US 5,176,138 A · Implantable pacemaker having means for automatically adjusting stimulation energy as a function of sensed SO.sub.2

Abstract

An implantable programmable pacemaker includes a sensor for measuring SO.sub.2 levels in blood on a periodic basis, e.g., every 15 seconds, while the pacemaker is operating in its programmed mode of operation. The energy of stimulation pulses generated by the pacemaker is automatically adjusted, as required, in order to maintain a prescribed level of SO.sub.2 in the blood. At least a minimum level of SO.sub.2 is presumed when the stimulation pulses are of sufficient energy to effectuate capture. Hence, the SO.sub.2 level is monitored to provide an indication of whether capture has been lost, and if so, to increase the stimulation energy. In one embodiment, the stimulation energy is increased by first increasing the pulse width of the stimulation pulse a prescribed amount. After the pulse width has been increased a maximum amount, and if capture is still lost, the stimulation energy is further increased by increasing the pulse amplitude a prescribed amount. After the pulse amplitude has been increased a maximum amount, and if capture is still lost, the operating mode of the pacemaker is changed, and the stimulation energy is reset to an appropriate value.

Claims25

Dependent claims

An implantable pacemaker comprising:

electronic circuit means housed within an implantable case for generating a stimulation pulse having a prescribed pulse amplitude and pulse width in response to a trigger signal;
lead means detachably secured to said implantable case and electrically connected to said electronic circuit means for delivering said stimulation pulse to a desired stimulation location of a mammalian heart;
sensor means for sensing SO.sub.2 in blood;
control means for generating said trigger signal in accordance with a prescribed pacemaker mode of operation, said control means including means for altering the energy of said stimulation pulse by changing at least one of said prescribed pulse amplitude or pulse width as a function of the amount of SO.sub.2 sensed by said sensor means.

1 more element

A programmable implantable pacemaker comprising:

pulse generating means for providing a stimulation pulse on demand, said stimulation pulse having an initial programmed pulse amplitude and pulse width, and hence an initial programmed energy;
delivery means for delivering said stimulation pulse to at least one of the atrial or ventricular chambers of a mammalian heart in accordance with a programmed mode of operation;
control means for operating said pacemaker in accordance with said programmed mode of operation;
sensor means for measuring the SO.sub.2 level of the blood within or near said mammalian heart every T1 seconds, where T1 is a programmed timed interval;
and
adjustment means for automatically increasing the programmed energy associated with said stimulation pulse in the event that the measured SO.sub.2 level is less than a prescribed reference level at the conclusion of said programmed timed interval;
whereby the energy of the stimulation pulse is adjusted to be only as high as is necessary to maintain a prescribed level of SO.sub.2 in the blood.

4 more elements

A method of determining and maintaining capture of a programmable implantable pacemaker with a minimum expenditure of energy, said pacemaker having means for providing a stimulation pulse on demand, said stimulation pulse having an initial programmed pulse amplitude and pulse width, and hence an initial programmed energy, said pacemaker further having means for delivering said stimulation pulse to at least one of the atrial or ventricular chambers of a mammalian heart in accordance with a programmed mode of operation, and said pacemaker further having means for measuring the SO.sub.2 level of the blood in or near said mammalian heart, said method comprising the steps of:

(a) operating said pacemaker in accordance with said programmed mode of operation;
(b) measuring the SO.sub.2 level of the blood within or near said mammalian heart every T1 seconds, where T1 is a programmed time interval;
and
(c) automatically increasing the programmed energy associated with said stimulation pulse in the event that the measured SO.sub.2 level is less than a prescribed reference level,
whereby the energy of the stimulation pulse is adjusted to be only as high as is necessary to maintain a prescribed level of SO.sub.2 in the blood.

2 more elements

Dependencies are inferred from the claim text.

Implantable pacemaker having means for automatically adjusting stimulation energy as a function of sensed SO.sub.2

Life of this patent

Implantable pacemaker having means for automatically adjusting stimulation energy as a function of sensed SO.sub.2

Life of this patent

Abstract

Claims25