Abstract: A medical sensing system (100) includes an elongate interventional device (101) and an adjustable capacitance circuit (102). The elongate interventional device (101) includes a sensor (103) having a capacitance (Css). The elongate interventional device (101) also includes a first electrical conductor (104) and a second electrical conductor (105). The first electrical conductor (104) and the second electrical conductor (105) are in electrical contact with the sensor (103) and extend along the elongate interventional device (101). The elongate interventional device (101) also includes i) an electrically conductive shield (106) that overlaps the electrical conductors (104, 105) and/or ii) an electrically conductive shaft (107).

Abstract: A wearable, multiphasic cardioverter defibrillator system and method are provided.

Abstract: A system can utilize interleaving periods or waveforms to stimulate patient tissue and sense signals using the stimulation electrodes. For example, the system can utilize alternating therapeutic periods and sensing periods. As another example, the system can alternate between biphasic waveforms having opposite temporal orders of positive and negative phases. As another example, waveforms that differ in a parameter, such as amplitude or pulse width, can be interleaved to provide different information in the respective sensed signals.

Abstract: Defibrillator shock discharge control systems and schemes are described that control the shock discharge based at least in part on discharge capacitor voltage measurement taken after the defibrillation shock has been initiated.

Abstract: A system for facilitating resuscitation includes: a first electrode assembly having a therapy side and a first motion sensor; a second electrode assembly having a therapy side and a second motion sensor; processing circuitry operatively connected to and programmed to receive and process signals from the first and second motion sensors to estimate at least one of a chest compression depth and rate during administration of chest compressions and to compare the chest compression depth or rate to a desired range; and an output device for providing instructions to a user to administer chest compressions based on the comparison of the estimated chest compression depth or rate to the desired range. One or both of the electrode assemblies may be constructed so that the conductive therapeutic portion is able to maintain substantial conformance to the anatomy of the patient when coupled thereto.

Abstract: An electrode test system of a defibrillator including electrodes in a face-to-face test arrangement forming a capacitor, an impedance measurement signal generator connected to the electrodes and configured to send an ac signal to the electrodes, an impedance measurement signal processor connected to the electrodes which is placeable in an electrode test state and configured to receive an electrode test ac signal from the electrodes and process the electrode test ac signal to obtain a processed electrode test ac signal, a defibrillator processor connected to the impedance measurement signal generator and the impedance measurement signal processor configured to place the impedance measurement signal processor in the electrode test state and to receive the processed electrode test ac signal, analyze the processed electrode test ac signal to obtain an electrode test impedance signal and analyze the electrode test impedance signal to determine a pass condition or a fail condition of the electrodes.

Abstract: Wearable sensors that measure one or more parameters such as pressure, force, acceleration, or skin temperature, are used to measure, record, display and monitor the efficacy of therapeutic maneuvers applied to a subject by an operator. Systems and methods for assessing the physiological efficacy of therapeutic maneuvers performed by an operator on a subject in need thereof, and provide a way to guide subsequent therapeutic maneuvers toward optimal outcome. In some embodiments, the systems and methods measure, record, and display physiological parameters of an operator and/or subject during application of cardiopulmonary resuscitation (CPR).

Abstract: In embodiments, an external defibrillator has an electrical circuit with a special output stage for the high-voltage defibrillation pulse. The output stage includes switches that can turn on for delivering the pulse, and off during all other times. The output stage also includes a diverting resistance to divert electrical current that could leak into the patient while a capacitor is being charged. An optional detector may notify if a component is malfunctioning. An advantage can be that an external defibrillator may be created according to embodiments that uses, in its output stage, semiconductor switches instead of relays. As semiconductor switches weigh less and occupy less volume than relays, an external defibrillator according to embodiments may have less weight and volume. Especially in wearable defibrillator applications, less weight means less effort to carry and less volume means easier concealment under clothing.

Abstract: An example of a mobile computing device for managing medical equipment includes a display and a processor, a memory, and associated circuitry, the processor configured to receive patient data gathering device location information for a plurality of patient data gathering devices, the patient data gathering device location information being indicative of one or more patient data gathering device locations in an assigned monitoring area corresponding to the mobile computing device, control the display to provide the patient data gathering device location information, capture a user selection of at least one patient data gathering device of the plurality of patient data gathering devices based on the provided patient data gathering device location information, and provide patient data gathering device information based on the user selection.

Abstract: An external defibrillator system is configured with at least two different algorithms for determining the duration of a shock administered to a patient being treated and selects the algorithm based on one or more patient parameters such as, for example, the patient's TTI. The patient's TTI can be measured prior to or while the shock is being administered to the patient. The shock can be, for example, a multiphasic defibrillation or a multiphasic cardioversion shock. The charge voltage of the system's energy storage device can additionally be varied depending on the one or more patient parameters. For example, the system may charge the energy storage device so that the charge voltage is higher or lower than a nominal charge voltage responsive to the patient's TTI is higher or lower compared to an average TTI, respectively.

Abstract: A system to deliver therapeutic energy to a patient, the system including a storage capacitor configured to store and release the therapeutic energy, a boost converter circuit coupled to the storage capacitor, and a current flow control circuit coupled to the boost converter circuit and including a plurality of control circuits configured to control a current output from the current flow control circuit in a therapeutic biphasic voltage waveform upon release of the therapeutic energy from the storage capacitor, wherein the therapeutic biphasic voltage waveform includes a ramped increase in voltage from approximately zero volts to a desired therapeutic voltage level over a time interval greater than 1 millisecond and less than a time associated with a phase switch.

Abstract: An external defibrillator may have a controller to set the defibrillator in a synchronous shock operating mode or an asynchronous shock operating mode, a shock module to cause the defibrillator to deliver shock therapy to a patient according to the present operating mode of the defibrillator, and a heart rhythm detector to detect a heart rhythm of the patient. The defibrillator may also have a mode assessment module to determine whether the present operating mode or selected defibrillation energy of the defibrillator is appropriate based on the detected heart rhythm of the patient.

Abstract: A system and method of controlling the application of energy to tissue using measurements of impedance are described. The impedance, correlated to the temperature, may be set at a desired level, such as a percentage of initial impedance. The set impedance may be a function of the initial impedance, the size and spacing of the electrodes, the size of a targeted passageway, and so on. The set impedance may then be entered into a PID algorithm or other control loop algorithm in order to extract a power to be applied to a treatment device.

Abstract: Systems and methods for electrocardiography monitoring use multiple capacitive sensors in order to determine reliable measurements of electrophysiological information of a patient. Relative coupling strength and/or reliability is used to select dynamically which sensors to use in order to determine, in particular, an electrocardiogram of the patient.

Abstract: The defibrillator may include a heart rhythm detector to detect the heart rhythm of a patient, a manual mode controller structured to set the defibrillator in a synchronous shock operating mode or an asynchronous shock operating mode depending on an input from a human operator, a shock module to cause the defibrillator to deliver a shock to the patient according to the operating mode, and an automatic mode controller structured to, after the shock module has delivered the shock to the patient, set the external defibrillator to the synchronous shock operating mode or the asynchronous shock operating mode depending on the detected heart rhythm of the patient and without input from the human operator.

Abstract: An external defibrillator can have a synchronous shock operating mode and an asynchronous shock operating mode and include a controller to set the defibrillator in the synchronous shock operating mode or the asynchronous shock operating mode. The defibrillator can also include a shock module to cause the defibrillator to deliver shock therapy to the patient according to the operating mode of the defibrillator, and a prompt module to transmit a prompt, after delivery of the shock therapy, that includes the operating mode of the defibrillator.

Abstract: A technique for identifying lead-related conditions, such as insulation breaches and/or externalization of lead conductors, includes analyzing characteristics of electrical signals generated on one or more electrode sensing vectors of the lead by a test signal to determine whether a lead-related condition exists. The characteristics of the electrical signals induced on the lead by the test signal may be significantly different on a lead having an insulation breach or externalized conductor than on a lead not having such lead-related conditions. As such, the implantable medical device may be subject to a known test signal and analyze the signals on the lead to detect lead-related conditions.

Abstract: A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.

Abstract: An external defibrillator, such as a wearable defibrillator can have a heart rhythm detector to detect the heart rhythm of a patient. The defibrillator can also have a synchronous shock operating mode and an asynchronous shock operating mode. A controller can set the defibrillator in the synchronous shock operating mode or the asynchronous shock operating mode. The defibrillator can also include a shock module to cause the defibrillator to deliver shock therapy to the patient according to the operating mode of the defibrillator and a sync module configured to identify a first portion of the heart rhythm detected from a first ECG lead with which to time the delivery of the shock therapy to the patient when the operating mode of the defibrillator is in synchronous shock operating mode. A comparator module can compare timing of a QRS complex detected from the first ECG lead with the timing of the QRS complex detected by the second EGG lead.

Abstract: When a defibrillator selects a dosage of energy or current to be delivered to a patient, the defibrillator selects an excitation current frequency and applies the excitation current at the selected frequency to the patient. The frequency of the excitation current is selected as a function of the dosage to be delivered. The patient's response to the excitation current at the selected frequency will accurately reflect the impedance that the defibrillator will “see” when delivering the selected dosage of energy or current.

Abstract: An implantable medical device (IMD) system communicates to a user information regarding the surrounding biological environment and the influence of that surrounding biological environment on IMD functionality. This influence can be static or dynamic. Providing information on the biological environment can assist the user in determining therapy parameters for an individual patient with an IMD.

Abstract: A peelable lid system includes a peelable lid, a seal configured to seal the peelable lid to a container, a handle coupled to the peelable lid, and a lifting mechanism coupled to handle. The lifting mechanism can be coupled to the peelable lid at a plurality of attachment points, including at least one attachment point coupled to the peelable lid away from the handle. The lifting mechanism can be configured to lift at least one portion of the peelable lid near each of the plurality of attachment points.

Abstract: The present application discloses systems and methods for displaying and operating a user interface having one or more channel group controllers corresponding to one or more groups of hearing prosthesis channels. The hearing prosthesis may be configured to generate a plurality of signals via a plurality of channels based on a channel profile. The channel profile may define at least one intensity level for each channel. In operation, the user interface may be configured to instruct the hearing prosthesis to change the channel profile of the plurality of channels in response to receiving an input via one of the channel group controllers. The user interface may be used to fit a hearing prosthesis to a recipient. In one embodiment, an initial channel profile may be automatically determined, and the prosthesis channel profile may be adjusted by changing a representative intensity level corresponding to the channel profile.

Abstract: Techniques are provided for controlling and delivering spinal cord stimulation (SCS) or other forms of neurostimulation. In one example, neurostimulation pulses are generated wherein successive pulses alternate in polarity so that a pair of electrodes alternate as cathodes. Each pulse has a cathodic amplitude sufficient to achieve cathodic capture of tissues adjacent the particular electrode used as the cathode for the pulse. The neurostimulation pulses are delivered to patient tissues using the electrodes to alternatingly capture tissues adjacent opposing electrodes via cathodic capture to achieve a distributed virtual stimulation cathode. Various pulse energy savings techniques are also set forth that exploit the distributed virtual stimulation cathode.

Abstract: An implantable medical device capable of sensing cardiac signals and delivering cardiac electrical stimulation therapies is enabled to detect a short circuit condition. In one embodiment, a cardiac signal is sensed by a sensing module coupled to electrodes. A controller identifies signal events in response to the cardiac signal and detects a short circuit condition in response to at least one of the signal events having an amplitude crossing a short circuit detection threshold and a maximum of two signal events crossing the short circuit detection threshold occurring between two adjacent events having amplitudes not crossing the short circuit detection threshold. In one embodiment, the signal events are identified from a differential signal determined from the sensed cardiac signal.

Abstract: A system and method for long-term monitoring of cardiac conditions such as arrhythmias is disclosed. The invention includes a pulse generator including means for sensing an arrhythmia. The pulse generator is coupled to at least one subcutaneous electrode or electrode array for providing electrical stimulation such as cardioversion/defibrillation shocks and/or pacing pulses. The electrical stimulation may be provided between multiple subcutaneous electrodes, or between one or more such electrodes and the housing of the pulse generator. In one embodiment, the pulse generator includes one or more electrodes that are isolated from the can. These electrodes may be used to sense cardiac signals.

Abstract: An external defibrillator includes patient electrodes (20) for obtaining the patient's electrocardiogram (ECG) and for applying a shock to the patient. A microprocessor (24) analyses the patient's ECU using a diagnostic algorithm to detect if the patient's heart is in a shockable rhythm, and shock delivery circuitry (10) is enabled when a shockable rhythm is detected by the diagnostic algorithm. The patient electrodes also allow obtaining a signal (Z) which is a measure of the patient's transthoracic impedance and the microprocessor is responsive to Z to detect conditions likely to cause the diagnostic algorithm to generate a false detection of a shockable rhythm. If such detection is made, the microprocessor prevents detection of a shockable rhythm by the diagnostic algorithm, at least for a period of time.

Abstract: Implantable medical devices switch from a constant current mode of operation to a constant voltage mode of operation. The switching may be based on the device determining that tissue impedance stability has occurred. The determination may be a measurement of output voltage stability of the constant current source or based on other factors such as an amount of time that has elapsed. The switching may be as the result of an externally generated request such as by a clinician via an external device. The implantable medical device may begin constant voltage mode by utilizing stimulation parameters based on those initially programmed for constant current mode and based upon a measurement of voltage amplitude being output by the constant current source prior to the switch.

Abstract: A method, apparatus, and system for determining an adverse operational condition associated with a lead assembly in an implantable medical device used for providing a therapeutic electrical signal to a cranial nerve. A first impedance associated with the lead assembly configured to provide the therapeutic electrical signal to a cranial nerve is detected. A determination is made as to whether the first impedance is outside a first predetermined range. A second impedance is detected. The detection of the second impedance is performed within a predetermined period of time from the time of the detection of the first impedance. A determination is made as to whether the second impedance is outside a second predetermined range. If the first impedance is outside the first range and the second impedance is outside the second range, the implantable medical device is prevented from providing the therapeutic electrical signal.

Abstract: A method of treating a patient for ventricular tachycardia using a wearable defibrillator includes monitoring the patient for a predetermined condition via one or more electrodes on the defibrillator, sending a message to the patient in response to the predetermined condition, activating the defibrillator so that the defibrillator delivers defibrillation energy to the patient, and storing at least one of the results of the monitoring, sending and activating steps in a memory on the defibrillator. The method also includes downloading information stored in the memory of the defibrillator to a base station having an external interface, and transmitting the information downloaded from the memory of the base station to an external location via the external interface of the base station.

Abstract: A method and associated stimulation device for ensuring firing of an action potential in an intended physiological target activated by a stimulus pulse generated by an electrode of a non-invasive surface based stimulation device irrespective of skin-to-electrode impedance by: (i) increasing internal impedance of the stimulation device so as to widen a Chronaxie time period thereby ensuring firing of the action potential of the intended physiological target irrespective of the skin-to-electrode impedance; and/or (ii) generating a stimulation waveform that optimizes a non-zero average current (e.g., non-zero slope of the envelope of the stimulation waveform) during preferably substantially the entire current decay of the stimulus pulse.

Abstract: A modular external defibrillator system in embodiments of the teachings may include one or more of the following features: a base containing a defibrillator to deliver a defibrillation shock to a patient, (b) one or more pods each connectable to a patient via patient lead cables to collect at least one patient vital sign, the pods operable at a distance from the base, (c) a wireless communications link between the base and a selected one of the two or more pods to carry the at least one vital sign from the selected pod to the base, the selection being based on which pod is associated with the base.

Abstract: A device and method for reducing patient transthoracic impedance for the purpose of delivering a therapeutic current are provided. In one embodiment, the device for reducing patient transthoracic impedance for the purpose of delivering a therapeutic current may be used in a defibrillator. The device for reducing patient transthoracic impedance for the purpose of delivering a therapeutic current may be a microneedle array that may have a number of different configurations and may be made with different materials.

Abstract: Embodiments of the present concept are directed to external defibrillators that include an electrode connection port having multiple connection options, and include a detection device to determine an electrode connection configuration so as to provide an appropriate electrical shock to a patient. The detection device detects the electrode connection configuration of a plug connector for connected electrodes to determine if the plug connector is in an adult orientation or a pediatric orientation. The external defibrillator is configured to a deliver an electrical shock with less energy when the pediatric orientation is detected rather than the adult orientation.

Abstract: Techniques are provided for use with an implantable medical device for detecting breaches in lead insulation or other lead failures. In one example, bipolar impedance is measured along single-lead vectors (i.e. intra-lead vectors) of a right atrial (RA) lead and a right ventricular (RV) leads. Impedance is also measured along various cross-lead vectors (i.e. inter-lead vectors) between electrodes of the two leads. A derived impedance value is then determined from a combination of the measured impedance values, wherein the derived impedance is sensitive to a shunt impedance arising from a breach within the RV lead. A lead breach is then detected relatively early based on the derived impedance by detecting a significant deviation in derived impedance over time. Unipolar impedance measurements are used to confirm the breach.

Abstract: Electrical energy delivery tissue site validation systems and methods can determine an indication of a tissue type at a tissue site. This information can be used to enable or inhibit electrical energy delivery to the tissue site. The tissue type at the tissue site can be determined such as by delivering a test electrical energy and sensing a responsive electrical energy. An electrical connectivity to the tissue site can also be determined, such as by using a sensed intrinsic electrical signal at the tissue site. Tissue type information may be communicated externally, such as to allow user confirmation or override of the determined indication of tissue type at the tissue site, such as by a physician, user, or other operator.

Abstract: An implantable medical device capable of sensing cardiac signals and delivering cardiac electrical stimulation therapies is enabled to detect a short circuit condition. In one embodiment, a cardiac signal is sensed by a sensing module coupled to electrodes. A controller identifies signal events in response to the cardiac signal and detects a short circuit condition in response to at least one of the signal events having an amplitude crossing a short circuit detection threshold and a maximum of two signal events crossing the short circuit detection threshold occurring between two adjacent events having amplitudes not crossing the short circuit detection threshold. In one embodiment, the signal events are identified from a differential signal determined from the sensed cardiac signal.

Abstract: A system and method of detecting a loss of electrical contact between a pair of electrodes that are electrically coupled to skin of a subject. The method includes monitoring parameters of a transthoracic impedance between the pair of electrodes in at least one of a low frequency regime and a high frequency regime, detecting an occurrence of chest compressions based on a signal indicative of chest compressions, establishing baseline levels of the parameters in at least one of the low and high frequency regimes, detecting whether changes in at least one parameter exceeds the baseline level by a threshold, determining that at least one electrode of the pair of electrodes is losing electrical contact with the skin responsive to the at least one parameter exceeding the baseline level by the threshold, and issuing an alert in response to a determination that the at least one electrode is losing electrical contact.

Abstract: Nano-constructs comprising nanoshells and methods of using the nano-constructs for treating or ameliorating a vascular condition are provided.

Abstract: One aspect of this disclosure relates to a system for dynamic battery management in implantable medical devices. An embodiment of the system includes two or more devices for measuring battery capacity for an implantable medical device battery. The embodiment also includes a controller connected to the measuring devices. The controller is adapted to combine the measurements from the measuring devices using a weighted average to determine battery capacity consumed. According to various embodiments, at least one of the measuring devices includes a coulometer. At least one of the measuring devices includes a capacity-by-voltage device, according to an embodiment. The system further includes a display in communication with the controller in various embodiments. The display is adapted to provide a depiction of battery longevity in units of time remaining in the life of the implantable medical device battery, according to various embodiments. Other aspects and embodiments are provided herein.

Abstract: An apparatus comprises an electrostimulation energy storage capacitor, a circuit path communicatively coupled to the electrostimulation energy storage capacitor and configured to provide quasi-constant current neural stimulation through a load from the electrostimulation energy storage capacitor, a current measuring circuit communicatively coupled to the circuit path and configured to obtain a measure of quasi-constant current delivered to the load, and a control circuit communicatively coupled to the current measuring circuit, wherein the control circuit is configured to initiate adjustment of the voltage level of the storage capacitor for a subsequent delivery of quasi-constant current according to a comparison of the measured load current to a specified load current value.

Abstract: In embodiments, a wearable cardiac defibrillator system includes an energy storage module configured to store a charge. Two electrodes can be configured to be applied to respective locations of a patient. One or more reservoirs can store one or more conductive fluids. Respective fluid deploying mechanisms can be configured to cause the fluids to be released from one or more of the reservoirs, which decreases the impedance at the patient location, and decreases discomfort for the patient. In some embodiments an impedance is sensed between the two electrodes, and the stored charge is delivered when the sensed impedance meets a discharge condition. In some embodiments, different fluids are released for different patient treatments. In some embodiments, fluid release is controlled to be in at least two doses, with an intervening pause.

Abstract: A neural stimulation system automatically corrects or adjusts the stimulus magnitude (stimulation energy) in order to maintain a comfortable and effective stimulation therapy. Because the changes in impedance associated with the electrode-tissue interface can indicate obstruction of current flow and positional lead displacement, lead impedance can indicate the quantity of electrical stimulation energy that should be delivered to the target neural tissue to provide corrective adjustment. Hence, a change in impedance or morphology of an impedance curve may be used in a feedback loop to indicate that the stimulation energy needs to be adjusted and the system can effectively auto correct the magnitude of stimulation energy to maintain a desired therapeutic effect.

Abstract: Provided is a ventricular assist device cannula, and more particularly, a ventricular assist device cannula with electrodes. An exemplary embodiment of the present invention provides a ventricular assist device cannula with electrodes, including: a connecting tube connecting an incision of a body tissue and a ventricular assist device so that blood can flow; and electrodes connected with the connecting tube and contacting the incision of the body tissue to transfer an electric signal to the body tissue. The ventricular assist device cannula with electrodes according to the exemplary embodiment of the present invention has effects as follows. First, a bio-signal of a patient wearing the ventricular assist device through the electrode attached to the conduit can be easily measured without a separate electrode implant and an electric stimulus can also be measured.

Abstract: A system and method for painlessly calculating an estimated defibrillation threshold, such as by using an implantable medical device and a controller. The estimated defibrillation threshold can be calculated using a delivered first energy to a first thoracic location, an electric field detected at a second thoracic location, and an electric field detected between a third thoracic location and a fourth thoracic location. The estimated defibrillation threshold represents an energy that, when delivered at the first thoracic location, can create an electric field strength in a target region of the heart that meets or exceeds a target electric field strength.

Abstract: One embodiment of the present subject matter includes a method for pulse generation in an implantable device, comprising measuring an impedance between a first electrode and a second electrode and delivering a pulse based on a pulse energy level and a pulse duration limit, comprising generating a pulse duration as a function of the pulse energy level and the impedance and selecting a capacitance value from a plurality of capacitances in a partitioned capacitor bank to deliver a pulse at the pulse energy level and wherein the pulse duration is less than the pulse duration limit.

Abstract: An instrument that utilizes body contact electrodes evaluates the quality of the connections made between the electrodes and the body. An electrode contact quality evaluation circuit performs the quality evaluation, such as by determining contact impedances for the electrodes. The corresponding contact quality of each electrode is conveyed to the user.

Abstract: A device for assisting a rescuer in delivering therapy to an adult or pediatric patient, the device including a user interface comprising a display and/or audio speakers, the user interface being configured to deliver prompts to a rescuer to assist the rescuer in delivering therapy to a patient; a processor configured to provide prompts to the user interface and to perform an ECG analysis algorithm on ECG information detected from the patient; at least one detection element configured to determine without rescuer input via the user interface that a pediatric patient is being treated; wherein, if a pediatric patient is detected, the processor modifies the ECG analysis algorithm or the prompts provided to the user interface to use an ECG analysis algorithm or prompts adapted for a pediatric patient rather than for an adult patient.

Abstract: A modular external defibrillator system in embodiments of the teachings may include one or more of the following features: a base containing a defibrillator to deliver a defibrillation shock to a patient, (b) one or more pods each connectable to a patient via patient lead cables to collect at least one patient vital sign, the pods operable at a distance from the base, (c) a wireless communications link between the base and a selected one of the two or more pods to carry the at least one vital sign from the selected pod to the base, the selection being based on which pod is associated with the base.

Abstract: Methods and apparatus for accurately and painlessly measuring the impedance between defibrillation electrodes implanted in a patient utilize a high current test pulse delivered with a sufficiently high current to produce an accurate measurement of the defibrillation electrode impedance while limiting the duration of the test pulse such that the pain sensing cells in the patient do not perceive the test pulse. In one embodiment, the test pulse is generated from the high voltage transformer without storing energy in the high voltage capacitors and is delivered to the defibrillation electrodes in the patient utilizing the high voltage switching circuitry.