Electromagnetic trap for a lead

Abstract

A method and an apparatus for trapping induced current resulting from an electromagnetic field. Embodiments of the present invention provide for an elongate body having a proximal and a distal end portion and a coil wound about the distal end, the coil to provide an electromagnetic trap for filtering radio frequency (RF) signal-induced currents.

What is claimed:  
     
         1 . A medical electrical lead, comprising: 
 an elongate body having a proximal and a distal end portion and a coil wound about said distal end, said coil to provide an electromagnetic trap for filtering radio frequency (RF) signal-induced currents.    
     
     
         2 . The medical electrical lead of  claim 1 , wherein said coil to provide an electromagnetic trap for filtering RF signal-induced currents resulting from the presence of a magnetic resonance imaging (MRI) signal.  
     
     
         3 . The medical electrical lead of  claim 1 , wherein said coil comprises: 
 a conductive wire; and    an electrically insulative layer surrounding said conductive wire.    
     
     
         4 . The medical electrical lead of  claim 3 , wherein said medical electrical lead comprising an equivalent resistance.  
     
     
         5 . The medical electrical lead of  claim 4 , wherein said coil to provide an inductive impedance in series with said equivalent resistance.  
     
     
         6 . The medical electrical lead of  claim 5 , wherein said inductive impedance is active during the presence of a radio frequency signal.  
     
     
         7 . The medical electrical lead of  claim 6 , wherein said inductive impedance is active during the presence of a electromagnetic field resulting from at least one of a 64 MHz and a 128 MHz signal.  
     
     
         8 . The medical electrical lead of  claim 5 , wherein said coil to provide a capacitive impedance in parallel with said inductive impedance, wherein said inductive impedance and said capacitive impedance from a parallel circuit in series with said equivalent resistance.  
     
     
         9 . The medical electrical lead of  claim 8 , wherein said capacitive impedance is active during the presence of a radio frequency signal.  
     
     
         10 . The medical electrical lead of  claim 9 , wherein said capacitive impedance is active during the presence of a electromagnetic field resulting from at least one of a 64 MHz and a 128 MHz signal.  
     
     
         11 . The medical electrical lead of  claim 8 , wherein said inductive and capacitive impedance to provide a self-resonant circuitry during the presence of an RF signal.  
     
     
         12 . A medical electrical lead, comprising: 
 an elongate body having a proximal and a distal end portion and a coil wound about said distal end, said coil to provide an inductive impedance in parallel with a capacitive impedance for reducing induced currents resulting in the presence of an electromagnetic field.    
     
     
         13 . The medical electrical lead of  claim 12 , wherein said inductive and said capacitive impedance are active during the presence of a electromagnetic field resulting from at least one of a 64 MHz and a 128 MHz signal.  
     
     
         14 . The medical electrical lead of  claim 12 , wherein said coil comprises: 
 a conductive wire; and    an electrically insulative layer surrounding said conductive wire.    
     
     
         15 . The medical electrical lead of  claim 12 , wherein said inductive and capacitive impedances to provide a self-resonant circuitry during the presence of an RF signal.  
     
     
         16 . A implantable medical device system, comprising: 
 an implantable medical device; and    a medical electrical lead operatively coupled to said implantable medical device, said medical electrical lead having a proximal and a distal end portion and a coil wound about said distal end, said coil to provide an inductive impedance in parallel with a capacitive impedance for reducing induced currents resulting in the presence of an electromagnetic field.    
     
     
         17 . The implantable medical device system of  claim 17 , wherein said inductive impedance and said capacitive impedance to form a filter to pass a sensor signal and to block said induced current.  
     
     
         18 . The implantable medical device system of  claim 17 , wherein said inductive impedance and said capacitive impedance to form a filter to pass a pacing signal and to block said induced current.  
     
     
         19 . The implantable medical device system of  claim 17 , wherein said inductive and capacitive impedance to provide a self-resonant circuitry during the presence of an said electromagnetic, said self-resonant circuitry to block an induced current resulting from an RF signal within a pre-determined range of frequency.  
     
     
         20 . A method for trapping an radio frequency (RF) signal induced current on a medical electrical lead, comprising: 
 providing a wound coil at a distal end of said medical electrical lead such that said coil    provides an inductive impedance in parallel with a capacitive impedance to reduce said induced current.    
     
     
         21 . The method of  claim 20 , wherein winding said coil at said distal end of said medical electrical lead further comprises winding said coil such that a self resonating circuit comprising an inductive impedance and a capacitive impedance is active in the presence of said RF signal.  
     
     
         22 . The method of  claim 21 , wherein winding said coil at said distal end of said medical electrical lead further comprises winding said coil such that said self resonating circuit is active in the presence of at least one of a 64 MHz and a 128 MHz signal.