Cryoplasty for the Treatment of Femoropopliteal Arterial Disease: Will Freezing Solve the Problem of Cold Feet?

Abstract

IN patients with symptomatic femoropopliteal arterial disease, percutaneous transluminal angioplasty (PTA) has been established as the first-line treatment for the majority of atherosclerotic lesions. A significant drawback of the procedure is the high rate of recurrent stenosis, which usually develops during the first 12 months after treatment (1). Initial failure of PTA caused by elastic recoil or hemodynamically relevant dissection can be managed by the implantation of stents, but clinical and experimental studies have shown that angioplasty triggers multiple cellular and molecular mechanisms that lead to a cascade of events that eventually results in increased vascular smooth muscle cell proliferation, synthesis of extracellular matrix, and consecutive formation of neointimal hyperplasia with luminal narrowing. Although stents may dramatically improve the appearance immediately after angioplasty, they have yet failed to show superior long-term efficacy, as intimal hyperplasia is even more pronounced after stent implantation than after PTA alone (2,3). In this respect, the search for new techniques and devices dedicated to endovascular management of peripheral artery disease is a contemporary issue and has to be continued. Each year, a vast number of experimental and clinical studies are performed to test refinements of current balloon/stent systems or to explore new and more innovative techniques for transluminal treatment of femoropopliteal obstructions. However, most of the new devices and strategies fail to show significant improvements in long-term outcome when finally introduced into clinical practice. Recanalization techniques like atherectomy (rotational and directional), excimer laser–assisted angioplasty, or subintimal angioplasty mainly address the appearance of the vessel immediately after angioplasty. Transluminal removal of the atherosclerotic plaque and/or creation of a subintimal channel results in a wider lumen (or neolumen) with a relatively smooth surface, while the profound vessel wall trauma of balloon angioplasty is avoided (4–7). However, the efficacy of these techniques in terms of reduction of neointimal hyperplasia has not been determined for treatment of femoropopliteal arterial disease. The same is true for cutting balloon angioplasty, which represents a modification of conventional balloon dilation. The cutting blades of the balloon make controlled longitudinal incisions into the plaque and reduce the force needed to dilate the vessel. This is thought to result in lower rates of dissection and to trigger a more benign course of arterial healing as a result of the limited stretch injury. Although cutting balloon angioplasty has been positively evaluated in the coronary circulation, there are few reports about its use for peripheral vessels (8). During the past two decades, nearly all available stent designs— mostly variations of balloon-expandable devices and thermal or self-expanding cobalt or nickel titanium alloy (ie, nitinol) systems—have been used at the femoropopliteal level for salvage of PTA or even off-label primary treatment. However, in randomized studies, stents have generally failed to prove a significant benefit when evaluated versus PTA alone (9). The fact that the stent design can have significant impact on neointimal thickness independently of the extent of stretch injury has been demonstrated by Garasic et al (10), thereby finding that the optimal structure for these devices might be a key requirement for restenosis prevention. Recent investigations have highlighted the various forces that affect a stent when implanted into the femoropopliteal artery. In this territory, a combination of stresses like longitudinal extension, torsion, flexion at the popliteal level, and muscle compression in the adductor channel are encountered that may significantly influence long-term success (11). Newer generations of nitinol self-expanding coil and mesh stents, which seem to provide the necessary flexibility in multiple dimensions, appear to have a positive impact on femoropopliteal patency, but this notion has not been confirmed in a randomized setting (12–14). Fabric-covered From the Department of Radiology, University Clinics Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 9, 24105 Kiel, Germany. Address correspondence to T.J.; E-mail: jahnke@medscape.com