Animal chronic total occlusion models: A review of the current literature and future goals

Coronary chronic total occlusions (CTOs) are commonly found in patients undergoing coronary angiography and is associated with poorer prognosis than in those patients with other forms of stable coronary artery disease. As such, with an increasing appreciation of this clinical entity, there is a need to identify, firstly the pathophysiological process driving its formation, as well as new percutaneous strategies for revascularisation with long term durability and improved outcomes. An appropriate, reliable and reproducible animal model is vital for both of these objectives. We review the prevalence of spontaneous collaterals in different species, as well as review the current literature with respect to animal models of CTOs, and compare and contrast the advantages and disadvantages of these differing models. Whilst both extrinsic compression models and endoluminal procedures may create situations analogous to a CTO in a human, the ideal animal model of a CTO will include an occluded artery, functional collaterals and a viable myocardium. This would allow study of the process driving collateral formation and arteriogenesis as well as percutaneous intervention strategies for both acute and long term benefits.