Orbital Atherectomy

Source- Cardiovascular Systems Inc.

Orbital atherectomy is the newest atherectomy procedure. It is similar to rotational atherectomy in that it abrades plaque using an abrasive burr spinning at 80,000-200,000 rpm. Also like rotational atherectomy, the grit size and high rotational speed of orbital atherectomy devices makes the tissue debris small enough to pass through the circulatory system harmlessly, minimizing the potential for distal embolic complications. However, orbital devices have key differences from rotational devices, including:

• the location of the burr on a coil consisting of three helically-wound wires (each with a 0.15 mm diameter). This coil can be compressed with the application of pressure (like a spring).

Source - Medical Design

• the orbital path of the device around the periphery of the lumen. This orbital motion allows the burr to attack the plaque as it moves in a specific direction, in contrast to the burr of a rotational device, which remains in one place.

These differences are designed to make orbital atherectomy superior to rotational atherectomy. Advantages conferred by the orbital design include:

• the ability of the physician to control the diameter of plaque to be removed by varying rotational velocity. A slowly-moving burr will have a lower centrifugal force and therefore will create a lower lateral pressure on the plaque.  Conversely, a higher speed will cause a greater later pressure.  This varying of pressure combined with the compressibility of the coil will allow the physician to control cut depth.  For example, a slow-moving burr will not cut deeply into plaque, leading to superficial ablation. If the rotational velocity is increased, however, the cut will be deeper.

Source - Cardiovascular Systems Inc.

• the orbital motion allows for more blood flow and cooling than other devices. This will minimize the potential for thermal trauma and ischemia and also make the procedure more comfortable for patients.

Orbital atherectomy technology is currently being developed by Cardiovascular Systems, Inc (CSI), and its introduction to the market is fast-approaching. In January 2005, CSI received clearance from the FDA to market the orbital atherectomy system (OAS) for the purpose of treating stenosis in synthetic arteriovenous shunts, which are used to provide vascular access for dialysis patients. In response to the foreign material of AV shunts, the body sometimes forms clots and neointimal stenosis (most frequently at the shunt-to-vein anastomosis). CSI expects to conduct initial market testing at clinical sites before issuing a full commercial release of the OAS for this treatment.

On February 3, the Freiberg Ethics Commission in Germany authorized CSI to begin a clinical study of the OAS to treat peripheral artery disease. The first-ever use of the device on a human was conducted successfully in Frankfurt on March 29. As of April 11, twelve patients have had successful debulking of lesions with no acute adverse effects. The trial is expected to enroll up to 65 patients at up to four centers. The company is also hoping to eventually obtain approval for use on the coronary arteries.

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