Metabolic demand driven rate-responsive pacemaker
First Claim
1. A dual-chamber rate-responsive pacemaker, comprising:
- means for generating ventricular pacing pulses,means for sensing atrial heartbeats,means responsive to said atrial heartbeat sensing means for deriving an indication of intrinsic atrial rate,sensor means for determining a metabolic indicator rate,means for determining a maximum atrial tracking rate as a function of said metabolic indicator rate,means for comparing said intrinsic atrial rate indication to said maximum atrial tracking rate, andmeans responsive to said comparing means for controlling said generating means to operate in a first mode in which ventricular pacing pulses are generated in synchrony with operations of said atrial heartbeat sensing means when said intrinsic atrial rate indication is slower than said maximum atrial tracking rate, and for controlling said generating means to operate in a second mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate, with timing independent of said atrial heartbeat sensing means, when said intrinsic atrial rate indication exceeds said maximum atrial tracking rate,said controlling means including;
means responsive to said comparing means for developing a record of the occurrence of recent cardiac cycles in which said intrinsic rate exceeded said maximum atrial tracking rate,decision means for deciding whether said record meets a predetermined criterion, andmeans responsive to said decision means for governing whether said ventricular pacing pulse generating means operates in said first or said second mode.
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Accused Products
Abstract
A rate-responsive dual-chamber pacemaker and pacing method for supporting the heart with electrical stimulation at a pacing rate driven by the heart'"'"'s sinus node or, alternatively, by a sensor adapted to determine the patient'"'"'s metabolic demand (a metabolic demand indicator). The pacemaker automatically selects between the indicated rates to determine the best pacing rate for appropriately satisfying metabolic demand at all times. The natural rate, driven by the sinus node, takes precedence over the metabolic indicator rate provided the natural rate meets a standard determined by the metabolic demand indicator rate. The pacemaker upper rate response mechanism allows atrioventricular synchrony at natural sinus rates ranging from low rates to high exercise rates, even up to the programmed maximum rate, but maintains ventricular rate stability during pathological atrial tachycardias by reverting to pacing in a rate-responsive VVI mode.
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Citations
78 Claims
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1. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating ventricular pacing pulses, means for sensing atrial heartbeats, means responsive to said atrial heartbeat sensing means for deriving an indication of intrinsic atrial rate, sensor means for determining a metabolic indicator rate, means for determining a maximum atrial tracking rate as a function of said metabolic indicator rate, means for comparing said intrinsic atrial rate indication to said maximum atrial tracking rate, and means responsive to said comparing means for controlling said generating means to operate in a first mode in which ventricular pacing pulses are generated in synchrony with operations of said atrial heartbeat sensing means when said intrinsic atrial rate indication is slower than said maximum atrial tracking rate, and for controlling said generating means to operate in a second mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate, with timing independent of said atrial heartbeat sensing means, when said intrinsic atrial rate indication exceeds said maximum atrial tracking rate, said controlling means including; means responsive to said comparing means for developing a record of the occurrence of recent cardiac cycles in which said intrinsic rate exceeded said maximum atrial tracking rate, decision means for deciding whether said record meets a predetermined criterion, and means responsive to said decision means for governing whether said ventricular pacing pulse generating means operates in said first or said second mode. - View Dependent Claims (2, 5)
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3. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating ventricular pacing pulses, means for sensing atrial heartbeats, means responsive to said atrial heartbeat sensing means for deriving an indication of intrinsic atrial rate, sensor means for determining a metabolic indicator rate, means for determining a maximum atrial tracking rate as a function of said metabolic indicator rate, means for comparing said intrinsic atrial rate indication to said maximum atrial tracking rate, and means responsive to said comparing means for controlling said generating means to operate in a first mode in which ventricular pacing pulses are generated in synchrony with operations of said atrial heartbeat sensing means when said intrinsic atrial rate indication is slower than said maximum atrial tracking rate, and for controlling said generating means to operate in a second in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate, with timing independent of said atrial heartbeat sensing means, when said intrinsic rate indication exceeds said maximum atrial tracking rate, said controlling means including; means for timing a postventricular atrial refractory period following generation of a ventricular pacing pulse, means responsive to said comparing means for maintaining a record for recent cardiac cycles of which of said intrinsic atrial rate and said maximum atrial tracking rate was greater and whether said atrial heartbeat sensing means operated during a postventricular atrial refractory period, decision means for deciding whether said record meets a predetermined criterion, and means responsive to said decision means for governing whether said ventricular pacing pulse generating means operates in said first or said second mode. - View Dependent Claims (4)
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6. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating ventricular pacing pulses, means for sensing atrial heartbeats, sensor means for deriving a metabolic indicator rate means for setting at least one atrial refractory period as a function of said metabolic indicator rate, means responsive to said atrial heartbeat sensing means for determining whether sensed atrial heartbeats fall within at least one of said atrial refractory periods, and means responsive to said determining means for controlling a first operting mode in which said generating means generates ventricular pacing pulses in synchrony with sensed atrial heartbeats and a second operating mode in which said generating means generates ventricular pacing pulses at a rate which is a function of said metabolic indicator rate with timing independent of sensed atrial heartbeats. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating ventricular pacing pulses; means for sensing atrial heartbeats; means for determining a metabolic indicator rate; means for deriving a maximum atrial tracking rate as a function of said metabolic indicator rate; means for comparing said maximum atrial tracking rate with the rate of operation of said atrial heartbeat sensing means over a plurality of cardiac cycles, and depending on the pattern of the results of the comparison for classifying whether the atrial heartbeat rate is physiological or pathological; and control means operative when the atrail heartbeat rate is physiological for keying the operation of said ventricular pacing pulse generating means to the operation of said atrial heartbeat sensing means, and operative when the atrial heartbeat rate is pathological for keying the operation of said ventricular pacing pulse generating means to said metabolic indicator rate independent of the operation of said atrial heartbeat sensing means. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating atrial and ventricular pacing pulses; means for sensing atrial and ventricular heartbeats; means for determining a metabolic indicator rate; means for ascertaining wherther sensed atrial heartbeats are occurring at a rate which is pathological for the current metabolic indicator rate; and means for controlling said generating and sensing means to operate normally in a DDDR mode but to switch to a VVIR mode when the rate of the atrial heartbeats is pathological, said controlling means operating to switch between modes based on the most recent cardiac cycles, with fewer cardiac cycles being necessary to effect a switch from DDDR to VVIR mode than from VVIR to DDDR mode. - View Dependent Claims (32, 33)
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31. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating atrial and ventricular pacing pulses; means for sensing atrial and ventricular heartbeats; means for determining a metabolic indicator rate; means for ascertaining whether sensed atrial heartbeats are occurring at a rate which is pathological for the current metabolic indicator rate; means for controlling said generating and sensing means to operate normally in a DDDR mode but to switch to a VVIR mode when the rate of the atrial heartbeat is pathological; means for detecting a PMVVIR condition when the pacemaker is operating in the VVIR mode; and means responsive to said detecting means for controlling a switch from VVIR mode to DDDR mode and for temporarily extending the V-A interval in the DDDR mode.
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34. A method of operating a dual-chamber rate-responsive pacemaker, comprising the step of:
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generating ventricular pacing pulses, sensing atrial heartbeats, deriving an indication of intrinsic atrial rate in response to the sensing of atrial heartbeats, determining a metabolic indicator rate, determining a maximum atrial tracking rate as a function of said metabolic indicator rate, comparing said intrinsic atrial rate indication to said maximum atrial tracking rate, and, in response to said comparing step, controlling ventricular pacing pulse generation in a first mode in which ventricular pacing pulses are generated in synchrony with atrial heartbeat sensing when said intrinsic atrail rate indication is slower than said maximum atrail tracking rate, and controlling ventricular pacing pulse generation in a second mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic inidator rate, with timing independent of atrial heartbeat sensing, when said intrinsic atrail rate indication exceeds said maximum atrial tracking rate. said controlling step including the sub-steps of; developing a record of the occurrence of recent cardiac cylces in which said intrinsic atrial rate exceeded said maximum atrial tracking rate, deciding whether said record meets a predetermined criterion, and governing whether ventricular pacing pulses are generated in said first or said second mode in accordance with whether said predetermined criterion is met. - View Dependent Claims (35, 38)
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36. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating ventricular pacing pulses, sensing atrial heartbeats, deriving an indication of intrinsic atrial rate in response to the sensing of atrial heartbeats, determining a metabolic indicator rate, determining a maximum atrial tracking rate as a function of said metabolic indicator rate, comparing said intrinsic atrial rate indication to said maximum atrial tracking rate, and in response to said comparing step, controlling ventricular pacing pulse generation in a first mode in which ventricular pacing pulses are generated in synchrony with atrial heartbeat sensing when said intrinsic atrial rate indication is slower than said maximum atrial tracking rate, and controlling ventricular pacing pulse generation in a second mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate, with timing independent of atrial heartbeat sensing, when said intrinsic atrial rate indication exceeds said maximum atrial tracking rate, said controlling step including the sub-steps of; timing a postventricular atrial refractory period following generation of a ventricular pacing pulse, maintaining a record for recent cardiac cycles of which of said intrinsic atrial rate and said maximum atrial tracking rate was greater and whether atrial heartbeat sensing occurred during a postventricular atrial refractory period, deciding whether said record meets a predetermined criterion, and governing whether ventricular pacing pulses are generated in said first or said second mode in accordance with whether said predetermined criterion is met. - View Dependent Claims (37)
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39. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating ventricular pacing pulses, sensing atrial heartbeats, deriving a metabolic indicator rate, setting at least one atrial refractory period as a function of said metabolic indicator rate, determining whether sensed atrial heartbeats fall within at least one of said atrial refractory periods, and in response to said determining step, controlling a first operating mode in which ventricular pacing pulses are generated in synchrony with sensed atrial heartbeats and a second operating mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate with timing independent of sensed atrial heartbeats. - View Dependent Claims (40, 41, 42, 43, 44)
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45. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating ventricular pacing pulses, sensing atrial heartbeats, determining a metabolic indicator rate, deriving a maximum atrial tracking rate as a function of said metabolic indicator rate, comparing said maximum atrial tracking rate with the rate of said sensed atrial heartbeats over a plurality of cardiac cycles, and, depending on the pattern of the results of the comparison, classifying whether the atrial heartbeat rate is physiological or pathological, and keying ventricular pacing pulse generation to atrial heartbeat sensing when the atrial heartbeat rate is physiological, and keying ventricular pacing pulse generation to said metabolic indicator rate independent of atrial heartbeat sensing when the atrial heartbeat rate is pathological. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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63. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating atrial and ventricular pacing pulses; sensing atrial and ventricular heartbeats; determining a metabolic indicator rate; ascertaining whether sensed atrial heartbeats are occurring at a rate which is pathological for the current metabolic indicator rate; and controlling said generating and sensing steps to take place normally in a DDDR mode but to switch to a VVIR mode when the rate of the atrial heartbeats is pathological, said switch between modes being based on the most recent cardiac cycles, with fewer cardiac cycles being necessary to effect a switch from DDDR to VVIR mode then from VVIR to DDDR mode. - View Dependent Claims (65, 66)
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64. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating atrial and ventricular pacing pulses; sensing atrial and ventricular heartbeats; determining a metabolic indicator rate; ascertaining whether sensed atrial heartbeats are occurring at a rate which is pathological for the current metabolic indicator rate; controlling said generating and sensing steps to take place normally in a DDDR mode but to switch to a VVIR mode when the rate of the atrial heartbeats is pathological, and detecting a PMVVIR condition when the pacemaker is operating in the VVIR mode, and in response thereto controlling a switch from VVIR mode to DDDR mode and temporarily extending the V-A interval in the DDDR mode.
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67. A dual-chamber rate-responsive pacemaker, comprising:
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means for generating ventricular pacing pulses, means for sensing atrial heartbeats, sensor means for deriving a metabolic indicator rate, means for setting at least one atrial refractory period as a function of said metabolic indicator rate, means responsive to said atrial heartbeat sensing means for determining whether sensed atrial heartbeats fall within said at least one atrial refractory period, and means reponsive to said determining means for controlling a first operating mode in which said generating means generates ventricular pacing pulses in synchrony with sensed atrial heartbeats and a second operating mode in which said generating means generates ventricular pacing pulses at a rate which is a function of said metabolic indicator rate with timing independent of sensed atrial heartbeats. - View Dependent Claims (68, 69, 70)
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71. A dual-chamber rate-responsive pacemaker in accordance with claim 79 wherein said controlling means includes:
means for maintaining a record of recent cardiac cycles in which atrial heartbeats fall within said at least one atrial refractory period but occur at a physiological rate, and means responsive to said record maintaining means satisfying predetermined criteria for governing switches between said first and second operating modes. - View Dependent Claims (72)
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73. A method of operating a dual-chamber rate-responsive pacemaker, comprising the steps of:
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generating ventricular pacing pulses, sensing atrial heartbeats, deriving a metabolic indicator rate, setting at least one atrial refractory period as a function of said metabolic indicator rate, determining whether sensed atrial heartbeats fall within said at least one atrial refractory period, and in response to said determining step, controlling a first operating mode in which ventricular pacing pulses are generated in synchrony with sensed atrial heartbeats and a second operating mode in which ventricular pacing pulses are generated at a rate which is a function of said metabolic indicator rate with timing independent of sensed atrial heartbeats. - View Dependent Claims (74, 75, 76, 77, 78)
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Specification