St. Jude Medical Ab

Pacesetter Ab

Asa Uhrenius

Nils Holmström

Sven-Erik Hedberg

Anders Björling

Hans G Strandberg

Peter Andersson

Göran Budgifvars

Karin Järverud

Berit Larsson

Goran Budgifvars

G&ouml;ran Budgivars

An implantable bi-ventricular heart stimulating device and system, suitable for treating congestive heart failure, have a control circuit with first and second pacing circuits and first and second sensing circuits. The device operates with time cycles corresponding to normal heart cycles. The control circuit determines: (a) whether a signal typical of an evoked response to a pacing pulse delivered by the first pacing circuit is sensed within a first time interval and (b) whether a signal typical for an R-wave transferred from the second ventricle, or from some other part of the heart, to the first ventricle is detected within a first time window. The operation of the device depends on whether the conditions (a) and (b) are fulfilled.

Bi-ventricular pacer, system and method

An implantable bi-ventricular heart stimulating device () has a control circuit with first and second sensing circuits for respectively sensing in the two ventricles and first and second stimulation circuits for respectively stimulating the two ventricles. The control circuit determines whether a signal, sensed by said second sensing circuit, occurs essentially simultaneously with a signal sensed by the first sensing circuit. Furthermore, the control circuit determines whether a further signal is sensed by said second sensing circuit within a predetermined time interval which follows after the signal sensed by the second sensing circuit but within the same time cycle as that signal. If this occurs, the control circuit determines whether the sensed signals represent actual cardiac events, or are likely the result of far field detection.

Implantable bi-ventricular stimulation device and system, and bi-ventricular stimulation and sensing method

An implantable bi-ventricular heart stimulating device has a control circuit that within a time cycle, delivers pacing pulses with both first and second pacing circuits with a time gap between a pacing pulse delivered by these pacing circuits. The time gap can be such that a pacing pulse delivered by the second pacing circuits falls substantially within a first time interval in which an evoked response can be expected to a pacing pulse delivered by the first pacing circuit. The control circuit performs a temporary modification of the operation of the device such that during at least one time cycle no pacing pulse is delivered by the second pacing circuit during the first time interval.

A heart stimulator has an evoked response detector for determining evoked response in the presence of polarization. The heart stimulator produces stimulation pulses of different amplitudes via a lead introduced to the heart of the patient. The evoked response detector measures an electrode signal picked up by the lead after each stimulation pulse. In order to set an evoked response threshold value, the pulse generator of the stimulator is controlled to deliver at least two stimulation pulses with different amplitudes, at least one of these stimulation pulses having a high amplitude that exceeds the stimulation threshold value. A measuring unit in the evoked response detector measures the picked up electrode signals, and a calculating unit in the evoked response detector calculates the polarization for the high stimulation amplitude and identifies a measured electrode signal for the lowest possible stimulation amplitude from the measured electrode signals. The evoked response detector also has an analyzing unit which sets a threshold value for the measured electrode signal from the calculated polarization and lowest possible stimulation amplitude.

Evoked response detector for a heart stimulator

An evoked response detector for a heart stimulator determines evoked response in the presence of polarization. The heart stimulator has a pulse generator which produces stimulation pulses of varying amplitudes, and a lead adapted for introduction into the heart of a patient is connected to the pulse generator for delivering stimulation pulses to the heart. The evoked response detector includes measuring and memory circuitry for measuring and storing the electrode signals picked up by the lead in response to the delivered stimulation pulses, at least one of these stimulation pulses having a sufficiently high amplitude for obtaining capture. Each measured electrode signal contains two signal components, one of these signal components being proportional to the amplitude of the associated stimulation pulse and the other signal component being substantially constant, independent of the associated stimulation pulse amplitude. An analyzing unit determines the evoked response signal from a predetermined relation between the amplitudes of at least two stimulation pulses of different amplitudes and the resulting measured electrode signals.

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Stockholm, Sweden

Asa Uhrenius