What is Peripheral Arterial Disease (PAD)?

What is Peripheral Arterial Disease (PAD)?

Peripheral Arterial Disease (PAD) is a clinical condition characterized by gradual narrowing of the arteries, known as stenosis, which disturbs blood flow to surrounding tissue. Symptomatic PAD in lower limbs is a common clinical condition that is prevalent in up to 10% of the general population. Predominant symptoms of PAD include cramping, intermittent claudication, and may cause numbness in the affected leg.  These symptoms are typically aggravated by walking or exercise and relief is usually experienced after a short period of rest.

Risk factors for PAD are similar to the risk factors associated with coronary arterial disease (CAD). The main risk factors include smoking, diabetes, hypertension, hyperlipidemia and a family history of vascular disease.

Continuing development of the disease may lead to complete blockage of the artery, known as chronic total occlusion.

What are Chronic Total Occlusions (CTO)?

CTOs, defined as arterial obstructions lasting more than 30 days, are frequently found in patients with advanced PAD. These arterial occlusions are mainly composed of smooth muscle cells, connective tissue, calcium, thrombus, lipids and inflammatory cells.

Chronic total occlusions may be more than 20cm long and are often heavily calcified or extremely fibrotic. Treatment of CTOs is considered highly challenging. The superficial femoral artery (SFA) is the most commonly diseased artery in the peripheral vasculature, partially because it is the longest artery in the human body, running the length of the thigh toward the knee.

CTOs of the SFA present in up to 50% of the patients treated for peripheral PAD.

Why open a CTO?

CTO crossing and blood flow restoration are essential for improved blood supply and tissue perfusion in the effected leg. All CTO revascularization techniques aim at reducing or eliminating the clinical symptoms associated with the disease, thereby improving patient quality of life, and in the most serious cases, preventing amputation of the limb. 

What are the treatment options for CTO?

Treatment strategies include medication, lifestyle modification, endovascular techniques and/or bypass surgery. Lifestyle modification and medication are advised for moderate PAD, however they have limited efficacy in treating a CTO. Endovascular therapy is the treatment of choice for many stenotic or occlusive lesions; however by-pass surgery is still the recommended treatment option for extremely long and/or calcified lesions. 

What is endovascular therapy?

Endovascular therapy is a minimally invasive technique where a physician gains access to the arterial vasculature via a single puncture site, usually the femoral artery. The equipment used during the revascularization procedure is advanced by the physician from the access site via the arteries toward the occluded artery. Endovascular techniques for CTO crossing typically require the use of guidewires – long metal wires less than 1mm in diameter. Crossing the occlusion with a guidewire is a prerequisite for opening the occluded artery. Following successful guidewire crossing, adjunctive therapies such as balloon dilatation or atherectomy are often used to expand the vessel lumen. Guidewire positioning distal to the occlusion may also be achieved by sub-intimal crossing. Sub-intimal crossing is a technique in which the vessel wall is deliberately dissected to allow guidewire advancement. The main challenge of this technique is the ability to re-enter into the vessels true lumen after tangential passing of the occlusion. Sub-intimal crossing will often result in uncontrolled guidewire advancement well beyond the target lesion, thus requiring sub-intimal angioplasty or stenting beyond the occluded segment.

Why is there a need for a crossing device?

Success rates of endovascular CTO procedures are highly variable and largely dependent upon lesion morphology and operator experience. Recanalization of CTOs has a failure rate of up to 30% when using traditional guidewire and balloon technology. The main reason for failure is the inability to cross the occlusion with a guidewire or inability to re-enter the true lumen following sub-intimal crossing (xi,xii). Crossing devices are intended to improve the safety and effectiveness of endovascular therapy for CTOs, potentially reducing the need for by-pass surgery and amputations.

What is the ENABLER-P Balloon Catheter System?

The ENABLER-P Balloon Catheter System is designed to facilitate the intraluminal advancement of standard guidewires beyond chronic total occlusions in the peripheral vasculature.

See Technology page for detailed description and animation.

References

  1. Norgren L, Hiatt WR, Dormandy JA, Nehler MR, Harris KA, Fowkes FG et al. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). Eur J Vasc Endovasc Surg. 2007;33 Suppl 1:S1-75. Epub 2006 Nov 29.
  2. Hirsch AT, Haskal ZJ, Hertzer NR et al. ACC/AHA 2005 Guidelines for the Management of Patients With Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic): J. Am. Coll. Cardiol. 2006;47;1-192
  3. Nadal, LL. et. al., Subintimal angioplasty for chronic arterial occlusions. Techniques in Vascular and Interventional Radiology, 2004; (7):16-22
  4. Nadal, LL. et. al., Subintimal angioplasty for chronic arterial occlusions. Techniques in Vascular and Interventional Radiology, 2004; (7):16-22
  5. Mustapha et al; Cover story: A new approach to diagnosing and treating CLI; EndoVasc Today, Bryn Mawr Communications II LLC; September 2010
  6. Khalid, MR, Khalid, FR, Ali Farooqui, F. et al. A Novel Catheter in Patients with peripheral chronic total occlusions: A single center experience; Catheterization and Cardiovascular Interventions 76:735-739 (2010)
  7. Gandini R, Volpi T, Pipitone V, et al. Intraluminal recanalization of long infrainguinal chronic total occlusions using the Crosser system. J Endovasc Ther 2009;16:23–27.
  8. Becker GJ, Katzen BT, Dake MD Noncoronary angioplasty. Radiology 1989; 170: 921—40
  9. Capek P., McLean GK, Berkowitz HD Femoropopliteal angioplasty. Factors influencing long-term success. Circulation 1991; 83: 170—180
  10. Murray JG, Apthorp LA, Wilkins RA Long segment (> 10 cm) femoropopliteal angioplasty: improved technical success and long term patency. Radiology 1995; 195: 158—62
  11. Krepel VM, van Andel GJ, van Erp WF, Breslau PJ Percutaneous transluminal angioplasty of the femoropopliteal artery: initial and long-term results. Radiology 1985; 156: 325—28
  12. Boccalandro F, Muench, A, Sdringola S, et al; Wireless laser-assisted angioplasty of the super?cial femoral artery in patients with critical limb ischemia who have failed conventional percutaneous revascularization; Catheterization and Cardiovascular Interventions 2004 63:7–12
  13. Charalambous N, Schafer PJ, Trentmann J, et al ; Percutaneous Intraluminal Recanalization of Long, Chronic Super?cial Femoral and Popliteal Occlusions Using the Frontrunner XP CTO Device: A Single-Center Experience Cardiovasc Intervent Radiol 2010 33:25–33