Implantable cardioverter defibrillator having a smaller energy storage capacity
First Claim
1. An implantable cardioverter defibrillator for subcutaneous positioning within a pectoral region of a human patient comprising:
- a sealed housing structure constructed of a biocompatible material;
one or more connector ports, each connector port disposed in a wall of the housing structure for providing electrical connections between an interior space of the housing structure and a corresponding electrical lead that is implanted within the human patient; and
circuitry disposed within the interior space of the housing structure and operably connected to the connector ports and responsive to a cardiac signal received from the human patient via one or more of the electrical leads to detect an arrhythmia in the cardiac signal and, in response, control delivery of one or more high energy electrical cardioversion/defibrillation countershocks of at least 0.5 joules to the human patient, the circuitry including a battery source of electrical energy having a total energy storage capacity of less than 1.0 amp-hours.
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Accused Products
Abstract
A capacitor-discharge implantable cardioverter defibrillator (ICD) has a relatively smaller energy storage capacity of less than about 1.0 Amp-hours. The smaller energy storage capacity of the ICD is achieved by selecting and arranging the internal components of the ICD to deliver a maximum defibrillation countershock optimized in terms of a minimum physiologically effective current (Ipe) rather than a minimum defibrillation threshold energy (DFT). As a result of the optimization in terms of a minimum effective current Ipe, there is a significant decrease in the maximum electrical charge energy (Ec) that must be stored by the capacitor of the ICD to less than about 30 Joules, even though a higher safety margin is provided for by the device. Due to this decrease in the maximum Ec, as well as corollary decreases in the effective capacitance value required for the capacitor and the net energy storage required of the battery, the overall displacement volume of the ICD is reduced to the point where subcutaneous implantation of the device in the pectoral region of human patients is practical. The size of the capacitor is reduced because the effective capacitance required can be less than about 125 μF. By optimizing both the charging time and the countershock duration for the smaller maximum Ec, the size of the battery is reduced because the total energy storage capacity can be less than about 1.0 Amp-hours. In the preferred embodiment, the charging time for each defibrillation countershock is reduced to less than about 10 seconds and the pulse duration of the countershock is reduced to less than about 6 milliseconds.
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Citations
16 Claims
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1. An implantable cardioverter defibrillator for subcutaneous positioning within a pectoral region of a human patient comprising:
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a sealed housing structure constructed of a biocompatible material; one or more connector ports, each connector port disposed in a wall of the housing structure for providing electrical connections between an interior space of the housing structure and a corresponding electrical lead that is implanted within the human patient; and circuitry disposed within the interior space of the housing structure and operably connected to the connector ports and responsive to a cardiac signal received from the human patient via one or more of the electrical leads to detect an arrhythmia in the cardiac signal and, in response, control delivery of one or more high energy electrical cardioversion/defibrillation countershocks of at least 0.5 joules to the human patient, the circuitry including a battery source of electrical energy having a total energy storage capacity of less than 1.0 amp-hours. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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7. The implantable cardioverter defibrillator of claim 26 wherein the effective capacitance value of the capacitor means is an optimum capacitance value (C) determined by the simultaneous solution of the equations:
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space="preserve" listing-type="equation">E.sub.c =0.5CV.sub.d.spsb.2
space="preserve" listing-type="equation">C=0.8d.sub.c /Rwhere Ec is said maximum charge amount, Vd is a maximum voltage for each electrical cardioversion/defibrillation countershock, dc is a cardioversion chronaxie value and R is a myocardial tissue resistance value.
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Specification