Method and apparatus for providing enhanced 2:1 block response with rate-responsive AV delay in a pacemaker
First Claim
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1. An implantable pacemaker, comprising:
- atrial sensing means for sensing an intrinsic atrial rate in an atrial chamber of the heart;
pulse generating means for generating pacing pulses for delivery to the atrial and ventricular chambers of the heart;
defining means for defining a block entry rate and a block exit rate, the block entry and block exit rates being substantially equal; and
control means, coupled to the atrial sensing means, the pulse generating means, and to the defining means, for determining when the intrinsic atrial rate exceeds the block entry rate and when the intrinsic atrial rate falls below the block exit rate, and for pacing in the ventricle in a 2;
1 block response when the intrinsic atrial rate exceeds the block entry rate and for terminating the 2;
1 block response mode when the intrinsic atrial rate falls below the block exit rate.
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Abstract
An implantable dual-chamber pacemaker programmed to operate primarily in an atrial tracking mode is provided, where the pacemaker maintains a consistent atrial rate of entry into, and exit from, a 2:1 block response mode by setting rate-responsive AV delay values in accordance with a continually monitored intrinsic atrial rate incorporating atrial events occurring during atrial refractory periods. The atrial rate of entry into, and exit from the 2:1 block response mode is determined by the length of a total atrial refractory period, which is the sum of the rate-responsive AV delay and a programmable refractory period.
80 Citations
18 Claims
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1. An implantable pacemaker, comprising:
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atrial sensing means for sensing an intrinsic atrial rate in an atrial chamber of the heart; pulse generating means for generating pacing pulses for delivery to the atrial and ventricular chambers of the heart; defining means for defining a block entry rate and a block exit rate, the block entry and block exit rates being substantially equal; and control means, coupled to the atrial sensing means, the pulse generating means, and to the defining means, for determining when the intrinsic atrial rate exceeds the block entry rate and when the intrinsic atrial rate falls below the block exit rate, and for pacing in the ventricle in a 2;
1 block response when the intrinsic atrial rate exceeds the block entry rate and for terminating the 2;
1 block response mode when the intrinsic atrial rate falls below the block exit rate. - View Dependent Claims (2, 3, 4, 5)
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6. An implantable pacemaker, comprising:
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atrial sensing means for sensing an intrinsic atrial rate in the atrial chamber of the heart; pulse generating means for generating pacing pulses for delivery to the atrial and ventricular chambers; defining means for defining a base rate and a maximum tracking rate (MTR); and control means, coupled to the atrial sensing means, the pulse generating means, and to the defining means, for pacing the ventricular chamber so that the ventricular chamber is paced at a rate at least equal to the base rate, and at most equal to the MTR, the control means further comprising; means for defining a programmable post ventricular atrial refractory period (PVARP); means for defining a rate responsive AV delay (RRAVD); means for sensing at least one cardiac cycle; means for defining a programmable total atrial refractory period (TARP) comprising a sum of the PVARP and the RRAVD in each sensed cardiac cycle; means for determining the intrinsic atrial rate by causing the atrial sensing means to sense all atrial events of each cardiac cycle, including atrial events occurring during the TARP of each cardiac cycle; means for setting the RRAVD to a maximum value, corresponding to a maximum TARP, when the intrinsic atrial rate is less than or equal to the base rate; means for setting the RRAVD to a minimum value, corresponding to a minimum TARP, when the intrinsic atrial rate is greater than or equal to a second threshold rate; and means for setting the RRAVD to at least one intermediate value, corresponding to an intermediate TARP, when the intrinsic atrial rate is greater than the base rate and less than the second threshold rate. - View Dependent Claims (7, 8, 9)
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10. An implantable pacemaker, comprising:
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means for defining a programmable total refractory period; atrial sensing means for sensing an intrinsic atrial rate in an atrial chamber of a heart, the atrial sensing means comprising means for sensing atrial events during the total refractory period; pulse generating means for generating pacing pulses for delivery to the atrial and ventricular chambers; means for defining a block entry rate and a block exit rate, the block entry and block exit rates being substantially equal; and first trigger means for initiating a 2;
1 block response when the intrinsic atrial rate exceeds the block entry rate; andsecond trigger means for terminating a 2;
1 block response when the intrinsic atrial rate decreases below the block exit rate. - View Dependent Claims (11, 12, 13, 14)
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15. a method of operating an implantable pacemaker comprising the steps of:
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coupling the pacemaker to, respectively, an atrial chamber and a ventricular chamber of a heart; generating pacing pulses for delivery to the atrial and ventricular chambers of the heart; defining a first refractory period and a second refractory period which are programmable by the physician; defining a programmable total refractory period comprising a sum of the first refractory period and the second refractory period; sensing an intrinsic atrial rate in an atrial chamber of the heart, including sensing of atrial events during the total refractory period; defining a first threshold rate and a second threshold rate; determining when the intrinsic atrial rate is less than or equal to the first threshold rate, when the intrinsic atrial rate is greater than or equal to the second threshold rate, and when the intrinsic atrial rate is greater than the first threshold rate and less than the second threshold rate; and automatically selecting a maximum value for the second refractory period when the intrinsic atrial rate is less than or equal to a first threshold rate, automatically selecting a minimum value for the second refractory period when the intrinsic atrial rate is greater than or equal to a second threshold rate, and automatically selecting at least one intermediate value for the second refractory period when the intrinsic atrial rate is greater than the first threshold rate and less than the second threshold rate; whereby the total refractory period equals a minimum total refractory period when the second refractory period is set to a minimum value, the total refractory period equals at least one intermediate total refractory period when the second refractory period is set to at least one intermediate value, and the total refractory period equals a maximum total refractory period when the second refractory period is set to a maximum value. - View Dependent Claims (16, 17, 18)
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Specification