Experimental Models in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a potentially fatal disease and survival rate is very low when rupture occurs. Experimental models related with abdominal aortic aneurysm are performed on intact and ruptured aneurysm (RAAA) models. By using AAA models; complex mechanisms of aneurysm formation, aneurysm progression, chance of rupture, preventative and treating methods are researched. Most commonly used methods for creating aneurysm are utilization of transgenic or knockout animals; intra/extraluminal pharmacologic treatments such as elastase, calcium chloride or angiotensin II; hyperlip- idemic diet application and surgical interventions such as xenograft, stenosis or graft. Pathogenesis of aneurysm is predominantly examined on rodents whereas studies aimed at development of treatment modalities such as surgical or endovascular interventions are predominantly performed on large animals like rabbit, porcine or dog. Experimental studies modeling aneurysm rupture (RAAA) simulate shock (total hypoperfusion) occurred due to rupture and ischemia/reperfusion (I/R) occurred due to surgical treat- ment; without creating aneurysm. In this model, end organ or distal organ injuries and methods for reducing these injuries or their hemodynamic effects are investigated by creating shock +I/R. After performing median laparotomy, aortic exploration and entrance right above aortic tri-furcation; balloon plasty and elastase infusion are performed. Amount of administered elastase when a pig weighting approximately 30 kg is 10 ml; and stenosing cuff is placed below renal arteries by performing balloon dilatation after infusion. Presence of palpable thrill on aorta is the indicator of adequate stenosis. Parameters like “pulsatility index” which provides quantitative measurement of degree of stenosis may also be used [ 44].