Dissecting aortic aneurysm (DAA) is characterized by the separation of the layers in the aortic wall. Due to the high risk of mortality, it is imperative to diagnose and treat urgently.
Patients with aortic aneurysms are usually asymptomatic. In fact, thoracic aortic aneurysms (TAAs), which account for 10% of all dissections, are discovered incidentally on imaging studies such as chest x rays. Abdominal aortic aneurysms (AAAs) are identified incidentally as well or diagnosed during the physical exam as reflected by a pulsatile abdominal mass.
While a wide range of patients will exhibit hypertension, symptoms may not present until an aneurysm enlarges. When rupture or dissection is impending, the clinical picture is characterized as sudden onset of tearing chest or back pain in many individuals, while others may experience only mild pain. In fact, 10% of patients will be asymptomatic, such as those with Marfan syndrome . These patients may be diagnosed late since the nonspecific features can be clouded by other differentials. The location of the pain can reflect the dissection site. A clinical picture resembling that of myocardial infarction (MI) suggests that the dissection is in the anterior arch or aortic root, which results in diminished blood perfusion to the coronary arteries. Additionally, jaw or neck pain is indicative of dissection in the aortic arch.
Extracardiac manifestations such as neurologic deficits are the initial signs in about 20% of patients. For example, syncope is observed in almost 5% of cases. Also, cardiovascular symptoms such as orthopnea and dyspnea reflect the development of congestive heart failure (CHF) secondary to aortic regurgitation. Moreover, respiratory signs such as dyspnea and hemoptysis occur if the anatomical airway is obstructed.
Physical exam findings may include blood pressure asymmetry between the upper extremities, in which a difference of more than 20mm Hg may be demonstrated. Account must be taken that this may be seen in individuals without aortic dissection as well. Severe aortic regurgitation can produce wide pulse pressure and diastolic murmur. The aortic regurgitation causes CHF which results in basilar crackles or increased jugular venous pressure . Other clinical signs include asymmetrical pulses and bruit in the carotid, brachial, and femoral ateries. A life threatening sign, hypotension, is indicative of heavy volume loss, cardiac tamponade, or increased vagal tone. Likewise, a hemothorax can occur in cases with bleeding into the pleura space.
All patients with chest pain or any clinical picture indicating a cardiac etiology should be evaluated urgently and thoroughly. In addition to a history and physical exam, imaging is crucial for establishing the diagnosis. The choice of imaging depends on the patient's cardiovascular status.
The initial test, a chest x ray, may reveal a widened aorta. But the CT with contrast study is commonly used as the test of choice in cases of emergency. Additionally, CT angiography reveals the anatomy of the dissection and identifies plaque development. It offers a sensitivity of 83% to 94% and a specificity of 87% to 100%. The 3D reconstruction, however, is not readily available in all hospitals . Finally, magnetic resonance imaging (MRI) could be an alternative for patients with allergies to dye contrasts. This test demonstrates a sensitivity of 98% and a specificity comparable to CT.
In these individuals, an echocardiogram is a key study.
Cardiac markers and biomedical profiles are obtained. Additionally, a complete blood count is important and can show low hemoglobin and hematocrit reflecting a rupture. Leukocytosis can also be revealed, indicating stress. Other findings such as increased blood urea nitrogen and creatinine suggest blood loss or dehydration secondary to conditions such as prerenal azotemia. With regards to coagulation studies, assessment of fibrin degradation products and fibrinogen may point to the diagnosis. Furthermore, another assay tests for smooth muscle myosin heavy-chain, which is typically elevated in the first 24 hours of DAA.
To differentiate between aortic dissection and MI, the classic electrocardiographic (ECG) findings are not usually found in the former.
Medical and surgical treatment options are available. The decision making incolves careful consideration of the patient’s age, comorbidities, the type of dissection, and overall clinical picture.
In all patients, intravenous antihypertensives should be initiated immediately if dissection is suspected (unless hypotension is present). The goals are to decrease the strength of cardiac contractions and systemic arterial pressure while still maintaining organ perfusion.
Surgical interventions aim to reduce complications, prevent rupture and fatality. The procedures include suturing of the layers of the aortic wall. Additionally, a graft is used to replace damaged tissue and reinforce the aorta. The DeBakey classification of aortic dissection guides the treatment strategy. Also, the following signs indicate emergency surgery: dissection, evidence of increased hematoma, impending rupture, hemorrhage into the lung cavity, and persistent pain not responding to treatment. The surgical technique for TAAA repair depends on the type. In Crawford type I TAAAs a Dacron graft is used to replace the aorta from left subclavian artery to visceral organ and renal arteries. In Crawford type II TAAAs the aorta is replaced from left subclavian artery to the aortic bifurcation with a Dacron graft. Finally, Crawford type III or IV TAAAs are repaired with a partial bypass of the left atrium to the femoral artery or renal bypass.
Patients will undergo close surveillance. Additionally, they will receive antihypertensive drug therapy and lipid lowering drugs if indicated.
DAA is associated with a high mortality rate, in which a majority of patients die before the arrival at the hospital. Furthermore, mortality in the hospital setting is almost 30%. In fact, those who undergo surgical intervention have a 30% fatality rate while this figure is doubled in individuals treated medically. Of important note, elderly patients and those with coexisting diseases are poor surgical candidates and hence require medical management. Furthermore, almost 60% of treated patients who survive the first 2 weeks will survive 5 weeks and 40% remain alive to the 10 years point.
In studies conducted decades ago, a majority of patients with acute dissection died within 3 months . In those that survived, most did not live beyond 5 years due to rupture  . However, surgincal intervention has improved survivability  .
There are risk factors that are heavily associated with DAA. These conditions may be congenital or acquired. Additionally, whether in isolation or conjunction with other factors, they contribute to the development of aortic dissection.
The list of congenital disorders associated with aortopathy includes Marfan syndrome, Ehlers Danlos syndrome and other connective tissue disorders such as Turner syndrome, familial aortic dissections, Adult polycystic kidney disease, Osteogenesis imperfecta, coarctation of the aorta, aortic valve anomalies, and metabolic disorders.
Hypertension, a significant predisposing condition , has been demonstrated in 70% of patients with aortic dissection. Furthermore, elevated blood pressure may help propagate the dissection. Further acquired causes include syphilitic aortitis, blunt chest trauma or injury, and cocaine use.
The incidence of this disease varies according to the risk factors exhibited in different populations  . Hence, the annual incidence lies between 5 to 30 individuals per million.
With regards to race, aortic dissection is more frequently observed in black people than in white. Additionally, it is less common in Asians. As for gender, there is a stronger male preference as it is 2 to 3 times more prevalent in males. Finally, the age demographics for this disease reveal that almost 75% of patients with aortic dissection fall in the range of 40 to 70 years of age, especially in the 50 to 65 years group.
The pathogenesis of aortic dissection is characterized by the influence of elevated pulsatile pressure and shear stress on the walls of the aorta. Hence, the large blood vessel becomes vulnerable to damage. In fact, this marked increase in wall tension accounts for the aortic rupture in situations of mechanical trauma or aneurysmal dilatation . This observation is supported by the Laplace law, which explains that an increase in the luminal radius causes greater stress on the wall.
Most cases of thoracic aneurysms are secondary to changes in elastin and collagen in arteriosclerotic disease. These degenerative conditions occur with increased age. Additionally, prior dissections can form pathologic changes making the aorta susceptible to future aneurysms. The aging aorta can develop cystic medial necrosis, which is the breakdown of collagen, elastin and smooth muscle leading to the fragility of the aortic wall. This can be severe in patients with hypertension, Marfan syndrome, and bicuspid aortic valves.
Aortic dissection typically arises from a rupture in the intimal layer of the aortic wall  which can lead to the propagation of the dissection into the medial layer. In fact, an intimal flap is characteristically found in aortic dissection. Additionally, hemorrhage or a hematoma in the media can cause intimal perforation .
In summary, degenerative diseases lead to a weakened aortic wall and aneurysmal dilation especially in patients with hypertension.
While there are no preventative measures for AD, there are modifiable risk factors. For example, blood pressure maintenance, smoking cessation, and weight control are all very important strategies. Additionally, patients with an aortic aneurysm can undergo surgical repair of the defect.
Dissecting aortic aneurysm (DAA) is a life-threatening condition, in which a tear in the intimal layer causes blood to enter the intima-media space resulting in the propagation of the dissection. There are numerous predisposing conditions associated with DAA. For example, hypertension, congenital aortic stenosis, bicuspid aortic valve, and connective tissue diseases are all frequently observed in patients with dissection .
Aortic aneurysms manifest mostly in the abdominal aorta but also occur in the thoracic aorta. Additionally, aneurysms can coexist in both segments, which is referred to as thoracoabdominal aneurysms (TAAA).
The clinical picture of an aortic aneurysm is variable as many cases are asymptomatic and incidentally discovered through a routine exam or imaging. When an aneurysm expands, patients may experience severe chest or back pain with possible cardiovascular, neurologic, and respiratory signs. Moreover, a potentially fatal complication of an aortic aneurysm is a rupture with hemorrhage.
Diagnosis is established by history, physical exam, imaging and laboratory tests. In the emergency setting a computed tomography (CT) with contrast is the test of choice. In addition, there are other imaging techniques that can be used depending on the patient's cardiovascular status.
Therapy includes medical and surgical options. Factors such as patient's age, coexisting morbidities, and stability play a role in the medical management. Prompt diagnosis and treatment are paramount for these patients as these cases are potentially fatal.
An aortic dissection is a potentially fatal condition in which the walls of the aorta exhibit a tear. The aorta is the large blood vessel carrying blood from the heart to the rest of the body. The tear can cause blood to spill between the layers of the aorta thereby separating the layers.
This disorder is much more common in men than women. It affects people aged between 40 to 70 years old. Also, it is more common in black people than in white.
In many cases, the wall of the artery becomes weakened because of long-term high blood pressure. Patients with arteriosclerosis are also at risk for developing dissection. In other cases, there are risks such as hereditary diseases in the connective tissue or birth defects such as coarctation of the aorta or abnormalities of the aortic valve.
Patients may either show no symptoms or have severe chest or back pain described as tearing. Exam findings such as diminished or absent pulses can be seen.
Certain tests such as chest x rays and CT scans are helpful to diagnose the disorder. Also, laboratory exams are important to provide the full extent.
Treatment is usually drug therapy and/or surgical intervention. The doctors will evaluate the patient's age, medical history, stability and other factors to determine the best course of therapy.
All patients will take blood pressure medications and cholesterol-lowering drugs for life. Additionally, they will be closely monitored.