Local Lead To Improve Energy Efficiency In Implantable Wireless Acoustic Stimulators

Abstract

A wireless cardiac stimulation device is disclosed comprising a controller-transmitter, a receiver, and a stimulating electrode, wherein the stimulating electrode and the receiver are separately implantable at cardiac tissue locations of the heart and are connected by a local lead. Having separately implantable receiver and stimulating electrodes improves the efficiency of ultrasound mediated wireless stimulation by allowing the receiver to be placed optimally for reception efficiency, thereby resulting in longer battery life, and by allowing the stimulating electrode to be placed optimally for stimulus delivery. Another advantage is a reduced risk of embolization, since the receiver and stimulating electrode ensemble is attached at two locations of the heart wall, with the connecting local leads serving as a safety tether should either the receiver or the stimulating electrode become dislodged.

1 . An implantable cardiac stimulator device for converting acoustic energy to electrical energy, comprising:
 an implantable receiver which produces a biologically stimulating electrical output in response to acoustic energy, the receiver configured to be implanted at a first cardiac tissue location to optimize acoustic energy reception;   a first implantable stimulating electrode which receives the biologically stimulating electrical output from the receiver and delivers said output to cardiac tissue, the stimulating electrode configured to be implanted at a second cardiac tissue location to optimize delivery of stimulation energy to cardiac tissue; and   a first local lead connecting the receiver and the first stimulating electrode.   
   
   
       2 . The device of  claim 1 , wherein the receiver comprises:
 one or more transducers which produce electrical energy in response to acoustic energy; and   one or more conversion circuits, wherein each conversion circuit is electrically connected to a corresponding transducer such that the electrical energy output from the transducers is converted to the biologically stimulating electrical output.   
   
   
       3 . The device of  claim 2 , wherein the transducers comprise piezoelectric material. 
   
   
       4 . The device of  claim 3 , wherein the piezoelectric transducer material is one of a polycrystalline ceramic piezoelectric material or a single crystal piezoelectric material. 
   
   
       5 . The device of  claim 2 , wherein the conversion circuits comprise rectifiers. 
   
   
       6 . The device of  claim 5 , further comprising protection circuitry to protect the rectifiers from damage due to high voltages. 
   
   
       7 . The device of  claim 6 , wherein the protection circuitry comprises a Zener diode. 
   
   
       8 . The device of  claim 1 , wherein the receiver is further configured to deliver the stimulating electrical output to cardiac tissue, thereby allowing multi-site stimulation. 
   
   
       9 . The device of  claim 8 , wherein the receiver comprises a stimulation electrode for delivering the stimulating electrical output to cardiac tissue. 
   
   
       10 . The device of  claim 1 , further comprising a second implantable stimulating electrode, thereby allowing multi-site stimulation. 
   
   
       11 . The device of  claim 11 , further comprising a second local lead connecting the receiver and the second stimulating electrode. 
   
   
       12 . The device of  claim 1 , wherein the receiver is configured to be implanted at an endocardial or epicardial location. 
   
   
       13 . The device of  claim 1 , wherein the first stimulating electrode is configured to be implanted at an endocardial or epicardial location. 
   
   
       14 . The device of  claim 1 , wherein the receiver is configured to be implanted at a cardiac tissue location at the septal apex of the right ventricle of the heart, wherein the first stimulating electrode is configured to be implanted at a cardiac tissue location of the left ventricle of the heart, and wherein the first local lead is configured to puncture through the ventricular septum of the heart to connect the receiver and the first stimulating electrode. 
   
   
       15 . The implantable cardiac stimulator device of  claim 1 , wherein the first local lead tethers the receiver to the stimulating electrode and retains the receiver and the stimulator within the heart when the receiver or stimulator is dislodged from the implanted location. 
   
   
       16 . The device of  claim 15 , wherein the local lead prevents embolization due to the dislocation of the receiver or stimulator from the implanted location. 
   
   
       17 . An implantable cardiac stimulator system for converting acoustic energy to electrical energy, comprising:
 an implantable receiver which produces a biologically stimulating electrical output in response to acoustic energy, the receiver configured to be implanted at a first cardiac tissue location to optimize acoustic energy reception;   a first implantable stimulating electrode which receives the biologically stimulating electrical output from the receiver and delivers said output to cardiac tissue, the stimulating electrode configured to be implanted at a second cardiac tissue location to optimize delivery of stimulation energy to cardiac tissue;   a first local lead connecting the receiver and the first stimulating electrode; and   a controller-transmitter for transmitting acoustic energy towards the receiver.   
   
   
       18 . The system of  claim 17 , wherein the controller-transmitter is subcutaneously implanted. 
   
   
       19 . The system of  claim 18 , wherein the controller-transmitter and the receiver are located such that acoustic energy is optimally transmitted to the receiver with minimal energy loss. 
   
   
       20 . The system of  claim 19 , wherein the optimal transmission is achieved by locating the receiver in close proximity to the transmitter. 
   
   
       21 . A method of using acoustic energy to stimulate cardiac tissue, comprising:
 subcutaneously implanting a transmitter;   implanting a receiver at a first cardiac tissue location, wherein the receiver receives acoustic energy transmitted by the transmitter and produces a biologically stimulating electrical output in response to the received acoustic energy; and   implanting a stimulating electrode at a second cardiac tissue location, wherein the stimulating electrode is connected to the receiver by a local lead, and wherein the stimulating electrode receives the biologically stimulating electrical output from the receiver and delivers said output to cardiac tissue.   
   
   
       22 . The method of  claim 21 , wherein the first cardiac tissue location is chosen to optimize acoustic energy transmission from the transmitter to the receiver. 
   
   
       23 . The method of  claim 22 , further comprising implanting additional stimulating electrodes, wherein the stimulating electrodes are connected to the receiver by the local lead. 
   
   
       24 . The method of  claim 22 , further comprising implanting additional stimulating electrodes, wherein the stimulating electrodes are connected to the receiver by additional local leads. 
   
   
       25 . A method of stimulating cardiac tissue by converting acoustic energy to electrical energy, comprising:
 transmitting acoustic energy from a subcutaneously implanted transmitter;   receiving acoustic energy at a first cardiac location;   producing a biologically stimulating electrical output in response to the received acoustic energy; and   delivering the biologically stimulating electrical output via a local lead to a stimulating electrode implanted at a second cardiac tissue location, thereby stimulating cardiac tissue.   
   
   
       26 . The method of  claim 25 , wherein the first cardiac tissue location is chosen to optimize acoustic energy reception from the transmitter. 
   
   
       27 . The method of  claim 26 , further comprising delivering the biologically stimulating electrical output to additional stimulating electrodes implanted at additional cardiac tissue locations via the local lead. 
   
   
       28 . The method of  claim 26 , further comprising delivering the biologically stimulating electrical output to additional stimulating electrodes implanted at additional cardiac tissue locations via additional local leads.