Limitations Of Re-Entry Devices In Lower Extremity Chronic Total Occlusions

Objective
Subintimal recanalization for the treatment of chronic total occlusions (CTO) occasionally requires re-entry devices to access the true lumen distally. Limited information is available on factors predicting success or failure of these devices.

Methods
A retrospective review of all CTO cases from 8/06-8/09 was performed. Age, gender, occlusion length, site of re-entry, and the angle of the aortic bifurcation were recorded. A calcification score (none, mild, moderate, severe) at the re-entry site was assigned based on procedural angiograms. Univariate and multi-variate logistic regression analyses were used to identify factors predicting failure of re-entry into the true lumen. All cases used the Outback LTD re-entry device (Cordis).

Results
Of 249 CTOs treated, the re-entry device was used 52 times (20.9%): 47 superficial femoral artery (SFA) occlusions and 5 combined SFA and popliteal artery occlusions (33 TASC II Type C and 18 Type D lesions). Of 48 procedures with available angiograms for review, the target re-entry site was at the adductor canal in 30 (62.5%), the above-knee popliteal artery in 13 (27.1%), behind the knee joint 4 (8.3%) and the mid-SFA in 2 (4.2%). The mean age was 73.1 years (54.0% males). Re-entry was successful in 34 attempts (64.5%). Causes of failure included inability to re-enter the true lumen in 11 (61.1%), difficulty tracking the device over a wire in 3 (16.7%), acute angle of aortic bifurcation in 2 (11.1%), mechanical failure of the device in 1 (5.6%) and difficulty tracking the device through the lesion in 1 (5.6%). Moderate or severe calcification at the site of re-entry was the only significant predictor of failure (OR: 6.3, p=0.01). An aortic bifurcation angle ≥40⁰ did trend toward predicting success (OR: 0.23, p=0.54).

Conclusions
Although re-entry devices can be successful in extending the applicability of endovascular management to difficult femoropopliteal occlusions, they are not uniformly successful in current clinical practice. Significant calcification at the proposed re-entry site is a strong predictor of failure.