Radiofrequency Energy for Catheter Ablative Procedures

Abstract

Radiofrequency energy is generally considered to range from 150,000 cycles per second or hertz (Hz) or 150 kHz to about 1,000,000 Hz or one megahertz (MHz). There are no finite limits to the radiofrequency range, which can extend up to the infrared range. One terminology used in medicine is to provide specific designations for the various ranges of radiofrequency energy according to their use (table 7–1). All frequencies between 100 kHz and 4 MHz can cut, coagulate, and desiccate tissue, and there appears to be little significant differences in performance. Frequencies below 100 kHz can stimulate muscles and nerves and are not used in electrosurgery. It is difficult to confine electrical currents to wires at frequencies above three to four MHz. Therefore, energy in the radiofrequency range, usually 500 kHz to 750 kHz are most commonly employed in electrosurgical devices. This type of device is often mistakenly called electrocautery. In electrocautery, electrical current not in the radiofrequency range remains in the wire that is heated by the current passing through the wire. In electrosurgery, the electrical current actually passes through the tissue. The radiofrequency current is delivered between an active electrode and a dispersive electrode, usually a large conductive pad placed on the patients skin or the radiofrequency current may pass between bipolar electrodes.