Tibial Interventions: Tips, Tricks, and Assessing Endpoints

Abstract

In this manuscript, we review the indications and techniques for tibial endovascular intervention and present a 79-year-old male patient with a right great toe ulcer that had been present for 6 weeks. Alternatives for intervention and assessing endpoints are also discussed.

VASCULAR DISEASE MANAGEMENT 2012:9(9):E163-E167

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Endovascular treatment for lower extremity peripheral arterial disease has gained significant momentum in the last decade. Appropriate modes of therapy continue to be a moving target. Although most interventionalists can agree on appropriate therapy for iliac disease, opinions are divided about whether the preferred treatment for infrainguinal occlusive disease is percutaneous transluminal angioplasty, stent, or atherectomy, among others. This dilemma is certainly magnified in patients undergoing tibial intervention. The indication for intervention in the tibial vessels is certainly not controversial. Endovascular tibial intervention or tibial bypass should be reserved for patients with critical limb ischemia (CLI). This would include tissue loss and rest pain, although predominantly tissue loss. Tibial revascularization for claudication is not performed as the risk/benefit ratio is unacceptable and improved distal perfusion does not often alleviate more proximal exercise-induced muscular ischemia. Outcome data for various techniques are more difficult to interpret in this vascular bed than any other. As endovascular treatments have evolved, the consensus guidelines have also evolved, specifically the Trans-Atlantic Society consensus statement (TASC).¹ The most recent iteration of these guidelines push an endovascular first treatment modality with open surgery reserved solely for endovascular failures. This is a dramatic change in the tibial bed from the first TASC document when surgical bypass was strongly recommended.

The balloon angioplasty in severe ischemia of limb (BASIL) trial helps guide treatment to some degree.² Depending on whether one is a surgical or endovascular zealot, the data from this study can be interpreted to fit the argument of choice. Very few patients treated with CLI fit in the anatomic extent of disease described in BASIL (70% had a single level of disease treated). Although better patency was noted with bypass than endovascular treatment (a balloon only approach), overall survival for either group was poor. Failure of either strategy had a poor prognosis and overall short-term mortality was high (37%). The importance of this data is the realization that surgical and endovascular treatments are complementary and this patient population is extremely fragile.

There are several descriptions of angiographic distribution of disease to ensure that the field is level in comparative studies. One commonly used is the SVS runoff score although this can be somewhat cumbersome.³ Graziani et al reported an alternative classification for diabetic patients with ischemic foot ulcers.⁴ This is a relatively simple classification system and translates well in all patients with CLI. Gray used this anatomic distribution of disease combined with comorbid medical conditions to help predict outcome.⁵ As one can imagine renal failure and gangrene were predictive of limb loss as was chronic obstructive pulmonary disease. Neither medical comorbidities nor distribution of disease were predictive of primary patency but isolated tibial disease was predictive of diminished secondary patency compared to multi-level peripheral arterial disease.

We will discuss techniques for facilitating intervention, endovascular treatment options that are available, and tips for optimizing primary and long-term outcomes. The most important aspects of treating those with limb-threatening ischemia are knowledge of the patient and what options are available. In general we treat patients with ischemic ulcers who lack a pedal pulse, have a toe pressure <40 mm Hg, or a transcutaneous pO₂ <40.

Case Report

A 79-year-old male presented to our practice with a right great toe ulcer that had been present for 6 weeks. He was referred to vascular surgery from a podiatrist who had been treating him with local wound care to no avail. His medical history included hyperlipidemia, coronary disease, diabetes, renal insufficiency, and congestive heart failure. Physical exam revealed a 1.5 cm ischemic right great toe ulcer with dependent rubor in the right foot. He had palpable femoral and popliteal pulses bilaterally with non-palpable pedal pulses. Non-invasive vascular labs showed an ABI of 0.31 on the right and 0.60 on the left. Given the patients physical exam it was obvious that his ulcer was ischemic and his disease distribution was limited to the tibial bed for the most part.

Initial angiogram with runoff revealed anterior and posterior tibial artery occlusions that were long-segment. The peroneal artery had a short segment occlusion with collateralization at the ankle to reconstitute the tarsal branches of the posterior tibial artery. This is a key decision point in the treatment algorithm. If the distal target is suitable, the patient can tolerate bypass, and has adequate conduit (single segment GSV) for popliteal-pedal bypass; this is a very reasonable alternative. If the patient has had prior vein harvest or poor cardiopulmonary reserve as in this case, endovascular strategy is favorable. Optimizing patient outcome and minimizing morbidity should be the goal of any intervention.

Our patient was initially treated with a small balloon after the lesion in the peroneal was crossed and intraluminal catheter position was confirmed (Figure 1). A pressure wire was placed through the catheter prior to balloon angioplasty. The completion angiogram revealed significantly improved flow without dissection. However, there was a residual Pd/Pa (pressure distal/pressure aortic) of <0.9 so we placed a short drug-eluting stent (DES) in an area of focal residual stenosis (Figure 2). The patient’s ulcer healed and he is currently on clopidogrel for maintenance.

Discussion

It is important to decide what the next step is when treating patients with this disease pattern. The next step for many of us would be arteriogram to define the extent of disease and guide intervention. It is also important to consider the angiosomes of the foot in determining best revascularization options. Although this is an important concept, there are limitations such as considerable variation in angiosomal patterns. Depending on the severity of the disease, revascularization of a given angiosome may not be plausible. This concept does not address the impact of treating proximal disease or account for the extent of collateralization. Additionally even with full revascularization of a given angiosome, some wounds don’t heal regardless of normal perfusion.

With currently available microcatheters and 0.014 systems, as well as improved imaging, the ability to intervene on tibial vessels is nearly limitless. Given the ability to treat this disease it would be wise to adhere to a few tips (Table 1). In tibial disease a luminal first strategy is preferred to subintimal techniques. Re-entry can often be much more difficult in the small distal tibial arteries. Realize that patience and selective imaging are more important in this vascular bed than more proximal occlusive disease. Initial proximal images may suggest long-segment occlusion. However distal catheter position may uncover treatable segments of disease (Figure 3). If the patient has severe multi-level peripheral arterial disease poor proximal flow can limit distal imaging. In this scenario we often traverse the proximal disease and uncover distal targets for surgical or endovascular revascularization (Figure 4). If we want to be aggressive at endovascular therapy then we have to consider less traditional approaches to reach target lesions (Figures 5 and 6). Pedal access can usually be achieved with a micropuncture set aiming for the contrast column on selected injections. This can then be upsized to facilitate retrograde crossing of occlusions.

There is a vast array of tools available when performing endovascular intervention. Various microcatheters and weighted 0.014″ and 0.018″ wires assist in crossing difficult occlusions. Once crossed, standard balloon angioplasty, cutting balloon, cryoplasty, and drug-coated balloons are a few options. Atherectomy, bare-metal stents, and DES are also a consideration. Regardless of the technique of intervention, real-time hemodynamic outcomes likely influence secondary interventions. Given the high-cost of failure of intervention, it is critical to maximize results. The Dutch iliac stent trial showed improved long-term outcomes in patients who had resolution of the pressure gradient at completion of intervention.⁶ A coronary study by Jensen revealed a significant reduction in binary restenosis at 9 months following bare-metal stents if the pressure gradient is resolved (8% vs 44%).⁷

The 2 common techniques for measuring pressure gradients are catheter pressure gradient and pressure wire technology. The downside of catheter pressure gradients are the consistent overestimation of gradient especially in smaller vascular beds, leading to over-aggressive therapy.⁸ Pressure wires are a relatively new tool that simplify measurements and give real-time data at the time of various techniques of intervention (Figures 7 and 8). Intravascular ultrasound has been touted by some but often leads to treating the image rather than the hemodynamic state. Intravascular ultrasound images often depict worse disease than the hemodynamics suggest in our experience.

DES have gained popularity in the tibial arteries with a proven track record in small caliber coronary vessels that are similar in caliber to the tibial vessels. Multiple trials have shown diminished amputation rate and target lesion revascularization with follow-up length ranging from 6 months to 3 years. A recent review article by Feiring outlines the available literature on below-the-knee DES technology.⁹ Drug-coated balloons and bioabsorbable stents are exciting technologies on the horizon.

Conclusion

Endovascular tibial intervention gained significant popularity in recent years. The indication for intervention remains CLI. As the arsenal of tools to treat this disease expands, an ongoing critical appraisal of the technology and supportive literature is imperative. We have yet to find the ideal treatment for this challenging vascular bed but monitoring real-time endpoints and close surveillance will likely lead to improved outcomes. Every interventionalist walks to the table with their own bias as to the best treatment option but individual knowledge of the patient and their needs should take precedence. One should consider all available options prior to any intervention. Good local wound care can often result in healing superficial ulceration despite ischemia. Surgical bypass should be considered in patients with long-segment tibial disease who are acceptable operative risk that have an adequate autologous vein. Prior to any endovascular therapy, the physician should take these alternatives under consideration so as to not limit future surgical options. Real-time hemodynamic endpoints such as pressure gradients should be utilized in an attempt to optimize perfusion and improve patient outcomes rather than relying on an “adequate” angiographic result. This is probably of greater importance in the tibial vessels than more proximal segments given the high cost of failure. Endovascular intervention for CLI, especially tibial artery intervention, requires a thorough knowledge of the various treatment options, an expanded skill set, and a willingness to adapt to new technology as it is developed.

References

1. Dormandy JA, Rutherford RB. Management of peripheral arterial disease (PAD). TASC Working Group. TransAtlantic Inter-Society Consensus (TASC). J Vasc Surg. 2000;31(1 Pt 2):S1-S296.
2. Adam DJ, Beard JD, Cleveland T, et al; for the BASIL trial participants. Bypass versus angioplasty in severe ischaemia of the leg (BASIL): multicentre, randomised controlled trial. Lancet. 2005;366(9501):1925-1934.
3. Rutherford RB, Baker JD, Ernst C, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg. 1997;26(3):517-538.
4. Graziani L, Silvestro A, Bertone V, et al. Vascular involvement in diabetic subjects with ischemic foot ulcer: a new morphologic categorization of disease severity. Eur J Vasc Endovasc Surg. 2007;33(4):453-460.
5. Gray BH, Grant AA, Kalbaugh CA, et al. The impact of isolated tibial disease on outcomes in critical limb ischemic population. Ann Vasc Surg. 2010;24(3):349-359.
6. Kamphuis AG, van Engelen AD, Tetteroo E, Hunink MG, Mali WP. Impact of different hemodynamic criteria for stent placement after suboptimal iliac angioplasty. Dutch Iliac Stent Trial Study Group. J Vasc Interv Radiol. 1999;10(6):741-746.
7. Jensen LO, Thayssen P, Thuesen L, et al. Influence of a pressure gradient distal to implanted bare-metal stent on in-stent restenosis after percutaneous coronary intervention. Circulation. 2007;116(24):2802-2808.
8. Garcia LA, Carrozza JP Jr. Physiologic evaluation of translesion pressure gradients in peripheral arteries: comparison of pressure wire and catheter-derived measurements. J Interv Cardiol. 2007;20(1):63-65.
9. Feiring AJ. Below-the-knee drug-eluting stents. Endovascular Today. 2011;10:65-72.

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From the Greenville Hospital System University Medical Center, Greenville, South Carolina.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted November 29, 2011, provisional acceptance given December 27, 2011, final version accepted May 22, 2012.

Address for correspondence: Dr. Mark P. Androes, Greenville Hospital System University Medical Center, 1690 Skylyn Drive, Suite 140, Spartanburg, SC 29307, USA. Email: mandroes@ghs.org