Author + information
- Andrew J.P. Klein, MD∗ ()
- Interventional Cardiology, Vascular and Endovascular Medicine, Piedmont Heart Institute, Atlanta, Georgia
- ↵∗Reprint requests and correspondence:
Dr. Andrew J.P. Klein, Interventional Cardiology, Vascular and Endovascular Medicine, Piedmont Heart Institute, 95 Collier Road, Suite 2065, Atlanta, Georgia 30309.
Critical limb ischemia (CLI) is the most severe phenotype of peripheral arterial disease. The management of these patients is analogous to sailing a ship through turbulent seas fraught with peril. Ideally, multidisciplinary teams help navigate the ship (patient) through the storms of adverse cardiovascular and limb outcomes to the shore of a healed wound. A critical component of CLI care is revascularization and with its low procedural morbidity and mortality, endovascular revascularization has been shown to be a viable alternative to surgical bypass. The end goal of all revascularization, whether surgical or endovascular, is to provide enough blood to permit healing or alleviate rest pain. However, the question is, how much revascularization is enough? With both endovascular and surgical revascularization, there is no immediate endpoint to predict the likelihood of wound healing. We currently have no beacon to tell us that we are heading toward the shore of a healed wound.
The common doctrine of endovascular therapy (EVT) for CLI is to provide straight-line flow to the foot. Sometimes straight-line flow to the wound is not possible and in other cases multiple vessels can be opened. Operators must determine when there has been sufficient revascularization. At the end of a CLI revascularization procedure, we have all been faced with deciding between performing further angioplasty of another vessel or the plantar vessels versus concluding the procedure and accepting the result, often reciting the phrase the enemy of good is better. We weigh the risks of additional revascularization (increased contrast, radiation, time, and the potential for vessel dissection or perforation) against watchful waiting in the hope that we may see the wound heal. Ideally, we would have a way to know at the conclusion of the case that there has been sufficient revascularization. Following the procedure, patients typically undergo repeat noninvasive testing to assess macro- and microcirculation, including ankle-brachial index, pulse volume recordings, segmental limb pressures, and skin perfusion pressure, toe brachial index, or TcPO2. However, these assessments are not available at the time of the intervention and therefore do not permit any immediate action to potentially improve outcomes. The ability to know intraprocedurally that the procedure has been successful in achieving enough blood flow to heal the wound may be the Holy Grail for CLI interventions. In this issue of JACC: Cardiovascular Interventions, Utsunomiya et al. (1) provide a possible beacon of hope to the question of when is enough enough?
In the arena of Rutherford stage V and VI disease, wound care and revascularization are paramount. Though not standard, many of us look for some form of angiographic blushing at the wound site at the end of the case as an assurance that perhaps we have done enough. This study suggests that this wound blushing (WB) may be predictive of wound healing. The authors previously published a smaller study that showed that WB post-revascularization indeed predicted wound healing in Rutherford stage V and VI CLI patients (2). WB is defined by the authors in these papers as an area densely stained with contrast media around the wound on the final angiograms when angiography is performed with a catheter in the popliteal artery. With this as a background, they sought to examine a larger sample size and analyzed angiograms and data from the OLIVE (Endovascular Treatment for Infrainguinal Vessels in Patients with Critical Limb Ischemia) registry, which was a multicenter prospective observational study conducted in Japan. Specifically, they sought to identify the optimal angiographic endpoints for assessing wound healing in response to endovascular revascularization.
The approach to this study was relatively straightforward. In essence, they reviewed the final angiograms of 185 patients with Rutherford stage V or VI CLI to determine the following: 1) How many below the knee vessels (0 to 3) were present? 2) How many below the ankle vessels (0 to 2) were depicted? 3) Was any portion of the pedal arch present? 4) Was direct in-line flow based on the angiosome concept obtained? and 5) Was wound blush obtained?
These results were then analyzed to determine whether they correlated with wound healing. An experienced revascularization specialist who was blinded to the clinical courses of the patients independently evaluated all angiograms. A core lab determined wound healing. After excluding patients who did not have adequate foot imaging or follow-up to 1 year, 185 of these patients were analyzed.
The patients enrolled in this study were mainly diabetic (75%) with over one-half on dialysis (56%), making this an extremely high-risk population for amputation and adverse cardiovascular events. This population is somewhat different given an average body mass index of only 22 (unusually low), a hemoglobin A1C of 6.2 (unusually low) along with statin use in only 22% (extremely low). The low statin use reminds us all to ensure that all CLI patients are on goal-directed medical therapy, as this directly impacts survival and limb outcomes (3,4).
The manner of endovascular revascularization was performed at the discretion of the operator. Of the 185 patients, 43 (23%) received treatment only in the femoropopliteal segment whereas the remaining 142 patients (77%) received infrapopliteal interventions. Thirty cases (16%) received additional treatment of vessels below the ankle. The final angiographic data are shown in Table 3 and WB was positive in 142 patients (76%) and negative in 43 patients (23%). Of these WB+ patients, 72 patients had 1 patent infrapopliteal vessel; 70 had 2, and 28 had 3 patent vessels, whereas 15 patients had none. In this group, 91% had at least 1 below the ankle vessel and 68% had some portion of the pedal arch identified. When compared to the group without WB, the only statistically significant differences were in the number of below the ankle vessels and the presence of a pedal arch. Interestingly, there was no difference between the WB+ and the WB− groups with respect to angiosome-direct patency or not. The authors did define that if the wound covered multiple angiosomes then revascularization of all angiosome-specific vessels was required to attain the label of successful angiosome-direct revascularization, which could impact these numbers.
The authors provide a comprehensive multivariable analysis of all angiographic variables in an effort to identify 1 that could predict wound healing. Using various models, only wound blush was predictive of wound healing. Overall wound healing was 73.5%, which is similar to most EVT CLI trials (5). The probability of wound healing in patients with wound blush obtainment was significantly higher than that of those without wound blush (79.6% vs. 46.5%; p = 0.01). In the multivariate analysis, wound blush obtainment remained an independent predictor of wound healing. Though patients without a wound blush have a 50/50 chance of healing their wound, the near 80% chance of wound healing with wound blush may be the sign we seek at the end of our cases to know that we have done enough to revascularize our patient.
The limitations of this paper are several. The obvious one is the endpoint of wound blush. Though it is defined as angiography of the foot with the catheter in the popliteal, there was neither standardization of the contrast volume administered nor the rate of delivery. The use of vasodilators was not mentioned and can be used to enhance vascular blush by dilating the microvasculature, thus altering the endpoint. Another limitation is using only 1 blinded experienced revascularization specialist to review all the angiograms, which raises the possibility of intraobserver variability. Ideally 3 observers would have reviewed the angiograms several times each to determine both interobserver and intraobserver variability.
This paper provides us a potential beacon to look for in the stormy seas of CLI therapy. An objective scoring and assessment of wound blush during EVT should provide a strong signal that there is a more than reasonable chance that the wound will heal. Though this needs to be confirmed in larger studies, this represents 1 viable option for determining whether there has been sufficient revascularization. Wound blush might be the way we determine that indeed enough is enough at the conclusion of the intervention and may be the beacon of hope that we seek in each procedure.
Dr. Klein has reported that he has no relationships relevant to the contents of this paper to disclose.
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