Abstract
Since its development a few decades ago, the subintimal angioplasty technique has been adapted to treat occlusive lesions in a variety of arterial beds. In their retrospective analysis, Zhu et al. 1 propose a narrowly targeted application in treating below-the-ankle occlusive disease in diabetic CLI patients. Though one would expect rather infrequent use of the below-the-ankle (BTA) technique in clinical practice, the authors reported encouraging results in terms of limb salvage at 1 year (94%), thanks to a skilled team knowledgeable in diabetic foot pathology. Although not the first to propose this application, Zhu et al. 1 offer valuable information that adds considerably to our current knowledge of the subintimal technique, focusing on microcirculatory aspects of critical ischemic lesions in the foot arch. This technique could be particularly useful in the diabetic context, as regaining flow in the distal arterial beds probably plays a key role in wound healing, especially in the neuroischemic foot compromised by both neuropathy and functionally impaired capillary perfusion. 2 Nevertheless, some corollaries to the main message of the article bear special mention.
Recanalizing the foot arteries and arches in diabetic CLI patients across the subintimal plane remains a challenging technique, although Zhu et al. 1 offer several useful technical tips. Nonetheless, success of subintimal angioplasty in this distal location could be influenced by two factors. First, there is the crucially important availability of an appropriate access throughout the tibial trunk, which usually requires synchronous treatment of upstream calf lesions (85% of cases in the Chinese cohort) typically burdened with calcifications particular to this district.2,3 Second, there is the need to overcome the medial calcifications (type II calcifications) 3 associated with diabetes in these rigid millimeter-size foot arteries. The “classical” steps of the (femoropopliteal) subintimal technique, especially the re-entry phase, may therefore be more arduous and challenging for the interventionist.
It has been suggested that the prevailing clinical goal in these subjects remains limb preservation, which seems to be more influential than patency, 4 as Zhu and colleagues 1 note in their conclusions. Though substantial clinical evidence to support its utility is lacking, the BTA subintimal technique may represent a useful tool for limb salvage, particularly owing to its repeatability in diabetic CLI patients who typically suffer ischemic relapses and re-emergence of trophic defects. Certainly, achieving clinical success (even temporary, but repeatable) offers these patients the chance to be among the 64% alive at 2 years or helping the 55% of survivors to avoid below-the-knee or thigh amputations at 3 years and beyond despite modest midterm patency. 5
The relatively high limb salvage rate reported by Zhu et al. 1 should be carefully interpreted. First, their outcomes seem to reflect not only recanalization of the sole plantar arches but also successful combined procedures including the crural, pedal, and/or plantar arteries (only 15% of their cases had isolated arch lesions treated). Second, regarding the subset of foot ulcers treated by BTA subintimal angioplasty, contemporary clinical experience suggests that it would be difficult to prove a linear correlation between successfully re-established flow and unconditional tissue healing in diabetic neuroischemic limbs unless a multidisciplinary follow-up was initiated. 6 However, the application of this multidisciplinary team approach in and of itself could influence the outcome. 6
Finally, choosing the optimal hemodynamic solution to restoring distal arterial flow in the foot, particularly in the diabetic milieu of risk factors, should probably include the subintimal remodeling approach as a valuable but not unequivocal alternative. Ultimately, the interventionist should decide upon the applicability of targeted recanalization in the lower resistance plane (either endoluminal or extraluminal) based upon road mapping and lesion distribution.