Abstract: In a method and apparatus for measuring the ejection fraction in a mammalian heart, the opening and closing of a heart valve is sensed with an implanted sensor, and a pre-ejection period is measured as a function of the sensed opening and closing of the heart valve. The ventricular ejection time also is measured, and the ejection fraction is determined as a function of the measured pre-ejection period and the ejection time.

Abstract: A method, an implantable medical device, and a computer-readable medium encoded with programming instructions allow monitoring of a hematocrit value and an SvO2 level of a patient, making use of at least one medical lead connected to an implantable medical device that carries an optical sensor module that measures at least one hematocrit value and at least one SvO2 value using at least first, second and third light radiation wavelengths, by determining a present hematocrit value from at least one of the measured hematocrit values and determining a present SvO2 value from at least one of the measured SvO2 values, and determining a patient status by evaluating the present hematocrit value and the present SvO2 value, to allow a change in the patient status to be identified.

Abstract: A subcutaneous cardiac stimulation system verifies accelerated arrhythmia detection before delivering accelerated arrhythmia therapy to the heart. The stimulation system includes a verification circuit that verifies detection of the accelerated arrhythmia with each of first and second sense channels utilizing first and second electrode configurations. The therapy circuit delivers the stimulation therapy to the heart if the accelerated arrhythmia detection is verified with each of the first and second electrode configurations. The system also compensates for transient rate changes during the detection of the accelerated arrhythmia.

Abstract: In an ischemia detection method, and in an ischemia detector and a cardiac stimulator embodying an ischemia detector, a workload of a patient is measured, as is an ejection fraction (EF) associated with the heart of the patient is determined. A predetermined reference relation between EF and workload for the patient is stored, and an analysis unit detects a state of ischemia of the patient from deviation in the determined EF for various workloads from the stored reference relation.

Abstract: Methods and systems are provided for performing ventricular arrhythmia monitoring using at least two sensing channels that are each associated with different sensing vectors, for example by different pairs of extracardiac remote sensing electrodes. Myopotential associated with each of the sensing channels in monitored, and a ventricular arrhythmia monitoring mode is selected based thereon (e.g., based on determined myopotential levels). Ventricular arrhythmia monitoring is then performed using the selected monitoring mode.

Abstract: In an implantable medical device and a method and computer-readable medium for operating the medical device to detect a condition of a heart of a patient, activity level of a patient and acoustic energy in a patient are sensed, and acoustic signals are generated that are indicative of heart sounds of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles. A signal corresponding to a first sound is extracted from the sensed acoustic signal of a cardiac cycle. A relation is calculated between a first signal corresponding to the first heart sound in a first activity range, and a second signal corresponding to the first heart sound in a second predetermined activity level range. The calculated relation is compared with at least one reference value to detect the condition or a change of the condition.

Abstract: A method for detecting a condition of a heart of a patient using an implantable medical device including the steps of sensing acoustic signals indicative of heart sounds of the heart of the patient; extracting signals corresponding to a first heart sound (S1) and a second heart sound (S2) from sensed signals; calculating an energy value corresponding to a signal corresponding to the first heart sound (S1) and an energy value corresponding to the second heart sound (S2); calculating a relation between the energy value corresponding to the first heart sound and the energy value corresponding to the second heart sound for successive cardiac cycles; and using at least one relation to detect the condition or a change of the condition. A medical device for determining the posture of a patient and a computer readable medium encoded with instructions are used to perform the inventive method.

Abstract: A method for operating an implantable medical device to control a stimulation therapy includes the steps of: sensing an acoustic energy; producing acoustic signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; extracting a signal corresponding to a first heart sound (S1) from a measured acoustic signal; calculating an energy value corresponding to the extracted signal; storing the energy value corresponding to the first heart sound; and initiating an optimization procedure, the optimization procedure comprising the steps of: iteratively controlling a delivery of the pacing pulses based on successive energy values corresponding to successive first heart sound signals and determining an optimal PV interval or AV interval with respect to the energy values. A medical device and a computer readable medium to implement the method.

Abstract: A method for operating an implantable medical device to obtain substantially synchronized closure of the mitral and tricuspid valves based on sensed heart sounds includes sensing an acoustic energy; producing signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; calculating a pulse width of such a signal; and iteratively controlling a delivery of the ventricular pacing pulses based on calculated pulse widths of successive heart sound signals to identify an RV interval or VV interval that causes a substantially synchronized closure of the mitral and tricuspid valve. A medical device for optimizing an RV interval or VV interval based on sensed heart sounds implements such a method and a computer readable medium encoded with instructions causes a computer to perform such a method.

Abstract: Methods and systems are provided for performing ventricular arrhythmia monitoring using at least two sensing channels that are each associated with different sensing vectors, for example by different pairs of extracardiac remote sensing electrodes. Myopotential associated with each of the sensing channels in monitored, and a ventricular arrhythmia monitoring mode is selected based thereon (e.g., based on determined myopotential levels). Ventricular arrhythmia monitoring is then performed using the selected monitoring mode. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: Methods and systems are provided for performing ventricular arrhythmia monitoring using at least two sensing channels that are each associated with different sensing vectors, for example by different pairs of extracardiac remote sensing electrodes. Myopotential associated with each of the sensing channels in monitored, and a ventricular arrhythmia monitoring mode is selected based thereon (e.g., based on determined myopotential levels). Ventricular arrhythmia monitoring is then performed using the selected monitoring mode. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: In a cardiac assist device and method, a microphone is placed in contact with the epicardium of the heart of a patient, and heart and lung sounds are simultaneously detected at the placement location of the microphone. The heart and lung sounds are automatically analyzed to set an appropriate cardiac therapy for the patient.

Abstract: In a method and apparatus for measuring the ejection fraction in a mammalian heart, the opening and closing of a heart valve is sensed with an implanted sensor, and a pre-ejection period is measured as a function of the sensed opening and closing of the heart valve. The ventricular ejection time also is measured, and the ejection fraction is determined as a function of the measured pre-ejection period and the ejection time.

Abstract: In a device and a method for determining a cardiac condition from a detected cardiac signal, an input signal is formed from the detected cardiac signal and supplied to an analysis unit. The analysis unit forms an analysis signal from the input signal, having a real part substantially corresponding to the input signal and an imaginary part that is a predetermined transformation of the input signal. A calculation unit operates on the analysis signal to calculated at least two heart-related parameters therefrom. The heart-related parameters are supplied to a processing unit that combines the heart-related parameters in a predetermined manner for identifying a cardiac condition.

Abstract: In an implantable heart stimulating device, system and method, electrical stimulation pulses are delivered to first and second ventricles of a heart with a variable time interval therebetween, and signals are sensed at two different positions in the heart, from which an impedance value is derived. A minimum value and a maximum value of the impedance value are determined during a heart cycle, and a relationship between the minimum and maximum values also is determined. The time interval is varied and the relationship is monitored over a number of heart cycles. The time interval is set so that the relationship satisfies a predetermined requirement.

Abstract: A heart stimulator for electric stimulation of a patient's heart has an impedance measuring unit that measures the impedance between at least two measurement electrodes implanted in a patient such that volume changes of at least one of the chambers of the left heart result in changes in the measured impedance. An analyzer analyzes the measured impedance for the control of the stimulation of the heart. A calculation unit calculates an average impedance morphology curve during a time interval of several cardiac cycles. The analyzer analyzes the average impedance morphology curve for use for the control of the stimulation to optimize the patient hemodynamics.

Abstract: A congestive heart failure monitor has an impedance measuring unit that measures the impedance between at least two electrodes implanted in a patient, to use a detected change of the measured impedance as an indication of a change in the left atrium volume. Any analyzing unit analyzes the measured impedance and detects insipient congestive heart failure dependent on a quotient of a maximum value of the measured impedance and a minimum value of the measured impedance during a cardiac cycle.

Abstract: A valve opening detector for use in an implantable medical device detects opening of at least one valve in the left side of heart, and has an impedance measuring unit for measuring electrical impedance between measuring poles and for generating an impedance signal corresponding thereto, at least one of the poles being arranged in the coronary sinus and/or in the great cardiac vein of the heart. The valve opening detector also includes an impedance signal processor which processes the impedance signal to detect the opening of one or both valves in the left side of the heart.

Abstract: A dual chamber pacing system normally operates in an atrial synchronized mode, and includes a mode switch that switches the pacing mode to a non-atrial synchronized ventricular stimulating mode in response to the detection of an atrial tachyarrhythmia, and switches the pacing mode back to the atrial synchronized mode in response to, or after a preset time following, detection of cessation of the atrial tachyarrhythmia. A mode switch supervising circuit includes a counter that accumulates an amount of mode switches from a starting point, and supplies the accumulated amount to a comparator, wherein the accumulated amount is compared to a predetermined mode switch amount threshold. The mode switch supervising circuit controls the mode switch to lock the pacing mode to the non-atrial synchronized ventricular stimulating mode for at least a predetermined time period in response to the mode switch amount exceeding the amount threshold.

Abstract: A pacemaker has a pulse generator for delivering stimulation pulses to a patient's heart, a sensor for measuring a parameter related to cardiac output, and a control unit for controlling the delivery of stimulation pulses from the pulse generator. The control unit includes an altering unit for altering at least one of the VV delay between consecutive stimulation pulses to the right and left ventricles and the AA delay between consecutive stimulation pulses to the right and left atria. The sensor measures the parameter in various time windows within a time of operation of predetermined VV- or AA-delay values. A determining unit includes a calculation unit for calculating an average value of the measured parameter during each of said time windows and the determining unit uses these average values to determine which one of the VV- and/or AA-delay values results in a higher cardiac output.