Abstract: For chronic monitoring of the effects of pacing and/or drug therapy in treating CHF, a strain gauge element is disposed at the distal end of a cardiac lead and is effective to produce a signal relating to the amount of flexure being induced into the lead by the beating action of the heart.

Abstract: A cardiac electro-stimulatory device and method for operating same in which stimulation pulses are distributed among a plurality of electrodes fixed at different sites of the myocardium in order to reduce myocardial hypertrophy brought about by repeated pacing at a single site and/or increase myocardial contractility. In order to spatially and temporally distribute the stimulation, the pulses are delivered through a switchable pulse output configuration during a single cardiac cycle, with each configuration comprising one or more electrodes fixed to different sites in the myocardium.

Abstract: A cardiac rhythm management device is configured to detect mechanical oscillations in cardiac rhythm. Upon detection of such oscillations, the device may adjust its operating behavior to compensate for the deleterious effects of the condition.

Abstract: A cardiac electro-stimulatory device and method for operating same in which stimulation pulses are distributed among a plurality of electrodes fixed at different sites of the myocardium in order to reduce myocardial hypertrophy brought about by repeated pacing at a single site and/or increase myocardial contractility. In order to spatially and temporally distribute the stimulation, the pulses are delivered through a switchable pulse output configuration during a single cardiac cycle, with each configuration comprising one or more electrodes fixed to different sites in the myocardium.

Abstract: An apparatus and method for reversing ventricular remodeling with electro-stimulatory therapy. A ventricle is paced by delivering one or more stimulatory pulses in a manner such that a stressed region of the myocardium is pre-excited relative to other regions in order to subject the stressed region to a lessened preload and afterload during systole. The unloading of the stressed myocardium over time effects reversal of undesirable ventricular remodeling.

Abstract: A cardiac rhythm management device for in which pre-excitation pacing is applied to one or more sites in proximity to an infarcted region of the ventricular myocardium. Such pacing servers to either prevent or minimize post-infarct remodeling.

Abstract: A method and apparatus for linear stimulation of the heart to resynchronize contraction for improved hemodynamic benefit. Linear stimulation may be accomplished using a linear source, which may comprise an elongated electrode or plurality of electrodes arranged so as to linearly stimulate the heart. A linear source may be coupled to the left ventricle, and one or more additional electrodes may be positioned so as to stimulate a separate region of the left ventricle or one or more additional chambers of the heart as well. Application of an electrical stimulus by the linear source may function to stimulate a larger region of the heart, thereby enhancing the resynchronization effect as well as providing other hemodynamic benefits.

Abstract: An apparatus and method for reversing ventricular remodeling with electro-stimulatory therapy. A ventricle is paced by delivering one or more stimulatory pulses in a manner such that a stressed region of the myocardium is pre-excited relative to other regions in order to subject the stressed region to a lessened preload and afterload during systole. The unloading of the stressed myocardium over time effects reversal of undesirable ventricular remodeling.

Abstract: A cardiac rhythm management device includes a dual chamber pacemaker, especially designed for treating congestive heart failure by pacing a plurality of sites. The device incorporates a program microcontroller which is operative to adjust the pacing mode and inter-site delay of the pacemaker so as to achieve optimum hemodynamic performance. Atrial cycle lengths measured during transient (immediate) time intervals following a change in the mode inter-site delay are signal processed and a determination can then be made as to which particular configuration yields the optimum performance. Performance is optimized when the patient is at rest and when the patient exercises so that a rate-adapted dynamic value of the optimum performance can be applied.

Abstract: A method and apparatus for performing impedance plethysmography on a living heart for diagnostic and therapy purposes involves placement of plural leads where at least one is disposed within a coronary vein traversing the myocardium on the left side of the heart with another lead having plural electrodes thereon disposed in the right ventricle. By appropriate selection of electrodes on the first and second leads for driving with an AC carrier signal and other such electrodes coupled to a sensing amplifier, an impedance vs. time signal can be derived that when signal processed provides useful information concerning cardiac performance. The multi-site impedance sensing has been found to yield more robust data especially in patients having CHF.

Abstract: Hemodynamic performance of the heart as a pump is optimized by using an accelerometer and signal processing circuitry to measure total acoustic noise (TAN) over predetermined time periods when a pacemaker is made to function in a variety of modes. By detecting the particular mode associated with minimum TAN, the optimum pacing mode is arrived at.

Abstract: Hemodynamic performance of the heart as a pump is optimized by using an accelerometer and signal processing circuitry to measure total acoustic noise (TAN) over predetermined time periods when a pacemaker is made to function in a variety of modes. By detecting the particular mode associated with minimum TAN, the optimum pacing mode is arrived at.

Abstract: 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.

Abstract: 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.

Abstract: A method and an apparatus for pacing the left ventricle of the heart includes the installation of a pacing electrode within the interventricular septum proximate the left ventricular wall thereof and then connecting the electrode to a source of electrical stimulating pulses. The electrode preferably comprises one and possibly two distalmost convolutions on an otherwise insulated corkscrew-style positive fixation lead.

Abstract: An implantable cardiac pacemaker especially designed for treatment of CHF includes an accelerometer for sensing heart sounds and processing circuitry for deriving from the heart sound information the mechanical AV delay of the patient's heart. The pacemaker's applied AV delay is then adjusted until the measured mechanical AV delay falls in a range of between 180 ms and 250 ms. Further optimization of the heart as a pump can then be achieved by incrementally adjusting the pacemaker's applied AV delay interval until a point is reached where a measure of cardiac performance such as aortic pulse pressure is optimized.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A cardiac pacemaker having an automatic pulse rate response gain factor responsive to at least one cardiac-related physiological characteristic of a patient. The pacemaker includes a rate controller that comprises a detector for detecting a plurality of individual measurements of at least one physiological characteristic over each of a plurality of pre-determined time periods, with each of the individual measurements being an average of values detected over each of a respective multiple number of incremental time periods occurring within each of the pre-determined time periods. The pacemaker saves the highest measurement from one incremental time period of each of several consecutive pre-determined time periods, and these highest measurements are averaged. Thereafter, the rate controller adjusts the rate response gain factor or slope of the pulse rate in relation to the physiological characteristic measurement and a pre-determined target pulse rate.