摘要:
A cardiac rhythm management device and method includes a dual-chamber pacemaker especially designed for treating congestive heart failure and a defibrillator as a back-up measure. The device incorporates a programmed microcontroller which is operative to adjust the AV delay of the pacemaker to a minimum or maximum length consistent with optimal cardiac function. The cardiac stimulator includes apparatus for sensing cardiac function from cycle-to-cycle and determining whether incremental changes made to the AV delay interval enhances or worsens the measured cardiac function. On each iterative cycle, the AV delay interval is changed, either incremented or decremented, until a cross-over point is reached in which it is noted that the cardiac function ceases to improve and this is followed with a further incremental adjustment in an opposite direction to compensate for any overshoot. By providing a cardiac defibrillator in combination with the pacing device with closed-loop control of the AV interval, incidences of sudden death due to lethal arrhythmias is reduced.
摘要:
A cardiac stimulating system incorporating a microprocessor-based controller is designed to automatically optimize both the pacing mode and one or more pacing cycle parameters in a way that results in optimization of a cardiac performance parameter, such as cardiac output. For each of a plurality of modes in which a DDD cardiac pacer can operate, a pacing parameter such as the AV interval of the pacer is incrementally adjusted and following that, an observation is made as to the effect of the adjustment on cardiac output. After the process has been repeated for all possible pacing modes, a determination is made to find the pacing mode and the AV interval or other pacing parameter that results in the maximum cardiac output or other optimal cardiac performance parameter. It is these pacing parameters that are then programmed into the microcontroller for causing the pacemaker to function in the desired mode and at the desired parameter values.
摘要:
A method and apparatus for automatically optimizing a cardiac performance parameter of the heart, such as its cardiac output mean arterial pressure pO.sub.2 or pCO.sub.2. The performance parameter is optimized by periodically pacing the heart for a short period of time with stimulating pulses having a modified pacing parameter value. The intrinsic operation of the heart is monitored a majority of the time and establishes a baseline value for the cardiac performance parameter. The heart is then paced with the modified pacing parameter value during an interval that is approximately a 1:4 ratio with respect to the baseline monitoring interval. The method of the present invention can be achieved using a totally implanted pacemaker, an implanted pulse generator in combination with external equipment communicating with the pacemaker via telemetry, or by using equipment located external the patient.
摘要:
A cardiac rhythm management device includes a dual-chamber pacemaker especially designed for treating congestive heart failure and a defibrillator as a back-up measure. The device incorporates a programmed microcontroller which is operative to adjust the AV delay of the pacemaker to a minimum or maximum length consistent with optimal cardiac function. The cardiac stimulator includes apparatus for sensing cardiac function from cycle-to-cycle and determining whether incremental changes made to the AV delay interval enhances or worsens the measured cardiac function. On each iterative cycle, the AV delay interval is changed, either incremented or decremented, until a cross-over point is reached in which it is noted that the cardiac function ceases to improve and this is followed with a further incremental adjustment in an opposite direction to compensate for any overshoot. By providing a cardiac defibrillator in combination with the pacing device with closed-loop control of the AV interval, incidences of sudden death due to lethal arrhythmias is reduced.
摘要:
An implantable monitor/stimulator is disclosed that monitors and assesses indices of cardiac function, including the strength and timing of cardiac contraction, then automatically executes a physician-selected mode of therapy. It accomplishes this by assessing impedance, electrocardiogram, and/or pressure measurements, then calculating various cardiac parameters. The results of these calculations may be stored within the device, telemetered to an external monitor or display and/or may be used by the physician to determine the mode of therapy to be chosen. If indicated, therapy is administered by the device itself or by telemetering control signals to various peripheral devices for the purpose of enhancing either contraction or relaxation of the heart. The cardiac parameters that are calculated all provide an assessment of level of cardiac function by monitoring changes in ventricular filling and ejection or by calculating isovolumic phase indices of heart contraction. Examples of such parameters are ejection fraction, cardiac output, stroke work, and/or various pressure-volume relationships. These parameters determine the mode of therapy that will be selected by a physician. Choices of therapy include several forms of pacing of cardiac or skeletal muscle, and telemetry to implanted or external units for drug infusion or for monitoring by a central data system.
摘要:
A cardiac stimulating apparatus and method which optimizes cardiac performance by determining, from a filtered waveform transmitted from an accelerometer contained within the cardiac pacer, an optimum timing interval between at least one of intrinsic and paced stimulations of pre-selected chambers of the heart. Digitized data of the accelerometer signal, corresponding with identified R--R intervals, are stored for a plurality of preselected timing intervals for analysis and comparison. The accelerometer signal is filtered to isolate features of the waveform associated with specific cardiac events including for example, the first heart sound, the second heart sound or an amplitude in the frequency domain thereof. Characteristic values of these features of the accelerometer signal are calculated over a plurality of complete R--R intervals for each of the preselected timing intervals. The characteristic values are analyzed and compared to determine which timing interval optimizes cardiac performance. The cardiac stimulating apparatus and method may be used in any of several pacing modes including A-V pacing, V--V pacing, or A--A pacing.
摘要:
An elongated monopolar or bipolar coronary vein lead having a reduced outer diameter and especially adapted to be advanced into a selected coronary vein for delivering a pacing signal to a predetermined region of a patient's heart, such as the left ventricle. A method of using the lead for pacing a patient's heart in the treatment of heart failure is also described. The method for pacing the heart includes advancing the coronary vein lead through both the coronary sinus and into a selected coronary vein of a patient's heart, connecting the lead to an electrical pacing source and applying electrical stimulation to a particular chamber of the patient's heart via the implanted lead. The lead includes a flexible tip and transition ring that enhances the ability to guide the lead through the coronary veins.
摘要:
Approaches for selecting an electrode combination of multi-electrode pacing devices are described. Electrode combination parameters that support cardiac function consistent with a prescribed therapy are evaluated for each of a plurality of electrode combinations. Electrode combination parameters that do not support cardiac function are evaluated for each of the plurality of electrode combinations. An order is determined for the electrode combinations based on the parameter evaluations. An electrode combination is selected based on the order, and therapy is delivered using the selected electrode combination.
摘要:
A two-part system for securing and stabilizing a lead at a location within a patient's internal jugular vein adjacent a region of the vagus nerve to be stimulated is described. The two-part system includes a lead and a stent-like fixation member that is provided separate from the lead. The stent-like fixation member is used to secure an electrode region of the lead at a location within the internal jugular vein adjacent the vagus nerve. The stent-like fixation member urges the electrode region of the lead against the vessel walls of the internal jugular vein such that at least one electrode is oriented in a direction towards the vagus nerve. In one example, the stent-like fixation member includes a channel sized to receive and retain a portion of the lead therein.
摘要:
A multipolar lead evaluation device may be configured to easily permit electrical contact to be made between a pacing system analyzer and the terminal pin and each of the terminal contacts of an implantable lead without damaging the implantable lead. Alligator clips may be used to secure electrical conductors from the pacing system analyzer to spring contact clips disposed within the lead evaluation device.