Current And Emerging Options For Intervention In CLI
Somewhere along the line, we have diverged from the principle of a graft pulse as we increasingly rely upon minimally invasive technology to revascularize patients with severe CLI. I hear discussions of “partial revascularizations” with the idea that “We will see how that works.” However, without the prompt, complete and sustainable restoration of blood flow to the wound bed, are we losing opportunities to salvage the maximal amount of at risk tissue? Surely, catheter-based interventions have the opportunity to improve blood flow but questions remain. How much improvement do such interventions provide? For how long will the improvement last? Are we immediately able to identify failure of our catheter-based intervention in a way that allows timely re-intervention?
Weighing The Various Limb Salvage Options
In the infrainguinal region, the various options for limb salvage range from catheter-based intervention with various therapeutic devices to traditional open surgical bypass.
The concern about patency associated with angioplasty, stenting and atherectomy of infrainguinal blood vessels is an ongoing and controversial topic. There is a shortage of good clinical data for many of the available devices. Much of the available data are from anecdotal or single center experiences.
There is a developing body of data regarding self-expanding bare metal stents in the femoral popliteal anatomy for the important one- to two-year follow-up period. McKinsey and colleagues reported a single center registry experience using directional atherectomy to treat 579 lesions in patients with lower extremity ischemia.1 This study reported that primary patency for all lesions at 12 and 18 months was 62.2 percent and 52.7 percent, respectively. These results are mediocre at best. Unfortunately, no large, prospective, randomized trials exist with any available atherectomy technology.
As a matter of disclosure, we are comfortable offering all of these options and do not believe we are partial to any single modality. What does appear to be clear at this point in time is that the patency of open vascular reconstructions using appropriate vein conduit with well selected inflow and target outflow vessels provides a substantial advantage with regards to patency and durability in comparison to the available catheter based approaches, especially in the infrapopliteal arteries. The infrapopliteal level, in many cases of CLI, must undergo revascularization to establish direct inline flow to the wound bed.
In our experience, there is a management dilemma when our podiatric colleagues call and note that wound healing has stalled after we have performed a minimally invasive infrapopliteal revascularization (angioplasty, stenting or atherectomy of a tibial level vessel). When one does not achieve palpable pulses after using a catheter-based modality in a partial revascularization, we do not know if the revascularization has failed. Noninvasive examination, including ultrasonography, magnetic resonance imaging (MRI), computed tomography angiography (CTA) and pulse volume recording (PVR), is minimally helpful for detecting subtle but clinically relevant disease recurrence.
Ultimately, the dilemma frequently leads us to repeat the invasive contrast arteriography, exposing the patient to cumulative radiation and risks like contrast nephropathy. If a repeat catheter-based intervention is possible, the same concerns arise regarding long-term patency of the subsequent re-intervention. With a tibial bypass, failure does occur. However, there is never a question of the patency of a tibial bypass. The bypass is either open or it is closed.
Key Insights On Catheter-Based Interventions
To be clear, catheter-based interventions certainly have an appropriate role in the treatment of infrainguinal PAD, including presentations of CLI with significant tissue loss. The inadequacy or unavailability of an autogenous vein conduit necessary to perform a tibial level revascularization may be a relative contraindication to an open bypass.