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The JetStream Navitus (JS) (Boston Scientific) is an atherectomy device that uses rotational cutting and aspiration to treat infringuinal arterial obstructive disease. The number of blades up (BU) runs needed to achieve safe and maximum tissue debulking using the JS is unknown.
In this swine model, 4 animals (8 limbs) were implanted with overlapping SMART (Cordis) nitinol self-expanding stents 1 month prior to JS treatment. In-stent restenosis (ISR) was treated 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. Quantitative vascular angiography using edge detection technique (QVA) was performed at baseline, after 2 BD runs, and after each BU run (BU1, BU2, BU3, BU4). Minimal luminal diameter (MLD), plaque surface area (PSA) and percent stenosis (PS) within the treated stented segment (n=8) were measured by QVA. Descriptive analysis was performed on all angiographic variables. 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 (n=8) MLD was 1.73 ± 0.84 mm. Following 2BD and 1 BU runs the mean MLDs were 2.56 ± 0.7 mm (p=0.025) and 3.12 ± 0.39 mm (p=0.005) when compared to baseline MLD respectively. There was also a significant increase in MLD between 2BD runs and BU1 run (p=0.005). No statistical difference in MLD was seen between BU runs (P > 0.05). Similarly, PSA was significantly reduced between baseline (83.9 ± 14.8) and 2 BD (67.7 ± 17.0, p=0.005) and BU1 (55.4 ± 9.0, p=0.005) runs and between BU1 and BU2 runs (50.7 ± 9.7, p < 0.05). No differences in PSA was seen between the BU2, BU3 and BU4 runs (p>0.05). Finally, PS was reduced from a mean of 63.13 ± 16.91 to 44.97 ± 15.08 (p=0.005) with BD runs and to 33.51 ± 6.73 (p=0.005) with BU1 run. There was also a significant reduction in PS between 2 BD runs and BU1 run (p=0.01) and between BU1 and BU2 runs (30.1 ± 7.0, p=0.05). No difference between PS was seen between BU 2 to 4 runs (p=0.10). There were no angiographic complications or stent strut discontinuities on high resolution radiographs following JS treatment.
JS achieved optimal tissue debulking after 2 BU runs with no further gain in debulking after the second BU run. Based on these observations, operators treating ISR with the JS device may need to limit their debulking to 2 BD and 2 BU runs performed at 1 to 2 mm per second speed to achieve optimal debulking and minimize the chance of complications from additional BU runs.