Therapy
Ascending Dissection
• Surgical emergency • Can only be treated by operation • May or may not require aortic valve replacement and/or coronary bypass surgery depending on the progression of the dissection • Mortality – about 20% depending on other medical problems and the presence of neurological symptoms
Definition
• Aortic dissection – Sudden catastrophic event in which a tear in the intima allows blood to escape from the true lumen of the aorta rapidly separating the inner from the outer layer of the media • Column of blood is driven by the force of the left ventricular systolic pressure which strips the intima from the adventitia
Physical Findings
• • • • Paralysis Muffled heart tones New onset aortic insufficiency murmur Unequal blood pressure and pulses in the extremities • Jugular venous distention – tamponade • Abdominal pain – acute • Acute hypertension and anuria
Symptoms
• Sudden, severe chest pain – tearing sensation in the anterior chest radiating to the arms or to between the scapulae • May have syncope, neurologic signs, weakness, hypotension.
Pathophysiology
• After dissection into the media, blood rushes into the dissected area • Necrosis of the aortic wall then develops several days after the event – observed in 62% of cases • Complications include aortic rupture, obstruction and occlusion of aortic branches
Causes of Aneurysm
• • • • • • • Medial degeneration and local dilatation Atherosclerosis Syphilis (ascending only) Bacterial infections (mycotic) Congenital abnormalities Trauma Annuloaortic ectasia
Definition
• True aneurysm – localized enlargement of the aorta contained by all the layers of the aortic wall • False aneurysm – enlargement contained by the aortic adventitia and periaortic fibrous tissue.
定位诊断
• 双侧颈内动脉系统，左侧著 • 椎基底动脉系统？
定性诊断
• 心源性栓塞 主动脉机械瓣膜组织 栓子脱落
Aortic Dissection
Anatomy,Physiology and Principles of Therapy
History
• 1555 – Vesalius diagnosed a pulsating tumor near the vertebrae in a patient’s back and called it “a dilatation of the aorta”1826 • 1826 – Laennec introduced the term dissecting aneurysm • 1800’s – surgery was performed on the entity by John Hunter, Astley Cooper and others even before the era of general anesthesia • Early operations were designed to produce distal internal fenestration to cause downstream decompression of the aorta.
心源性脑栓塞
病历特点
• 中年男性，反复发作渐进性病程； • 既往高血压史，夹层动脉瘤及主动脉瓣关闭不 全换瓣术后3年，口服抗凝药不规范。近2年多 次脑梗塞史。 • 发病表现为反复发作的神经功能缺损，渐进性 的神经功能缺损。 • 查体主要表现为言语表达障碍，构音含混，右 面部麻木及右肢轻偏瘫，及右侧同向偏盲。 • 辅助检查：凝血象（INR）偏低； CT：脑内多发梗塞
Classification
• Type I - Begins at the aortic valve and may proceed to and include the abdominal aorta • Type II – Begins distal to the left subclavian artery and can encompass the entire aorta to the iliac arteries
History
• 1951 Lam and Aram introduced homografts for repair of descending thoracic aneurysms • 1953 Cooley and DeBakey used artificial grafts for repair • 1953 Bahnson introduced aneurysmorrhaphy • 1957 cardiopulmonary bypass became available
Anatomical Considerations
Pathoanatomy
• Dissection of the ascending aorta arises within several centimeters of the aortic valve – 66% • Dissection of the descending aorta occur just beyond the left subclavian artery at the ligamentum arteriosum • Small percentage occur at the transverse arch or descending aorta
Descending Dissection
• Therapy controversial • If rupture present – operation is the only alternative • In the absence of rupture, medically treated patients do better than those undergoing operation due to comorbidities
Natural History
• Many patients with dissection die acutely due to cardiac tamponade or dissection of the LAD • 8% of ascending ruptures survive without treatment • 75% survive descending dissection
Definition
• Acute – less than 14 days old • Chicken or the egg ? – Hemorrhage in the media causes rupture of the intima or dissetear.
Pathophysiology
• Law of Laplace: As a sphere increases in size, the wall tension of the sphere increases • Weakened wall • Dilatation • Expansion with pressure-related symptoms • Rupture
Clinical Signs and Symptoms
Demographics
• Males > females 3:1 • Sixth or seventh decade of life • Patients with ascending dissection are about ten years younger at presentation than those with descending dissection