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Addressing the Limitations of Standard Balloon Angioplasty
Peripheral artery disease (PAD) has been estimated to affect at least 8.5 million Americans over the age of 40 years and affects approximately 202 million people worldwide.1 Symptoms range widely for patients with PAD. On one extreme are the patients who are either asymptomatic or have sufficiently compensated their activity levels to avert symptom onset. The lack of symptoms may lead to underdiagnosis and underestimated disease prevalence. On the other extreme of the spectrum are the patients with end-stage disease with critical limb ischemia (CLI) in the form of rest pain, tissue loss, and/or gangrene. CLI has an estimated incidence of 500 to 1,000 new cases per 1 million people annually in a North American or European population.2
The quality of life limitations imposed by lifestyle-limiting claudication and CLI have previously been described.3,4 The cornerstone of therapy for any patient with PAD is medical optimization to minimize cardiac risk factors. Intermittent claudicants should also undergo guideline-directed structured exercise therapy and consideration of revascularization in patients with ongoing symptoms despite optimized medical therapy.1 Conversely, patients with CLI are referred for revascularization up front to minimize tissue loss and promote limb salvage.1 In the last decade, given significant advancements in endovascular techniques and equipment, an endovascular approach has become increasingly favored over open surgery for revascularization in CLI.5
Despite innovations in the endovascular space such as drug-coated balloons (DCBs), increasingly flexible self-expanding stents, and drug-eluting stents, there remain significant limitations in long-term primary patency rates.6 Patency rates are lower in the peripheral vasculature compared to the coronaries owing to two distinct differences between these vascular beds: (1) the composition of the arterial wall and extracellular matrix is a consequence of each specific vascular bed and the physiological demands affiliated with its location and purpose, and (2) the macroscopic mechanical pressures impressed upon the peripheral vascular bed (torsion, flexion, compression, elongation, and contraction) with activities of daily living.7 Given these limitations in the periphery, the primary endovascular revascularization strategy is to perform balloon angioplasty with or without adjunctive DCB depending on lesion location and a primary goal of avoiding stent placement.
However, limitations exist with the mechanism of action in conventional percutaneous transluminal angioplasty (PTA). First, given the nature of a folded balloon, unraveling of the balloon folds during inflation results in a shear stress produced upon the overlying plaque (Figure 1).8 Furthermore, given that there is no mechanism to control the expansion of a conventional balloon, dilation occurs in the path of least resistance. This renders vessels to be most susceptible to stress deformation and dissection at the ends of the balloon, as it “dog bones” during inflation. The consequence of these mechanisms of injury is vessel trauma (Figure 2) resulting in significant dissections and necessitating bailout stenting.
The mechanism of action in the Chocolate™ PTA balloon catheter is derived from its unique nitinol-constrained structure (Figure 3). The nitinol cage prevents the shear stress caused by unpredictable balloon unfolding, and allows for the uniform distribution of longitudinal and circumferential forces as the balloon is expanded. The “pillows” exert a gentle pressure for vessel dilation while the “grooves” created by the nitinol cage allow for stress relief (Figure 4), ultimately resulting in less wall stress compared to conventional balloon angioplasty (Figure 5). Even in severely calcified lesions, adjunctive atherectomy along with Chocolate™ PTA balloon dilation can yield optimal results without flow-limiting dissection or a need for stenting (Figure 6).
As a proof of concept, the Chocolate™ Balloon Angioplasty Registry (Chocolate BAR) was created as a prospective, core lab–adjudicated registry to analyze the effects of Chocolate™ balloon dilation in above- and below-the-knee interventions. The primary endpoint was defined as optimal (≤ 30% residual stenosis) angiographic outcomes without flow-limiting dissection, and secondary endpoints included the rate of bailout stenting, freedom from target lesion revascularization (TLR), and major amputation-free survival. The interim analysis from 2014 has shown significantly favorable results with a dissection rate of 2%, bailout stenting rate of 3%, 95% freedom from TLR, and 98% amputation-free survival at 3 months in the below-the-knee cohort.9
The concomitant use of a Chocolate™ specialty balloon for angioplasty along with DCB to provide adequate lesion preparation while also inhibiting neointimal hyperplasia is attractive. A recently published single-center observational study describes the use of the Chocolate™ balloon followed by DCB in patients with claudication.10 The rate of chronic total occlusion in this study population was 65.5%, approximately one-third of which was an occlusion > 150 mm in length. The rate of bailout stenting in this study was 9.5%, with an overall primary patency rate of 98.8% and freedom from TLR of 97.6% at 12-month follow-up.10 This study illustrates the importance of a symbiotic relationship between achieving satisfactory lesion preparation and expansion with antiproliferative drug deposition to improve long-term patency rates.
1. Gerhard-Herman MD, Gornik HL, Barrett C, et al. 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2017;69:1465-1508.
2. Norgren L, Hiatt WR, Dormandy JA, et al. Inter-society consensus for the management of peripheral arterial disease (TASC II). J Vasc Surg. 2007;45:S5-S67.
3. Liles DR, Kallen MA, Petersen LA, Bush RL. Quality of life and peripheral arterial disease. J Surg Res. 2006;136:294-301.
4. Remes L, Isoaho R, Vahlberg T, et al. Quality of life among lower extremity peripheral arterial disease patients who have undergone endovascular or surgical revascularization: a case-control study. Eur J Vasc Endovasc Surg. 2010;40:618-625.
5. Agarwal S, Sud K, Shishehbor MH. Nationwide trends of hospital admission and outcomes among critical limb ischemia patients: from 2003-2011. J Am Coll Cardiol. 2016;67:1901-1913.
6. Li J, Parikh SA. Drug-coated balloons for long lesions in peripheral arterial disease. J Cardiovasc Surg (Torino). 2017;58:698-714.
7. Li J, Tzafriri R, Patel SM, Parikh SA. Mechanisms underlying drug delivery to peripheral arteries. Interv Cardiol Clin. 2017;6:197-216.
8. Ward C, Mena-Hurtado C. Novel use of pillows and grooves: the Chocolate PTA balloon catheter. Endovasc Today. 2014;13:24-28.
9. Mustapha JA. Summary of initial results for tibial lesions treated in the BTK cohort of the Chocolate® Balloon Angioplasty Registry (Chocolate BAR). Presented at: Amputation Prevention Symposium (AMP); August 12–15, 2014; Chicago, Illinois.
10. Sirignano P, Mansour W, d’Adamo A, et al. Early experience with a new concept of angioplasty nitinol-constrained balloon catheter (Chocolate®) in severely claudicant patients [published online November 20, 2017]. Cardiovasc Intervent Radiol.
Jun Li, MD
Cardiovascular Interventional Center
Harrington Heart & Vascular Institute
Mehdi H. Shishehbor, DO, MPH, PhD
Professor of Medicine
Case Western Reserve University
Cardiovascular Interventional Center
Harrington Heart & Vascular Institute
Disclosures: Consultant and advisor to Medtronic, Boston Scientific Corporation, Philips, and Abbott Vascular.
Chocolate™ PTA Balloon Catheter
Indications, contraindications, warnings and instructions for use can be found in the product labelling supplied with each device.
Indications for Use:
The Chocolate™ PTA Balloon Catheter is intended for balloon dilatation of lesions in the peripheral vasculature, including the iliac, femoral, ilio-femoral, popliteal, infra-popliteal, and renal arteries.
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