Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Fig. (1). Angiography images of a patient with a Chronic Total Occlusion (CTO) of the Left Anterior Descending artery (LAD). (A): contrast injected into the left coronary artery demonstrates severe stenosis in the proximal part of the LAD, contrast flow stops abruptly at the point of complete occlusion in the mid-LAD. (B): contrast injected into the right coronary demonstrating retrograde filling of the LAD via multiple collateral channels, both septal (i) as well as epicardial (ii, iii) channels can be identified. (C): contrast injected into the left coronary artery after successful revascularisation of the LAD. Two stents have been implanted (one in the proximal LAD and a second at the site of the occlusion). (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (2). Pressure gradient of a developing collateral. Early after the development of arterial stenosis, low pressure distal to the stenosis draws flow through the collateral and increases shear stress on the endothelium (A). Collateral development reaches a plateau; collateral diameter increases, reducing collateral shear stress (B). An increase in donor artery pressure during exercise training reintroduces a pressure gradient across the collateral; fluid shear stress again increases across the collateral endothelium (C). (A higher resolution / colour version of this figure is available in the electronic copy of the article).