Method and Devices for Cardiac Radiofrequency Catheter Ablation

Abstract

Embodiments of the invention comprise methods and devices that allow quantification of blood convective cooling at the cardiac RF catheter ablation site and allow for prediction of lesion size and/or computation of RF energy parameters and characteristics.

1 . A method for determining ablation lesion size comprising: 
 a. Applying a pulse of RF energy to a treatment site positioned catheter;    b. Taking a temperature measurement of the catheter over time;    c. Generating a parameter representing convective cooling for the treatment site;    
     
     
         2 . The method of  claim 1  further comprising inputting the convective cooling parameter into a computer model wherein the computer model computes the ablation lesion size.  
     
     
         3 . The method of  claim 1  wherein the temperature measurement is taken during the application of the pulse of RF energy.  
     
     
         4 . The method of  claim 1  wherein the temperature measurement is taken over a time period commencing after the application of the pulse of RF energy.  
     
     
         5 . The method of  claim 1  further comprising the computer model computing catheter operating parameters for a given ablation lesion size.  
     
     
         6 . The method of  claim 1  wherein the temperature measurement is taken over the time period of the application of the pulse of RF energy.  
     
     
         7 . The method of  claim 1  wherein the temperature measurement is taken for a time period after the application of the pulse of RF energy.  
     
     
         8 . The method of  claim 1  wherein the generation of the convective cooling parameter comprises computing the maximum catheter tip temperature change during the application of the pulse of RF energy.  
     
     
         9 . The method of  claim 1  wherein the generation of the convective cooling parameter comprises computing the slope of catheter tip temperature decay after application of the pulse of RF energy.  
     
     
         10 . The method of  claim 1  wherein the treatment site positioned catheter is positioned in a human heart.  
     
     
         11 . The method of  claim 10  wherein the method is used in the treatment of a cardiac arrhythmia.  
     
     
         12 . A device for performing cardiac ablation comprising: 
 a. A catheter for receiving and emitting RF energy wherein the catheter comprises a tip;    b. A means for generating and transmitting to the catheter RF energy;    c. A temperature measuring device contiguous with the catheter tip;    d. A controller wherein said controller is coupled to the RF energy generating and transmitting means and controls the RF energy transmitted to the catheter;    e. A processing unit comprising a means for receiving and processing the temperature measurement signals from the temperature measuring device, and computing a convection cooling parameter.    
     
     
         13 . The device of  claim 12  wherein the processing unit further comprises a means for receiving from the controller information which characterizes the RF energy emitted to the catheter.  
     
     
         14 . The device of  claim 13  wherein the processing unit further comprises a means for computing estimated ablation lesion dimensions.  
     
     
         15 . The device of  claim 13  wherein the processing unit further comprises a means for computing RF energy controller information from information comprising the temperature measurement signals.  
     
     
         16 . The device of  claim 12  wherein the temperature measuring device is located within the catheter tip.  
     
     
         17 . The device of  claim 12  wherein the cardiac ablation takes place within a human heart.  
     
     
         18 . A computer readable medium having stored therein a computer program that when executed causes a computer to perform the steps comprised of: 
 a. Receiving temperature measurements from a temperature measuring device located contiguous to a cardiac ablation catheter;    b. Receiving control information from a controller wherein the controller controls the characteristics of RF energy applied to the cardiac ablation catheter;    c. Generating a convective cooling parameter from data comprising the temperature measurements and the control information.    
     
     
         19 . The medium of  claim 18  wherein generation of the convective cooling parameter comprises computing the maximum catheter temperature change during the application of a pulse of RF energy to the catheter.  
     
     
         20 . The medium of  claim 18  wherein generation of the convective cooling parameter comprises computing the slope of catheter temperature decay after application of a pulse of RF energy to the catheter.