| How is normal anatomy of the aorta? | diameter 3 cm ascending, 2.5 cm descending, 1.7-2 cm abdomen.
Wall (thick intima composed of endothelium, subendothelial CT, elastic lamina, thick media of smooth muscles and extracellular matrix, adventitia CT enclosing the vasa vasorum and nervi vascularis)
Aorta distended durng systole allows stroke volume and elastic energy to be stored, and recoils during diastole so that blood flows to periphery |
| What are congenital anomalies of the aorta? | Double aortic arch, origin of right subclavian distal to left subclavian, right-sided aortic arch with abberrant left subclavian artery, Kommerell's diverticulum anatomic remnant of right aortic arch |
| What is an aortic aneurysm? | Aneurysm is a pathological dilation of segment of blood vessel, true aneurysm involves all three layers, pseudoaneurysm intima and media are disrupted and dilated segment is lined by adventitia only and sometimes perivascular clot.
Fusiform aneursym affects entire circumference of vessel diffusely dilated artery, saccular aneursym only a portion of circumference outpouching of vessel wall.
Aortic aneurysms can be classified by location (abdominal/thoracic, descending aorta usually contigouos with infra-diaphragmatic aneurysms thoracoabdominal aneurysms. |
| How is etiology of aneurysms? | Conditions that cause degradation or abnormal production of structural components of aortic wall [elastic/collagen].
Inflammation, oxidative stress, proteolysis, wall stress, mediated by B and T cells, macrophages, cytokines, MMPs.
Etiologies (degenerative aging [cigarettes, hyperTG ,HTN], chronic aortic dissection, aortitis, infective, trauma, genetic [Marfan's, Loeyz, Ehler, Turners, Familial, Bicuspid aortic valve]
Acute aortic syndrome (aortic dissection, intramural hematoma, atherosclerotic ulcer)
Aortitis (vasculitis, rheumatic, infective [syphilis, TB, fungus])
Familial (20% of pt)
Trauma (penetrating and non-penetrating chest trauma mostly descending aorta beyond insertion of ligamentum arteriosum)
Weakening of wall by chronic aortic dissection. |
| How are thoracic aortic aneurysms? | Clinical manifestations and natural hx depends on location, medical degeneration most common pathology of ascending aorta, average growth rate 0.1-0.2 cm/year.
Risk of rupture related to size and symptoms (2-3% /year <4 cm, to 7% /year >6cm)
Most are asymptomatic but compression or erosion of adjacent tissues cause symptoms (chest pain, SoB, cough, dysphagia)
CXR (widening of mediastinum shadow/displacement/compression of trachea)
TTE/TEE (asses proximal ascending aorta and descending)
Contrast CT, MRI, Invasive aortography
Tx (b blockers (marfan's, aortic dilatation) control HTN, prosthetic graft is symptomatic/ asymptomatic >5.5cm, if marfan's/ bicuspid aortic valve aneurysm 4-5cm surgery
Repair if >6cm descending, endovascular repair >5.5cm, or when diameter increases 1cm/year |
| How are abdominal aortic aneurysms? | More frequent in males than females, incidence increases with age, >4 cm affects 1-2% males >50, 90% related to atherosclerosis and most below renal arteries.
Prognosis related to size and severity of coexisting CAD and CVD.
Risk of rupture increases with size (<5cm 5 year risk 1-2%, 20-40% if >5cm) can form mural thrombus and predispose peripheral embolism
May become painful, harbinger of rupture pain and is a medical emergency, acute rupture is life-threat, hypotension requires emergency operation.
US sees aneurysm, documents size and screening recommended for age 65-75 years who have smoked.
CT contrast and MRI accurate plan endovascular repair, aortography used to evaluate but complication risk and mural thrombi may reduce the size so underestimate the aneurysm
Tx op repair, graft, if expanding size, asymptomatic repair if diameter >5.5cm |
| What are the acute aortic syndromes? | Aortic rupture, aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer. |
| What is aortic dissection? | Aortic dissection is caused by a circumferential or, less frequently, transverse tear of the intima. It often occurs along the right lateral wall of the ascending aorta where the hydraulic shear stress is high, Another common site is the descending thoracic aorta just below the ligamentum arteriosum |
| How does aortic dissection occur? | • The initiating event is either a primary intimal tear with secondary dissection into the media or a medial hemorrhage that dissects into and disrupts the intima.
• The pulsatile aortic flow then dissects along the elastic lamellar plates of the aorta and creates a false lumen.
• The dissection usually propagates distally down the descending aorta and into its major branches, but it may propagate proximally.
• Distal propagation may be limited by atherosclerotic plaque. In some cases, a secondary distal intimal disruption occurs, resulting in the reentry of blood from the false to the true lumen. |
| What are the pathologic and radiologic variants of aortic dissection? | Intramural hematoma w/out intimal flap
(• Acute intramural hematoma is thought to result from rupture of the vasa vasorum with hemorrhage into the wall of the aorta.
• Most of these hematomas occur in the descending thoracic aorta
• Acute intramural hematomas may progress to dissectiion and rupture)
Penetrating Atherosclerotic Ulcer (• caused by erosion of a plaque into the aortic media， are usually localized， and are not associated with extensive propagation.
• They are found primarily in the middle and distal portions of the descending thoracic aorta and are associated with extensive atherosclerotic disease.
• The ulcer can erode beyond the internal elasEc lamina, leading to medial hematoma, and may progress to false aneurysm formaEon or rupture.) |
| What are classifications of aortic dissection? | • DeBakey and colleagues initially classified aortic dissections as
• type I: in which an intimal tear occurs in the ascending aorta but involves the descending aorta as well;
• type II: in which the dissection is limited to the ascending aorta
• type III: in which the intimal tear is located in the descending aorta with distal propagation of the dissection
• Stanford is that of
• type A: in which the dissection involves the ascending aorta (proximal dissection)，
• type B: in which it is limited to the arch and/or descending aorta (distal dissection) |
| What are clinical manifestations of aortic dissection? | • The peak incidence of aorAc dissecAon is in the sixth and seventh decades.
• Men are more affected than women by a ratio of 2 : 1 .
• Presents with the sudden onset of pain， which often is described as very severe and tearing and is associated with diaphoresis
• The pain may be localized to the front or back of the chest， often the interscapular region, and typically migrates with propagation of the dissection |
| What are physical findings in aortic dissection? | • hypertension or hypotension
• loss of pulses, aortic regurgitation
• pulmonary edema
• neurologic findings due to carotid artery obstruction (hemiplegia, hemianesthesia) or spinal cord ischemia (paraplegia)
• Hemopericardium and cardiac tamponade may complicate a type A lesion with retrograde dissection.
• Acute aortic regurgitation is an important and common (>50%) complication of proximal dissection. |
| What are image findings in aortic dissection? | • Chest X-ray often reveals a widened superior mediastinum.
• A pleural effusion (usually left-sided) also may be present. This effusion is typically sero-sanguineous and not indicative of rupture unless accompanied by hypotension and falling hematocrit.
(ascending aorta)
• In dissections of the descending thoracic aorta, a widened mediastinum may be observed on chest x-ray.
• the descending aorta may appear to be wider than the ascending portion |
| How is dx and tx of aortic dissection? | dx (ECG, CT, MRI)
Tx (Acute dissection [b blockers PRL IV to achieve 60BPM + lower HTN]
Acute Ascending aortic dissection and intramural hematoma type A and complicated type B[urgent surgical correction]
Stable Type B medical therapy
Chronic type B followed outpatient 6-12 months with contrast CT or MRI to detect any propagation/expansion. |
| What are chronic atherosclerotic occlusive diseases? | • Atherosclerosis may affect the thoracic and abdominal aorta.
• Occlusive aortic disease caused by atherosclerosis usually is confined to the distal abdominal aorta below the renal arteries
• Claudication characteristically involves the buttocks, thighs, and calves and may be associated with impotence in males (Leriche's syndrome)
• The severity of the symptoms depends on the adequacy of collaterals.
• The physical findings include the absence of femoral and other distal pulses bilaterally and the detection of an audible bruit over the abdomen (usually at or below the umbilicus) and the common femoral arteries
• Atrophic skin， loss of hair， and coolness of the lower extremities usually are observed |
| How is dx of chronic occlusive atherosclerotic occlusive diseases? | • Physical examination and noninvasive testing， including leg pressure measurements，
• Doppler velocity analysis，
• Pulse volume recordings
• Duplex ultrasonography.
• MRI， CT， or conventional aortography， defining the anatomy |
| What is acute aortic occlusion? | • Acute occlusion in the distal abdominal aorta constitutes a medical emergency because it threatens the viability of the lower extremities; it usually results from an occlusive (saddle) embolus that almost always originates from the heart.
• Diagnosis should be established rapidly by MRI， CT， or aortography.
• Emergency thrombectomy or revascularization is indicated. |
| iWhat is aortitis? | • Referring to inflammatory disease o f the aorta， may be caused by large vessel vasculi7s such as
• Takayasu's arteritis
• Giant cell arteritis，
• Rheumatic and HLA-B27-spondyloarthropathies，
• Behçet's syndrome，
• Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides，
• Cogan's syndrome，
• IgG4-related systemic disease
• infections such as syphilis， tuberculosis， and Salmonella |
| What is takayaso artheritis? | • This inflammatory disease often affects the ascending aorta and aortic arch, causing obstruction of the aorta and its major arteries.
• It also may involve the descending thoracic and abdominal aorta and occlude large branches such as the renal arteries.
• The pathology is a panarteritis characterized by mononuclear cells and occasionally giant cells， with marked intimal hyperplasia，medial and adventitial thickening， and， in the chronic form，fibrotic occlusion.
• During the acute stage， fever， malaise， weight loss， and other systemic symptoms may be evident. Elevations of the erythrocyte sedimentation rate and C-reactive protein are common.
• The chronic stages of the disease， which is intermittently active，present with symptoms related to large artery occlusion， such as upper extremity claudication， cerebral ischemic and syncope.
• The process is progressive， and there is no definitive therapy.
• Glucocorticoids and immunosuppressive agents are effective in some patients during the acute phase.
• Surgical bypass or endovascular intervention of a critically stenotic artery may be necessary |
| What is giant cell arteritis? | • This vasculi7s occurs in older individuals and affects women more oSen than men.
• Primarily large and medium size arteries are affected.
• The pathology is that of focal granulomatous lesions involving the en7re arterial wall; it may be associated with polymyalgia rheuma7ca
• Obstruc7on of medium-size arteries (e.g.， temporal and ophthalmic arteries) and major branches of the aorta and the development of aor77s and aor7c regurgita7on are important complica7ons of the disease.
• High -dose glucocor7coid therapy may be effec7ve when given early. |
| What is rheumatic aortitis? | • AorCCs involving the ascending aorta:
• rheumatoid arthri,s
• ankylosing spondyli,s
• psoria,c arthri,s
• reac,ve arthri,s (formerly known as Reiter's syndrome)，
• relapsing polychondri,s
• inflammatory bowel disorders
• The inflammatory lesions usually involve the ascending aorta and may extend to the sinuses of Valsalva， the mitral valve leaflets， and adjacent myocardium.
• The clinical manifestaCons are aneurysm， aorCc regurgitaCon， and involvement of the cardiac conducCon system. |
| What is infective aortitis? | • Infective aortitis may result from direct invasion of the aortic wall by bacterial pathogens such as Staphylococcus， Streptococcus， and Salmonella or by fungi.
• These bacteria cause aortitis by infecting the aorta at sites of atherosclerotic plaque.
• Bacterial proteases lead to degradation of collagen， and the ensuing destruction of the aortic wall leads to the formation of a saccular aneurysm referred to as a mycotic aneurysm
• The pathologic characteristics of the aortic wall include acute and chronic inflammation， abscesses， hemorrhage， and necrosis.
CT and MRI dx, Tx Abx and surgical removal and revascularization of lower extremitis with uninfective tissue. |
