An insight into Stereotaxis Magnetic Navigation System
Today I had this rare opportunity to visit a Cardiac centre in Taipei that is equipped with a state of the art navigation system to assist percutaneous electrophysiology studies and coronary intervention.
We were accompanied by a long known rep called Tam (knew him from the day I first worked in UKM, Tam was with St. Jude’s selling pacemakers), Chloe from Singapore and Prisca. Cheng Hsin Hospital Taipei was located about half an hour away from our hotel – Sherwood Taipei Hotel. We were met by the cath lab director a friendly Dr Yin who has performed over 70 cases of PCI using this navigation system.
This particular stereotaxis belongs to brandname Niobe that originated from St. Louis US a few years back. Its main use has been in the field of Electrophysiology (EP) for EP mapping, localisation of arrhythmic focus and ablation of pulmonary vein in Atrial Fibrillation. Lately, it has also been used in percutaneous coronary intervention (PCI). In this cardiac centre, they are using the system for both. I have come to learn the application in PCI.
The basis of this navigation system is utilisation of magnetic energy to manipulate the tip of the wire (catheter) which itself is made from magnetic material. First of all, there are currently two major cardiac angiogram system that support Stereotactic machine – Siemen and Phillip. The imaging system has to be fully compliant to the system in order to allow both of them to work hand in hand.
The control units consist of two gigantic ‘tubes’ or parts, more resembling the flat receiver of fluoroscopy system, albeit much much larger surface and body, of course. The two units when in operation are made to face each other, with cardiac angiogram table in between where the patient lies down. Simply put, these two units behave almost the same way like the lateral planes of a biplane cardiac angiogram system – by stating this, I mean, the cardiac angiogram that can be operated with stereotactic system must be a single plane one, so that the space vacated by the lateral plane is replaced by the stereotactic units.
The control panel is a touchscreen monitor mounted on the fluoroscopy table, which connects to a display facing the operator, while outside, at the control station, it connects to an external display allowing the catheter manipulation process to be viewed from the control station as well.
Next, we should spend time on the navigation wire. It basically is the same as a standard angiplasty wire (0.014mm) with a magnetic tip, and the tip is pre-shaped (it is not possible or recommended to change the pre-shaped tip). The wire is advanced in the same way as routine PCI to cross the coronary lesion. Once in the vessel, the operator control or manipulate the wire as he would with ordinary angioplasty, with the additional ability of remotely controlling the tip of the wire using the stereotactic console. Touching the console screen (a complete circle divided into twelve points like a clock) will direct the wire tip according to the desired direction up or down (or left/right), as well as anterior/posterior direction. It is this remote control of wire tip that will assist in crossing lesions, particularly difficult lesions such as bifurcation or extremely tortuous vessels. Once the wire crossed, the rest of the procedure goes on in the usual way.
It is important to note, that presence of any magnetic items such as metals, cellphones or even credit cards within radius of the magnetic field may cause interference to the navigation system, however a patient with pacemakers or other metal implants should have no problem undergoing the procedure, I was told.
This is a sophisticated system with great potentials in percutaneous interventions, the potential of expanding indications of use is there. I could think of peripheral interventions including lower limbs and cranial system, or even the emerging new procedure like renal denervation.
One may wonder how much do you need to invest for such a system? It’s estimated to cost around 5 million RM (this, easily exceed the cost of a simple single plane cardiac angiogram! However if utilised to its full potential as described in above paragraph, and perhaps bundled with manufacturer’s Odyssey (remote transmission system) then it may be worth the investment.
For further info refer to www.stereotaxis.com
