Snapshot A 32-year-old man with eunuchoid proportions and arachnodactyly presents to the emergency department with severe substernal chest pain that radiates to the back. He says that the pain occurred acutely and denies any recent trauma. Medical history is significant for Marfan syndrome. On physical exam, there are unequal blood pressures in the upper extremity. A chest radiograph demonstrates a widened mediastinum. A CT angiography demonstrates a Stanford A type aortic dissection. Summary Aortic dissection is a condition that results from a tear in the innermost layer of the aorta leading to a hematoma and separation of layers of the aortic wall. Patients with hypertension and advanced age are more at risk for dissection. These patients typically present with abrupt onset of severe, tearing chest pain. Diagnosis is made with CT angiography or transoesophageal echocardiogram. Chest X-ray is often acquired first, which may show a widening of the mediastinum. Treatment depends on the type of dissection. Regardless though, medical therapy is concurrently initiated with IV beta-blockers, IV fluids for hypotension, and surgical therapy indicated for type A dissections. Epidemiology Incidence common > 1/100,000 annual incidence Demographics 3:1 male to female ratio typically affects adults between the ages of 40-70 risk factors include hypertension atherosclerosis aortic aneurysm Turner syndrome Marfan syndrome Ehlers-Danos syndrome Etiology Pathophysiology mechanism an intimal tear of the aorta causes an intramural aortic hemorrhage that separates the intima from the media the resulting hematoma may rupture through the adventitia, leading to a thoracic or abdominal cavity hemorrhage or cardiac tamponade there are two types of aortic dissection Stanford A type a dissection involving the ascending aorta Stanford B type a dissection involving only the descending aorta cell biology dissection involves fragility of the media layer of the aorta formation of extracellular matrix on the media wall with accumulation of mucoid material resulting in cystic degeneration Associated conditions Hypertension (most common) Connective tissue disease Iatrogenic (e.g., coronary catheterization) Trauma bicuspid aortic valves lead to backflow which can enlarge the aorta and weaken the wall stability e.g., Turner syndrome Marfan syndrome results in cystic medial necrosis in the tissue of the aorta Anatomy The aorta has three distinct wall layers Adventitia outermost layer loose connective tissue Media middle layer smooth muscle cells organized in concentric layers collagen, elastin, and proteoglycans composing the extracellular matrix tears in the intima allows blood to collect between the intima and media Intima innermost layer single layer of vascular endothelium initial tear in the intima leads to the progression of aortic dissection Presentation History sudden onset of severe, 'tearing' chest pain can be painless in some patients, commonly those with Marfan syndrome Symptoms acute chest or back pain (most common) classically anterior chest pain that radiates to the back between the scapulae Physical exam inspection unequal blood pressures in the arms weak or absent pulses auscultation findings diastolic decrescendo murmur when the aortic valve is involved resulting in aortic regurgitation Imaging Radiographs indication to rule out other causes of chest pain (e.g., pneumothorax) recommended views chest x-ray with anteroposterior (AP) view finding widened mediastinum deviation of the trachea to the right deviation of the esophagus CT angiography of the chest indication most accurate imaging test for aortic dissection MR angiography of the chest can be used in stable patients with iodine contrast allergies considered gold standard for diagnosis findings intimal dissection flap dilation of the aorta and hematoma double lumen contrast leak Transesophageal echocardiography indications can be used if kidney injury is present or patient is allergic to contrast findings thrombosis in the new lumen pericardial effusion Differential Aortic embolism findings found with aortic embolism but not with aortic dissection occlusion at aortic bifurcation on CT angiography limb pain cyanosis, pulselessness, and pallor Myocardial infarction (MI) findings found with myocardial infarction but not with aortic dissection electrocardiogram findings (e.g., ST-segment elevation) increased cardiac biomarkers (i.e. troponin) Treatment Medical Pharmacological IV ß-blockers and anti-hypertensives indications Initial treatment for all stable patients rate control with a goal of around 60 bpm IV fluids and vasopressors indications unstable and hypotensive patients Surgical Aortic dissection repair indication Stanford type A aortic dissection considered a surgical emergency outcomes excellent 1- and 3-year survival rate for patients surgically treated for Type A aortic dissection Techniques Aortic dissection repair approach open heart surgery with a cardiothoracic surgeon under general anesthesia technique sternotomy and aortic flap creation complications endoleak infection bleeding stroke lower limb ischemia Complications End-organ damage secondary to poor perfusion acute renal failure acute abdomen mesenteric ischemia ischemic colitis paraplegia or weakness of lower extremities aortoiliac occlusive disease aortic regurgitation Myocardial infarction from coronary artery occlusion incidence estimated to be 1% to 5% risk factors coronary artery disease hypertension treatment percutaneous coronary intervention dual antiplatelet therapy anticoagulation Stroke incidence between 3-32% of aptients risk factors patients with concomitant chest pain, shock, and hypotension. treatment anti-thrombolytics or tPA mechanical thrombectomy Cardiac tamponade incidence between 8-31% of patients risk factors surgical repair for type A aortic dissection treatment pericardiocentesis pericardectomy Prognosis Overall poor prognosis 20-30% mortality rate for patients prognosis dependent on type of dissection Stanford type A effective blood pressure control and surgical treatment improve mortality up to 30% of patients die prior to reaching the emergency room Stanford type B effective conservative or surgical treatment improves mortality up to 90% of patients survive to discharge following medical therapy