Bundle of his stimulation system

Abstract

A system for therapeutically stimulating a His bundle includes an implantable pulse generator and a multi-polar medical electrical lead. The generator is configured for subcutaneous implantation and to generate a pacing stimulus. The lead includes a connector assembly, a flexible tubular body, a distal tip assembly and coil conductors. The body extends intravascularly from the generator to a location proximate the His bundle and includes a proximal end, a distal end, and a longitudinal lumen. The tip assembly includes an electrode, a fixation helix, and a shank portion. The helix extends to a location proximate the His bundle and is operable as an electrically isolated electrode. The shank portion extends within the lumen and includes a receptacle for receiving a stylet tip. The conductors extend longitudinally through the lumen and are coupled to the electrode and the helix. One or both of the conductors defines a stylet lumen.

1 . A system for therapeutically stimulating a His bundle of a patient's heart, the system comprising:
 an implantable pulse generator configured for subcutaneous implantation in the patient and to generate an electrical pacing stimulus; and   a multi-polar medical electrical lead operatively coupled to the pulse generator for delivering the pacing stimulus to cardiac tissue proximate the His bundle, the lead comprising:
 a proximal connector assembly configured to mechanically and electrically couple the lead to the pulse generator; 
 a flexible tubular body dimensioned to extend at least partially intravascularly from the implantation site of the pulse generator through a superior vena cava of the patient to a location proximate the His bundle, the body including a proximal end coupled to the proximal connector, a distal end opposite the proximal end and a longitudinal conductor lumen extending from the proximal end of the body to the distal end of the body; 
 a distal tip assembly fixedly coupled to the distal end of the body, the tip assembly comprising:
 a first electrode spaced from the distal end of the body; 
 a fixation helix fixedly coupled to the body and extending distally of the first electrode, the fixation helix configured as a second electrode electrically isolated from the first electrode, the fixation helix further dimensioned to extend from a wall of a right atrial septum of the patient to a location proximate the His bundle and including a sharpened distal tip; and 
 a shank portion extending proximally of the first electrode and the fixation helix within the conductor lumen of the body, the shank portion including a proximal face having a receptacle for receiving and engaging a stylet tip; 
 
 a first coil conductor extending longitudinally through the conductor lumen of the body and electrically and mechanically coupled to the first electrode; and 
 a second coil conductor extending longitudinally through the conductor lumen of the body and electrically and mechanically coupled to the fixation helix, 
 wherein one or both of the first and second coil conductors defines a stylet lumen. 
   
   
   
       2 . The system of  claim 1 , wherein the distal tip assembly further includes a blunt distal tip, wherein the fixation helix extends distally of the blunt distal tip, and wherein the first electrode is located on the blunt distal tip of the distal tip assembly. 
   
   
       3 . The system of  claim 1 , wherein the distal tip assembly includes a tapered distal tip, wherein the fixation helix extends distally of the tapered distal tip, and wherein the first electrode is located on the tapered distal tip. 
   
   
       4 . The system of  claim 1 , wherein an insulating material is disposed between the first electrode and the fixation helix to electrically isolate the first electrode and the fixation helix. 
   
   
       5 . The system of  claim 4 , wherein the insulating material is a masking layer on a portion of the fixation helix proximate the first electrode. 
   
   
       6 . The system of  claim 1 , wherein the first electrode has a helical shape and extends longitudinally adjacent a portion of the fixation helix, and wherein the first electrode terminates proximal to the distal tip of the fixation helix and includes a sharpened distal end. 
   
   
       7 . The system of  claim 1 , wherein the fixation helix includes an electrically insulating masking material along a portion of the fixation helix adjacent to the second electrode, wherein the masking material terminates proximal to the distal tip of the fixation helix. 
   
   
       8 . The system of  claim 1 , wherein the first and second coil conductors are co-axially disposed, and wherein the first conductor is disposed about the second conductor. 
   
   
       9 . The system of  claim 1 , wherein the first and second electrodes are co-radially disposed. 
   
   
       10 . The system of  claim 1 , wherein the receptacle in the face of the shank portion is in the shape of a linear slot configured to receive and engage a bladed stylet tip. 
   
   
       11 . The system of  claim 1 , wherein a torque transfer ratio of the body and the fixation helix is about 1:1. 
   
   
       12 . The system of  claim 1 , wherein the lead further comprises:
 longitudinally spaced third and fourth electrodes coupled to the lead body proximal to the distal tip assembly; and   third and fourth conductors mechanically and electrically coupled to the third and fourth electrodes.   
   
   
       13 . The system of  claim 12 , wherein the lead body includes a second conductor lumen and a third conductor lumen, wherein the third and fourth conductors are cable conductors disposed, respectively, within the second and third conductor lumens. 
   
   
       14 . The system of  claim 12 , wherein the first, second, third, and fourth conductors are arranged as individual filars in a single, quad-filar coil, and wherein each of the individual filars is electrically insulated from each of the other filars. 
   
   
       15 . The system of  claim 1 , wherein the pulse generator is configured to selectively transmit an electrical stimulus to the first electrode or the second electrode. 
   
   
       16 . The system of  claim 1 , wherein the first electrode is a conductor needle extending longitudinally within a portion of the fixation helix, wherein the conductor needle is longitudinally extendable and retractable relative to the fixation helix. 
   
   
       17 . A system comprising:
 a pulse generator configured to generate an electrical pacing stimulus;   a separable, splittable or slittable guide catheter configured to deliver electrical stimulation to a His bundle of a patient's heart, the catheter comprising:
 a proximal shaft having a proximal end; 
 a pre-curved distal portion extending distally from the proximal shaft and terminating in a distal tip, the distal portion including a series of contiguous pre-formed curved segments, each having a different radius of curvature and extending along a different arc length than each immediately adjacent segment, the distal portion being configured to locate the distal tip proximate an atrial wall of the heart adjacent the His bundle when the proximal shaft portion is at least partially located in a superior vena cava of the heart; 
 an open lumen extending longitudinally from the proximal end of the proximal shaft to the distal tip of the pre-curved distal portion; 
 at least one electrode proximate the distal tip; and 
 an electrically conductive member extending from at least the proximal end of the proximal shaft to the electrode for electrically coupling the electrode to an external device for mapping electrical activity of the heart; 
   an implantable medical electrical lead sized to be slidably received within the open lumen of the catheter, the lead comprising:
 a proximal connector assembly configured to mechanically and electrically couple the lead to the pulse generator; 
 a flexible tubular body dimensioned to extend at least partially intravascularly from the pulse generator through the patient's superior vena cava to a location proximate the His bundle, the body including a proximal end coupled to the proximal connector, a distal end opposite the proximal end, and a longitudinal conductor lumen extending from the proximal end of the body to the distal end of the body; 
 a distal tip assembly fixedly coupled to the distal end of the body, the tip assembly comprising:
 a first electrode positioned adjacent to the distal end of the body; 
 a fixation helix fixedly coupled to the body and extending distally of the first electrode, the fixation helix operable as a second electrode electrically isolated from the first electrode, the fixation helix further dimensioned to extend from a wall of a right atrial septum to a location proximate the His bundle; and 
 a shank portion extending proximally of the first electrode and the fixation helix within the conductor lumen, the shank portion including a proximal face having a receptacle for receiving and engaging a stylet tip; 
 
 a first coil conductor extending longitudinally through the conductor lumen and electrically and mechanically coupled to the first electrode; and 
 a second coil conductor extending longitudinally through the conductor lumen and electrically and mechanically coupled to the fixation helix, 
 wherein one or both of the first and second conductors defines a stylet lumen; and 
 a stylet having a proximal end and a distal end including an engaging feature configured to mate with and engage the receptacle on the shank portion of the distal tip assembly, the stylet being configured to transmit a torque applied at its proximal end to the distal tip assembly to cause rotation of the fixation helix and the body. 
   
   
   
       18 . The system of  claim 17 , wherein the distal tip assembly further includes a blunt distal tip, wherein the fixation helix extends distally of the blunt distal tip, and wherein the first electrode is located on the blunt distal tip of the distal tip assembly. 
   
   
       19 . The system of  claim 17 , wherein the distal tip assembly includes a tapered distal tip, wherein the fixation helix extends distally of the tapered distal tip, and wherein the first electrode is located on the tapered distal tip. 
   
   
       20 . The system of  claim 17 , wherein an insulating material is disposed between the first electrode and the fixation helix to electrically isolate the first electrode and the fixation helix. 
   
   
       21 . The system of  claim 17 , wherein the first electrode has a helical shape and extends longitudinally adjacent a portion of the fixation helix, the first electrode terminating proximal to the distal tip of the fixation helix and including a sharpened distal end. 
   
   
       22 . The system of  claim 17 , wherein the first and second electrodes are co-radially disposed. 
   
   
       23 . The system of  claim 17 , wherein a torque transfer ratio of the body and the fixation helix is about 1:1. 
   
   
       24 . The system of  claim 17 , wherein the first electrode is a conductor needle extending longitudinally within a portion of the fixation helix, wherein the conductor needle is longitudinally extendable and retractable relative to the fixation helix. 
   
   
       25 . A method of implanting a lead for stimulating a His bundle in a patient's heart, the method comprising:
 introducing the lead in the right atrium of the patient's heart proximate to the apex of the triangle of Koch;   mapping the His bundle with at least a helix of the lead;   engaging a shank portion of the lead with a bladed stylet to fixate the helix into cardiac tissue of the patient's heart; and   monitoring a His capture threshold and a ventricular capture threshold of the His bundle obtained by the helix while torquing the helix into the cardiac tissue.