Catheter robotics is in the early stages of evolution. A new 6F catheter, designed to permit diagnostic angiography, delivery of embolic agents and access to more distal vasculature such as the below-the-knee vessels, has recently become commercially available. There is no other technology that allows the same degree of accuracy in control and stability for delivery of therapy into a variety of vascular beds, writes Alan Lumsden.
The new catheter (Hansen Medical) is a single catheter with a 6F outer diameter (4.3F inner diamater), with two bending zones. It easily traverses the system, and can be used for stents or balloons of up to 4mm in diameter or anything that is compatible with a 5F guide catheter. Because of the two bending zones (proximal and distal bend) the catheter driving is somewhat different from the previous 9F platform. For most peripheral vascular procedures, we still rely on the 9F system since it will allow insertion of devices up to 6F.
Catheter control, catheter stability and pushability are all features which potently can provide benefit in crossing of complex peripheral lesions. We have seen that interventionists can control pin point motion of the catheter tip. Still, there is little point in having pin point navigation in the absence of high resolution, and in our opinion, 3D imaging. Likewise, there is little need for such imaging in the absence of pin point control. It is the marriage of this imaging with catheter robotics, where we believe transformational endovascular change can be made. This may take time to achieve, but this marriage promises to spawn a new series of complex endovascular procedures.
How it all began
Hansen’s first robotic system, the Sensei X Robotic System, received FDA 510(k) clearance in 2007 and was intended to facilitate manipulation, positioning and control of the company’s robotically steerable catheters for collecting electrophysiological data within the heart atria with electro-anatomic mapping and recording systems in electrophysiology procedures. This system was designed for a transvenous approach and was too large for arterial use. However, it was used by our group in the first extra cardiac application of catheter robotics during placement of a pulmonary artery stent in a lung transplant patient. This was really our first exposure to the system, as we observed electrophysiologists control pin point motion of the catheter tip, while applying a known force sensor to the atrial wall. Millimeter catheter tip and force control in a beating heart certainly piqued our curiosity regarding the peripheral vascular potential of this system. Catheter control, catheter stability and pushability are all features which potently can provide benefit in crossing of complex peripheral lesions. The challenge was that the catheter was too large for peripheral use and the control needed to be further optimised for navigation in peripheral vessels.
There then followed fairly rapid iteration of both the robotic controller and catheter. The commercially available Magellan Robotic System is the first CE-marked and FDA-cleared robotic system for peripheral vascular use, and is based on a master/slave control system that enables positioning of the robotic catheter tip at a desired position in the vasculature by selective actuation of the catheter pull wires and for the insertion axes of the telescoping catheters. The set-up of the robotic catheter generally occurs at the beginning of the procedure and requires assembly and insertion of the inner leader catheter and outer sheath. Insertion can be either directly percutaneously or via a second short introducer sheath, which is dictated by the surgeon performing the procedure.
It is important to remember that catheter robotics allows the operator to be removed from the radiation field, a factor which allows us to shed the lead which may have contributed to the cervical and lumbar spine maladies experienced by many interventionists.
Alan Lumsden is professor and chairman, Department of Cardiovascular Surgery and medical director, Methodist DeBakey Heart & Vascular Center at the Methodist Hospital, Houston, USA. He has disclosed that he has received research support from Hansen and is on the company’s scientific advisory board.