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Treating heart rhythm disturbances

Dr G André Ng 
Senior Lecturer in Cardiology, University of Leicester, and Consultant Cardiologist, University Hospitals of Leicester, Leicester, UK

Over the past two decades, there has been significant breakthrough and development in the management of heart rhythm disturbances (arrhythmias). Drugs used to control arrhythmias are not 100% effective and side-effects are a major issue, especially if their long-term use is required.  

Catheter ablation was developed in the late 1980s to early 1990s where long tubes or catheters mounted with electrodes are inserted via veins or arteries into heart chambers to destroy rogue tissues responsible for the electrical disturbance and hence arrhythmia. Over the last 20 years or so, catheter ablation has established itself as an effective treatment in almost all types of cardiac arrhythmias, in which it is now first-line treatment in many.

In modern cardiological practice, the cure it provides for patients suffering from arrhythmias with palpitation, breathlessness and dizziness as a result of these arrhythmias is a far cry from the ‘trial and error’ drug approach, which is often ineffective.

For catheter ablation to be effective, the cardiac electrophysiologist (heart rhythm specialist) would need to carry out an electrophysiology (EP) study by placing a number of catheters at specific locations in the heart, whereby the electrical abnormality of the heart would be diagnosed and mapped out.

Once the diagnosis is made, the specific rogue tissues that need to be ‘burned’ will be targeted with an ablation catheter, which has to be placed with reasonable precision at strategic locations within the heart. The catheter handle contains mechanisms by which the electrophysiologist controls the movement of the tip and distal shaft of the catheter. Catheter movements are monitored and guided by the use of X-rays during the procedure.

While ‘simple’ arrhythmias are relatively easy to tackle, more complex arrhythmia problems require ablation at a number of locations in the heart, not infrequently involving ‘burning’ along lines by joining up the dots in point-by-point ablation. In these cases, the lines have to be continuous to be effective, while in other cases, the ablation location can pose challenges of catheter stability during the ‘burn’, as the heart is beating all the time.

Advances in technology have come hand in hand with the increased use of catheter ablation over the years, including the development of three-dimensional mapping systems and better catheter design and mode of ablation delivery. Remote catheter navigation systems have emerged over the past few years as part of this development. These are designed to navigate catheters without the operator directly touching them.

One such system uses a huge magnetic field to move a catheter containing a magnetic tip, while another uses mechanical robotics to move a sheath within which there is a catheter. Both of these systems are sophisticated to use due to the dedicated installation requirements in the former and the complex coupling between the robotic interface with mapping system in the latter.

The Amigo Remote Catheter Manipulation System is a brand new robotic system for catheter navigation made by Catheter Robotics Inc., New Jersey, USA. The system contains a robotic arm that is installed on the end of the table in the procedure room. A standard EP catheter is placed on the system, with the handle ‘gripped’ by the robotic arm, by which catheter movement can be controlled via a remote controller connected to the arm via a cable.

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I am indeed very privileged to be invited to be the first clinician in the world to use this in patients for EP and catheter ablation procedures. The system obtained CE mark at the end of March 2010. After successfully fulfilling the local regulatory requirements, the first clinical procedures were carried at Glenfield Hospital, Leicester, UK, at the end of April 2010.

A cautious approach was taken first to assess the functionality of the new robotic system in moving a catheter to specific locations within the heart during EP study. The use of the Amigo is intuitive via the control knobs of the remote controller and the robotic arm can replicate exactly the movements the electrophysiologist makes on the catheter as if he or she were touching the handle.

After using the Amigo for the first case within the EP room, I could operate the robotic arm via the remote controller from the adjacent control room, watching catheter movements and electrical signals on monitors while communicating with staff in the room via microphone and headphones.

The immediate benefit is that the operator could move the catheters around the heart via a remote controller outside the X-ray zone. Hence, it was not necessary to wear the heavy lead aprons, which weigh around 7kg. In addition, I could sit by the desk close to the monitors displaying the X-ray and electrical information, instead of standing next to the patient and the X-ray machine, with the display monitors being some distance away.

The EP catheters can be mounted and dismounted from the robotic arm with ease. The ability to use standard EP catheters is a big advantage, as the electrophysiologist skilled at manual catheter manipulation would be familiar with the behaviour of the catheter inside the body, which minimises the learning curve for using the system and increases its efficacy. A significant advantage of navigating the catheter using the robotic arm over manual manipulation is that very fine movements can be achieved via the robot mechanics. The catheter can be advanced, withdrawn, deflected and turned in tiny increments, which greatly increases the precision of these movements beyond what is humanly possible by hand.

We have successfully performed initial standard EP studies in ten patients using the Amigo to position a diagnostic catheter at specific locations in the heart. At the time of writing, we have successfully completed ablation for right atrial flutter in seven patients using the new robotic system to navigate the ablation catheter. We chose this particular heart rhythm disturbance to tackle first using the robotic arm due to the well-defined ablation location which is at the lower part of the right atrial chamber along a line across the region know as the cavo-tricuspid isthmus.

Behaviour from ablation is predictable and success in ablation accurately measured. We completed these procedures successfully in good time with some achieved in much shorter time than standard practice, hinting at the benefit of increased catheter stability in these preliminary data. The finesse in catheter movement with the robotic arm along a line in small increments was well demonstrated in these cases.

The success of research and development of new therapeutic interventions depends on collaborative effort from a good team with the necessary support system. This work had come in a timely fashion with support from the newly established Leicester Cardiovascular Biomedical Research Unit – funded by the National Institute for Health Research – as well as the University 
of Leicester.

Our excellent team of arrhythmia specialist nurses liaised closely with the patients who were all rather excited to take part in this pioneering ‘world first’ endeavour at Leicester. The clinical team of cardiac physiologists, radiographers, nurses and clinical fellows all helped to make the experience a great success.

Plans are now being made to extend the use of the new robotic technology to more complex procedures, to tackle difficult arrhythmias such as atrial fibrillation and ventricular tachycardia. Some of these procedures can take several hours and require ablation with precision over a number of specific locations of the heart, sometimes in a continuous linear fashion as described above.

It is not difficult to imagine the desirable application and potential advantages of the Amigo in these procedures. The precision with which effective ablation can be performed using the robotic arm could greatly increase the success and efficiency of the procedures. Instead of standing for long periods of time wearing heavy lead aprons, using the Amigo while sitting close to the monitor screens outside the X-ray zone would mean less tiring procedures for the operator with better concentration, which could be translated into better outcome. We are indeed very excited about the prospects of these future developments and are poised to move this work forward to the next stage.