A new percutaneous porcine coronary model of chronic total occlusion

Objective. Chronic total occlusion (CTO) of coronary arteries represents a challenge for percutaneous treatment. Although ameroid constrictors have been used to create CTOs from extrinsic compression of coronary arteries, this model is not suitable for evaluation of novel angioplasty equipment. Thus, the objective of this study was to create a new percutaneous animal model of CTO. Methods. To create an animal model of CTO, we implanted copper-plated stents in the left circumflex coronary arteries of 18 pigs, and assigned the pigs to early group (n = 6; sacrifice at ∼1 week), intermediate group (n = 6; sacrifice at ∼4 weeks), and late group (n = 6; sacrifice at ∼8 weeks). Results. Follow-up angiography prior to sacrifice revealed complete occlusion in 14/17 animals, with the subtotal occlusive lesions (mean 60% stenosis) only in the early group. Most of the pigs with total occlusions (12/14) showed bridging collateral flow ? grade 2 (grade 2: 4; grade 3: 8). Histology revealed organizing thrombus in the early group with persistent inflammation, and organized thrombus with fibrosis and calcification in the intermediate and late groups. Interestingly, there were fibrotic components in the proximal and distal edges of the occlusions with softer, organizing thrombus in the middle of the CTO in the late group, suggesting that the major areas of difficulty are at the entrance and exit segments of the CTO with percutaneous recanalization. Conclusion. This study shows the feasibility and reproducibility of a new porcine coronary percutaneous CTO model. This model may be useful in improving our percutaneous treatment of CTO.