"OFTHE LATEST CONCEPTAORTIC ANEURYSM
THE LATEST CONCEPT OF AORTIC ANEURYSM
INTRODUCTIONPrevalence.3/4 confined to the abdominal aorta1/4 involve the thoracic aortaRiskfactors:Decreased type IlI collagen to type I collagen ratioHypertension-Atherosclerosis
INTRODUCTION • Prevalence: – 3/4 confined to the abdominal aorta – 1/4 involve the thoracic aorta • Risk factors: – Decreased type III collagen to type I collagen ratio – Hypertension – Atherosclerosis
PATHOGENESISMechanisms.Atherosclerosis erodes the aortic wall, destroying themedial elastic elements-This weaken the aortic wall and leads to fusiform orsaccular dilationLaplace's law: tension is proportional to the productofpressure &radiusVicious circle: Dilatation results in greater tension,which in turn leads to acceleration in the rate ofenlargementoftheaneurysm
PATHOGENESIS Mechanisms: – Atherosclerosis erodes the aortic wall, destroying the medial elastic elements – This weaken the aortic wall and leads to fusiform or saccular dilation – Laplace’s law: tension is proportional to the product of pressure & radius – Vicious circle: Dilatation results in greater tension, which in turn leads to acceleration in the rate of enlargement of the aneurysm
ABDOMINALANEURYSMMost arise just below the renal arteries and extend to theaorticbifurcationOnly 2~5% are suprarenal (these usually resultfromthedistal extension of a thoracic aneurysm into the abdomen)Majority are asymptomatic & are discovered on routinePEorX-rayIn contrast to musculoskeletal back pain, it is not affectedbymovement. Apalpable,pulsatile abdominal mass
ABDOMINAL ANEURYSM • Most arise just below the renal arteries and extend to the aortic bifurcation • Only 2 ~ 5% are suprarenal (these usually result from the distal extension of a thoracic aneurysm into the abdomen) • Majority are asymptomatic & are discovered on routine PE or X-ray • In contrast to musculoskeletal back pain, it is not affected by movement • A palpable, pulsatile abdominal mass
AAARUPTURE80% rupture retroperitoneally, 20% rupture into theperiotoneal cavity>6cmin diameter:50% rupture<1year<6cmin diameter:15~20%rupture<1yearElective surgery is advised for all = or > 6 cm indiameterExpanding or ruptured AAAsurgicalaretrueemergencies: sudden onset of severe low back orabdominal pain, may radiate to the groin, buttocks, orlegsRupture, stabilized by using a compression G-suit
AAA RUPTURE • 80% rupture retroperitoneally, 20% rupture into the periotoneal cavity • > 6 cm in diameter: 50% rupture < 1 year • < 6 cm in diameter: 15 ~ 20% rupture < 1 year • Elective surgery is advised for all = or > 6 cm in diameter • Expanding or ruptured AAA are true surgical emergencies: sudden onset of severe low back or abdominal pain, may radiate to the groin, buttocks, or legs • Rupture, stabilized by using a compression G-suit