2006; 166:1350–6. 9 - Screening for abdominal aortic aneurysm: A best-evidence systematic review for the U.S. Preventive Services Task Force. Fleming C, Whitlock EP, Beil TL, Lederle FA. Ann Intern Med.2005; 142:203–11. 10 - Recommendations from ESC task force on aortic dissection (2001)11 - Management of acute aortic dissections. Daily PO, Trueblood HW, Stinson EB, Wuerflein RD, Shumway NE. Ann Thorac Surg. 1970; 10:237–47. 12 - Acute aortic syndromes. Tsai TT, Nienaber CA, Eagle KA. Circulation. 2005; 112:3802–13. 13 - Thoracic aortic aneurysms: A population-based study. 1982; 92:1103–8. 14 - Epidemiology and clinicopathology of aortic dissection. Mészáros I, Mórocz J, Szlávi J, et al. Chest.2000; 117:1271–8. 15 - Acute aortic dissection: Population-based incidence compared with degenerative aortic aneurysm rupture. Clouse WD, Hallett JW, Jr, Schaff HV, et al. Mayo Clin Proc. 2004; 79:176–80. Other Resources: Recommendations from ESC task force on aortic dissection (2010)Echo in aortic diseases recommendations (2010). Ascending aortic aneurysms from e-journal (2011)Position paper on TEVAR (2012)Congress report on the Management of acute aortic syndromesMulti-modality, clinical imaging in thoracic aortic diseasecongress report (2013).
Barman M, Djamel B, Mathews J. Heart Care Center Al Ahli Hospital, Doha, Qatar.
Authors' disclosures: None declared.
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