Intravascular ultrasound predictors of restenosis after balloon angioplasty of the femoropopliteal artery

LumenRECON Guidewire: Pilot Study of a Novel, Nonimaging Technology for Accurate Vessel Sizing and Delivery of Therapy in Femoropopliteal Disease

BACKGROUND

Proper vessel sizing during endovascular interventions is crucial to avoid adverse procedural and clinical outcomes. LumenRECON (LR) is a novel, nonimaging, 0.035-inch wire-based technology that uses the physics-based principle of Ohm's law to provide a simple, real-time luminal size while also providing a platform for therapy delivery. This study evaluated the accuracy, reliability, and safety of the LR system in patients presenting for a femoropopliteal artery intervention.

METHODS AND RESULTS

This multicenter, prospective pilot study of 24 patients presenting for peripheral intervention compared LR measurements of femoropopliteal artery size to angiographic visual estimation, duplex ultrasound, quantitative angiography, and intravascular ultrasound. The primary effectiveness and safety end point was comparison against core laboratory adjudicated intravascular ultrasound values and major adverse events, respectively. Additional preclinical studies were also performed in vitro and in vivo in swine to determine the accuracy of the LR guidewire system. No intra- or postprocedure device-related adverse events occurred. A balloon or stent was successfully delivered in 12 patients (50%) over the LR wire. Differences in repeatability between successive LR measurements was 2.5±0.40% (R²=0.96) with no significant bias. Differences in measurements of LR to other modalities were 0.5±1.7%, 5.0±1.8%, -1.5±2.0%, and 6.8±3.4% for intravascular ultrasound core laboratory, quantitative angiography, angiographic, and duplex ultrasound, respectively.

CONCLUSIONS

This study demonstrates that through a physics-based principle, LR provides a real-time, safe, reproducible, and accurate vessel size of the femoropopliteal artery during intervention and can additionally serve as a conduit for therapy delivery over its wire-based platform.

Possible impact of iridium-192 source centering on restenosis rate after femoro-popliteal angioplasty and endovascular brachytherapy in Vienna-2 study

PURPOSE

Endovascular brachytherapy (EVBT) has been proven to significantly reduce restenosis after percutaneous transluminal angioplasty (PTA). The object of this analysis was to assess the possible correlation between iridium-192 source non-centering and angiographic-determined restenosis.

MATERIALS AND METHODS

A total of 113 patients with long-segment lesions of the superficial femoro-popliteal artery (SFA) were randomized to receive either PTA alone or PTA followed by EVBT in the Vienna-2 study. This analysis was performed on a subgroup of 34 out of 57 patients, who received PTA+EVBT. Angiographic restenosis was defined as lumen reduction of more than 50%. Angiograms taken immediately after PTA (34 patients) and at follow-up (25 patients) were analyzed. The distance between the vessel wall and the actual position of the source at the time of EVBT was measured (in mm) and correlated with the follow-up vessel lumen diameter. Measurements were performed at points at a distance of 10 mm from each other. The dose was determined at the luminal surface and at the reference depth of 2 mm into the vessel wall for different distances from the source.

RESULTS

Among the 622 measured points, 62 (10.0%) were within restenotic areas; 560 (90.0%) were in arterial segments without proven angiographic restenosis. As far as source centering is concerned, 7.9% of restenotic points were observed when the maximum distance to the arterial wall was <3 mm and 9.6% for 4 mm, respectively. The percentage of restenotic points increased up to 15.9% when the maximum distance to the arterial wall was 5 mm and reached 22.2% when it was >5 mm.

CONCLUSIONS

The proportion of restenotic points significantly increased with source non-centering. This observation was interpreted as being related to a decrease in dose at the target. When the maximum distance between the source and the vessel surface was >5 mm, the dose at the reference depth (2 mm into the vessel wall) decreased to values lower than 5 Gy.

Reproducibility of calcified lesion quantification: a longitudinal intravascular ultrasound study

In view of a prospective intravascular ultrasound (IVUS) study, the reproducibility of the extent of the calcified lesion in IVUS images derived from separate pull-back maneuvers was assessed. Patients (n = 34) were imaged with IVUS before and after percutaneous transluminal angioplasty (PTA) and at 1-y follow-up. In the presence of a calcified lesion, the largest arc and the length of the matched calcified lesions was assessed. Interobserver differences in arc measurements were low (< or = 0.7%), with low coefficients of variation (< or = 5.8%). Similarly, interexamination differences in arc and length measurements were small (< or = 1.1%), with low coefficients of variation (< or = 3.2%). At follow-up, a nonsignificant increase in both the arc (1.9%) and length (1.7%) of the calcified lesion was observed. This study showed that measurements of the calcified lesion are highly reproducible; changes seen at 1-y follow-up were not significant. We conclude that IVUS may be used to monitor the effect of medical intervention on the extent of the calcified lesion in a longitudinal study.