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The JetStream Navitus (JS) atherectomy device is a rotational cutter with aspiration capability designed to treat infrainguinal arterial obstructive disease. JS XC can be operated with blades down (BD) (2.1 or 2.4 mm perimeter) or blades up (BU) (3.0 or 3.4 mm perimeter) to treat femoropopliteal obstructive disease. It is unclear whether an orbital effect is present while operating the JS leading to a larger minimal luminal area (MLA) than predicted based on device size. Also, the minimum MLA and plaque surface area (PSA) needed in a typical size femoral artery (5-6 mm) for the device to be effective has not been defined. Using an in-stent restenosis (ISR) porcine model and intravascular ultrasound (IVUS) assessment of lesions these questions were addressed.
4 pigs (8 limbs) were implanted with overlapping SMART (Cordis) nitinol self-expanding stents using an overstretch balloon/stent model. ISR was treated 1 month after stent implantation with an initial 2 blades down (BD) runs followed by 4 BU runs. IVUS measurements were performed at baseline, after 2 BD runs, and after each BU run on a total of 24 lesions. Minimal luminal area (MLA, mm2) and plaque surface area (PSA, %) were obtained. 1-sample Wilcoxon signed-rank test was performed between MLA obtained after BU runs and theoretical maximal MLA of the XC 2.4-3.4 cutter with BU. MLA and PSA at baseline were plotted against net MLA and PSA gain (BU - baseline) respectively. The minimum MLA and PSA at baseline needed for a positive increase in MLA and reduction in PSA were determined.
The femoral artery mean diameter was 4.7 mm. A strong correlation was present between MLA at baseline and after BU runs (Pearson correlation p=0.006) and between PSA at baseline and after BU runs (p<0.0001). An approximate MLA ≤ 9.0 mm2 or PSA ≥ 60% were needed to see a positive effect of atherectomy on treated lesion (i.e. increase in MLA or reduction in PSA). Theoretical MLA achievable from the XC BU 2.4-3.4 device is 9.08 mm2 (A = πr2 using r=3.4/2=1.7mm). No difference is seen between this calculated MLA and the IVUS measured MLAs after BU runs using 1-sample Wilcoxon test indicating no orbital effect of the device on tissue cutting.
JS XC 2.4-3.4 BU achieved positive cutting of ISR tissue inside a 4.7 mm femoral artery when the baseline lesion MLA was ≤ 9.0 mm2 or PSA ≥ 60% on IVUS. No orbital cutting was seen with the JS BU as MLA obtained after treatment was not different from theoretical MLA.