摘要:
In a method and an apparatus for detecting the status of a battery in an implantable heart stimulator, the battery impedances measured and an increased value of the measured impedance is detected, from which an impedance based value of the remaining battery capacity is determined. The increase in impedance is analyzed to determine whether the impedance increase is a reliable indicator of the remaining battery capacity. If it is determined that the impedance increase is not reliable for determining the battery capacity, the total charge depletion of the battery is measured and a charge depletion-based value of the remaining battery capacity is determined.
摘要:
In a method and apparatus for determining the depleted capacity of a CFx type battery used in an implantable medical device, average values of battery voltage and battery current drawn from the battery are measured during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and wherein the actual depleted capacity of the battery is determined by predetermined relations between combinations of the average values of voltage and current and depleted battery capacity.
摘要:
An apparatus for producing heart defibrillation sequences formed of stimulation pulses and defibrillation shocks contains a unit for delivering pulses through an intracardiac or epicardiac electrode, normally for cardiac pacing, and defibrillator circuitry for delivering defibrillation shocks through defibrillation electrodes. The unit for delivering pacing pulses has an output stage which is capable of generating a stimulation pulse, delivered to the heart via the pacing electrode, having a higher energy content than a pacing pulse, but considerably less energy than a conventional defibrillation shock. A control unit is connected to the unit for delivering stimulation pulses and to the defibrillator circuitry for forming a defibrillation sequence consisting of stimulation pulses and defibrillation shocks. The control unit determines the timing for delivering the stimulation pulses and the defibrillation shocks.
摘要:
A heart stimulator, operable for single-chamber and/or dual-chamber pacing, includes a first unipolar electrical lead placeable in the atrium of a heart, and a second unipolar electrical lead placeable in the ventricle of the heart. In the heart stimulator, a differential detector is connected to each of these unipolar leads and detects a differential signal representative of cardiac activity between the atrial electrode and the ventricular electrode. The differential signal is supplied to decision logic which evaluates each of those outputs including using a morphology analysis, if necessary. Depending on the type of cardiac activity identified as a result of the evaluation, the decision logic supplies a signal to a control unit in the heart stimulator to cause the therapy administered by the heart stimulator to be altered as warranted. The decision logic may also derive a respiration signal from the differential signal, which can also be used to modify the administered therapy.
摘要:
A heart stimulating device for avoiding problems related to fusion beats contains a pulse generator for delivering stimulation pulses to a patient's heart and having a basic escape interval, a detector with a filter which senses QRS characteristics in IEGM signals, a logic stage which controls the pulse generator, and a detector without a filter which senses QRS characteristics in IEGM signals. The logic stage activates the detector without a filter preceding an end of the basic escape interval and prolongs the basic escape interval by a predetermined extension interval if the detector without a filter senses a QRS indication.
摘要:
A temporarily implantable electrode device, intended for sensing electrical signals from living tissue, has an insulating sheath of resorbable material, and at least one non-toxic, liquid conductor contained inside the insulating sheath in order to form an electrical conductor which, via an electrode adapted for interaction with living tissue can sense and carry electrical signals from living tissue to a medical apparatus connected to the electrode device. The resorbable material ultimately dissolves completely into the body of the subject in whom the electrode device was temporarily implanted, and the non-toxic, liquid conductor simultaneously mixes with other fluids, making explantation of the electrode device unnecessary.
摘要:
An implantable defibrillator has a capacitor which, through a controllable switch arrangement, can either be connected to a voltage source for charging the capacitor, or connected across electrodes placed at the heart for delivering a defibrillation pulse. To calculate the minimum pulse energy required for successful defibrillation, ventricular fibrillation is first induced, so that a plurality of defibrillation attempts, with energy increasing from attempt-to-attempt can be undertaken until successful defibrillation occurs. For inducing ventricular fibrillation, the capacitor of the implantable defibrillator is connected to the voltage source until a prescribed charging voltage, which is significantly below the voltage necessary for defibrillation, is reached, and subsequently, the capacitor is disconnected from the voltage source during brief time spans at intervals within the framework of a sequence and is connected during those time spans to the electrodes. Between the time spans, the capacitor is again charged.
摘要:
In a method and an arrangement for evaluating operational effectiveness of an implantable medical device for different lead placements associated with the medical device, a measuring unit records signals that are characteristic of cardiac activity at respectively different lead positions, and these signals are stored. A processor accesses the stored signals and, from the stored signals, determines a measure of cardiac activity at each of the lead positions. The recorded signals may be intracardiac ECG signals, surface ECG signals, heart sound signals obtained from a microphone, or impedance signals. The lead position at which the best hemodynamic behavior of the heart is identified from the analysis of the stored signals, and is determined as being the optimum site for placement of the electrode leads.
摘要:
A heart monitoring device has a control circuit that derives an impedance value indicative of the impedance between different electrode surfaces. The control circuit determines and monitors a negative rate of change of the impedance value and determines whether the negative rate of change, or its absolute value, increases or decreases over a number of heart cycles. Alternatively or additionally, the control circuit may determine and monitor a relationship between a positive rate of change and a negative rate of change of the impedance value. The device can, in particular, be used to detect and treat a diastolic dysfunction of a heart.
摘要:
An implantable heart stimulator has an electrically conductive housing containing a pulse generator, with an electrode lead connected to the housing. The electrode lead has a proximal portion extending substantially from the housing to a location, after implantation, which is beyond the entry of the lead into the venous system and before the entry of the lead into the superior vena cava. A current source supplies an infection control current between the housing and an electrically conductive surface on the exterior of the proximal portion of the electrode lead, for counteracting bacterial growth. The housing may have a header to which the electrode lead is connected, in which case the header is provided with an electrically conductive surface as well, which can serve as an electrode for the infection control current.