Patent ID: 6210406
Filing Date: 2001-04-03
Classification: A61B

Abstract:
An ablation system comprising:a split tip electrode catheter comprising:an elongated catheter body having a proximal and distal end and at least one lumen extending therethrough;a catheter tip section at the distal end of the catheter body comprising a section of flexible tubing having proximal and distal ends and at least one lumen therethrough, the proximal end of the flexible tubing being fixedly attached to the distal end of the catheter body, said catheter tip section further comprising a split-tip electrode which comprises at least two electrically isolated electrode members fixedly attached to the distal end of the flexible tubing;at least one indifferent electrode attachable to the exterior of a patient;means for generating low level RF impedance current and for transmitting said impedance current to each electrode member of the split tip electrode; andmeans for generating an RF ablation current and for transmitting said ablation current to each electrode member of the split tip electrode;means for electrically connecting each electrode member of the split tip electrode to the low level RF impedance current generating means and the RF ablation current generating means;means for estimating the surface temperature of tissue in contact with electrode members of the split tip electrode during an ablation procedure comprising temperature sensing means, attached to each electrode member of the split tip electrode, for generating a signal indicative of the temperature of the electrode member to which it is attached;means, including a pump, for infusing a cooling fluid through the catheter and each of the electrode members to cool the electrode members during ablation; anda programmable signal processor for receiving electrical signals indicative of the impedance between each of the electrode members of the split tip electrode and at least one indifferent electrode and for identifying the electrode member(s) associated with the highest impedance signal(s) received as the electrode members in contact with tissue and for activating the RF ablation current generating means to transmit an RF ablation current to only the electrode member(s) identified as being in contact with said tissue, wherein the signal processor is programmed to deactivate the RF ablation current generating means if the estimated surface temperature reaches a predetermined level;and further wherein the signal processor is electrically connected to each such temperature sensing means and is further programmed to intermittently activate the pump of the infusing means and the RF ablation current generating means so that there are ON periods wherein cooling fluid is delivered to the electrode members and RF ablation current is transmitted to the electrode members in contact with tissue and OFF periods wherein no cooling fluid is delivered to the electrode members and no RF ablation energy is transmitted to the electrode members in contact with tissue and wherein the signal processor is programmed to estimate the surface temperature of tissue in contact with the electrode members from the signals received from the temperature sensing means during the OFF periods.