Tissue ablation using gap distance

Abstract

Methods for ablating tissue in a patient having atrial fibrillation comprise advancing an elongate flexible shaft through a patient's vasculature into a chamber of a heart. The elongate flexible shaft has an energy source and a sensor. Tissue in the heart is scanned with the sensor and data about the tissue is captured. The captured data is grouped into one of a plurality of tissue classifications and an anatomical map of the tissue showing the grouped data is displayed. At least a portion of the tissue is ablated so as to form a conduction block that blocks aberrant electrical pathways in the heart. The ablated tissue is grouped into one or more predefined tissue classifications during or prior to the ablation.

What is claimed is: 
     
         1 . A method of ablating tissue in a patient, the method comprising:
 providing an elongate shaft having an energy source and a sensor associated with a distal end of the elongate shaft;   moving the elongate shaft over a surface of a heart to generate gap data including a set of data points correlating positions of the elongate shaft with gap distances between the sensor and the surface of the heart;   generating a map of the surface of the heart based at least in part on the gap data; and   determining an ablation path associated with the map.   
     
     
         2 . The method of  claim 1 , wherein the method further comprises revising the ablation path to avoid one or more exclusion zones to generate a revised ablation path. 
     
     
         3 . The method of  claim 2 , further comprising ablating at least a portion of the surface of the heart along the revised ablation path. 
     
     
         4 . The method of  claim 1 , wherein the map comprises a three dimensional representation of the surface of the heart. 
     
     
         5 . The method of  claim 2 , wherein the map shows one or more regions of the heart with color characteristics that indicate gap distances associated with the one or more regions, respectively. 
     
     
         6 . The method of  claim 5 , wherein the one or more regions correspond to one or more exclusion zones. 
     
     
         7 . The method of  claim 1 , wherein the energy source comprises an ultrasound transducer. 
     
     
         8 . The method of  claim 1 , wherein the sensor comprises an ultrasound transducer. 
     
     
         9 . The method of  claim 1 , wherein the energy source is configured to scan the surface of the heart using emissions having first energy level and ablate biological tissue of the surface of the heart using emissions having a second energy level, the second energy level being greater than the first energy level. 
     
     
         10 . A method of ablating tissue, the method comprising:
 advancing an ultrasound transducer to a treatment site of a patient;   rastering the ultrasound transducer over biological tissue to generate gap distance data correlating positions of the ultrasound transducer with respective gap distance between the ultrasound transducer and a tissue surface associated with the treatment site;   identifying an ablation portion of the tissue surface based at least in part on the gap distance data; and   generating a tissue map using the gap distance data, the tissue map indicating the ablation portion of the tissue surface.   
     
     
         11 . The method of  claim 10 , further comprising ablating at least a portion of the ablation portion of the tissue surface by emitting ultrasound energy from the ultrasound transducer at an ablation energy level at the at least a portion of the ablation portion of the tissue surface. 
     
     
         12 . The method of  claim 11 , wherein the ablation energy level is sufficient to form a conduction block in the at least a portion of the ablation portion of the tissue that blocks aberrant electrical pathways therein. 
     
     
         13 . The method of  claim 11 , wherein said generating the gap distance data comprises emitting ultrasound energy at a sensing energy level at one or more portions of the tissue surface, wherein the sensing energy level is lower than the ablation energy level. 
     
     
         14 . The method of  claim 13 , further comprising receiving, using the ultrasound transducer, reflected ultrasound energy reflected off the one or more portions of the tissue surface. 
     
     
         15 . The method of  claim 10 , further comprising identifying a non-ablation portion of the tissue surface based at least in part on the gap distance data. 
     
     
         16 . The method of  claim 10 , wherein the tissue map indicates current gap distances and previous gap distances associated with the tissue surface. 
     
     
         17 . The method of  claim 10 , wherein said rastering involves:
 moving the ultrasound transducer over the tissue surface in a pattern; and   altering the pattern to approximate an ideal positioning of the ultrasound transducer.   
     
     
         18 . The method of  claim 10 , further comprising determining an ablation path associated with the tissue map. 
     
     
         19 . The method of  claim 18 , wherein said determining the ablation path comprises at least one of selecting, positioning, scaling, and rotating a shape overlaid on the tissue map to define the ablation path. 
     
     
         20 . The method of  claim 19 , wherein said determining the ablation path comprises overlaying multiple shapes on the tissue map, wherein the ablation path is associated with an outer most outline of the multiple shapes.