Acute Aortic Dissection

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Overview

Aortic dissection is a life-threatening condition in which there is a tear in the aorta intimal layer, resulting in separation of the layers of the aortic wall.[1]  This vascular condition is the most common catastrophe of the aorta, 2-3 times more common than rupture of the abdominal aorta. When left untreated, about 33% of patients die within the first 24 hours, and 50% die within 48 hours. The 2-week mortality rate approaches 75% in patients with undiagnosed ascending aortic dissection.

Dissections of the thoracic aorta have been classified anatomically by two different methods. The more commonly used system is the Stanford classification, which is based on involvement of the ascending aorta and simplifies the DeBakey classification.

Stanford classification

The Stanford classification divides dissections into two types, type A and type B, on the basis of the extent of the dissection.[2] Type A involves the ascending aorta (DeBakey types I and II); type B does not (DeBakey type III); it arises distal to the left subclavian artery.[3]

This system helps to delineate treatment. Usually, type A dissections require surgery, whereas type B dissections may be managed medically or endovascularly under most conditions.

DeBakey classification

The DeBakey classification divides dissections into three types, as follows:

Type III dissections are further divided into IIIa and IIIb, on the basis of anatomic involvement.[2] Type IIIa refers to dissections that originate distal to the left subclavian artery but extend proximally and distally, mostly above the diaphragm (ie, thoracic aorta).

Type IIIb refers to dissections that originate distal to the left subclavian artery, extend only distally, and may extend below the diaphragm (ie, abdominal aorta).

Thoracic aortic dissections should be distinguished from aneurysms (ie, localized abnormal dilatation of the aorta) and transections, which are caused most commonly by high-energy trauma.

Non-A, non-B dissections

Non-A, non-B dissections involve a retrograde extent or proximal tear in the aortic arch between the brachiocephalic trunk and left subclavian artery.[3]

Proposed: Type-Entry-Malperfusion (TEM) classification

More recently, the TEM classification is a proposed classification that aims to provide improved accuracy in defining aortic dissection, thereby providing risk stratification, particularly for patients whose conditions don't clearly fit into the Stanford or DeBakey classifications (ie, non-A, non-B dissections).[2, 4]  This classification features the extent of the dissection, entry tear site, and presence of malperfusion,[2] as described below.

Entry tear [2]

Malperfusion [2]

Note: Further investigation of this proposed TEM classification is needed.

The following organizations have released guidelines for the management of aortic dissection. Key diagnostic and treatment recommendations have been reviewed and integrated throughout the article.

Pathophysiology & Risk Factors

Aortic dissection essentially features a tear in the intimal layer, followed by the formation and propagation of a subintimal hematoma. The dissecting hematoma commonly occupies up to 50% and, occasionally, 100% of the aortic circumference, leading to the development of a false lumen or double-barreled aorta. This can reduce the flow of blood to any of the major arteries arising from the aorta. If the dissection involves the pericardial space, cardiac tamponade can result.

The normal aorta contains collagen, elastin, and smooth muscle cells, which help contribute to the layers of the aorta, the intima, the media, and the adventitia. Degenerative changes associated with aging lead to the breakdown of the collagen, elastin, and smooth muscle, as well as to an increase in basophilic ground substance. This is termed cystic medial necrosis, the hallmark histologic change associated with dissection and with Marfan syndrome.

Any disease that weakens the strength of the aortic wall will predispose one to aortic dissection. Shearing forces give rise to the separation of the layers in the media of the aorta. Intimal rupture occurs at points of fixation along the aorta where the hydraulic stress is maximal. The most common site is the first few centimeters of the ascending aorta, with 90% found within 10 cm of the aortic valve. The second most common site is just distal to the left subclavian artery.

Risk factors

Risk factors for aortic dissection include the following[1, 4] :

Prehospital Care

Assure adequate breathing, maintain oxygenation, treat shock, and obtain useful historical information.

Establishing the diagnosis in the field is usually difficult or impossible, but certain salient features of aortic dissection may be observed. It is life threatening if not quickly recognized and treated.

Radio communication with the receiving hospital permits the medical control physician to direct care and select a capable destination hospital, while permitting the emergency department (ED) to mobilize appropriate resources.

In the rare event that the diagnosis can be made based on prehospital information, the physician directing prehospital care should request transport to a facility capable of operative treatment of an aortic dissection.

Emergency Department Care

The mortality rate of patients with aortic dissection is 1-2% per hour for the first 24-48 hours and up to 50% in the first week.[1] Initial therapy should begin when the diagnosis is suspected. This includes two large-bore intravenous lines (IVs), oxygen, respiratory monitoring, and monitoring of cardiac rhythm, blood pressure, and urine output.

Clinically, the patient must be assessed frequently for hemodynamic compromise, mental status changes, neurologic or peripheral vascular changes, and development or progression of carotid, brachial, and femoral bruits.

Note the following:

End organ perfusion should be evaluated. Balancing the risks of dP/dt on the aortic wall versus the benefits of acceptable end organ perfusion may be a difficult clinical decision.

Aortic dissection associated with cocaine ingestion is challenging. It has been argued that using beta blockers alone without any simultaneous alpha blockers may allow unopposed alpha aderenergic vasoconstriction, potentially worsening myocardial ischemia. Therefore, it is recommended labetalol be used as it has both alpha- and beta-blocking properties.

Retrograde cerebral perfusion may increase the protection of the central nervous system during the arrest period.

Up to one third of patients with acute aortic dissection may have their diagnosis missed.[8]  Factors that contribute to an initial missed diagnosis of aortic dissection include female sex, the absence of back pain, and/or the presence of extracardiac atherosclerosis. Patients whose aortic dissection was initially missed also tend to have more imaging studies and longer time to surgery; however, these do not appear to affect adjusted long-term all-cause mortality.[8]

Use of a multiparametric algorithm that comprises the aortic dissection detection-risk score (ADD-RS) with D-dimer may aid in ruling out acute aortic dissection.[4]

The European Society of Cardiology (ESC) recommends use of a focused transthoroacic echocardiography (with contrast, if feasible) in the emergency department, if available, for the workup of acute aortic syndromes.[4] This imaging modality allows evaluation of pericardial effusion, wall motion anomalies, aortic regurgitation, and aortic dimension.

Magnetic resonance angiography (MRA) may help in the evaluation of, and guide management of, suspected acute aortic dissection in patients with contraindications to compute tomography angiography (CTA) in the emergency department.[9]  In the setting of suspected acute aortic syndrome, the ESC indicates the preferred imaging technique for confirmation of the diagnosis is ECG-gated cardiac CT scanning from neck to pelvis.[4] If cardiac CT is not available or the patient is hemodynamically unstable, diagnostic confirmation and assessment of the celiac trunk and mesenteric artery can be achieved with transesophageal echocardiography (TEE).[4] TEE is also recommended for perioperative management guidance in those with suspected acute aortic syndrome and for identification of complications.

Mortality from aortic arch dissections is about 10-15%, with significant neurologic complications occurring in another 10% of patients. The patient's clinical condition influences mortality.

ACR Criteria for Diagnosis, Treatment, and Follow-up

The American College of Radiology has established ACR Appropriateness Criteria for the diagnosis and treatment of suspected aortic dissection.[10]  Imaging modalities that are usually appropriate In patients with acute aortic syndrome, which includes aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer, are[10] :

Type A dissections

Urgent surgical intervention is required in type A dissections. The area of the aorta with the intimal tear usually is resected and replaced with a Dacron graft. The operative mortality rate is usually less than 10%, and serious complications are rare with ascending aortic dissections. In general, in-hospital mortality following prompt surgical repair is an estimated 15-30%; the estimated postoperative 5-year survival is 70-80%, falling to 50-60% after 10 years.[1]

The development of more impermeable grafts, such as woven Dacron, collagen-impregnated Hemashield, aortic grafts, and gel-coated Carbo-Seal Ascending Aortic Prothesis, has greatly enhanced the surgical repair of thoracic aortic dissections.

With the introduction of profound hypothermic circulatory arrest and retrograde cerebral perfusion, morbidity and mortality associated with this highly invasive surgery have decreased.

Dissections involving the arch are more complicated than those involving only the ascending aorta, because the innominate, carotid, and subclavian vessels branch from the arch. Deep hypothermic arrest usually is required. If the arrest time is less than 45 minutes, the incidence of central nervous system complications is less than 10%.

Aortic stent grafting is a challenging technique. It may prove feasible and has offered good results in a small series of patients. It may be a reasonable alternative in high-risk patients in the near future.

Planning for endovascular or open repair

When planning for endovascular or open repair of thoracoabdominal aorta aneurysm/dissection, the ACR indicates it is usually appropriate to obtain chest, abdominal, and pelvic MRA without and with IV contrast, or without IV contrast, and chest, abdominal, and pelvic CTA with IV contrast.[5]

Type B dissections

The definitive treatment for type B dissections is less clear. Uncomplicated distal dissections may be treated medically to control blood pressure. Distal dissections treated medically have a mortality that is the same as or lower than that of patients who are treated surgically. In general, there is a 10-15% in-hospital mortality for patients with type B dissection who receive medical management, rising to more than 30-40% in the setting of complicated type B dissections (eg, related to malperfusion syndromes, rupture, rapid expansion) that are not promptly treated with endovascular or surgical intervention.[1] The estimated 5-year survival of patients with type B dissection is 75-85%.[1]

Surgery is reserved for distal dissections that are leaking, ruptured, or compromising blood flow to a vital organ.

Acute distal dissections in patients with Marfan syndrome usually are treated surgically.

Inability to control hypertension with medication is also an indication for surgery in patients with a distal thoracic aortic dissection.

Patients with a distal dissection are usually hypertensive, emphysematous, or older.

Long-term medical therapy involves a beta-adrenergic blocker combined with other antihypertensive medications. Avoid antihypertensives (eg, hydralazine, minoxidil) as these drugs would increase dP/dt (ie, rate of aortic pressure rise).

Survivors of surgical therapy also should receive beta-adrenergic blockers.

A series of patients with type B dissections demonstrated that aggressive use of distal perfusion, CSF drainage, and hypothermia with circulatory arrest improves early mortality and long-term survival rates.

Endovascular stenting remains an option for treatment of some type B dissections. Some studies recommend that patients with complicated acute type B dissections undergo endovascular stenting with the goal of covering the primary intimal tear.[11]  More recent studies suggest that a combination medical therapy with endovascular aortic repair may inprove outcomes in acute and chronic uncomplicated type B dissections.[12]

Definitive treatment

Definitive treatment involves segmental resection of the dissection, with interposition of a synthetic graft.

When thoracic dissections are associated with aortic valvular disease, replace the defective valve. With combined reconstruction–valve replacement, the operative mortality rate is approximately 5%, with a late mortality rate of less than 10%.

Operative repair of the transverse aortic arch is technically difficult, with an operative mortality rate of 10% despite induction of hypothermic cardiocirculatory arrest.

Repair of the descending aorta is associated with a higher incidence of paraplegia than repair of other types of dissections because of interruption of segmental blood supply to the spinal cord.

The operative mortality rate is approximately 5%.

In a study by Mimoun et al of patients with Marfan syndrome who had acute aortic dissection, the patients were found to have a better event-free survival when there were no dissected portions of the aorta remaining after surgery.[13]

A study by Rylski et al indicated that in patients with type A aortic dissection, aggressive hemiarch replacement is associated with a low mortality rate and a low incidence of reintervention. The study involved 534 patients with acute type A dissection who underwent hemiarch replacement. The investigators found that at 1-, 5-, and 10-year follow-up, the patient survival rate was 80%, 68%, and 51%, respectively. During the same follow-up period, no distal reintervention was required in 97%, 90%, and 85% of patients, respectively.[14]

Follow-up

For follow-up in the setting of known thoracoabdominal aortic aneurysm/dissection without repair in the presence or absence of new symptoms, the ACR notes it is usually appropriate to obtain chest, abdominal, and pelvic MRA without and with IV contrast, or without IV contrast, as well as chest, abdominal, and pelvic CTA with IV contrast.[5]

When following up after endovascular or open repair of thoracoabdominal aortic aneurysm/dissection, it is usually appropriate to obtain a chest, abdominal, and pelvic MRA without and with IV contrast.[5] Chest, abdominal, and pelvic CTA with IV contrast is also usually appropriate.[5]

Inpatient & Outpatient Care

Inpatient care

Patients with symptomatic dissection should undergo immediate repair, especially if it is leaking or expanding.

Symptomatic patients require admission to a center experienced in cardiopulmonary bypass and operative care.

Completely asymptomatic patients may have their repair performed electively but may require admission to expedite their evaluation or for preoperative stabilization of their condition.

Patients with chest pain should undergo serial echocardiograms (ECGs) and creatine kinase (CK) determinations if acute myocardial infarction (AMI) is indicated.

Type A acute aortic dissection (class I recommendations)

Obtain emergency surgical consultation and evaluation; the ESC recommends immediate surgical intervention.[4]

In the setting of extensive destruction of the aortic root, a root aneurysm, or a known genetic aortic condition, the ESC recommends aortic root replacement using a mechanical or biological valve conduit.[4]

If a partially dissected root is present but there is no significant pathology of the aortic valve leaflet, the ESC prefers aortic valve suspension over valve replacement.[4]

In the setting of aortic repair, survival can be improved and false lumen thrombosis rates raised with an open distal anastomosis.[4]

In the absence of an intimal tear of the aortic arch or a significant arch aneurysm, a hemi-arch repair is recommended over more extensive arch replacement.[4]

Type A acute aortic dissection and malperfusion (class I recommendations)

Immediate surgery is recommended in individuals with acute type A aortic dissection with malperfusion of the brain, mesentery, lower limb, or kidney.[4]

Type B acute aortic dissection (class I recommendations)

All affected patients should receive medical therapy (eg, pain relief, blood pressure control).[4]

Emergency intervention is recommended in the setting of complicated acute type B aortic dissection.[4] Thoracic endovascular aortic repair (TEVAR) is the recommended first-line treatment in this scenario.

Type B chronic aortic dissection (class I recommendations)

All affected individuals should receive antihypertensive therapy.[4]

Emergent intervention is recommended in the setting of acute symptoms of malperfusion, rupture, or disease progression.[4]

In the setting of a descending thoracic aortic diameter of at least 50 mm, the ESC recommends intervention in those at reasonable surgical risk.[4]

Outpatient care

Follow-up examinations with radiologic studies are recommended at 3-month intervals for the first year and every 6 months for the next 2 years. After this, patient follow-up should occur annually.

Consultations

Once a thoracic dissection is suspected, consult a thoracic surgeon. Because many patients with this disorder have concomitant medical illness, consult the patient's primary care provider to expedite preoperative preparation. Early consultation is encouraged when ordering further imaging studies if the patient requires rapid operative intervention.

Consult a radiologist prior to obtaining aortography. Although this imaging modality is no longer used as frequently as before in the initial diagnosis of aortic dissection, aortography can be useful during planning for endovascular stent placement.[1]

Transfer

Symptomatic patients require care at a facility equipped to perform cardiopulmonary bypass with aortic and/or valvular repair.

Contact the receiving physician as soon as possible to transfer patients before their condition deteriorates.

Early airway management is indicated in the presence of hemoptysis or stridor.

If coronary insufficiency is suspected, nitrates may be used, but therapy with thrombolytic agents and aspirin should be avoided.

Patients should be monitored and accompanied by personnel capable of resuscitation.

If a prolonged ground transport time is anticipated, consider air transport.

Medications

Initial therapeutic goals include elimination of pain and reduction of systolic blood pressure to 100-120 mm Hg or to the lowest level commensurate with adequate vital organ (ie, cardiac, cerebral, renal) perfusion.

Whether systolic hypertension or pain is present, beta blockers are used to reduce arterial dP/dt.

To prevent exacerbations of tachycardia and hypertension, treat patients with IV morphine sulfate. This reduces the force of cardiac contraction and the rate of rise of the aortic pressure (dP/dt). It then retards the propagation of the dissection and delays rupture.

Antihypertensives

These agents are used to reduce arterial dP/dt. For acute reduction of arterial pressure, the potent vasodilator sodium nitroprusside is effective. To reduce dP/dt acutely, administer an IV beta blocker in incremental doses until a heart rate of 60-80 beats/min is attained.

When beta blockers are contraindicated, such as in second- or third-degree atrioventricular block, consider using calcium channel blockers. Sublingual nifedipine successfully treats refractory hypertension associated with aortic dissection.

Analgesics

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and prevents exacerbations of tachycardia and hypertension.

Checking for dissection prior to the administration of thrombolytics in the patient presenting with chest pain and ECG changes

Multiple case reports describe patients who received thrombolytics and were found later to have a dissection. The diagnosis of aortic dissection can be subtle.

The diagnosis depends on clinical suspicion, with contributory findings on history, physical examination, and imaging studies.

Obtaining a chest radiograph prior to administering thrombolytics is considered prudent.

Checking blood pressures in both arms and listening for carotid bruits also can help to diagnose aortic dissection prior to administering thrombolytics. The entire clinical picture must be taken into account.

What is acute aortic dissection (AAD)?What is the Stanford classification of acute aortic dissection (AAD)?What is the DeBakey classification of acute aortic dissection (AAD)?What is the pathophysiology of acute aortic dissection (AAD)?What are risk factors for acute aortic dissection (AAD)?What is the prehospital care for acute aortic dissection (AAD)?How is acute aortic dissection (AAD) in the emergency department (ED)?What is the mortality rate for acute aortic dissection (AAD)?What is included in inpatient care of acute aortic dissection (AAD)?What is included in the long-term monitoring following treatment of acute aortic dissection (AAD)?Which specialist consultations are beneficial to patients with acute aortic dissection (AAD)?When is patient transfer indicated for the treatment of acute aortic dissection (AAD)?What is the role of medications in the treatment of acute aortic dissection (AAD)?What is the role of antihypertensives in the treatment of acute aortic dissection (AAD)?What is the role of analgesics in the treatment of acute aortic dissection (AAD)?What are the ACR appropriateness criteria for the diagnosis and treatment of acute aortic type A dissection?What are the ACR appropriateness criteria for the diagnosis and treatment of acute aortic type B dissection?What is the definitive treatment of acute aortic dissection (AAD)?

Author

John M Wiesenfarth, MD, FACEP, FAAEM, Associate Clinical Professor, Division of Emergency Medicine, University of California, Davis, School of Medicine; Assistant Physician-in-Chief for Quality, Patient Safety, Risk, and Medical/Legal, Service Line:Emergency Medicine, Kaiser-Permanente Hospital of Sacramento/Roseville

Disclosure: Nothing to disclose.

Specialty Editors

Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Gary Setnik, MD, Chair, Department of Emergency Medicine, Mount Auburn Hospital; Assistant Professor, Department of Emergency Medicine, Harvard Medical School

Disclosure: Medical Director for: SironaHealth.

Chief Editor

Barry E Brenner, MD, PhD, FACEP, Program Director, Emergency Medicine, Einstein Medical Center Montgomery

Disclosure: Nothing to disclose.

Additional Contributors

Joseph J Sachter, MD, FACEP, Consulting Staff, Department of Emergency Medicine, Muhlenberg Regional Medical Center

Disclosure: Nothing to disclose.

References

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  2. Ramesh P, Al-Zubaidi FI, Abdelghaffar M, et al. TEM Classification of aortic dissection-the evolving scoring system: a literature review. Heart Lung Circ. 2024 Jan. 33 (1):17-22. [View Abstract]
  3. Wilczek M. Stanford classification of aortic dissection. Radiopaedia. Available at http://radiopaedia.org/articles/stanford-classification-of-aortic-dissection-1?lang=us. Revised: April 4, 2025; Accessed: April 16, 2025.
  4. [Guideline] Mazzolai L, Teixido-Tura G, Lanzi S, et al, for the ESC Scientific Document Group. 2024 ESC Guidelines for the management of peripheral arterial and aortic diseases. Eur Heart J. 2024 Sep 29. 45 (36):3538-700. [View Abstract]
  5. [Guideline] Contrella BN, Khaja MS, Majdalany BS, et al, for the Expert Panels on Vascular Imaging and Interventional Radiology. ACR Appropriateness Criteria thoracoabdominal aortic aneurysm or dissection: treatment planning and follow-up. J Am Coll Radiol. 2023 May. 20 (5S):S265-84. [View Abstract]
  6. Wojnarski CM, Svensson LG, Roselli EE, et al. Aortic dissection in patients with bicuspid aortic valve-associated aneurysms. Ann Thorac Surg. 2015 Nov. 100(5):1666-73; discussion 1673-4. [View Abstract]
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  8. Jansen Klomp WW, Brandon Bravo Bruinsma GJ, Peelen LM, Nierich AP, Grandjean JG, van 't Hof AW. Clinical recognition of acute aortic dissections: insights from a large single-centre cohort study. Neth Heart J. 2017 Mar. 25(3):200-6. [View Abstract]
  9. Wang GX, Hedgire SS, Le TQ, et al. MR angiography can guide ED management of suspected acute aortic dissection. Am J Emerg Med. 2017 Apr. 35(4):527-30. [View Abstract]
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  11. Chaikof EL, Mutrie C, Kasirajan K, et al. Endovascular repair for diverse pathologies of the thoracic aorta: an initial decade of experience. J Am Coll Surg. 2009 May. 208(5):802-16; discussion 816-8. [View Abstract]
  12. Cooper M, Hicks C, Ratchford EV, Salameh MJ, Malas M. Diagnosis and treatment of uncomplicated type B aortic dissection. Vasc Med. 2016 Dec. 21(6):547-52. [View Abstract]
  13. Mimoun L, Detaint D, Hamroun D, et al. Dissection in Marfan syndrome: the importance of the descending aorta. Eur Heart J. 2011 Feb. 32(4):443-9. [View Abstract]
  14. Rylski B, Milewski RK, Bavaria JE, et al. Long-term results of aggressive hemiarch replacement in 534 patients with type A aortic dissection. J Thorac Cardiovasc Surg. 2014 Dec. 148(6):2981-5. [View Abstract]
  15. Gawinecka J, Schonrath F, von Eckardstein A. Acute aortic dissection: pathogenesis, risk factors and diagnosis. Swiss Med Wkly. 2017 Sep 5. 147:w14489. [View Abstract]
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Aortic dissection

Chest radiograph of a patient with aortic dissection. Image courtesy of Dr. K. London, University of California at Davis Medical Center.

Chest radiograph of a patient with aortic dissection presenting with hemothorax.

Chest radiograph demonstrating widened mediastinum in a patient with aortic dissection.

Angiogram demonstrating dissection of the aorta in a patient with aortic dissection presenting with hemothorax.

Electrocardiogram of a patient presenting to the ED with chest pain; this patient was diagnosed with aortic dissection.

Patient with an ascending type A aortic dissection showing the intimal flap. Image courtesy of Kaiser-Permanente.

Patient with an ascending type A aortic dissection showing the intimal flap. Image courtesy of Kaiser-Permanente.

Patient with an ascending type A aortic dissection showing the intimal flap. Image courtesy of Kaiser-Permanente.

Patient with an ascending type A aortic dissection showing the intimal flap. Image courtesy of Kaiser-Permanente.

Patient with a type A aortic dissection involving the ascending and descending aorta. Image courtesy of Kaiser-Permanente.

Patient with a type A aortic dissection involving the ascending and descending aorta. Image courtesy of Kaiser-Permanente.

Patient with a type A aortic dissection involving the ascending and descending aorta. Image courtesy of Kaiser-Permanente.

Patient with a type A aortic dissection involving the ascending and descending aorta. Image courtesy of Kaiser-Permanente.

Patient showing a type B aortic dissection with extravasation of blood into the pleural cavity. Image courtesy of Kaiser-Permanente.

Patient showing a type B aortic dissection with extravasation of blood into the pleural cavity. Image courtesy of Kaiser-Permanente.

Patient showing a type B aortic dissection with extravasation of blood into the pleural cavity. Image courtesy of Kaiser-Permanente.

Patient showing a type B aortic dissection with extravasation of blood into the pleural cavity. Image courtesy of Kaiser-Permanente.