Maestro-AF

Maestro-AF

Maestro-AF stands for Magnetic Ablation Escorting for Treatment of Atrial Fibrillation.

Maestro-AF technology proposes a unique catheter system which will provide a simple, efficient, reproducible and controllable Percutaneous Catheter Ablation approach to treat Atrial Fibrillation with higher safety.

Project description

Atrial fibrillation (AF) is a rhythm disorder of the heart affecting significantly the quality of life of more than 5 million people in the industrialized world. Left untreated AF could cause sometimes severe life-threatening complications. 
Percutaneous Catheter Ablation (PCA) is the new and promising treatment of AF based on inactivation (Ablation) of selected parts of the heart tissue by applying energy.
The main component of PCA is the catheter. It has several functionalities such as therapy delivery, electrical sensing using four electrodes, irrigation of the tip, and temperature monitoring. Moreover, it needs to be very flexible in reaching points at various locations. Despite all the functionalities mentioned, the catheter is unable neither to glide on the inner surface of the atrium in a controllable way nor to measure the tissue temperature during the ablation. The electrophysiologist has to move the catheter tip from one point to another on a jumping manner. By this technique sepa-rate ablation points are created rather than lines. The distance between those points is difficult to be controlled as well as the depth of the ablation points. Insufficient energy delivery and gaps between the points lead to the relapse of the arrhythmia. Excessive amounts of energy may result in formation of vapour bubbles leading to perforation or thrombi formation which is a major safety concern. Temperature monitoring directly inside the tissue as well as good mechanical and electrical contact with tissue over time are neces-sary to deliver the right amount of energy. These conditions are not present in the currently available ablation catheters.  Current limitations of PCA result from the complexity of navigating a catheter inside the beating heart and controlling energy delivery to targeted locations. 
In order to overcome these technological limitations, we propose a new concept, based on magnetic coupling between two catheters – the Ablation Catheter (AC) and the Escorting Catheter (EC). 
 

 
 Current PCA(1) Maestro-AF(2) 
– Variable tissue contact
– “Points by Points” lines
– Variable ablation size and depth
– Not measuring tissue Tº (irrigation)
– Requires experience
+ Constant tissue contact
+ Transmural continuous ablation 
+ Continuous Tissue Tº  control 
+ Improved safety and efficiency
+ Reproducibility of the procedure 

Maestro-AF technology will increase operator control of position and navigation inside the heart through magnetic coupling. Moreover, the measurement of temperature from the back side of the tissue provides a unique parameter making the ablation of the entire cardiac wall thickness (transmural) possible. The proposed technology will primarily increase safety, efficacy and efficiency of the PCA procedure.

References:
(1) PCA image has been partially created from an existing video located on Biosense Webster ® website.
(2) Maestro-AF concept image has been drawn using textures described on reference (1).

Scientific/technical/business objectives

Maestro-AF technology will provide a new simple, efficient, reproducible and controllable PCA approach to treat AF with higher safety. Thus, the system will significantly reduce duration of the PCA procedure and shorten the learning curve of the operator. The concept of magnetic coupling of two catheters provides multiple advantages such as:
1) A stable position of the AC against the atrium wall. It provides optimal conditions to deliver energy inside the tis-sue. 
2) A smooth displacement of AC by means of an EC placed within vessels surrounding the heart. The displacements are continuous and not affected by the beats of the heart. 
3) A unique opportunity to measure the tissue temperature from the back side of the atrial wall during ablation. Temperature monitoring guides the propagation of energy depending on the tissue thickness and ensures that the ablation has been done in the entire thickness of the tissue.
The unique value proposition of Maestro-AF will drive the growth of PCA for AF market because the penetration for current indications (about 6.7% today) will increase and the number of patient treated by PCA will be extended. The current mar-ket for AF PCA therapy is CHF 380 million. It grows with 15% – 20% annually resulting in a CHF 1 billion market by 2015.

Results

Prototypes of catheters containing perma-nent magnets on the extremities have been made and tested in a pig beating heart. Experiments demonstrate the work-ing principle of guiding a catheter inside the atrium with the help of a second catheter placed in the vessels surrounding the heart.

In order to estimate the efficacy of the ablation lines production with our technique, we have performed a computer simulation. We used the Lausanne Heart model developed in the Signal Processing Lab 1 (Jean-Marc Vesin) of EPFL which consists of a computer model of human atria used to study the complex spatiotemporal dynamics of electrical currents of AF. The obtained results are promising and confirm the potential of such lines to effectively interrupt the AF. 

 

To perform in-vivo ablation lines under irrigation flow, more complex prototypes of catheters integrating temperature sensor have been realized. Ablation lines under temperature control were performed in a controlled way on excised bovine myocar-dial tissue. As expected, lines were continuous and transmural. These results confirm that measuring the temperature from the back side of the tissue is reliable to achieve transmural ablation lines.

 

 

Implementation stage/perspectives

Animal experiments with these improved prototypes of catheters will be held in the coming months.  In order to optimize the design of the catheters further experimental and modeling analysis are needed. Friction on the cardiac tissue, magnetic forces, flexibility of the catheter body as well as temperature measurement are the main challenges in the development of the catheters. To resolve these technical issues, a CTI support of 24 months has been accepted (May 2009). The proposed time will permit to demonstrate the reliability and feasibility of the Maestro-AF approach based on sufficient animal data. In addition, it will help to prepare the first clinical application.

Outlook

Maestro-AF technology will increase the operator control of position and navigation inside the heart. Moreover, the measurement of temperature from the back side of the tissue provides a unique parameter making the ablation of the entire cardiac wall thickness (transmural) possible. Maestro-AF system will significantly reduce duration of the PCA procedure and shorten the learning curve of the operator.In consequence, it will drive the growth of PCA for AF market (only 6.7% today)  and increase the number of patient treated.