A novel method for the measurement of proximal fibrous cap puncture force in chronic total occlusions: the effect of increasing age.

Abstract

AIMS: The composition of CTO lesions changes significantly as they age. These changes may adversely affect PCI outcome. We present a robust ex vivo technique to measure the force required to puncture the proximal cap of CTOs, and to determine whether the puncture force differs according occlusion age to examine the effects of compositional changes over time on lesion stiffness. METHODS AND RESULTS: Occlusions were created in 44 rabbit femoral arteries by thrombin injection. Between two and 15 weeks following induction, vessels were harvested and tested in a custom setup to determine the force required to puncture the proximal cap. The puncture force mean values at 2, 6, 12, and 15 weeks were 0.61N, 0.78N, 1.21N and 1.52N, respectively. The puncture force required in occlusions of &#x2264;6 weeks was significantly lower those&#x2265;12 weeks (0.72&#xb1;0.10N versus 1.45&#xb1;0.13N, p<0.01). Using a cutoff point of 1N, 86% of lesions&#x2264;6 weeks of age required<1N compared to 30% of those&#x2265;12 weeks. CONCLUSIONS: We have shown an objective and reproducible testing system for measuring CTO puncture force. Puncture force is correlated with occlusion age. This technique would be useful to evaluate therapies that alter CTO composition/compliance, as well as guidewire testing.