Design of a Novel Circuit for Charge Delivery During RF Energy Delivery
A key requirement of the circuit is to be able to deposit charge continuously on the electrodes without affecting the electrogram signal amplitude/quality or the ability of the ablation unit to deliver energy to the tissue. This is done by using an arrangement of high-impedance current delivery parallel to the signal processing pathway. A 9-V battery was used as the source of DC current. Matched metal film resistors are then used to convert this voltage into the required current. High resistor values prevent loading of the signal and ablation voltages. Matching allows the signal processing circuitry to maintain a high common-mode rejection. The return path for the current is through an external large-area patch that is connected to the return electrode of the isolated power supply. The electrodes were advanced into the atria and ventricles of the dogs via the femoral veins. RF = radiofrequency.