Source: http://www.google.com/patents/US4750494?dq=6,208,537
Timestamp: 2015-12-02 01:51:22
Document Index: 353965098

Matched Legal Cases: ['art. 5', 'art. 8', 'art. 9', 'art. 10', 'art. 11', 'art. 12', 'art. 15']

Patent US4750494 - Automatic implantable fibrillation preventer - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsApparatus and method for sensing the probable onset of ventricular fibrillation or other harmful tachyarrythmias and delivering electrical cardioverting stimulation pulses in response thereto. The sensing of the onset of the harmful tachyarrhythmia is accomplished using two different types of sensors....http://www.google.com/patents/US4750494?utm_source=gb-gplus-sharePatent US4750494 - Automatic implantable fibrillation preventerAdvanced Patent SearchPublication numberUS4750494 APublication typeGrantApplication numberUS 07/063,807Publication dateJun 14, 1988Filing dateJun 24, 1987Priority dateMay 12, 1981Fee statusPaidPublication number063807, 07063807, US 4750494 A, US 4750494A, US-A-4750494, US4750494 A, US4750494AInventorsWendell L. KingOriginal AssigneeMedtronic, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (20), Non-Patent Citations (27), Referenced by (175), Classifications (12), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetAutomatic implantable fibrillation preventer
4. The apparatus of claim 1 further comprising means for establishing a threshold current vector rate of change signal; and wherein:said first means further comprises means for determining the rate of change of the current vector and for providing a current vector rate of change signal; and said triggering means further comprises means responsive to the measured and threshold current vector rate of change signals for causing said pulse generating means to provide a stimulating pulse to the heart. 5. The apparatus of claim 4 wherein said first sensing means further comprises:three dimensional current sensing means for sensing in three mutually orthogonal directions the electrical depolarization signals of the heart and producing three respective directional electrical signals; circuit means for developing said first electrical signal and said current vector rate of change signal from the directional signals. 6. The apparatus of claim 5 wherein said three dimensional current sensing means further comprises:a lead body for introduction into a heart chamber; three pairs of mutually orthogonal electrodes supported on the lead body; three pairs of electrical conductors extending within said lead body and electrically connected to said respective three pairs of electrodes; terminal means electrically connected to said conductors; body compatible insulating means for covering and electrically insulating said conductors; and means for connecting said terminal means to said circuit means. 7. The apparatus of claim 1 further comprising means for establishing a threshold current vector rate of change signal; and wherein:said first means further comprises means for determining the measured value of the current vector and the rate of change of the current vector and for providing measured value and rate of change current vector signals; and said triggering means further comprises means responsive to the measured and threshold value signals and the measured and threshold rate of change current vector signals for causing said pulse generating means to provide a stimulating pulse to the heart. 8. The apparatus of claim 7 further comprising:programmable memory means for storing data representative of a threshold current vector value and a threshold ionic concentration value; and wherein: said triggering means further comprises means responsive to said first signal and said threshold current vector value and said second signal and said threshold ionic concentration value for causing said pulse generating means to provide a stimulating pulse to the heart. 9. The apparatus of claim 1 further comprising means for establishing a threshold ionic concentration signal; and wherein:said triggering means further comprises means responsive to the measured second electrical signal and the threshold ionic concentration signal for causing said pulse generating means to provide a stimulating pulse to the heart. 10. The apparatus of claim 1 further comprising means for establishing a threshold ionic concentration rate of change signal; and wherein:said second means further comprises means for determining the rate of change of the ionic concentration of said certain ion in the blood and for providing an ionic concentration rate of change signal; and said triggering means further comprises means responsive to the measured and threshold ionic concentration rate of change signals for causing said pulse generating means to provide a stimulating pulse to the heart. 11. The apparatus of claim 1 further comprising means for establishing a threshold ionic concentration signal and rate of change signal; and wherein:said second means further comprises means for determining the measured value and the rate of change of the ionic concentration of said certain ion in the blood and for providing ionic concentration measured value and rate of change signals; and said triggering means further comprises means responsive to the measured value and threshold ionic concentration signals and the measured and threshold ionic concentration rate of change signals for causing said pulse generating means to provide a stimulating pulse to the heart. 12. The apparatus of claim 1 wherein said first sensing means further comprises:three dimensional current sensing means for sensing in three mutually orthogonal directions the electrical depolarization signals of the heart and producing three respective directional electrical signals; and circuit means for developing said first electrical signal from the directional signals. 13. The apparatus of claim 12 wherein said three dimensional current sensing means further comprises:a lead body for introduction into a heart chamber; three pairs of mutually orthogonal electrodes supported on the lead body; three pairs of electrical conductors extending within said lead body and electrically connected to said respective three pairs of electrodes; terminal means electrically connected to said conductors; body compatible insulating means for covering and electrically insulating said conductors; and means for connecting said terminal means to said circuit means. 14. A method of cardioverting the heart comprising the steps of:(a) sensing the intracardiac ECG in three dimensional space; (b) deriving a current vector signal for the sensed intracardiac ECG; (c) storing the current vector signal; (d) repeating steps (a) and (b) to derive a current vector rate of change signal; (e) storing a threshold rate of change value; (f) comparing the derived current vector rate of change signal to the threshold rate of change value; (g) generating stimulating pulses to cardiovert the heart whenever the comparison reveals that the derived current vector differs from the threshold rate of change value by a predetermined amount indicative of fibrillation; and (h) applying said pulses to the heart. 15. The method of claim 14 further comprising the steps of:(a) sensing the amount of a certain extracellular ion in the blood; (b) storing a threshold value for the ionic concentration; (c) comparing the sensed amount to the threshold value; and (d) generating said electrical stimulating pulses to cardiovert the heart if said comparisons reveal both that said sensed amount of said threshold value are in a predetermined mathematical relationship and that said derived current vector differs from said threshold rate of change value by said predetermined amount. 16. The method of claim 15 further comprising the steps of:(a) deriving a signal representative of the rate of change of the sensed ionic concentration; (b) storing a threshold ionic concentration rate of change value; (c) compari