Diseases Of The Aorta

DISEASES OF THE AORTA

ANATOMY • Layers 1. Intima – thin • • •

Endothelium Subendothelial connective tissue Internal elastic lamina

2. Tunica media • •

Smooth muscle cells Extracellular matrix

3. Adventitia (connective tissue)

ANEURYSM • Any pathologic dilatation of a segment of blood vessel • True aneurysms: all layers are involved • Pseudoaneurysm: intima and media • Fusiform: entire circumference is involved (diffuse dilatation)

Etiology and Associated Factors • Aortic – Atherosclerosis – Cystic medial necrosis – Chronic aortic dissection – Infectious – Trauma

Acute aortic syndrome – Dissection, acute intramural hematoma, penetrtating atherosclerotic ulcer – Aortic occlusion: atherosclerosis thromboembolism

Aortitis – Vasculitis – Rheumatic – Idiopathic retroperitoneal fibrosis – Infectious (SY, TB, mycotic)

Thoracic Aneurysm • Mostly asymptomatic • Cystic medial necrosis-most common cause of ascending aortic aneurysms • Athrosclerosis: most common cause in aneurysms of the aortic arch and descending aorta

Manifestations • Ascending aneurysm – CHF sec. to aortic regurgitation – Marked compression of SVC

Diagnosis • Chest Xray – mediastinal widening – Displacement or compression of trachea or left mainstem bronchus

• 2D echo – Assess proximal ascending aorta

• CT with contrast/MRI • Conventional aortography

Treatment • Beta blockers • Surgery – Placement of prosthetic graft – Indications: • Symptomatic • >5.5-6 cm aortic diameter or • >1 cm per year increase in aortic diameter

Normal aorta

Aortic aneurysm

Abdominal Aneursym • Male>female • Increases with age • 90% of abdominal aneurysms with >4cm are related to ATHEROSCLEROTIC DISEASE • Below the level of the renal arteries

Physical Examination ASYMPTOMATIC PATIENTS • Palpable, pulsatile, expansile nontender mass • Incidental finding on ultrasound or abdominal Xray

SYMPTOMATIC PATIENTS • Emergency • Strong abdominal pulsations • Chest pain (lower back and scrotum)

Diagnosis • Abdominal Xray: calcified outline in 25% • Abdominal ultrasound – Mural thrombus – For screening of relatives – For serial documentation of aneurysm size

• CT/MRI with contrast – Accurate – Determine size and location

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Normal aortogram

Aortic aneurysm

• Contrast aortography – Risk: allergies bleeding atheroembolism

Treatment • Surgery and insertion of prosthetic device • Mortality: 40-50% after acute rupture

Acute Aortic Syndrome 1. 2. 3. 4.

aortic rupture (discussed) Aortic dissection Intramural hematoma with an intimal flap Penetrating atherosclerotic ulcer

Aortic Dissection • Sec. to circumferential or transverse tear of the intima – Along the right lateral wall of the aorta producing a false lumen – Along the descending aorta below the ligamentum arteriosum

• Initiating event – Primary intimal tear with secondary dissection into the media – Medial hemorrhage that disrupts and dissects into the intima

• Peak incidence: 6th and 7th decade of life

• Intramural hematoma: descending aorta (trauma) • Ulcer: erosion of plaque into the media – Mid and distal portion of descending thoracic aorta – Sec. to ATHEROSCLEROSIS

Acute valvular insufficiency

dissection

De Bakey Classification of Aortic Dissection Type I – Intimal tears in the ascending and descending aorta

• Type II – Ascending aorta

• Type III – Descending aorte with distal propagation

Stanford Classification Type A – Ascending aorta (proximal)

Type B – Descending aorta (distal)

Predisposing Factors 1. Systemic hypertension 2. Coexisting conditions – Marfan syndrome – Pregnancy – Trauma

3. Cystic medial necrosis

Manifestations • Sudden, tearing, severe pain (intrascapular, back) • Diaphoresis • Syncope • Dyspnea • Weakness • Hypertension • hypotension

• • • •

Loss of pulses Aortic regurgitation Pulmonary edema Neurologic findings

• Compression symptoms – Acute aortic regurgitation • >50% complication of proximal dissection • Bounding pulse, wide pulse pressure, diastolic murmur along the right sternum • CHF

Diagnosis • Chest Xray – Ascending: widened superior mediatinum. Left sided effusion – Descending: descending aorta appears to be wider than the ascending aorta

• Transthoracic echo – Proximal ascending aorta: >80% sensitivity

• CT/MRI – intimal flap, extent, and involvement of major arteries – Sensitivity 90% – Specificity 90% – To differentiate intramural hemorrhage and penetrating ulcer – MRI: antegrade vs retrograde dissection

Treatment • Beta blockers • Sodium nitroprusside • May or may not use alpha/beta blockers (labetalol) • Alternative – Calcium antagonist – ACE inhibitors

• Surgery – Excision of intimal flap – Obliteration of false lumen – Placement of interposition graft

• Major cause perioperative mortality 1. 2. 3. 4. 5. 6.

MI Paraplegia Renal failure Tamponade Hemorrhage Sepsis

Type B:

medical 10-20% mortality

Aortic Occlusion 1. Chronic atherosclerotic occlusive disease Distal abd. Aorta below the renal arteries Claudication (buttocks, thighs,calves) Dx: P.E. leg pressure measurement Duplex ultrasound MRI/CT Aortography Tx:catheter-based endovascular procedure

1. Acute occlusion – – – –

Distal aorta (abdominal) Enboli (from the heart) Ischemia of the lower extremities Absence of distal pulses bilaterally

Dx: CT/MRI, aortography Tx: emergency thrombectomy or revascularization

1. Aortitis – Inflammation (Takayasu arteritis, giant cell arteritis) – Infections (TB, salmonella) – Result in aneurysmal dilatation and aortic regurgitation, occlusion of aorta

Takayasu – Ascending aorta and aortic arc – Young male Asians

Pathology – panarteritis – Mononuclear cells, giant cells, medial and adventitial thickening, fibrotic occlusion

• Acute: fever, malaise, weight loss, Increased ESR and CRP • Chronic: • upper extremity claudication • Cerebral ischemia • Syncope

POOR PROGNOSIS Tx: steroids, surgical bypass

Giant cell arteritis – Older patients – Male>female – Large,medium sized arteries

Pathology: focal granulomatous lesions (entire abdominal wall)

• Complications – Obstruction of mesium-sized arteries and major branches of aorta – Development of aortitis and aortic regurgitation

Rheumatic aortitis – Ascending aorta – Manifestation: • Aneurysm • Aortic regurgitation • Involvement of cardiac conduction system

Syphilitic infective aortitis – Staph, strep, salmonella, fungi – Infects aorta at sites of atherosclerotic plaque

Mycotic – Suprarenal – Elderly – Male>female – Patholgy: • • • •

Acute chronic inflammation Abscess Hemorrhage necrosis

Diagnosis – CT/MRI – Destruction of collagen and elastic tissues leads to dilatation of aorta and scar formation – Calcification – Symptoms: sec. to AR, narrowing of coronary ostia due to syphylitic aortitis, compression, rupture – Diagnosis: rapid plasmin reagin fluorescent treponemal antibody – Tx: surgical excision and repair, penicillin