In the drug-eluting stent era, minimum stent diameter is one independent predictor of restenosis. Some plaque modification is necessary before stenting to obtain the minimum stent diameter, but plaque modification using current devices is difficult in certain lesions, such as those in eccentric small vessels. As a potential solution to this problem, we investigate the usefulness of a single-blade Cutting Balloon (SCB) in this study.
We used the SCB in 5 porcine coronary arteries (2 LAD, 1 LCx and 2 RCA) to investigate the feasibility of directional atherotomy. We also tried the kissing balloon technique (KBT) with the SCB in 3 bifurcations from the same arteries. We used intravascular ultrasound (IVUS) guidance to position and direct the atherotome using the side holes of the guiding catheter as a marker. We also assessed plaque modification with IVUS before and after percutaneous coronary intervention and took coronary sections to inspect tissue pathology after the procedures.
In all 5 porcine models, we were able to view and confirm the success and accuracy of our incision on IVUS. We were successfully able to control the direction of the blade without balloon rupture during KBT. We were also able to verify the directional incisions afterwards from examination of tissue pathology.
Our investigation suggests that this SCB may be used effectively for directional atherotomy. We can accurately modify the plaque with this device by correctly positioning the blade to choose the direction of the incision. The next challenge is to improve the reliability of the device and to move on to in vivo trials.
[Show abstract][Hide abstract] ABSTRACT: Little is known about causes of intimal hyperplasia (IH) after sirolimus-eluting stent (SES) implantation.
Intravascular ultrasound was performed in 24 lesions with intra-SES restenosis and a comparison group of 25 nonrestenotic SESs. To assess stent strut distribution, the maximum interstrut angle was measured with a protractor centered on the stent, and the visible struts were counted and normalized for the number of stent cells. In SES restenosis patients, minimum lumen site was compared with image slices 2.5, 5.0, 7.5, and 10.0 mm proximal and distal to this site. The minimum lumen site had a smaller IVUS lumen area at follow-up (2.7+/-0.9 versus 6.2+/-1.9 mm2; P<0.01), larger maximum interstrut angle (135+/-39 degrees versus 72+/-23 degrees; P<0.01), larger IH area (3.4+/-1.5 versus 0.6+/-1.1 mm2; P<0.01) and thickness (0.7+/-0.3 versus 0.1+/-0.2 mm; P<0.01) at maximum interstrut angle, and fewer stent struts (4.9+/-1.0 versus 6.0+/-0.5; P<0.01) even when normalized for the number of stent cells (0.78+/-0.15 versus 0.97+/-0.07; P<0.01). Compared with nonrestenotic SES, the restenosis lesions also had a smaller minimal lumen area, larger IH area, thicker IH at maximum interstrut angle, fewer stent struts, and larger maximum interstrut angle. Multivariate analysis identified the number of visualized stent struts normalized for the number of stent cells and maximum interstrut angle as the only independent IVUS predictor of IH cross-sectional area (P<0.01 and P<0.01), minimum lumen area (P<0.01 and P<0.01), and IH thickness (P<0.01 and P<0.01).
The number and distribution of stent struts affect the amount of neointima after SES implantation.
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