Assessing Vascular Surgery Options In Patients With PAD
A Closer Look At The SilverHawk Plaque Excision System
Over 100,000 cases of lower extremity amputation performed annually in the U.S. are attributed to PAD. Lower extremity interventions for PAD are limited by their invasiveness and a large restenosis rate, necessitating a therapy that is less invasive and exhibits clinical success in long-term outcome studies.19
The SilverHawk Plaque Excision System (ev3) was approved by the U.S. Food and Drug Administration in 2003 and is an improvement on earlier percutaneous plaque excision devices such as the Simpson atherectomy catheter (Guidant Corp.), the Bard Rotary Atherectomy System (CR Bard), the Rotoblator (Boston Scientific), and the Xtrak device (Xtrak Medical, Inc.).13
The main advantages the SilverHawk has over these older devices is its smaller size (sized more to the target vessel lumen) and the fact that it does not include a balloon as one of its components. The lack of a balloon prevents barotraumas.13 Other changes include its faster speed (2,000 to 8,000 revolutions per minute), a carbide (as opposed to steel in the older devices) cutting blade, and a low-profile monorail design to better facilitate device delivery and catheter exchanges.13,17,20
The SilverHawk is a battery-powered catheter with a 135 cm flexible shaft ending in a cutting apparatus, consisting of a blade and a nosecone designed to collect the long strips of atherosclerotic plaque.15 The blade can also be rotated in 10-degree increments using a dial at the base of the catheter. One typically has to empty the collected plaque from the nosecone after two to six passes, depending on the length of the vessel.20 Physicians can empty the nosecone via vigorous saline flushing or mechanically using specially designed adaptors.15
The original SilverHawk comes in four sizes that correspond to femoral, popliteal and tibial vessels. There are two modifications available in the original device: the flush version and two with greater capacity nosecones.15 Newer innovations to the original device include the development of smaller sizes and the newest device, the DS, for use in vessels as small as 1.5 to 2 mm. There are also larger sizes for the treatment of PAD above the knee.
Micro Efficient Compression (MEC) technology refers to laser-drilled vent holes in the tip of the catheter. These vent holes release fluid pressure and allow more space for the collection of tissue in the tip. This has the potential to reduce procedure time by allowing the physician to collect more tissue and empty the nosecone less frequently.