Peripheral atherectomy devices debulk atheroma in contrast to balloon angioplasty and stenting where the atheroma is displaced outwards and longitudinally (Katsanos et al., 2017). The goal of this therapy is to aid treatment of heavily calcified lesions and possibly improve drug delivery and reduce the need for stents, particularly in suboptimal locations for stent such as the popliteal and common femoral artery. Although the evidence is currently limited, atherectomy plus drug-coated balloon treatment has been compared with drug-coated balloon alone in patients with peripheral vascular disease, in both de novo (Kokkinidis et al., 2018; Zeller et al., 2017; Cioppa, 2018; Cioppa et al., 2017) and instent restenotic stenoses (Gandini et al., 2013; Sixt et al., 2013). This combination, if effective, could be particularly useful in areas where stent use should be minimized, such as the common femoral artery, popliteal artery, ostial lesions and heavily calcified lesions (Zeller et al., 2017). One must bear in mind, concerns have been raised in regards to higher complication rates in patients who received atherectomy (with or without PTA) in comparison to PTA alone, with one review finding a higher incidence of amputation and other major adverse events (Ramkumar et al., 2019). Consideration should also be given to the increased sheath sizes required for many of the devices and added cost over and above standard plain and drug coated balloons (Katsanos et al., 2017). Since the first rotational atherectomy devices were introduced in the 1980s (Höfling et al., 1987), multiple new designs have been developed, however there remains no data directly comparing the different available devices (A Critical View of the Peripheral Atherectomy Data in the Treatment of Infrainguinal Arterial Disease, 2012). These can be divided into four groups according to the method of plaque removal and include directional atherectomy (Cioppa, 2018), excimer laser atherectomy (Gandini et al., 2013; Kokkinidis et al., 2018), rotational atherectomy (Beschorner et al., 2013) and orbital atherectomy (Shammas et al., 2012a; Das et al., 2014; Safian et al., 2008).
Directional atherectomy employs a side-cutting rotating blade to excise plaque which is collected in the nose cone. The catheter is directed alongside the plaque of interest and the device is activated, and is of particular use in eccentric plaque (Katsanos et al., 2017). The nose cone must be emptied after a few passes once the nose cone becomes full, making this technique potentially more time consuming that other similar atherectomy devices. Devices include the Hawk system, such as the SilverHawk, TurboHawk and HawkOne (Medtronic, MN, USA), see Fig. 1. The non-randomized DAART trial (directional atherectomy and anti-restenotic therapy vs drug-coated balloon alone in the popliteal) showed a trend towards increased 12 month primary patency (82% versus 65%, p = 0.021) for the DAART arm (Stavroulakis et al., 2017), however aneurysmal dilatation was seen more often after DAART (although this was not statistically significant). Furthermore, while the DEFINITIVE AR atherectomy pilot trial of directional atherectomy with either the SilverHawk or TurboHawk devices followed by paclitaxel coated balloon (Cotavance, Germany) therapy showed superior outcomes initially compared with a drug-coated balloon alone, the trial was not powered to and also did not show differences at 12 months (see Fig. 2).
Excimer laser atherectomy employs ultraviolet radiation to disintegrate atheroma from the arterial lumen without heating, and is commonly indicated for both de novo and, especially, instent restenosis (Katsanos et al., 2017). The catheter should be advanced slowly with saline flushing to remove energy absorbing blood and contrast from the vessel. In combination with drug coated balloons (DCB), laser atherectomy demonstrated a higher 1-year patency rate in two separate recent studies. One randomized trial where atherectomy plus DCB was compared with DCB alone in the management of instent restenosis/occlusion (66.7% vs 37.5%) (Gandini et al., 2013) and one retrospective study of atherectomy and DCB of de novo lesions in comparison with atherectomy in combination with plain balloon angioplasty (86.7% vs 56.9%) (Kokkinidis et al., 2018).
In rotational atherectomy plaque is ground by a high speed concentrically rotating tip (burr). The Peripheral Rotablator (Boston Scientific, MN, USA) has a burr coated distally with diamond chips, that macerate atheroma into debris smaller than red blood cells which embolizes. The Pathway Jetstream (Boston Scientific) is a over-the-wire cutting rotational atherectomy system, which fits through a 7 Fr sheath, and has the ability to actively aspirate during use, thereby reducing procedure time (Fig. 1). Luminal diameter gain is limited by burr diameter so if a larger lumen is desired, the burr needs to be swapped out for a larger one. Other rotational devices include the Phoenix device (AtheroMed, CA, USA). An European multicentre prospective registry (Beschorner et al., 2013) of the Pathway system demonstrated improved ankle brachial index and Rutherford scores yet low primary patency rates of 33 and 25% at 12- and 24-month follow-up.
The Diamondback 360° (Cardiovascular Systems Inc., MN, USA) is the only commercially available orbital atherectomy device, which employs the orbital rotation of a diamond coated crown to macerate plaque; a technique that is similar to rotational atherectomy. The device therefore enables circumferential plaque removal, and the volume of debulking increases with increased rotational speed. There is no aspiration and distal embolization is possible. Evidence is accumulating that orbital atherectomy is also useful in calcified disease, particularly in the infrapopliteal segment (Shammas et al., 2012a; Das et al., 2014; Safian et al., 2008).
The Pantheris device (Avinger Inc., CA, USA) is an over-the-wre catheter which with a combination of optical coherence tomography (OCT) and a more traditional directional atherectomy device, with the goal of aiding the operator in targeting the appropriate plaque to be treated, whilst minimising damage to the non-diseased wall. The nose cone must also be emptied on a regular basis for this device, similar to the other directional atherectomy devices. Safety and efficacy has been recently demonstrated, with a high primary efficacy (97% of the 198 lesions treated), with no significant perforations and 1 catheter rated dissection (0.5%) (Schwindt et al., 2017).
All atherectomy devices probably carry some risk of distal embolization of plaque debris, therefore distal filter protection should be considered. The Emboshield NAV6 (Abbott Vascular, CA, USA) is usually recommended for rotational atherectomy devices such as the Jetstream, and SpiderFX (ev3, MN, USA) usually recommended with directional devices (Shammas et al., 2012b). Vasodilators should also be considered to counteract vasopasm in response to plaque modification (Franzone et al., 2012).