INTRODUCTION — Acute aortic syndromes include a spectrum of life-threatening aortic conditions. By convention, acute disease is distinguished from chronic disease at an arbitrary time point of two weeks from initial clinical presentation (hyperacute: <24 hours, acute: 1 to 14 days, subacute: >14 to 90 days, chronic: >90 days) and typically manifests with symptoms. Acute aortic dissection is the most familiar and is defined by a separation of the layers of the aortic wall by an inciting intimal injury. Intimal tear without hematoma, penetrating aortic ulcer, aortic intramural hematoma, and periaortic hematoma are variants of the classically described aortic dissection (figure 1) [1-3]. The changes associated with these are more localized, though they are similar to those of aortic dissection, with penetration and weakening of the aortic wall that predisposes to aortic rupture, which may manifest as a contained periaortic hematoma or free rupture into the chest or abdomen . Each of these conditions can affect the thoracic aorta, abdominal aorta, and, in some cases, both.
An overview of the clinical features, classification, diagnosis, and approach to treatment of acute aortic syndromes including acute aortic dissection, aortic intramural hematoma, and penetrating aortic ulcer are reviewed.
Acute and chronic aortic dissection is also discussed in greater detail separately; aortic intramural hematoma and penetrating aortic ulcer are reviewed here.
DEFINITION AND PATHOPHYSIOLOGY
Acute aortic dissection — Acute aortic dissection is defined as a separation of the layers of the aortic wall due to an intimal tear (figure 1).
Spontaneous — For spontaneous dissection, it is uncertain whether the initiating event is a primary rupture of the intima with secondary dissection of the media or primary hemorrhage within the media and subsequent rupture of the overlying intima . The initial intimal tear can occur in the ascending aorta or descending aorta and occasionally can originate in the abdominal aorta. Blood at high pressure passes through the tear and separates the intima from the media and/or adventitia, creating a false lumen. The dissection can propagate proximally or distally from the initial tear to involve the aortic valve, coronary arteries, or branches of the thoracic or abdominal aorta . Such propagation is responsible for many of the associated clinical features of aortic dissection (acute chest or back pain, neurologic symptoms). A higher mean pressure in the false lumen can cause dynamic or static compression and occlusion of the true lumen with malperfusion of the branches of the aorta, resulting in end-organ ischemia (coronary, cerebral, spinal, extremity, visceral) . Aortic regurgitation, coronary ischemia, and cardiac tamponade can occur if the dissection progresses proximally to involve the aortic valve and coronary arteries or the pericardial sac, respectively. In addition, multiple communications may form between the true lumen and the false lumen. (See "Clinical features and diagnosis of acute aortic dissection", section on 'Clinical features'.)
Abdominal aortic dissection can occur as an extension of a thoracic aortic dissection with the intimal flap located in the proximal or descending thoracic aorta, or it can occur in isolation [7-13]. Isolated abdominal aortic dissection is reported occasionally and can be due to spontaneous, iatrogenic, or traumatic mechanisms . The infrarenal abdominal aorta is more commonly involved than the suprarenal aorta. In one review of 52 reported cases, the entry site for spontaneous isolated abdominal aortic dissections (SIAADs) most commonly occurred between the renal arteries and inferior mesenteric artery . A concomitant abdominal aortic aneurysm was identified in 40 percent of patients and indicated the need for repair. (See "Management of asymptomatic abdominal aortic aneurysm".)
Iatrogenic or traumatic — Aortic dissection that does not occur spontaneously can be due to instrumentation or trauma. Traumatic tears typically involve the descending thoracic aorta just distal to the subclavian artery and are reviewed in detail elsewhere . Iatrogenic or traumatic injury (eg, intra-aortic balloon pump placement, rapid deceleration motor vehicle accident) was responsible for 6 percent of cases of aortic intramural hematoma in one review . (See "Clinical features and diagnosis of blunt thoracic aortic injury" and "Surgical and endovascular repair of blunt thoracic aortic injury".)
Aortic intramural hematoma — Aortic intramural hematoma is defined as a hematoma confined within the medial layer of the aorta in the absence of a detectable intimal tear, although microtears may be present (figure 1). The absence of an intimal lesion distinguishes aortic intramural hematoma from the hematoma that may be associated with a penetrating aortic ulcer, for which there is a clear break in the intima. Aortic intramural hematoma can be a precursor to acute aortic dissection . In different series, aortic intramural hematoma accounted for 5 to 20 percent of patients with symptoms consistent with an aortic dissection (eg, acute aortic syndrome) [16-20].
The mechanism by which an intramural hematoma is created is not certain. Two mechanisms have been described: rupture induced by a penetrating atherosclerotic ulcer and spontaneous rupture . Spontaneous rupture of the vasa vasorum as a pathogenesis has not been proven [21,22]. In this scenario, the false lumen originates from spontaneous rupture of the vasa vasorum into the media of the aortic wall. Because there is no continuous flow, the blood contained within the wall quickly thromboses (picture 1).
Some believe that intramural hematoma represents acute aortic dissection with thrombosis of the false lumen and that an intimal tear is always present whether or not it is identified . Intimal defects have been identified surgically and radiographically in approximately 70 percent of cases initially diagnosed as an intramural hematoma [24,25]. However, there appears to be a difference in the affected plane of the aortic media. For intramural hematoma, the outer media (toward the adventitia) is thinner, which may explain the higher risk of rupture for intramural hematoma compared with acute dissection [26-29]. Between 8 and 16 percent will evolve into aortic dissection [27,29,30].
Intimal tear without hematoma — Intimal tear without hematoma (figure 1) is an uncommon variant of aortic dissection that is characterized by a stellate or linear intimal tear associated with exposure of the underlying aortic media or adventitia. There is no separation of the medial layers or progression .
Penetrating aortic ulcer — Penetrating aortic ulcer refers to a region of the aorta (ulcer-like projection) where the aortic intima is denuded with the lesion progressing through a variable amount of the aortic wall, over which there may or may not be overlying thrombus [31,32]. Penetrating aortic ulcers are typically associated with atherosclerotic changes of the adjacent aortic wall .
Penetrating aortic ulcer may be associated with hematoma within the media and may progress to perforation or aortic dissection [2,32-34]. Penetrating ulcer is the initiating lesion in <5 percent of all aortic dissections (image 1) [33,35].
Periaortic hematoma — Periaortic hematoma represents a contained aortic rupture due to slow oozing from the damaged aorta at or near the site of aortic injury (figure 1). Periaortic hematoma is more common in aortic intramural hematoma compared with acute aortic dissection. In a review of 971 patients with acute dissections from the International Registry of Acute Aortic Dissections (IRAD), 227 (23 percent) had a periaortic hematoma . Not surprisingly, patients with periaortic hematoma had higher rates of shock, cardiac tamponade, and altered consciousness/coma and had a significantly higher mortality rate compared with those without a periaortic hematoma (33 versus 20 percent).
CLASSIFICATION — Aortic dissection and other aortic syndromes are described in terms of the anatomic location of the intimal tear, duration of time from its occurrence, and clinical features, including the absence or presence of symptoms and whether disease becomes complicated. The nature of the complications differs for each variant, but each has the potential to cause life- or limb-threatening complications. (See 'Clinical features' below.)
Location of entry tear — Several anatomic classifications have been devised to stratify primarily aortic dissection. The variants of aortic dissection (figure 1), intimal tear without hematoma, penetrating aortic ulcer, aortic intramural hematoma, and periaortic hematoma can also be described in a similar manner based upon the location of the aortic abnormality.
The DeBakey and the Daily (Stanford) aortic dissection classification systems (figure 2) are commonly used [37,38]. Of the two, the Daily (Stanford) system predominates and will be used in this review.
●The Daily (Stanford) system classifies aortic dissections that involve the ascending aorta as type A, regardless of the site of the primary intimal tear, and all other dissections as type B [2,5,37,38].
•In patients with an ascending aortic dissection, aortic arch involvement is seen in up to 30 percent .
●The DeBakey system is based upon the site of the origin of the tear, with type 1 originating in the ascending aorta and propagating to at least the aortic arch, type 2 originating in and confined to the ascending aorta, and type 3 originating in the descending aorta and extending distally or proximally, but not proximal to the left subclavian artery [3,41,42].
•Aortic intramural hematoma more commonly involves the descending aorta [17,27,30,39,43]. For some patients, the intramural hematoma lesion in the ascending aorta may represent the early stage of an acute aortic dissection [16,20].
•Most penetrating aortic ulcers are located in the descending thoracic aorta (85 to 95 percent), but they can also occur in the ascending aorta or arch [34,35,44-47].
However, the DeBakey and Daily (Stanford) systems have limitations [37,38]. Both are relatively nonspecific regarding the precise extent of the dissection and are ambiguous regarding the involvement of the aortic arch. A modification that incorporates false lumen configuration into the Daily (Stanford) classification has been proposed for the purpose of stratifying risk for complications .
A task force commissioned by the Society for Vascular Surgery (SVS) and Society for Thoracic Surgery (STS) developed a classification system to address these issues. This system distinguishes type A from B by entry point as well as specifies the distal extent of the dissection (figure 3) .
●Type A aortic dissection is classified as an entry tear in zone 0, and the distal extent can range from zone 1 to 12.
●Type B has an entry tear in a zone >1 and the proximal and distal extent are noted.
Another classification that provides additional detail regarding the entry tear and extent of the dissection has also been proposed; the DISSECT system assesses six characteristics of dissection that provide the most important details influencing the choice of treatment, particularly those that are important when considering an endovascular procedure .
Duration — In the past, type B aortic dissection was classified simply as acute (<14 days) or chronic (>14 days) from the time of symptom onset, which was based on the timing of death in the era of open surgery [51,52]. The Society of Vascular Surgery (SVS)/Society of Thoracic Surgery (STS) reporting guidelines have provided additional classifications based on the timing from the onset of symptoms as follows :
Hyperacute – <24 hours
Acute – 1 to 14 days
Subacute – 15 to 90 days
Chronic – >90 days
For the purposes of our discussion, we will use the term "acute" type B aortic dissection to refer to the period ≤90 days encompassing the hyperacute, acute, and subacute periods. Chronic refers to the period after 90 days. (See "Management of acute type B aortic dissection" and "Management of chronic type B aortic dissection".)
Symptomatology — Type B aortic dissection or other aortic syndromes are considered uncomplicated or complicated based on symptomatology and other clinical features. Type B aortic dissection is considered complicated if there is evidence of malperfusion (figure 4 and figure 5), rapid expansion or aneurysmal degeneration of the aortic wall, impending or frank rupture, uncontrolled pain, or refractory hypertension (persisting despite three or more classes of antihypertensives at max doses) . Patients with type B aortic dissection are otherwise considered uncomplicated. Approximately 25 percent of patients presenting with type B aortic dissection are acutely complicated [54,55]. (See 'Clinical features' below.)
EPIDEMIOLOGY AND RISK FACTORS — The overall incidence of acute aortic syndromes ranges from two to four cases per 100,000 individuals. Acquired or genetically mediated conditions can weaken the aortic wall tissues, predisposing to acute aortic syndromes .
Acute aortic dissection comprises the majority of acute aortic syndromes [56-60]. Risk factors associated with acute aortic dissection include hypertension (including mediated by cocaine or other mechanisms [61,62]), atherosclerosis, prior cardiac surgery, aortic aneurysm, connective tissue disorder (eg, Marfan syndrome (table 1), Loeys-Dietz syndrome), bicuspid aortic valve, and prior aortic surgery [41,60]. Acute aortic dissection is more common in men (65 percent in an International Registry of Acute Aortic Dissections [IRAD] review), while women tend to be older at presentation (67 versus 60 years) [1,60]. Systemic hypertension, which increases the stress on the aortic wall, is the most important factor precipitating acute aortic dissection [4,60,63]. In a review of the IRAD data, 72 percent had a history of hypertension, and 31 percent had a history of atherosclerosis . These factors are less important in young patients, who are more likely to have a genetic component. In a separate review, in patients under age 40, only 34 percent had a history of hypertension, and only 1 percent had a history of atherosclerosis . (See "Clinical features and diagnosis of acute aortic dissection", section on 'Incidence and associated conditions' and "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders".)
Aortic intramural hematoma accounts for 5 to 20 percent of patients with symptoms consistent with acute aortic syndrome, although the incidence may be higher [16-20]. In a review of 1010 patients in the IRAD registry, intramural hematoma was present in 58 patients (5.7 percent). Among 51 patients with only aortic intramural hematoma at the initial diagnosis, eight (16 percent) progressed to aortic dissection on serial imaging studies . Compared with acute aortic dissection, patients with intramural hematoma are older and more commonly present with aortic aneurysm, and fewer have Marfan syndrome [26-28,39]. None of the 58 patients with intramural hematoma had Marfan syndrome in the IRAD review . Also distinguishing intramural hematoma from aortic dissection is the higher prevalence of females that are affected [29,39]. But like aortic dissection, aortic intramural hematoma is most often associated with longstanding hypertension [17,30,43]. In a meta-analysis of 143 reported cases, approximately one-half were hypertensive . In another series of 94 patients, 79 (84 percent) of aortic intramural hematomas were associated with hypertension . Cocaine-related aortic intramural hematoma has also been reported .
Penetrating aortic ulcers account for 2 to 7 percent of acute aortic syndromes . Patients with penetrating aortic ulcers are older (over 70 years) and have risk factors for atherosclerosis, including hypertension, hyperlipidemia, coronary artery disease, tobacco use, and infrarenal abdominal aortic aneurysm [34,45-47]. As discussed below, the presence of a penetrating atherosclerotic ulcer is associated with a higher likelihood of disease progression with medical therapy alone . (See 'Management' below.)
CLINICAL FEATURES — In the authors' experience, acute aortic syndromes are rarely identified as incidental findings with minimal symptoms on advanced imaging studies, although this has been reported [66-69]. Although very similar, there are some differences in the clinical manifestations of acute aortic dissection and those of other acute aortic syndromes.
The acute onset of severe chest or back pain occurs in 80 to 90 percent of patients with acute aortic dissection . The pain is usually described as severe, sharp, or "tearing" and is located in the anterior chest pain for type A aortic dissection and in the posterior chest or back pain for type B aortic dissection. Other symptoms or signs can be related to progression of the dissection and end-organ malperfusion (eg, shock, syncope, acute heart failure, myocardial ischemia, stroke, paraplegia, extremity ischemia, mesenteric ischemia) [41,58,60,63,70]. A complete discussion of the symptoms and signs of acute aortic dissection is provided separately. (See "Clinical features and diagnosis of acute aortic dissection".)
Pain is also common with intramural hematoma [26,27,30], but since patients with intramural hematoma are more likely to have type B aortic lesions compared with acute aortic dissection (eg, 60 versus 35 percent in the International Registry of Acute Aortic Dissections review), patients are more likely to present with upper or lower back pain [17,30,71]. Other manifestations seen with type A aortic dissections, such as myocardial infarction, stroke, aortic regurgitation, and syncope, are relatively infrequent with type A intramural hematomas [17,30,43,72]. Several studies have noted a higher risk of rupture for acute intramural hematoma compared with acute aortic dissection (26 percent versus 8 percent) [27-29]. Pericardial effusion occurs in 60 to 70 percent of type A aortic intramural hematoma and is much more common than with acute aortic dissection [26,27,30,39]. Malperfusion and aortic valve regurgitation is less common with aortic intramural hematoma.
Symptomatic penetrating aortic ulcers present similarly to other acute aortic syndromes, primarily with pain, the location of which depends upon the location of the ulcer.
No biomarkers are available to provide a diagnosis of acute aortic syndrome; however, for acute aortic dissection, a low D-dimer (less than 500 mcg/L) may help exclude the diagnosis among those who present with chest pain . (See "Clinical features and diagnosis of acute aortic dissection", section on 'Laboratory studies'.)
Although certain radiographic features, such as a widened mediastinum and pleural effusions, may raise suspicion for aortic disease, chest radiographs are not sensitive for a diagnosis of acute aortic syndromes but are also often not completely normal [30,74]. (See "Clinical features and diagnosis of acute aortic dissection", section on 'Chest radiograph' and "Clinical features and diagnosis of acute aortic dissection", section on 'Diagnosis'.)
DIAGNOSIS — Imaging confirmation is necessary to determine the type of acute aortic syndrome, classify the location and extent of the pathology, and identify any anatomic complications [16,17,72,75]. Acute aortic syndromes cannot be distinguished reliably from each other clinically, although certain clinical features may suggest ascending versus descending aortic involvement. (See "Clinical features and diagnosis of acute aortic dissection", section on 'Cardiovascular imaging' and "Clinical features and diagnosis of acute aortic dissection", section on 'Ascending versus descending aortic involvement'.)
Imaging confirmation — Computed tomographic (CT) angiography (eg, 3 to 4 mL/second peripheral injection with a 35-second imaging delay) is the diagnostic imaging modality of choice in hemodynamically stable patients. It is highly sensitive and specific for imaging aortic pathology. The study should include the entire aorta, including the iliac and femoral vessels. Other imaging modalities such as transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE) may be useful in hemodynamically unstable patients. Both TTE and TEE can identify aortic valve disruption leading to regurgitation, hemorrhagic pericardial effusion and tamponade, and regional wall motion abnormalities from coronary artery involvement. However, complete imaging of the distal arch and descending aorta are limited with TTE, and these may not be diagnostic for intramural hematoma. Magnetic resonance (MR) imaging is very sensitive and specific for aortic pathology, but is seldom used due to the wider availability of CT in the emergency department; catheter-based arteriography is rarely necessary . (See "Clinical features and diagnosis of acute aortic dissection", section on 'Cardiovascular imaging' and "Clinical features and diagnosis of acute aortic dissection", section on 'Ascending versus descending aortic involvement'.)
The imaging diagnosis of aortic dissection by CT scanning requires the identification of two distinct lumens; the intimal flap may or may not be demonstrated. The presence of intraluminal thrombus is a good marker of the false lumen, especially in the chronic phase. In the majority of cases, the false lumen is larger than the true lumen.
Absence of an intimal flap is a prerequisite for the imaging diagnosis of aortic intramural hematoma . In one review of 143 cases of aortic intramural hematoma, 81 percent were diagnosed by CT scan, and the remaining patients by MR imaging and/or TEE . The main finding on CT and MR angiography is a crescentic or circular high attenuation area along the aortic wall that does not enhance with contrast, absence of an intimal flap, and absence of compression of the patent lumen (image 2). However, the appearance of an aortic intramural hematoma and an acute dissection with complete thrombosis of the false lumen is similar, and an aortic intramural hematoma may be difficult to identify correctly. On TEE, findings include regional thickening of the aortic wall of more than 7 mm in a crescentic (nontraumatic) or circular shape (traumatic) and/or evidence of intramural accumulation of blood . In one series of 49 patients in whom the diagnosis of aortic intramural hematoma was confirmed by surgery or follow-up changes, the sensitivity and specificity of TEE were 100 and 91 percent, respectively .
These same imaging modalities also identify a penetrating aortic ulcer (image 3 and image 4 and image 5). Radiographic imaging of penetrating aortic ulcers show a lesion that penetrates the aortic wall to varying degrees, causing hematoma formation within the media, pseudoaneurysm, or rupture (image 6 and image 7). Penetrating atherosclerotic ulcer without medial thrombosis is more common in the ascending aorta . Identification of penetrating aortic ulcer may have prognostic importance as it is associated with a higher rate of disease progression . (See 'Intervention' below.)
Missed diagnosis — Acute aortic syndromes are frequently mistaken for other etiologies that cause chest pain, the most common being acute coronary syndromes. The incidence of initial misdiagnosis is up to 40 percent and may be more common when the ascending aorta is involved [77,78]. (See "Evaluation of the adult with chest pain in the emergency department".)
●In one review of 68 patients, the likelihood of missed diagnosis, which occurred in 38 percent, was significantly higher in the absence of a pulse deficit or absence of widened mediastinum on chest radiography. Thus, these features cannot be used to exclude a diagnosis.
●In a review of 127 patients with a final diagnosis of type A aortic dissection, an inappropriate initial diagnosis occurred in 37 percent of patients . Significant factors leading to the initially incorrect diagnosis were walk-in status and presence of coronary malperfusion.
Errors in diagnosis delay proper treatment and can lead to use of inappropriate therapies (eg, antithrombotic agents), which increase the risk for complications. In one review of 66 patients, of whom 26 patients with acute aortic syndrome were initially misdiagnosed, acute coronary syndrome was the most common misdiagnosis and resulted in treatment with aspirin in all patients, clopidogrel in 1, heparin in 22, and fibrinolytic agents in 3 . Exposure to antithrombotic agents was associated with major bleeding and a trend toward greater in-hospital mortality. In addition, there were higher rates of hemodynamic instability, hemorrhagic pericardial fluid, and hemorrhagic pleural effusion.
Differential diagnosis — The differential diagnosis of acute aortic syndromes includes other entities associated with acute chest or back pain, pulse deficit, and neurologic deficits, which includes both nonvascular and vascular pathologies . Non-aortic pathologies include acute coronary syndrome, pulmonary embolus, spontaneous pneumothorax, esophageal rupture, pericarditis, and pleuritis, among others (table 2). Triple rule-out CT (TRO-CT) is a modified coronary CT angiography protocol with extended thoracic coverage that may have advantages for identifying life-threatening causes of chest pain in the emergency department beyond coronary heart disease, such as pulmonary thromboembolism or acute aortic syndromes . (See "Evaluation of the adult with chest pain in the emergency department".)
Other acute aortic pathologies include aortic aneurysm, chronic aortic disease with new symptoms, and complications of prior aortic repair (eg, endoleak, pseudoaneurysm) . These may be suspected by risk factors and patient history, but cardiovascular imaging distinguishes these from the acute aortic syndromes discussed here. In patients with new symptoms and chronic pathologies, detailed comparison with existing/prior imaging data is necessary to distinguish dissection extension from other causes of their symptoms.
Artifact on transthoracic echocardiography can also mimic the appearance of a dissection flap .
Treatment overview — The general principles of the treatment of acute aortic syndromes are similar to acute aortic dissection (table 3). A crucial aspect of early therapy is ensuring an early and correct diagnosis so that the appropriate treatment can be instituted in a timely fashion. Approximately two-thirds of aortic dissections present as type A, and one-third are type B .
●Acute medical management of acute aortic syndromes includes controlling pain and anti-impulse therapy by controlling the blood pressure to minimize the likelihood of rupture or progression, unless hypotension is present. These should be initiated immediately for all patients (type A and type B dissections) once the diagnosis has been made but should not interfere with the timely transfer to the operating room for those with indications for immediate aortic repair. (See 'Acute medical management' below.)
●The treatment of type A acute aortic syndromes is surgical, with ongoing medical management of type A lesions reserved for patients who would not survive surgery. By contrast, type B acute aortic syndromes can generally be managed medically, with surgery or endovascular intervention reserved for those experiencing complications or progressive symptoms. (See 'Ascending aorta (type A)' below and 'Descending aorta (type B)' below.)
●The association of intramural hematoma and penetrating ulcer may imply a more aggressive clinical course, particularly in the ascending aorta, and intervention should be considered . Type B penetrating aortic ulcer may also have a more aggressive course even when identified incidentally and may merit early intervention.
●In general, type A aortic pathologies are repaired using open surgical techniques, while an initial endovascular approach is appropriate for most type B aortic pathologies provided the patient's anatomy is suitable for endograft placement and the etiology is not due to a genetically mediated condition. (See 'Intervention' below.)
Acute medical management — Patients with suspected acute aortic syndromes should be admitted to an intensive care unit as rapidly as possible after confirmation of the diagnosis for pain control with morphine and anti-impulse therapy to reduce systolic blood pressure to the lowest level tolerated, typically using beta blockers (table 3) [2,80].
A toxicology screen should be considered in any patient presenting with an acute aortic syndrome, particularly if there are no other known predisposing factors. The results of toxicology screening may alter the pharmacological agents chosen for acute medical management. (See "Testing for drugs of abuse (DOAs)" and 'Caution in cocaine-related events' below.)
Patients generally require blood pressure monitoring with an arterial line to facilitate rapid management of changes in blood pressure. Patients who are hemodynamically unstable or with airway compromise should be intubated. Acute medical therapies should not interfere with timely transfer to the operating room for those in whom immediate surgery is indicated. An experienced cardiovascular surgeon should be consulted early in the course to discuss any decision for surgery and its timing, which must be individualized taking into account the patient's comorbidities (eg, prior stroke), age, neurologic and renal function, and patient and family wishes.
Before fluid volume is administered, hypotensive patients should be evaluated to determine if the cause is hemopericardium with tamponade, valvular dysfunction, or left ventricular systolic dysfunction. In patients with cardiac tamponade, percutaneous pericardiocentesis can accelerate bleeding and shock .
Anti-impulse therapy — Anti-impulse therapy aims to reduce the velocity of left ventricular contraction, thereby decreasing shear stress and minimizing lesion progression . This is usually accomplished with antihypertensive therapy, typically using intravenous beta blockers (table 4). Inotropic agents should be avoided since they will increase aortic wall shear stress and may lead to progression. Systolic blood pressure should be reduced to the lowest level that is tolerated without compromising mentation or urine output, generally between 100 and 120 mmHg. Although there are no randomized trials in patients with acute aortic syndromes, but observational studies suggest that lowering blood pressure reduces the rate of progression [86,87]. (See 'Intervention' below.)
Initial treatment consists typically of an intravenous beta blocker to reduce the heart rate below 60 beats/minute. Esmolol is useful in the acute setting due to its short half-life and ability to titrate to effect (500 mcg/kg loading dose over one minute, then infuse at 25 to 50 mcg/kg/minute; maximum of 300 mcg/kg/minute). Esmolol is also advantageous in patients who might be intolerant of beta blockers due to asthma or heart failure, for example . Labetalol can be given as a bolus (20 mg initially, followed by 20 to 80 mg every 10 minutes to a total dose of 300 mg) or as an infusion (0.5 to 2 mg/minute). Diltiazem or verapamil are alternatives in patients who cannot tolerate beta blockers .
If after beta blockade the systolic blood pressure remains elevated, nitroprusside can be added, if needed, to achieve a systolic blood pressure of 100 to 120 mmHg. The initial dose of nitroprusside is 0.25 to 0.5 mcg/kg per minute to a maximum of 10 mcg/kg per minute. Nitroprusside should not be used without first controlling heart rate with beta blockade since vasodilation alone induces reflex activation of the sympathetic nervous system, leading to enhanced ventricular contraction and increased aortic wall shear stress. Patients receiving nitroprusside should be continuously monitored, preferably using an intra-arterial cannula from the arm with the highest auscultatory pressure. While nitroprusside is the preferred second-line agent, intravenous nicardipine, clevidipine, angiotensin converting enzyme (ACE) inhibitors, verapamil, or diltiazem may also be effective in lowering blood pressure [2,84,88,89]. Other direct vasodilators, such as hydralazine, should be avoided since they increase aortic wall shear stress and provide less accurate and reversible control of the blood pressure.
Caution in cocaine-related events — Initial management in patients with acute cocaine toxicity should aim to reverse centrally mediated sympathetic nervous system stimulation. (See "Cocaine: Acute intoxication", section on 'Approach to management'.)
Beta blockers are generally avoided in patients with acute cocaine intoxication [90,91], but selective beta blockers such as esmolol or mixed agents such as labetalol may be reasonable for treating patients with acute aortic dissection or other acute aortic syndromes, when needed (table 4). The use of non-selective beta blockers alone may lead to unopposed alpha stimulation worsening hypertension [92-94]. The use of drugs with mixed activity (alpha and beta blockade) lowered blood pressure but did not reverse coronary vasoconstriction in one small study . Calcium channel blockers or nitroglycerin can be used in conjunction with esmolol or labetalol if additional blood pressure lowering is needed.
For patients with acute aortic dissection, anti-impulse therapy is usually initiated prior to learning the result of any drug screening (eg, cocaine, methamphetamine), and as such, many patients do receive beta blockers. In an IRAD review of cocaine-related dissection, there were no differences in the type of treatment received comparing cocaine and noncocaine users, including beta blocker therapy . However, when more than one antihypertensive agent was used, it was not stated which medication was used first.
Pain control — Means to provide pain control other than antihypertensive therapies are warranted. This may include intravenous opioids as needed or patient-controlled analgesia (PCA) as would be administered to a postoperative patient, in the absence of contraindications.
Pain refractory to optimal medical management has been associated with worse outcomes in patients with aortic dissection . However, recurrence of pain may not always be associated with failure of medical therapy. In a study of 34 patients who experienced recurrent pain after diagnosis of type B aortic dissection , repeat imaging studies revealed no change in aortic diameter and no radiographic evidence of worsening. Overall, only 2 of the 34 patients had a complicated hospital course. On the basis of these observations, the authors concluded that among patients with early recurrent pain after type B aortic dissection, in the absence of clinical or radiographic signs of anatomic changes such as effusion, dilation, or refractory hypertension, a conservative strategy of continued medical management is a reasonable approach .
Intervention — Intervention for acute aortic syndromes depends upon the location of the involved aorta and the presence of complications. In general, type A lesions are treated with urgent surgical repair, whereas in many cases type B lesions can be treated with ongoing medical care [2,5,17,19,71].
Ascending aorta (type A) — Patients with acute aortic syndromes affecting the ascending aorta (type A) should be referred for emergency surgical evaluation and treatment. (See "Management of acute type A aortic dissection", section on 'Surgical referral or transfer'.)
Type A aortic dissection is a surgical emergency. Rupture of the dissected aorta is fortunately uncommon but is an ominous complication with certain mortality unless prompt surgical intervention can be undertaken. The development of malperfusion in type A aortic dissection is associated with mortality rates up to 44 percent [85,97,98]. In one IRAD study, 87 to 90 percent of patients with acute type A aortic dissections were able to initially be treated surgically. Among patients with acute type A aortic dissection who are treated with medical management alone, mortality progressively increases with time (20, 30, 40, and 50 percent at 1, 2, 7, and 30 days, respectively) . Despite other improvements in patient care, the in-hospital mortality rate for type A aortic dissection has remained at approximately 20 percent over the past 20 years. Repair of type A aortic dissection involves replacement of the ascending aorta, resection of intimal tears and aneurysmal aorta, and either restoring the competency of or replacing the aortic valve. (See "Surgical and endovascular management of acute type A aortic dissection".)
The treatment of type A penetrating aortic ulcer is also emergency surgery owing to its natural history and predilection for rupture. Even asymptomatic acute ascending or arch penetrating aortic ulcers should generally be managed operatively as these do not appear to follow a benign course [29,34,45,47]. The risk of rupture of a type A penetrating aortic ulcer may be as high as 33 to 40 percent [29,45]. Graft replacement of the ascending aorta is the standard treatment of a penetrating aortic ulcer of the ascending aorta. Transverse arch penetrating aortic ulcers can be managed by open graft replacement or by using endovascular techniques, often with brachiocephalic vessel debranching.
Similarly, treatment of type A aortic intramural hematoma is aggressive to prevent progression to aortic dissection or rupture [27,28,99,100]. Among medically treated patients, mortality rates range from 33 to 40 percent [27,28,99]. In a multicenter study of 66 patients who were admitted to the hospital within 48 hours after the onset of symptoms, 39 patients (59 percent) showed evidence of progression to dissection, rupture, or aneurysm within 30 days; most of these patients had ascending lesions . In a review of 143 patients with aortic intramural hematoma, patients with lesions of the ascending aorta had a lower mortality with surgery than medical treatment (14 versus 36 percent) . Mortality for surgically treated intramural hematoma is similar to that of aortic dissection [27,28,39,99]. Among those patients with type A aortic intramural hematoma for whom surgery is deemed too high a risk because of advanced age or other comorbid conditions, mortality rates are lower with medical treatment compared with similar patients with type A aortic dissection (6 versus 58 percent with classic dissections, in one study ).
It has also been suggested that good outcomes can be achieved in type A intramural hematomas when therapy is guided by specific patient characteristics and only those deemed at high risk for complications are taken for surgery. A maximum aortic diameter ≥50 mm on initial computed tomography (CT) may identify patients who are more likely to progress . However, progression also occurs in patients with smaller lesions . In one series of 41 patients, only 11 (27 percent) underwent early surgical intervention, in each case because of cardiac tamponade or aortic rupture . Among the remaining patients, who were managed conservatively, nine (22 percent) subsequently required surgery for progression of the aortic intramural hematoma. In another study, the three-year survival rate was 78 percent. However, such good outcomes have not been noted in other reports . Until more data are available, surgery should remain the preferred approach for type A aortic intramural hematomas .
Descending aorta (type B) — Most lesions associated with acute aortic syndromes affecting the descending aorta (type B) are initially treated by medical management. Intervention (surgical or endovascular) is generally reserved for patients who have persistent severe hypertension, persistent or recurrent pain, progression (to dissection or propagation of dissection), aneurysmal expansion, malperfusion leading to end-organ ischemia, or rupture . An exception may be penetrating aortic ulcer associated with intramural hematoma, for which earlier intervention may be needed to prevent complications. The mortality associated with such complications can exceed 60 percent. The rapid evolution of the use of endovascular treatments mandates their immediate availability in the acute phase or the transfer of the patient to a regional medical center with experience and such resources.
Complications of type B aortic dissection (early or late) in medically managed patients occur in approximately one-third of patients, necessitating intervention. (See "Management of acute type B aortic dissection" and "Management of chronic type B aortic dissection".)
Aortic intramural hematoma is more common in the descending aorta compared with aortic dissection (60 versus 35 percent in the IRAD review) . Many patients with type B aortic intramural hematoma respond well to medical therapy with resolution of the aortic abnormality over time [5,19,39,43,104,105]. In a review of 143 patients with type B aortic intramural hematoma, mortality rates were similar for medical versus surgical treatment (14 versus 20 percent) . As many as 10 percent of aortic intramural hematoma may completely resolve with medical therapy [27,29,30]. Predictors of progression, which occurs in 8 to 16 percent of patients with type B intramural hematoma (defined as aortic rupture, hematoma expansion, or dissection) in spite of adequate medical management, include maximum aortic diameter ≥40 mm, maximum aortic thickness ≥10 mm on CT scan , age >70 years, and presence of a penetrating atherosclerotic ulcer [17,104]. Late progression can also occur in patients with aortic intramural hematoma who survive the initial episode [71,104]. Patients who progress are less likely to have been treated with a beta blocker compared with those who were treated (49 versus 7 percent) . One study evaluated 53 patients with a type B aortic intramural hematoma and 57 with a type B aortic dissection, all of whom were initially treated medically . At three years, 77 percent of intramural hematomas had regressed or disappeared. Survival at five years was significantly better for patients with aortic intramural hematoma compared with aortic dissection (97 versus 79 percent). However, a similar analysis found similar survival for patients with type B aortic intramural hematoma and type B aortic dissection (85 versus 89 percent) .
Aortic intramural hematoma associated with penetrating atherosclerotic ulcer has a higher rate of progression with medical therapy [34,108]. This was illustrated in a series of 65 symptomatic patients with aortic intramural hematoma, 34 (52 percent) of whom had an associated penetrating atherosclerotic ulcer, almost all of whom (31 patients) had a type B hematoma . Progression with medical therapy (defined as aortic rupture, hematoma expansion, or dissection) occurred significantly more often in patients with a penetrating aortic ulcer compared with those who did not (48 versus 8 percent).
Among patients with a penetrating atherosclerotic ulcer associated with aortic intramural hematoma or persistent pain, early endovascular intervention has been proposed as a less invasive alternative to treat these lesions and prevent complications. In a small series of 26 patients, all had successful device deployment . Three patients died within 30 days and two had an early endoleak (leakage of blood around the graft within the aortic lumen). Actuarial survival estimates at one, three, and five years were 85, 76, and 70 percent, respectively.
Open surgical and endovascular techniques — Type A lesions are treated using an open surgical approach, although some hybrid approaches may be available for a limited number of focal lesions. For most patients with type B lesions, an endovascular approach is appropriate; however, patients with genetically mediated thoracic aortic aneurysm/dissection who have complications should be managed using open surgical techniques. Open surgical and endovascular methods for treating thoracic aortic dissection are reviewed separately. (See "Surgical and endovascular management of acute type A aortic dissection" and "Surgical and endovascular management of acute type B aortic dissection" and "Management of chronic type B aortic dissection", section on 'Endovascular versus open repair'.)
CLINICAL AND IMAGING FOLLOW-UP — For patients who are not undergoing immediate intervention, follow-up clinical examination and vascular imaging (computed tomographic [CT] or magnetic resonance [MR] angiography) are performed at 1, 3, 6, and 12 months and annually thereafter to detect malperfusion or aneurysm formation . (See "Management of acute type B aortic dissection", section on 'Surveillance imaging'.)
Patients who have undergone surgical or endovascular repair are followed accordingly. (See "Surgical and endovascular management of acute type A aortic dissection", section on 'Postoperative care' and "Surgical and endovascular management of acute type B aortic dissection" and "Endovascular repair of the thoracic aorta", section on 'Postoperative endograft surveillance'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic dissection and other acute aortic syndromes".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Thoracic aortic aneurysm (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Acute aortic syndromes – Acute aortic syndromes include a spectrum of life-threatening aortic conditions including acute aortic dissection, which is the most familiar to clinicians, but also aortic intramural hematoma, penetrating aortic ulcer, intimal tear without hematoma, and periaortic hematoma. (See 'Introduction' above and 'Definition and pathophysiology' above.)
●Classification – Acute aortic syndromes are classified according to the location and extent of involvement of the aorta (figure 2). The Stanford system, which is the more widely used, classifies aortic dissections that involve the ascending aorta as type A, regardless of the site of the primary intimal tear, and all other dissections as type B. Variants of aortic dissection, intimal tear without hematoma, penetrating aortic ulcer, aortic intramural hematoma, and periaortic hematoma can be described in a similar manner. A classification from Society for Vascular Surgery (SVS) and Society for Thoracic Surgery (STS) also distinguishes type A from B aortic dissection by entry point but specifies the distal extent of the dissection as well. (See 'Classification' above.)
●Clinical features – Acute onset severe chest pain is the most common presenting symptom of acute aortic syndromes. Anterior chest pain is more typical of ascending (type A) lesions, while upper or lower back pain is more common with descending (type B) lesions. Other manifestations seen with type A aortic dissections, such as myocardial infarction, stroke, aortic regurgitation, syncope, and paraplegia, are less common manifestations of the other acute aortic syndromes. (See 'Clinical features' above.)
●Diagnosis – Since clinical manifestations are nonspecific, the diagnosis of acute aortic syndromes relies on vascular imaging studies to define the aortic abnormality, classify the location and extent, and identify any anatomic complications. A crucial aspect of early therapy is ensuring a correct diagnosis so that the appropriate management scheme can be instituted in a timely fashion. Diagnostic imaging modalities include computed tomography (CT) or magnetic resonance (MR) angiography of the chest (with or without contrast) and transesophageal echocardiography. Exclusion of an intimal flap is a prerequisite for the radiologic diagnosis of aortic intramural hematoma. Imaging may also identify a penetrating atherosclerotic ulcer as the etiology of aortic intramural hematoma. (See 'Diagnosis' above.)
●Management – The general principles of medical treatment of acute aortic syndromes are similar (table 3) and include pain control and anti-impulse therapy to reduce the rate of progression, which should be initiated for all patients unless hypotension is present but should not interfere with the timely transfer to the operating room for those with indications for immediate aortic repair. (See 'Management' above.)
•Anti-impulse therapy – Intravenous beta blockers (eg, esmolol, labetalol) are typically used as initial anti-impulse therapy (table 4). Intravenous sodium nitroprusside can be added if the systolic blood pressure remains above 100 mmHg, provided mentation and renal function are intact. Nitroprusside should not be used without beta blockade since vasodilation induces reflex activation of the sympathetic nervous system, leading to enhanced ventricular contraction and aortic shear stress. (See 'Acute medical management' above.)
•Type A acute aortic syndromes – For type A acute aortic syndromes, the definitive treatment is surgical. Surgery may not be feasible in patients of advanced age or other comorbid conditions, and these patients are managed medically. Compared with patients with classic ascending aortic dissection who are managed medically, patients with type A aortic intramural hematoma have a better prognosis. (See 'Ascending aorta (type A)' above.)
•Type B acute aortic syndromes – For type B acute aortic syndromes, the treatment is generally medical, with surgery or endovascular intervention reserved for those experiencing complications or refractory pain or progressive symptoms. For most patients with complicated type B lesions, we suggest an initial endovascular approach, rather than open surgery, provided the patient's anatomy is suitable for endograft placement (Grade 2C). Perioperative morbidity and mortality is lower for an endovascular compared with open surgical approach. However, patients with genetically mediated thoracic aortic aneurysm/dissection affecting the descending thoracic aorta who have complications should be managed using open surgical techniques. (See 'Descending aorta (type B)' above.)
●Clinical follow-up and surveillance – For patients who are not undergoing immediate intervention, follow-up clinical examination and vascular imaging (CT or MR angiography) are performed at 1, 3, 6, and 12 months and annually thereafter to detect malperfusion or aneurysm formation. (See 'Clinical and imaging follow-up' above.)
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