Application of CVD-diamond for catheter ablation in the heart

Catheter ablation is an invasive treatment method for cardiac arrhythmia like atrioventricular nodal reentrant tachycardia without the need for thorax surgery For high precision and reproducibility, an accurate temperature measurement and control at the catheter tip is crucial. Conventional ablation electrodes, which are powered with radio frequency energy (RFE) provide only a poor control of destroyed tissue (lesion) depth and direction due to inhomogeneous thermal and electrical tissue properties. In this work, a new technology using diamond heating elements is presented. Due to its exceptional properties, e.g. biocompatibility and chemical inertness, diamond possesses ideal prerequisites for medical applications. The specific electrical resistance of diamond can be adjusted through boron doping over a wide range from insulating to quasi-metallic. An activation energy of E-ak1=380 meV for low doped layers allows for the fabrication of precise temperature sensors. For initial experiments, micro heaters on chemical vapor deposited (CVD) diamond films on silicon have been designed and fabricated. The experiments were performed on cardiac muscle tissue (myocardium) of pigs to demonstrate the feasibility of this new concept. It was shown that a treatment using these devices results in a defined shape of the lesion. No current flows through the body and, therefore inhomogeneous conductance of the tissue does not affect the ablation direction. (C) 2003 Elsevier B.V. All rights reserved.