Impedance guided tunneling tool

Abstract

A system includes a first electrode at a tip of a tunneling tool and a second electrode. The system includes a circuit configured to determine whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue of a patient based on a measurement of an impedance between the first electrode and the second electrode.

1 . A system comprising:
 a first electrode at a tip of a tunneling tool;   a second electrode; and   a circuit configured to determine whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue of a patient based on a measurement of an impedance between the first electrode and the second electrode.   
   
   
       2 . The system of  claim 1 , wherein the tunneling tool comprises a conductive rod coated with an insulation material except at the tip such that the tip provides the first electrode. 
   
   
       3 . The system of  claim 2 , wherein the insulation material comprises a silicon rubber. 
   
   
       4 . The system of  claim 1 , wherein the second electrode is attached to the tunneling tool. 
   
   
       5 . The system of  claim 1 , wherein the second electrode is attached to the patient's skin. 
   
   
       6 . The system of  claim 1 , wherein the first electrode comprises a stylet within a central lumen of a lead, and
 wherein the second electrode comprises a coil of the lead.   
   
   
       7 . The system of  claim 1 , wherein the circuit comprises an audible indicator configured to indicate whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue based on the impedance measurement. 
   
   
       8 . The system of  claim 1 , wherein the circuit comprises a visible indicator configured to indicate whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue based on the impedance measurement. 
   
   
       9 . The system of  claim 1 , wherein the circuit comprises a voltage source and a meter, the voltage source configured for applying a voltage across the first electrode and the second electrode, the meter configured to measure a current between the first electrode and the second electrode for measuring the impedance between the first electrode and the second electrode. 
   
   
       10 . The system of  claim 9 , wherein the voltage source comprises a DC voltage source. 
   
   
       11 . The system of  claim 9 , wherein the voltage source comprises an AC voltage source. 
   
   
       12 . A tunneling tool comprising:
 a first electrode at a tip of the tunneling tool; and   a second electrode,   wherein an impedance measurement between the first electrode and the second electrode indicates whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue of a patient.   
   
   
       13 . The tunneling tool of  claim 12 , wherein the second electrode is attached to the tunneling tool. 
   
   
       14 . The tunneling tool of  claim 12 , wherein the second electrode is attached to the patient's skin. 
   
   
       15 . The tunneling tool of  claim 12 , wherein the first electrode comprises a stylet within a central lumen of a lead, and
 wherein the second electrode comprises a coil of the lead.   
   
   
       16 . A method for guiding the placement of a subcutaneous device, the method comprising:
 providing a first electrode at a tip of a tunneling tool;   providing a second electrode;   inserting the tunneling tool into a patient;   determining whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue of the patient based on a measurement of impedance between the first electrode and the second electrode; and   advancing the tunneling tool based on the determination to place the subcutaneous device at a desired location.   
   
   
       17 . The method of  claim 16 , wherein providing the second electrode comprises providing the second electrode on the tunneling tool. 
   
   
       18 . The method of  claim 16 , wherein providing the second electrode comprises attaching the second electrode to the patient's skin. 
   
   
       19 . The method of  claim 16 , wherein the subcutaneous device comprises a lead,
 wherein the first electrode comprises a stylet within a central lumen of the lead, and   wherein the second electrode comprises a coil of the lead.   
   
   
       20 . The method of  claim 16 , further comprising:
 providing an audible indicator indicating whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue based on the impedance measurement.   
   
   
       21 . The method of  claim 16 , further comprising:
 providing a visual indicator indicating whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue based on the impedance measurement.   
   
   
       22 . The method of  claim 16 , wherein determining whether the tip of the tunneling tool is within subcutaneous fat tissue or muscle tissue of the patient comprises:
 applying a voltage between the first electrode and the second electrode; and   measuring a current between the first electrode and the second electrode to determine the impedance between the first electrode and the second electrode.   
   
   
       23 . The method of  claim 22 , wherein applying the voltage comprises applying a DC voltage. 
   
   
       24 . The method of  claim 22 , wherein applying the voltage comprises applying an AC voltage.