摘要:
An implantable automatic cardioverter/defibrillator device for a cardiac patient is automatically responsive to sensing of electrical cardiac activity of the heart of a patient in which the device is implanted for detection and treatment of fibrillation. A prescribed electrical shock waveform regimen is generated as electrical defibrillation therapy for application to the heart in response to detection of fibrillation of the heart. A timing function circuit responds to the detection by timing the delivery of the generated prescribed electrical waveform regimen to be applied at a point in time at which the fibrillation ECG has substantially its highest amplitude and lowest frequency, as a point of high susceptibility to reversion to sinus rhythm upon application of a shock, and with low defibfillation threshold, to enhance the probability of successful defibrillation, and to synchronize the shock delivery to this sensed intracardiac event.
摘要:
A defibrillator has a signal generator implemented to deliver output shock waveforms and housed in a case adapted to be implanted in the left pectoral region of a cardiac patient. The case is implemented to interact with internal circuitry of the generator to maintain the case active as an electrode. An electrical transvenous lead has a proximal electrode for electrical connection to the internal circuitry of the signal generator and a distal end adapted to be positioned in the right ventricle (RV) of the patient's heart. The lead includes a sensing tip for contacting the RV to sense the patient's ECG signal and a shocking coil arranged to be located in the RV when the transvenous lead is implanted in the patient. The internal circuitry of the signal generator includes triggerable output circuit for developing an output shock waveform when triggered in response to detection of ventricular fibrillation of the patient's heart from the sensed ECG signal. The internal circuitry also includes a timer responsive to the sensed ECG signal for timing the application of the shock waveform developed by the output circuit across the transvenous lead and the active case with a predetermined delay relative to the occurrence of an R-wave of the sensed ECG signal next following detection of fibrillation until at least about 50% of the R-R cycle length of the ECG signal has elapsed, to optimize the timing of delivery of an electric field vector derived from the shock waveform across a myocardial mass of the patient's heart between the shocking coil and the active case.
摘要:
An interventional medical device has a capability to sense cardiac dysrhythmias and to selectively respond with one among a hierarchy of therapies appropriate to terminate the sensed dysrhythmia and return the heart of the patient in whom the device is adapted to be implanted to normal sinus rhythm. The device includes a therapy generator having a housing and electronics for conducting bidirectional communication with the patient. The bidirectional communication is carried out by detecting the occurrence of a predetermined dysrhytlnia, such as atrial fibrillation, to alert the patient of such occurrence, and by responding to instructions from the patient following such alert for addressing the detected predetermined dysrhythmia. The detection is performed by electrodes mounted directly on the header of the device housing to both detect occurrence of the atrial fibrillation and for alerting the patient thereof by stimulating body tissue such as pectoral muscle in the vicinity of the header electrodes. Response to patient-initiated instructions is implemented by triggering certain device functions such as storage of ECG events detected by the header electrodes, or deliver of a therapy appropriate to terminate the atrial defibrillation, or delay of delivery of the appropriate therapy, according to the nature of the patient-initiated instructions.
摘要:
An implantable cardioverter/defibrillator device is implemented to be selectively non-invasively upgraded from time to time after implantation to enable the device to provide additional therapy for arrhythmia treatment as the patient's need for such treatment undergoes change. The device is adapted to provide a plurality of functions corresponding to different levels of therapy for treating arrhythmias, and to respond to each different type of arrhythmia that may be sensed, to supply a function which is designated as being appropriate to relieve that respective arrhythmia. Each function is not necessarily unique to treating a particular arrhythmia, and, in at least some instances, may be used to treat more than one of the plurality of different types of arrhythmias. At the time of its implant, the device is restricted from providing those of the plurality of functions which are deemed as being non-essential to the patient's needs at that time. From time to time thereafter, however, as the patient experiences periodic need for additional therapy, restricted functions of the device are selectively restored by external programming, but only if the programmer is able to supply to the device an enabling code which is substantially unique to that device. In this way, restoration of the restricted functions is locked out except with a prescribed key.
摘要:
A programmable dual-chamber artificial cardiac pacemaker senses atrial activity and normally tracks the sensed atrial activity in pacing the ventricular activity. An accelerometer located in the case of the pulse generator portion senses physical exercise by a patient when the pacemaker is implanted in the patient, and generates a rate control signal indicative of extent of the sensed physical exercise. The pulse generator is programmed for ventricular pacing rate control in multiple rate zones bounded by rate limits including a ventricular tracking limit (VTL) that varies dynamically with sensed physical exercise and a higher mode switch rate. The ventricular pacing rate tracks the sensed atrial activity on a 1:1 basis for atrial rates below the dynamic VTL (DVTL) during a predetermined interval of time for which the DVTL applies, and tracks the sensed atrial activity in Wenckebach behavior for atrial rates above the DVTL up to the mode switch rate with the ventricular pacing rate limited by the DVTL. The mode switch rate is set to effect a switch from dual-chamber to single-chamber mode when the sensed rate of atrial activity exceeds the mode switch rate for a programmed number of cardiac cycles, in which the ventricular pacing rate is controlled solely by sensed spontaneous ventricular activity without regard to the DVTL or sensed physical exercise. The mode switch rate also effects a reversion to the dual-chamber mode when the sensed rate of atrial activity drops below the mode switch rate for a programmed number of cardiac cycles, in which the ventricular pacing rate is controlled according to the respective one of the multiple rate zones in which the atrial activity rate is present.
摘要:
Device and method are disclosed in which leads with pacing and defibrillating electrodes are implanted into both the right and left ventricles of a patient's heart to enable simultaneous pacing of both ventricles to reduce the width of the QRS complex of the patient's cardiac activity to a more normal duration, and, when appropriate, to apply electrical shock waveforms to both ventricles simultaneously for lower energy defibrillation of the ventricles. In applying the defibrillation therapy, the defibrillating electrode in the left ventricle may be used as the anode and the defibrillating electrode in the right ventricle may be used as the cathode, or both ventricular defibrillating electrodes may be the anode and the metal case in which the shock waveform generator is implanted may be the cathode. Implanting a lead with pacing and defibrillating electrodes in the right atrium enables selective pacing and defibrillation of the atria, in which atrial fibrillation is treated by applying the shock waveform across the right atrial and left ventricular defibrillation electrodes.
摘要:
A method of implanting small diameter conductive leads for an artificial cardiac pacemaker or other body-implantable medical device includes inserting the lead to be implanted into a predetermined path within the patient's body with the assistance of a stylet for guiding the lead along the path. At least a portion of the stylet which is to traverse the path has an enhanced radiopaque characteristic attributable to the application or addition to the material of which the stylet is composed, of a substance having such radiopaque characteristic. When viewed under fluoroscopy external to the patient's body as the lead is maneuvered along the path, although the thin lead itself may be difficult to see, the stylet is readily discernible by virtue of its enhanced radiopacity, thereby enabling the physician to position the lead at a desired location within the patient's body. For various reasons, the thin lead itself may not be amenable to similar enhancement, which makes the stylet a suitable solution. A portion of the distal end of the stylet, such as its distal tip or a plurality of spaced apart points along its distal end, is provided with the enhanced radiopacity, as by application or addition of gold to the stylet material.
摘要:
An interventional medical device has a capability to sense cardiac dysrhythmias and to selectively respond with one among a hierarchy of therapies appropriate to terminate the sensed dysrhythmia and return the heart of the patient in whom the device is adapted to be implanted to normal sinus rhythm. The device includes a therapy generator having a housing and electronics for conducting bidirectional communication with the patient. The bidirectional communication is carried out by detecting the occurrence of a predetermined dysrhythmia, such as atrial fibrillation, to alert the patient of such occurrence, and by responding to instructions from the patient following such alert for addressing the detected predetermined dysrhythmia. The detection is performed by electrodes mounted directly on the header of the device housing to both detect occurrence of the atrial fibrillation and for alerting the patient thereof by stimulating body tissue such as pectoral muscle in the vicinity of the header electrodes. Response to patient-initiated instructions is implemented by triggering certain device functions such as storage of ECG events detected by the header electrodes, or deliver of a therapy appropriate to terminate the atrial defibrillation, or delay of delivery of the appropriate therapy, according to the nature of the patient-initiated instructions.
摘要:
An automatic defibrillator is arranged and adapted to be implanted in a cardiac patient. The defibrillator includes a stimulus generator for sensing fibrillation of the patient's heart and for responding by delivering defibrillation energy to the patient's heart via a defibrillation electrode positioned in the right ventricle of the heart. An electrically conductive case houses the stimulus generator, and a conforming biocompatible electrically non-conductive layer is coated over only a predetermined portion less than all of the case to produce a predetermined shape of electric field between the intracardiac defibrillation electrode and the case when the case is used as an electrode for defibrillation. The predetermined portion of the case coated with the non-conductive layer includes a side of the case to be implanted in a direction facing the heart of the patient, with the non-conductive layer being confined solely to the central portion of that side.
摘要:
An implantable medical interventional device responds to detection of any of a plurality of cardiac dysrhythmias in a human patient by performing an appropriate therapy which may include cardiac pacing, cardioversion or defibrillation according to the nature of the detected dysrhythmia. A first sensor detects whether and what type of dysrhythmia is occurring. A generator produces pulses and/or shocks for delivery to the patient's heart according to whether a detected dysrhythmia is bradycardia or slow pathologic tachycardia on the one hand, or fast tachycardia or fibrillation on the other hand. An optimizer in the device at all times maintains a substantial match of the cardiac pacing rate to the hemodynamic needs of the implant patient under conditions of rest and physical activity; including sensing and distinguishing periods of patient physical activity and rest, and generating a signal representative thereof to control the cardiac pacing rate accordingly. In this way, the device focuses on correction of cardiac pacing problems before they become sufficiently aggravated to require more aggressive cardioversion and defibrillation therapies.