Small loop ablation catheter

Abstract

A catheter system for creating lesions for the treatment of cardiac arrhythmias is disclosed that includes a catheter having a distal ablation segment that has an electrode array comprising a plurality of spaced ablation and recording electrode devices arranged in a tight loop configuration that is used to create a series of overlapping loop-shaped ablation footprints to produce a continuous lesion resembling a chain-link configuration.

What is claimed is: 
     
         1 . A medical device comprising:
 an elongate catheter shaft member having a proximal end and distal end;   an ablation segment attached at or near the distal end of the catheter shaft member, said ablation segment comprising an electrode array of spaced ablation and recording electrodes in an arrangement shape selected from a generally linear extension of the catheter shaft and a fixed tight loop, wherein the generally linear shaped arrangement includes a distally attached pull wire device for causing said array to form a tight loop when it is retracted.   
     
     
         2 . A medical device as in  claim 1  wherein in use the ablation segment is configured to create a loop-shaped, chain link ablation footprint and wherein a plurality thereof in an overlapping pattern creates a continuous lesion in tissue of a patient. 
     
     
         3 . A medical device as in  claim 1  wherein the ablation segment comprises an array of spaced ablation electrodes arranged in a fixed tight loop. 
     
     
         4 . A medical device as in  claim 3  wherein said fixed tight loop includes a collapsible nose segment. 
     
     
         5 . A medical device as in  claim 1  wherein electrode array comprises at least one temperature sensor. 
     
     
         6 . A medical device as in  claim 1  further comprising an irrigation system that supplies cooling irrigation fluid to said ablation electrodes. 
     
     
         7 . A medical device as in  claim 6  wherein each said ablation electrode includes an irrigation port. 
     
     
         8 . A medical device as in  claim 1  wherein said catheter shaft comprises at least one inner shaft and core. 
     
     
         9 . A medical device as in  claim 3  wherein said fixed tight loop has two ends separately attached to said catheter shaft. 
     
     
         10 . A medical device as in  claim 3  further comprising a membrane covering an open central portion of said loop. 
     
     
         11 . A medical device as in  claim 10  wherein said membrane is provided with sensing and pacing electrodes. 
     
     
         12 . A medical device as in  claim 10  wherein said membrane is irrigated. 
     
     
         13 . A medical device as in  claim 1  wherein the ablation electrodes apply RF energy to accomplish ablation of tissue to form a lesion in the tissue enclosed by the loop. 
     
     
         14 . A medical device as in  claim 13  wherein said RF energy is applied using bipolar energy delivery to limit lesion formation. 
     
     
         15 . A medical device as in  claim 11  wherein the ablation electrodes apply RF energy using bipolar energy delivery to limit lesion formation. 
     
     
         16 . A medical device as in  claim 1  wherein the ablation segment has one end attached as a generally linear extension of said catheter shaft and said pull wire enables adjustment of loop size. 
     
     
         17 . A medical device as in  claim 6  wherein said irrigation fluid is distributed substantially equally to all connected ablation electrodes. 
     
     
         18 . A medical device as in  claim 6  wherein said ablation segment comprises a tight fixed loop and said irrigation system supplies halves of said loop separately. 
     
     
         19 . A medical device as in  claim 13  further comprising a reference electrode for controlling the amount of RF energy applied to each ablation electrode. 
     
     
         20 . A medical device comprising:
 an elongate, flexible steerable outer sheath member having a proximal and a distal end and a lumen extending therebetween;   a catheter having an elongate outer shaft member and an inner torqueable control shaft disposed in said outer sheath in slideable relation thereto, wherein the distal portion of said catheter shaft includes an ablation segment having an electrode array comprising a plurality of sequentially arranged, spaced ablation and recording electrode devices arranged to assume a tight loop configuration.   
     
     
         21 . A medical device as in  claim 20  wherein in use the ablation segment is configured to create a loop-shaped, chain link ablation footprint and wherein a plurality thereof in an overlapping pattern creates a continuous lesion in tissue of a patient. 
     
     
         22 . A medical device as in  claim 20  wherein said tight loop is achieved and adjusted using a pull wire attached to said ablation segment. 
     
     
         23 . A medical device as in  claim 20  wherein said ablation segment is in the form of a fixed tight loop. 
     
     
         24 . A medical device as in  claim 23  wherein said fixed tight loop includes a collapsible nose segment. 
     
     
         25 . A medical device as in  claim 20  wherein electrode array comprises at least one temperature sensor. 
     
     
         26 . A medical device as in  claim 20  further comprising an irrigation system that supplies cooling irrigation fluid to said ablation electrodes. 
     
     
         27 . A medical device as in  claim 25  wherein each said ablation electrode includes an irrigation port. 
     
     
         28 . A medical device as in  claim 23  wherein said fixed tight loop has two ends separately attached to said catheter shaft. 
     
     
         29 . A medical device as in  claim 23  further comprising a membrane covering an open central portion of said loop. 
     
     
         30 . A medical device as in  claim 29  wherein said membrane is provided with sensing and pacing electrodes. 
     
     
         31 . A medical device as in  claim 20  wherein the ablation electrodes apply RF energy using bipolar energy delivery to limit lesion formation. 
     
     
         32 . A medical device as in  claim 30  wherein the ablation electrodes apply RF energy to accomplish ablation of tissue to form a lesion in the tissue enclosed by the loop. 
     
     
         33 . A medical device as in  claim 32  wherein said RF energy is applied using bipolar energy delivery to limit lesion formation. 
     
     
         34 . A medical device as in  claim 29  wherein said membrane is irrigated. 
     
     
         35 . A medical device as in  claim 20  further comprising a reference electrode for controlling the amount of RF energy applied to each ablation electrode. 
     
     
         36 . A medical device as in  claim 20  further comprising a pull wire attached to said ablation segment and extending proximally for forming said ablation segment into a loop arrangement of adjustable size. 
     
     
         37 . A method of creating continuous lesions for the treatment of cardiac arrhythmias comprising:
 providing a catheter having a distal ablation segment having an electrode array comprising a plurality of spaced ablation and recording electrode devices arranged in a tight loop configuration;   using said ablation segment in a procedure to create a series of overlapping loop-shaped ablation footprints to create a continuous lesion resembling a chain-link configuration.   
     
     
         38 . A method of  claim 37  wherein said ablation electrodes are operated using RF energy in a bipolar mode to limit lesion formation to tissue enclosed by the loop. 
     
     
         39 . A method as in  claim 36  including using irrigation to cool said ablation electrodes during use. 
     
     
         40 . A method as in  claim 36  further comprising monitoring lesion formation and evaluating the maturation of tissue ablation of said ablation footprints. 
     
     
         41 . A method as in  claim 36  wherein said procedure includes isolation of pulmonary veins in the left atrium of a heart. 
     
     
         42 . A method as in  claim 41  further comprising providing a left atrial isthmus lesion and connecting lesion between the pulmonary vein lesions and the left atrial isthmus lesion. 
     
     
         43 . A method as in  claim 40  wherein said monitoring and evaluating involves recording and temperature sensing technology. 
     
     
         44 . A method as in  claim 36  including providing a membrane barrier between tissue being ablated and adjacent blood flow.