Successful Limb Salvage: Utility of Orbital Atherectomy and PTA for the Treatment of Major Occlusions Below the Ankle

Patients with peripheral artery disease (PAD) who present with below-the-knee (BTK) lesions, especially lesions below the ankle (BTA), are routinely considered to be candidates exclusively for amputation, as opposed to intervention.¹ Variable anatomy, tortuosity, calcification, and a high prevalence of flush chronic total occlusions make the BTA territory particularly challenging.² In light of the decreased mobility and reduced quality of life of amputees, however, attitudes in the medical community have evolved regarding the propriety and efficacy of arterial revascularization in extensive or multilevel BTK disease. Among many vascular surgeons who assent to the superiority of revascularization over primary amputation to treat advanced PAD, surgical bypass is still often considered to be the best or only therapeutic option.³ Traditional bypass surgical options are not feasible BTA, however, and physicians are increasingly considering intervention on inframalleolar arteries.⁴

With advances in technology and clinical appreciation of the small size of BTA vessels, catheter-based procedures have become an increasingly attractive option to treat patients with critical limb ischemia (CLI). In recent years, percutaneous transluminal angioplasty (PTA) has been established as the primary therapeutic intervention for CLI.⁵ BTK lesions characteristically are comprised of heavy, circumferential calcification, which often accompanies CLI. This provides a challenge to all types of revascularization, but most significantly, to endovascular therapy.³ CLI patients often have TransAtlantic Inter-Society Consensus (TASC) D lesions, total occlusions and/or heavily calcified lesions, none of which are well-suited for PTA intervention. Surgical bypass grafting yields results far superior to PTA (with or without stenting), as long as the patient has an adequate ipsilateral saphenous vein and a suitable non-calcified recipient artery.⁶ Unfortunately, many CLI patients, specifically those with BTA lesions, do not have this conduit available, and their various comorbidities leave them at an increased risk for major adverse events (MAEs) following open surgical revascularization. 

These significant anatomical difficulties are increasingly prevalent in the PAD patient population, due to the rise of diabetes and end-stage renal disease (ESRD) in the general population.⁷ Ethically and economically, these challenges highlight the necessity for a more effective treatment regimen for complex infrapopliteal PAD. While PTA enjoys high procedural success rates in focal lesions, the first line of therapy for the elderly, diabetic, ESRD patient population tends to be amputation.⁸ Ideally, BTA lesions in these CLI patients could instead be addressed effectively by angioplasty, considering that this territory is out of reach of surgical revascularization, and forgoing the necessity of amputation. However, PTA will not supplant more risky procedures until it is shown to be effective at treating the types of lesions commonly found in such patients. 

In these complex, calcified lesions, PTA frequently results in early elastic recoil, dissections, and poor primary and secondary patency rates, which require bail-out stenting in up to 50% of the cases.⁹ To this end, lesion compliance is a critical factor in determining the effectiveness of angioplasty. Complex lesions may respond more favorably to PTA therapy if the vessel is first prepared. For example, increasing the lumen diameter prior to angioplasty could facilitate lesion crossing and result in improved long-term patency rates.⁷ For BTA lesions, pedal arch intervention can be performed safely when knowledgeably utilizing appropriate technologies, such as orbital atherectomy.² The usage of atherectomy to prepare vessels for PTA confers several putative advantages: removal or debulking of the plaque rather than just being compressed against the vessel wall; lack of barotrauma, reducing the risk of intimal/medial hyperplasia; lesser risk of dissection; and the advantage of using adjunctive balloon angioplasty at lower pressures.⁷ If stenting is not necessary, balloon angioplasty following atherectomy also preserves the option of performing surgical bypass of BTK lesions in the future. 

According to the 2016 American Heart Association (AHA)/American College of Cardiology (ACC) Guideline on the Management of Patients with PAD,¹⁰ amputation is no longer acceptable as a first-line PAD therapy, even in patients with BTK disease. Endovascular revascularization is recommended in CLI patients with comorbidities such as congestive heart failure, cardiomyopathy, severe lung disease, and chronic kidney disease. If a patient has rest pain and multilevel disease, an endovascular-first approach is also advised. In patients with nonhealing wounds or gangrene, endovascular procedures are recommended to establish in-line blood flow to the foot.¹⁰  Even in claudicants, revascularization is a reasonable treatment option, if the claudication is lifestyle-limiting and has inadequately responded to medical management and exercise. In all CLI cases, the Guideline insists an evaluation for revascularization options should be performed by an interdisciplinary care team before amputation is considered.¹¹ 

Case Presentation 

A 53-year-old African-American male with a history of diabetes, chronic obstructive pulmonary disease, peripheral neuropathy, claudication, congestive heart failure, and renal insufficiency presented to the emergency department with complaints regarding a left lower extremity wound. The patient had recently been admitted to hospital with gangrene of his left great and second toes, which had turned completely necrotic. He underwent a 1st and 2nd transmetatarsal amputation, and was told his leg was “unblocked.”  He experienced difficulty with wound healing; he also noticed his third toe was becoming dark and blackened.  The patient was admitted to our service with gangrene of his left third toe. Preoperative diagnoses were left foot dry gangrene and PAD with CLI. 

Diagnostic Angiography

After informed consent was obtained, the patient was taken to the catheterization laboratory. Under ultrasound guidance, the right common femoral artery was accessed using a micropuncture needle.

Subsequently, a 4 French Precision access sheath (Terumo) was placed. Diagnostic aortogram with runoff was obtained (Figure 1A). A summary of the angiography findings:

1. No hemodynamically significant disease in the aorta, bilateral iliac arteries or common femoral arteries.
2. No hemodynamically significant disease in the left superficial femoral artery or popliteal artery.
3. The left anterior tibial artery was occluded shortly after its origin without reconstitution.
4. Left posterior tibial artery was the main runoff, but was almost occluded above the ankle and had severe stenosis, with the tarsal artery into the foot being occluded midfoot onward.
5. Left peroneal artery was a small vessel and stopped at the ankle.

Intervention

The patient was heparinized and activated clotting time (ACT) maintained at more than 200 seconds. The 4 French sheath was exchanged for a 6 French, 45 cm Destination sheath (Terumo). The posterior tibial artery was selectively cannulated. The stenosis and occlusion were crossed using a Glidewire Advantage .014-inch Glidewire (Terumo). The Glidewire was then exchanged for a ViperWire Advance guidewire (Cardiovascular Systems, Inc. [CSI]). Orbital atherectomy was performed on the left posterior tibial artery and the plantar artery (Figure 1B) in the foot using the Diamondback 360 peripheral orbital atherectomy system with 1.25 mm Micro Crown (CSI) (Table 1). Orbital atherectomy was followed by angioplasty using a 2.5 mm x 40 mm balloon for the posterior tibial artery and 1.5 mm x 150 mm balloon for the tarsal artery in the foot. Post procedural final angiography was performed (Figure 1C) with and without the wire, after giving 500 µg of nitroglycerin, which showed good in-line flow all the way to the toes. The patient tolerated the intervention well and there were no complications.  

Discussion & Conclusion

Individuals with type 2 diabetes and ESRD, such as in the case presented here, often have such occlusive below-the-ankle disease that restoring straight-line outflow through the foot has been considered impossible.¹² Consequently, there exists a dearth of published literature reporting successful intervention on inframalleolar arteries, despite the fact that, as the U.S. population ages, diabetes and renal disease are increasingly prevalent. These comorbidities are further associated with an increase in PAD lesion complexity and calcification, as well as a high risk of amputation and mortality. In the CLI patient population (elderly, diabetic, ESRD), amputation is considered a first-line therapy in up to 67% of cases, despite the fact that the majority of these patients have had no diagnostic angiogram or prior vascular procedure.⁸ A recent study retrospectively analyzed Rutherford 5 and 6 patients who underwent BTA revascularization for CLI at a single center. The technical success rate and the limb salvage rate (defined as “preservation of ankle joint”) were both 97%, suggesting that below-ankle recanalization is not only a feasible intervention, but a safe and successful one.¹³

The likelihood of amputation for African-Americans is approximately twice as high as for Caucasians, as these patients tend to be admitted when they are sicker and in emergency circumstances, such as in the case presented here.¹³ In addition to the racial disparities evident in the treatment of CLI patients, the significant decrease in quality of life associated with amputations highlights the need to find successful alternatives for these patients. Regrettably, limb amputations tend to be progressive in nature, as primary amputation is rarely a terminally successful procedure.⁸ For patients who have undergone amputation at, or proximal to, the transmetatarsal level, re-amputation has been required in as little as two weeks, and contralateral amputation has been necessary within one day.¹⁴ Indeed, revision of the index amputation to a higher level is itself a risk factor for subsequent contralateral amputation. Further, survival post-amputation is confounded by several factors, all of which were present in the case described here: COPD, diabetes, ESRD, PAD, and prior amputation.¹⁵ Considering his significant comorbidities, socioeconomic status, and medical history, this patient had an overwhelmingly poor prognosis. However, the ability of orbital atherectomy to be used in small vessels, such as those BTA,¹⁷ and the successful use of orbital atherectomy in changing the compliance of severely calcified lesions, not only allowed the adjunctive PTA to be performed safely and effectively, but it ultimately allowed the patient’s foot to be saved.

This case of an African-American male with CLI shows the utility of orbital atherectomy and PTA in successfully salvaging a limb with major occlusions below the ankle.¹⁷

References

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​Disclosure: Dr. Prateek Gupta reports he is a consultant for Medtronic. Drs. Brad Martinsen and Bynthia Anose are employed by, and own stock in, Cardiovascular Systems, Inc. 

The authors can be contacted via Dr. Prateek K. Gupta at pgupta5@uthsc.edu.