Siemens Elema Ab

Siemens Aktiengesellschaft

Pacesetter Ab

Per Franberg

Anders Lindgren

Hans G Strandberg

Lennart Moberg

A heart stimulator for detecting atrial tachycardia, contains a control device to which are connected an atrial detector, having a blanking period, for detecting atrial events, a ventricular stimulation unit for delivering stimulation pulses in the ventricle, a counter for generating a variable PV interval between a detected atrial event and a stimulation pulse delivered in the ventricle, a time measurement unit for measuring time between two consecutive, detected atrial events and a calculation unit which, in a test mode for determining of whether atrial tachycardia is present, is arranged to cause the counter to generate a PV interval so the PV interval plus the atrial detector's blanking period is equal to half or less than half of an adjustable threshold level PP tachycardia. The time measurement unit sends a detection signal to the control device when a defined number of measured, consecutive PP intervals is less than a defined threshold value PP for the PP interval (threshold value PP tachycardia).

Atrial tachycardia-detecting heart stimulator comparing a plurality of

In a heart stimulator which delivers stimulation pulses to a heart when the heart's spontaneous rate drops below a defined basic rate, in order to reduce the period during which the heart stimulator emits stimulation pulses, the defined basic rate is slow. When the spontaneous heart rate drops below the defined basic rate, stimulation pulses are initially emitted at a faster stimulation rate, in relation to the basic rate, the stimulation rate then dropping toward the defined basic rate.

Heart stimulator

A heart stimulator is disclosed which is capable of sensing and stimulating both the atrium and the ventricle in a heart such that a ventricular stimulation pulse is emitted, either after expiration of an atrioventricular interval following a stimulated or spontaneous atrial event, or after expiration of a minimum synchronous interval following a stimulated or spontaneous ventricular event, depending on which of the two intervals expires last. After each ventricular event, an atrial refractory period is imposed during which atrial detections are interpreted as noise. Operation of the heart stimulator when the atrium's spontaneous rate is faster than a stimulation rate corresponding to the minimum synchronous interval is improved by measuring the interval between atrial events. If a detection during the atrium's refractory period occurs at a time corresponding to the latest interval timed, the detection is interpreted as an approved atrial event, and a ventricular stimulation pulse is emitted after expiration of the minimum synchronous interval.

Method and apparatus for stimulating a heart

A heart stimulator is disclosed which is capable of sensing and stimulating both the atrium and ventricle in a heart such a way that a ventricular stimulation pulse is emitted either after a stimulated or spontaneous atrial event following the atrioventricular interval, or after the expiration of a minimum synchronous interval following a stimulated or spontaneous ventricular event, depending on which interval elapses last. The functioning of the heart stimulator, when the atrium's spontaneous rate is faster than a stimulation rate corresponding to the minimum synchronous interval, is improved by delivering an extra atrial stimulation pulse at a second predetermined atrioventricular interval before the next ventricular stimulation pulse, if the interval between the most recently detected atrial event and the next ventricular stimulation pulse exceeds a predetermined threshold value.

In a dual chamber pacemaker capable of stimulating the atrium and ventricle in a heart, a stimulation pulse in the atrium could be sensed as a ventricular event which cannot be distinguished from a premature ventricular contraction, so the pacemaker institutes a blanking interval in which no sensing occurs and a crosstalk interval in which sensing occurs, detections in the crosstalk interval causing the emission of a ventricular stimulation pulse with a shortened A-V interval. A dual chamber pacemaker and a method for operating same are disclosed wherein the blanking interval is optimized so as to reduce the risk of a PVC being missed and so as also to minimize the number of detected events, caused by crosstalk from the atrium, in crosstalk intervals. This is accomplished by counting, for a number of cardiac cycles, the number of detections in crosstalk intervals and forming a relationship of the count to the number of cardiac cycles. This reduction is then used to determine the length of the blanking interval.

Dual chamber pacemaker and method for operating same

In an implantable medical device for stimulating a heart, an activity signal from an activity sensor is transformed by response amplification into a stimulation rate at which a stimulation pulse generator delivers stimulating pulses to the heart. The response amplification is automatically optimized because the device contains an evaluation stage which, over a period of time, registers the stimulation rate and then compares this rate to a preset average rate, whereupon a control unit in changes the response amplification so the response amplification is increased when the registered stimulation rate is slower than the average rate and is decreased when the registered stimulation rate is faster than the average rate.

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Stockholm, Sweden

Per Franberg