Cardiac catheter with deformable body

Abstract

Aspects of the instant disclosure relate to an electrophysiological catheter system for performing diagnostics and therapies within a cardiac muscle; more specifically, to a deformable body, at a distal end of a catheter, that deforms in response to a force being exerted upon a tip of the catheter. The deformation of the deformable body being measured by a measurement device, and the deformation associated with both a magnitude and vector of the force exerted upon the catheter tip.

What is claimed is: 
     
         1 . An ultrasonic transducer assembly comprising:
 an elongated shaft that extends along a longitudinal axis of the ultrasonic transducer assembly, the elongated shaft configured and arranged to structurally support the ultrasonic transducer assembly;   a backing layer coupled to the elongated shaft, the backing layer configured and arranged to attenuate ultrasonic impulses and prevent the ultrasonic impulses from being reflected back on the ultrasonic transducer assembly;   a first piezoelectric electrode coupled to a distal end of the backing layer;   an intermediate layer coupled to a distal end of the first piezoelectric;   a second piezoelectric electrode coupled to a distal end of the intermediate layer;   a ground wire electrically coupled to both the first and second piezoelectrics, and extending proximally from the second piezoelectric electrode through the backing layer, first piezoelectric electrode and the intermediate layer, the ground wire configured and arranged to provide a common ground to both the first and second piezoelectric electrodes;   piezoelectric crystals positioned within the intermediate layer and configured and arranged to generate the ultrasonic impulses, the piezoelectric crystals electrically coupled to the first piezoelectric, wherein the first piezoelectric electrode is configured and arranged to supply current to and thereby excite the piezoelectric crystals; and   a matching layer at a distal most end of the ultrasonic transducer assembly configured and arranged to optimize the ultrasonic impulse emission.   
     
     
         2 . The ultrasonic transducer assembly of  claim 1 , further including
 solder pads positioned on a distal surface of the intermediate layer are electrically coupled to the piezoelectric crystals; and   via wires extending through at least a portion of the ultrasonic transducer assembly and electrically coupling the piezoelectric crystals to the first piezoelectric.   
     
     
         3 . The ultrasonic transducer assembly of  claim 1 , wherein the matching layer consists of a material optimized at the level of the acoustic impedance of a medium the ultrasonic impulse will be traveling through, and thereby optimized to mitigate acoustic loss. 
     
     
         4 . The ultrasonic transducer assembly of  claim 1 , wherein a thickness of the piezoelectric crystals is controlled by λ/2, where λ is a transmitted ultrasonic wavelength of the ultrasonic transducer assembly. 
     
     
         5 . The ultrasonic transducer assembly of  claim 1 , wherein the thickness of the matching layer is controlled by λ/4, where λ is a transmitted ultrasonic wavelength of the ultrasonic transducer assembly. 
     
     
         6 . The ultrasonic transducer assembly of  claim 1 , wherein the ultrasonic transducer assembly is configured and arranged to be positioned at a fixed distance from a deformable body in an electrophysiology catheter tip, and output an electrical signal in response to the ultrasonic transducer transmitting an ultrasonic pulse and receiving a reflected ultrasonic pulse within a threshold time period. 
     
     
         7 . The ultrasonic transducer assembly of  claim 6 , wherein the output signal of the ultrasonic transducer assembly is indicative of a distance between the ultrasonic transducer assembly and the deformable body. 
     
     
         8 . The ultrasonic transducer assembly of  claim 6 , wherein a lack of electrical signal output from the ultrasonic transducer assembly is indicative of an occlusion in an irrigant lumen within the elongated shaft, between the ultrasonic transducer assembly and the deformable body, that prevents the flow of irrigant fluid to the electrophysiology catheter tip. 
     
     
         9 . The ultrasonic transducer assembly of  claim 6 , further including controller circuitry configured and arranged to receive the electrical signal output of the ultrasonic transducer assembly and ignore variations in the output signal that do not exceed a threshold indicative of external contact with the electrophysiology catheter tip. 
     
     
         10 . An electrophysiological catheter system comprising:
 a catheter shaft;   a catheter tip coupled to a distal end of the catheter shaft, and configured and arranged to conduct diagnostics or therapies on intravascular tissue;   an elongated shaft that extends along a first length of the catheter shaft;   a deformable body coupled to the elongated shaft, the deformable body configured and arranged to deform in response to a force being translated from the catheter tip, through the elongated shaft, to the deformable body; and   three measurement devices configured and arranged to measure the resulting deformation of the deformable body in response to the force exerted on the catheter tip, and wherein the measured deformation of the deformable body is associated with the magnitude and vector of the force exerted on the catheter tip.   
     
     
         11 . The electrophysiological catheter system of  claim 10 , further including a disk positioned at a proximal end of the elongated shaft;
 wherein the three measurement devices are ultrasonic transducers configured and arranged to measure the displacement of the disk due to the deformation of the deformable body in response to the force exerted on the catheter tip and translated to the disk by the elongated shaft.   
     
     
         12 . The electrophysiological catheter system of  claim 11 , wherein the ultrasonic transducers are each positioned offset from a longitudinal axis of the catheter shaft and circumferentially distributed thereabout, each of the ultrasonic transducers are configured and arranged to measure the displacement of the disk at a unique location relative to the other ultrasonic transducers. 
     
     
         13 . The electrophysiological catheter system of  claim 11 , further including a force sensing subsystem configured and arranged to receive electrical signals from each of the three measurement devices indicative of the sensed measurement between the measurement device and the disk, and derive the magnitude and vector of the force exerted on the catheter tip based on the deformation measurements. 
     
     
         14 . The electrophysiological catheter system of  claim 13 , wherein the measured deformation at the disk by the three measurement devices is indicative of an axial compressive force exerted on the catheter tip, where the output signal of each of the measurement devices is D 1 (t 1 )=D 2 (t 1 )=D 3 (t 1 ), where D 1 (t 1 )<D 0 (t 0 ) and D 0 (t 0 ) is indicative of the catheter tip at rest. 
     
     
         15 . The electrophysiological catheter system of  claim 13 , wherein the measured deformation at the disk by the three measurement devices is indicative of trans-axial compressive force exerted on the catheter tip, where the output signal of the measurement devices are D 1  (t 2 ), D 2 (t 2 ), D 3  (t 2 ), where D 1 (t 2 )<D 0 (t 0 ), D 2 (t 2 )=D 1 (t 1 ), and D 3 (t 2 )>D 0 (t 0 ), and D 0 (t 0 ) is indicative of the catheter tip at rest. 
     
     
         16 . The electrophysiological catheter system of  claim 10 , wherein the deformable body is a deformable disk. 
     
     
         17 . The electrophysiological catheter system of  claim 10 , wherein the deformable body includes two deformable disks, where the two deformable disks are longitudinally offset from one another, the two deformable disks are configured and arranged to facilitate a trans-axial/axial compliance ratio of less than 5. 
     
     
         18 . The electrophysiological catheter system of  claim 17 , wherein the two deformable disks are coupled to the elongated shaft at an inner diameter of the deformable disks and an external housing of the deformable body at an outer diameter of the two deformable disks. 
     
     
         19 . The electrophysiological catheter system of  claim 10 , wherein the deformable body includes three deformable disks, where the three deformable disks are longitudinally offset from one another.