IRE Ablation Systems and Protocols Using a Basket Catheter

Abstract

A medical apparatus includes a probe, including an insertion tube configured for insertion into a body cavity of a patient and a basket assembly, which has a proximal end that is connected distally to the insertion tube and includes a plurality of resilient spines, which are configured to bow radially outward around a longitudinal axis of the basket assembly and are conjoined at a distal end of the basket assembly. A plurality of electrodes are configured to contact tissue in the body cavity and include radial electrodes disposed on the spines and an axial electrode disposed on the longitudinal axis of the basket assembly. An electrical signal generator is configured to apply to the electrodes, including the axial electrode, pulses having an amplitude sufficient to cause irreversible electroporation (IRE) in the tissue contacted by the electrodes.

1 . A medical apparatus, comprising:
 a probe, comprising:
 an insertion tube configured for insertion into a body cavity of a patient; 
 a basket assembly having a proximal end that is connected distally to the insertion tube and comprising a plurality of resilient spines, which are configured to bow radially outward around a longitudinal axis of the basket assembly and are conjoined at a distal end of the basket assembly; and 
 a plurality of electrodes, which are configured to contact tissue in the body cavity and comprise radial electrodes disposed on the spines about the longitudinal axis and an axial electrode disposed on the longitudinal axis of the basket assembly; 
   an electrical signal generator configured to apply to the electrodes, including the axial electrode, pulses having an amplitude sufficient to cause irreversible electroporation (IRE) in the tissue contacted by the electrodes.   
     
     
         2 . The apparatus according to  claim 1 , wherein the spines comprise respective proximal and distal tips, wherein the proximal tips of the spines are joined proximate a proximal end of the basket assembly, and the distal tips of the spines are joined to a distal end of the basket assembly, and the spines bow radially outward away from the longitudinal axis when the basket assembly is deployed in the body cavity so that the radial electrodes contact the tissue in the body cavity. 
     
     
         3 . The apparatus according to  claim 2 , wherein the basket assembly comprises a stable collapsed state, and wherein the apparatus comprises a puller attached to the distal end of the basket assembly and slidably disposed within the insertion tube, so that the spines bow radially outward in response to pulling the puller in a proximal direction through the insertion tube. 
     
     
         4 . The apparatus according to  claim 1 , wherein the insertion tube comprises a flexible catheter configured for insertion into a chamber of a heart of the patient, and the electrodes are configured to contact and apply the electrical signals to myocardial tissue within the chamber. 
     
     
         5 . The apparatus according to  claim 1 , wherein the radial electrodes comprise a single respective radial electrode on each of the spines. 
     
     
         6 . The apparatus according to  claim 1 , wherein the radial electrodes comprise multiple radial electrodes on each of the spines in respective locations that are longitudinally staggered among the spines. 
     
     
         7 . The apparatus according to  claim 1 , wherein the pulses applied by the electrical signal generator comprise a sequence of the pulses having an amplitude of at least approximately 200 V, and a duration of each of the pulses is less than approximately 20 μs. 
     
     
         8 . The apparatus according to  claim 7 , wherein the sequence of the pulses comprises biphasic pairs of the pulses, wherein each pair comprises a positive pulse and a negative pulse. 
     
     
         9 . The apparatus according to  claim 1 , wherein the electrical signal generator is configured to apply the pulses in a bipolar mode between one or more of the radial electrodes and the axial electrode. 
     
     
         10 . The apparatus according to  claim 1 , wherein the electrical signal generator is configured to apply the pulses in a unipolar mode between one or more of the electrodes on the basket assembly, including the axial electrode, and a common electrode that is separate from the probe. 
     
     
         11 . The apparatus according to  claim 1 , wherein the electrical signal generator is configured to apply the pulses between different pairs of the electrodes sequentially in accordance with a predefined protocol. 
     
     
         12 . The apparatus according to  claim 11 , wherein in accordance with the predefined protocol, the pulses are applied in a bipolar mode between each of the radial electrodes and the axial electrode. 
     
     
         13 . The apparatus according to  claim 12 , wherein in accordance with the predefined protocol, the pulses are applied simultaneously between two or more of the radial electrodes and the axial electrode. 
     
     
         14 . The apparatus according to  claim 11 , wherein in accordance with the predefined protocol, the pulses are applied in a bipolar mode between multiple pairs of the radial electrodes, each pair including a first radial electrode on a first one of the spines and a second radial electrode on a second of the spines, which is not adjacent to the first one or the spines. 
     
     
         15 . The apparatus according to  claim 11 , wherein in accordance with the predefined protocol, the pulses are applied to the radial electrodes on different ones of the spines in a predefined sequence in which the pulses are not applied in immediate succession to the radial electrodes on mutually adjacent spines. 
     
     
         16 . The apparatus according to  claim 11 , wherein the radial electrodes comprise at least first and second radial electrodes on each of the spines, and wherein in accordance with the predefined protocol, the pulses are applied to only one of the first and second radial electrodes on each of the spines. 
     
     
         17 . A method for medical treatment, comprising:
 providing a basket assembly for insertion into a body cavity of a patient, the basket assembly comprising a plurality of resilient spines, which are configured to bow radially outward around a longitudinal axis of the basket assembly and are conjoined at a distal end of the basket assembly, and a plurality of electrodes, which are configured to contact tissue in the body cavity and comprise radial electrodes disposed on the spines and an axial electrode disposed on the longitudinal axis of the basket assembly; and   applying to the electrodes, including the axial electrode, pulses having an amplitude sufficient to cause irreversible electroporation (IRE) in the tissue contacted by the electrodes.   
     
     
         18 . The method according to  claim 17 , wherein the spines have respective proximal and distal tips, wherein the proximal tips of the spines are coupled together at a at a proximal end of the basket assembly, and the distal tips of the spines are coupled together at a at a distal end of the basket assembly, and the spines bow radially outward when the basket assembly is deployed in the body cavity, whereby the radial electrodes contact the tissue in the body cavity. 
     
     
         19 . The method according to  claim 18 , wherein the basket assembly comprises a stable collapsed state, and wherein providing the basket assembly comprises a attaching a puller to the distal end of the basket assembly and slidably disposed within the insertion tube, so that the spines bow radially outward in response to pulling the puller in a proximal direction through the insertion tube. 
     
     
         20 . The method according to  claim 17 , wherein the insertion tube comprises a flexible catheter configured for insertion into a chamber of a heart of the patient, and the electrodes are configured to contact and apply the electrical signals to myocardial tissue within the chamber. 
     
     
         21 . The method according to  claim 17 , wherein the radial electrodes comprise a single respective radial electrode on each of the spines. 
     
     
         22 . The method according to  claim 17 , wherein the radial electrodes comprise multiple radial electrodes on each of the spines in respective locations that are longitudinally staggered among the spines. 
     
     
         23 . The method according to  claim 17 , wherein applying the pulses comprises applying a sequence of the pulses having an amplitude of at least approximately 200 V, and wherein a duration of each of the pulses is less than approximately 20 μs. 
     
     
         24 . The method according to  claim 23 , wherein the sequence of the pulses comprises biphasic pairs of the pulses, wherein each pair comprises a positive pulse and a negative pulse. 
     
     
         25 . The method according to  claim 17 , wherein applying the pulses comprises applying the pulses in a bipolar mode between one or more of the radial electrodes and the axial electrode. 
     
     
         26 . The method according to  claim 17 , wherein applying the pulses comprises applying the pulses in a unipolar mode between one or more of the electrodes on the basket assembly, including the axial electrode, and a common electrode that is separate from the probe. 
     
     
         27 . The method according to  claim 17 , wherein applying the pulses comprises applying the pulses between different pairs of the electrodes sequentially in accordance with a predefined protocol. 
     
     
         28 . The method according to  claim 27 , wherein in accordance with the predefined protocol, the pulses are applied in a bipolar mode between each of the radial electrodes and the axial electrode. 
     
     
         29 . The method according to  claim 28 , wherein in accordance with the predefined protocol, the pulses are applied simultaneously between two or more of the radial electrodes and the axial electrode. 
     
     
         30 . The method according to  claim 27 , wherein in accordance with the predefined protocol, the pulses are applied in a bipolar mode between multiple pairs of the radial electrodes, each pair including a first radial electrode on a first one of the spines and a second radial electrode on a second of the spines, which is not adjacent to the first one or the spines. 
     
     
         31 . The method according to  claim 27 , wherein in accordance with the predefined protocol, the pulses are applied to the radial electrodes on different ones of the spines in a predefined sequence in which the pulses are not applied in immediate succession to the radial electrodes on mutually adjacent spines. 
     
     
         32 . The method according to  claim 27 , wherein the radial electrodes comprise at least first and second radial electrodes on each of the spines, and wherein in accordance with the predefined protocol, the pulses are applied to only one of the first and second radial electrodes on each of the spines.