主动脉夹层

nullAorta DissectionAorta DissectionBackgroundBackgroundClassic aortic dissection is a longitudinal split or partition in the media of the aorta. The smaller true lumen is lined by intima, and the false lumen is lined by media. The dissection usually stops at an aortic branch vessel or at the level of an atherosclerotic plaque. pathophysiology pathophysiology nullMost classic aortic dissections anatomic locations Most classic aortic dissections anatomic locations the aortic root 2 cm above the aortic root just distal to the left subclavian artery Common reasons of causing deathCommon reasons of causing deathwall rupture hemopericardium and tamponade occlusion of the coronary ostia with myocardial infarction severe aortic insufficiency. Aortic intramural hematoma (AIH) Aortic intramural hematoma (AIH) a more recently described entity in which no intimal flap is present ; It results in a spontaneous medial hematoma that may be secondary to an infarction of the vasa vasorum of the adventitia. Aortic intramural hematoma accounts for approximately 25% of aortic dissections. Involvement of the ascending aorta, associated risk factors associated risk factors Chronic hypertension Connective tissue disorders (Marfan syndrome, Ehlers-Danlos syndrome) Bicuspid aortic valve Coarctation of the aorta Turner syndrome Takayasu arteritis Giant cell arteritis Pregnancy Trauma Crack cocaine use Cardiac catheterization Metabolic disorders Mortality/Morbidity Mortality/Morbidity The mortality rate increases with a delay in diagnosis, especially for ascending aortic dissections. The mortality rate is 1% per hour for the first 48 hours. The incidence is approximately 2000 cases per year. lack of reporting and the small number of autopsies performed grossly underestimate the true incidence. Sex,age and race Sex,age and race Aortic dissections are more common in men than in women (ratio, 3:1) ; in patients aged 35-85 years, with a peak in those aged 50-65 years.; Aortic dissection is more common in African-Americans; It is least common in Asians. classification classification DeBakey classification Type I: The entire aorta is involved. Type II: Only the ascending aorta is involved. Type III: Only the descending aorta is involved. Type IIIA involves the descending aorta as far as the diaphragm. Type IIIB involves the descending aorta below the diaphragm. Stanford classification Type A: The ascending aorta is involved. Type B: The descending aorta is involved.nullImage A represents a Stanford A or a DeBakey type 1 dissection. Image B represents a Stanford A or DeBakey type II dissection. Image C represents a Stanford type B or a DeBakey type III dissection. Image D is classified similar to A but contains an additional entry tear in the descending thoracic aorta. Note that a primary arch dissection does not fit neatly into either classification. nullDissection of the aorta descendens (3), which starts from the left subclavian artery, reaching to the abdominal aorta (4). Aorta ascendens (1) and aortic arch (2) are not involved.Clinical ManifestationsClinical ManifestationsRipping or tearing pain in the intrascapular area Abrupt onset of the pain Acute, severe chest pain (Anterior chest pain can mimic acute myocardial infarction) Pain extending to the neck or jaw Altered mental status Cerebrovascular accident symptoms Syncope Clinical ManifestationsClinical ManifestationsLimb paresthesias Horner syndrome Dyspnea Dysphagia Flank pain if the renal arteries are involved Hypertension Hypotension if associated with cardiac tamponade, hypovolemia, excessive vagal tone Preferred Examination Preferred Examination contrast-enhanced spiral CT ; transesophageal echocardiography (TEE) ; MRI for hemodynamically stable patients .1. The ability of TEE to evaluate the status of the aortic valve and the ostia of the coronary arteries is an advantage over CT and MRI. 2. CT and MR angiography has largely replaced conventional diagnostic angiography in the assessment of aortic dissection. Limitations of Techniques Limitations of Techniques CT and MRI are associated with high sensitivity and specificity of 94-100% and 95-100%, respectively. TEE is less sensitive and specific than spiral CT or MR, and TEE is operator-dependent. And approximately 1% of patients have a contraindication to TEE (eg, esophageal varices). X-RayMediastinal widening (most common plain radiographic finding in aortic dissection, noted in 80% of patients) ; Double aortic knob sign (in 40% of patients) ; Diffuse enlargement of the aorta with poor definition or irregularity of the aortic contour ; Inward displacement of aortic wall calcification of more than 10 mm ; Tracheal displacement to the right ; Pleural effusion (more common on the left side, suggests leakage) ; Pericardial effusion ; Cardiac enlargement ; Displacement of a nasogastric tube ; Left apical opacity;X-RayFalse Positives/Negatives: Mediastinal fat can commonly cause a widened mediastinum and a false-positive diagnosis of aortic dissection.nullPlain anteroposterior view of the chest demonstrates a wide mediastinum. CT SCAN CT SCAN Typical CT findings : Aortic intramural hematoma: Crescentic high-attenuating clot within the media, with internally displaced calcification (see Image1 ) Intimal flap separating the two aortic channels (see Image2) (see Image 3) nullComputed tomography (CT) LegendAortic dissection Type Stanford A 1 Aorta ascendens, true Lumen ; 2 false Lumen ; 3 Pulmonary artery; 4 Aorta descendens; 5 thoracic vertebra MRI MRI MRI findings of aortic dissection include the following: MRI shows an intimal flap of medium–signal intensity surrounded by a signal void of fast-flowing blood on "black blood" echocardiogram (ECG)-gated spin-echo or double inversion recovery single shot fast spin-echo. With cine gradient echo imaging, the intimal flap is a dark line against the high -signal intensity of the flowing blood and may change configuration during the cardiac cycle. Careful examination of the aortic flap during the cardiac cycle on cine MR imaging is important to detect the presence of "true lumen collapse," which may be associated with end-organ ischemia. When the intima is stripped 360° from the media and is essentially "free floating," this may result in catastrophic intimo-intimo intussusception.null1 Aorta descendens with dissection 2 Aorta isthmus nullType B dissection. Green arrow indicates entry. False lumen is indicated by yellow arrows and is seen spiraling around the true lumen.Aortography Aortography Oblique arteriogram of the thoracic aorta demonstrates the double-barrel aorta sign of aortic dissection. Both the true and false lumina are opacified. TreatmentTreatment1. Intensive care units, where their vital signs (pulse, blood pressure, and rate of breathing) are closely monitored. 2. As soon as possible, drugs, usually sodium nitroprusside plus a beta-blocker, are given intravenously to reduce the heart rate and blood pressure to the lowest level that can maintain a sufficient blood supply to the brain, heart, and kidneys. 3. Surgery Aortic fenestration ; 1. 2. Surgical repair ; OVEROVERnullNonenhanced CT scan of the chest demonstrates a type B acute aortic intramural hematoma with displacement of intimal calcification and a crescentic high-attenuating clot without mass effect on the aortic lumen. nullContrast-enhanced axial CT image demonstrates an intimal flap that separates the two channels in the ascending and descending aorta diagnostic of a Stanford A type dissection. nullContrast-enhanced axial CT image demonstrates an intimal flap that separates the two channels in the ascending aorta and descending aorta and begins at the level of the aortic root.