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The JetStream Navitus (JS) atherectomy device (Boston Scientific) is a rotational cutter with aspiration capability to treat infrainguinal arterial obstructive disease. Intravascular ultrasound (IVUS) assessment of the number of blades up (BU) runs needed to achieve optimal tissue debulking in in-stent restenosis (ISR) using the JS is unknown.
4 pigs (8 limbs) were implanted with overlapping SMART (Cordis) nitinol self-expanding stents using an overstretch balloon/stent model. In-stent restenosis (ISR) was treated 1 month after stent implantation with an initial 2 blades down (BD) runs followed by 4 BU runs. A run was defined as a single proximal to distal pass of the device within the stent at a speed of approximately 1-2 mm per sec. IVUS quantitative measurements were performed at baseline, after 2 BD runs, and after each BU run (BU1, BU2, BU3, BU4) on a total of 24 lesions. Minimal luminal area (MLA, mm2) and plaque surface area (PSA, %) were obtained in each of the proximal, mid, and distal segments of the lesion. Wilcoxon signed-rank test and paired t-test (1-tail) were performed to compare baseline, BD and BU 1 to 4 runs.
The mean baseline MLA was 7.8 ± 2.7 mm2. Following 2BD and 1 BU runs the mean MLAs were 8.1 ± 2.5 mm2 (p<0.044) and 8.7 ± 2.0 mm2 (p=0.007) when compared to baseline MLA respectively. There was also a significant increase in MLA between 2BD runs and BU1 run (p=0.033) and between BU1 and BU2 runs (9.4 ± 2.4, p=0.007). No statistical difference in MLA was seen between BU 2 to 3 runs (P>0.05). Similarly, PSA was significantly reduced between baseline (65.2 ± 11.7) and 2 BD (63.0 ± 10.5, p=0.015) and BU1 (60.7 ± 9.2, p=0.011) runs, and between BU1 and BU2 runs (57.5 ± 7.5, p=0.025). No differences in PSA was seen between the BU2, BU3 and BU4 runs (p=0.12). Vessel area at site of treatment remained unchanged between baseline and BU4 run (23.3 ± 5.8 vs. 22.5 ± 4.9 mm2 respectively, p=0.73) indicating that the increase in MLA and reduction in PSA is a true plaque cutting rather than a dottering effect by the JS. There were no IVUS stent strut disruption following JS treatment which was later confirmed by high resolution radiographs.
JS achieved optimal and true tissue debulking after 2 BD and 2 BU runs. Based on these IVUS observations, performing more than 2 BU runs in a femoral artery ISR model is unlikely to yield further tissue debulking.