Implantable medical device for treating cardiac mechanical dysfunction by electrical stimulation
First Claim
1. In an implantable medical device, a system for monitoring the state of heart failure of the heart of a heart failure patient and delivering a therapy comprising:
- pulse generating means for selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber commencing a heart cycle and for selectively generating and applying an extrasystolic electrical stimulus to the at least one heart chamber at the time out of an extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
electrical signal sense means for sensing the electrical signals of the heart in said at least one heart chamber and providing a sense event signal signifying the contraction of the heart commencing a heart cycle;
heart chamber volume measuring means for measuring the volume of a heart chamber over at least a portion of a heart cycle and providing a chamber volume value;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
parameter deriving means for selectively enabling operation of said pulse generating means, said electrical signal sense means, said heart chamber volume measuring means, and said blood pressure measuring means for periodically deriving a plurality of heart failure parameters signifying the state of heart failure from selected measured values of chamber volume and blood pressure, the heart failure parameters including;
a tau parameter representing one of a relaxation and contraction time constant of the heart chamber, a mechanical restitution parameter representing the mechanical response of a heart chamber to electrical stimuli applied to the heart chamber prematurely at differing times during a plurality of heart cycles, a recirculation fraction parameter representing the increase in strength of a contraction of the heart chamber in response to an electrical stimuli applied to the heart chamber during a heart cycle and the rate of decay of the increase in strength of successive contractions of the heart chamber over a series of heart cycles; and
an elastance parameter representing the slope of plotted sets of end systolic blood pressure versus end systolic chamber volume over a plurality of heart cycles; and
therapy delivery means responsive to a determined heart failure parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state.
1 Assignment
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Accused Products
Abstract
An implantable stimulator and monitor measures a group of heart failure parameters indicative of the state of heart failure employing EGM signals, measures of blood pressure including absolute pressure P, developed pressure (DP=systolic P−diastolic P), and/or dP/dt, and measures of heart chamber volume (V) over one or more cardiac cycles. These parameters include: (1) relaxation or contraction time constant tau (τ); (2) mechanical restitution (MR), i.e., the mechanical response of a heart chamber to premature stimuli applied to the heart chamber; (3) recirculation fraction (RF), i.e., the rate of decay of PESP effects over a series of heart cycles; and (4) end systolic elastance (EES), i.e., the ratios of end systolic blood pressure P to volume V. These heart failure parameters are determined periodically regardless of patient posture and activity level. The physician can determine whether a particular therapy is appropriate, prescribe the therapy for a period of time while again accumulating the stored patient data for a later review and assessment to determine whether the applied therapy is beneficial or not, thereby enabling periodic changes in therapy, if appropriate. Drug therapies and electrical stimulation therapies, including PESP stimulation, and pacing therapies including single chamber, dual chamber and multi-chamber (bi-atrial and/or bi-ventricular) pacing can be delivered. In patient'"'"'s prone to malignant tachyarrhythmias, the assessment of heart failure state can be taken into account in setting parameters of detection or classification of tachyarrhythmias and the therapies that are delivered.
179 Citations
86 Claims
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1. In an implantable medical device, a system for monitoring the state of heart failure of the heart of a heart failure patient and delivering a therapy comprising:
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pulse generating means for selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber commencing a heart cycle and for selectively generating and applying an extrasystolic electrical stimulus to the at least one heart chamber at the time out of an extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
electrical signal sense means for sensing the electrical signals of the heart in said at least one heart chamber and providing a sense event signal signifying the contraction of the heart commencing a heart cycle;
heart chamber volume measuring means for measuring the volume of a heart chamber over at least a portion of a heart cycle and providing a chamber volume value;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
parameter deriving means for selectively enabling operation of said pulse generating means, said electrical signal sense means, said heart chamber volume measuring means, and said blood pressure measuring means for periodically deriving a plurality of heart failure parameters signifying the state of heart failure from selected measured values of chamber volume and blood pressure, the heart failure parameters including;
a tau parameter representing one of a relaxation and contraction time constant of the heart chamber, a mechanical restitution parameter representing the mechanical response of a heart chamber to electrical stimuli applied to the heart chamber prematurely at differing times during a plurality of heart cycles, a recirculation fraction parameter representing the increase in strength of a contraction of the heart chamber in response to an electrical stimuli applied to the heart chamber during a heart cycle and the rate of decay of the increase in strength of successive contractions of the heart chamber over a series of heart cycles; and
an elastance parameter representing the slope of plotted sets of end systolic blood pressure versus end systolic chamber volume over a plurality of heart cycles; and
therapy delivery means responsive to a determined heart failure parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In an implantable medical device, a system for monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient and delivering a therapy comprising:
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means for determining a stable cardiac cycle of a heart chamber having a heart cycle escape interval;
means for timing out an extrasystolic escape interval during the heart cycle escape interval;
pulse generating means for selectively generating and applying an extrasystolic electrical stimulus to the heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
mechanical restitution parameter deriving means for selectively enabling operation of said pulse generating means and said blood pressure measuring means for periodically deriving a mechanical restitution parameter representing the mechanical response of a heart chamber to the electrical stimuli applied to the heart chamber prematurely at differing extrasystolic escape intervals during a plurality of heart cycles; and
therapy delivery means responsive to a determined heart failure parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (10)
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11. In an implantable medical device, a system for monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient and delivering a therapy comprising:
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pacing pulse generating means for selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber commencing a paced heart cycle;
extrasystolic escape interval timing means for timing an extrasystolic escape interval from a previously generated and applied pacing pulse;
extrasystolic stimuli generating means for selectively generating and applying electrical stimuli to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
mechanical restitution parameter deriving means for selectively enabling operation of said pacing pulse generating means to generate and apply pacing pulses to the heart chamber, said extrasystolic escape interval timing means to time out a predetermined extrasystolic escape interval following predetermined applied pacing pulses, said extrasystolic stimuli generating means to generate and apply extrasystolic stimuli to the heart chamber at the time out of each extrasystolic escape interval, and said blood pressure measuring means to determine a blood pressure value representing the force of contraction of the heart chamber following each applied extrasystolic stimuli, whereby a data set of such determined blood pressure values correlated to the extrasystolic escape intervals is derived and represents the mechanical restitution parameter of the heart chamber; and
therapy delivery means responsive to a determined heart failure parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (12, 13, 14, 15, 16)
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17. In an implantable medical device, a method of monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient, deriving a mechanical restitution parameter, and delivering a therapy comprising the steps of:
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(a) timing out a pacing escape interval;
(b) selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber upon time out of the pacing escape interval to commence a paced heart cycle;
(c) measuring blood pressure within the heart chamber during a paced heart cycle and providing a reference blood pressure value;
(d) establishing an extrasystolic escape interval;
(e) timing the extrasystolic escape interval from a previously generated and applied pacing pulse;
(f) selectively generating and applying electrical stimuli to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
(g) measuring blood pressure within the heart chamber during the heart cycle in which the electrical stimuli is applied and providing an extrasystolic blood pressure value;
(h) processing the extrasystolic blood pressure value with said reference systolic blood pressure value to determine a data point of mechanical restitution parameter of the heart chamber correlated to the extrasystolic interval;
(i) incrementing the extrasystolic escape interval;
(j) repeating steps (e) through (i) a predetermined number of times to obtain a plurality of data points from the extrasystolic blood pressure values at the plurality of extrasystolic escape intervals comprising the mechanical restitution parameter; and
(k) in response to a determined mechanical restitution parameter providing a therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. In an implantable medical device, a method of monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient, deriving a mechanical restitution parameter, and delivering a therapy comprising the steps of:
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(a) timing out a pacing escape interval;
(b) selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber upon time out of the pacing escape interval to commence a paced heart cycle;
(c) measuring blood pressure within the heart chamber during a paced heart cycle and providing a reference systolic blood pressure value and diastolic blood pressure value;
(d) establishing an extrasystolic escape interval;
(e) timing the extrasystolic escape interval from a previously generated and applied pacing pulse;
(f) generating and applying electrical stimuli to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
(g) measuring blood pressure within the heart chamber during the heart cycle in which the electrical stimuli is applied and providing an extrasystolic systolic blood pressure value and diastolic blood pressure value;
(h) processing each extrasystolic systolic blood pressure value with said reference systolic blood pressure value and each -extrasystolic diastolic blood pressure value with said reference diastolic blood pressure value to determine systolic and diastolic data points referenced to the extrasystolic interval;
(i) incrementing the extrasystolic escape interval;
(j) repeating steps (e) through (i) a predetermined number of times to obtain a plurality of sets of post-extrasystolic systolic blood pressure value and diastolic blood pressure values at a plurality of extrasystolic escape intervals; and
(k) in response to a determined mechanical restitution parameter, providing a therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (25, 26, 27, 28)
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29. In an implantable medical device, apparatus for monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient, deriving a mechanical restitution parameter, and providing a therapy comprising:
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means for timing out a pacing escape interval;
pulse generating means for selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber upon time out of the pacing escape interval to commence a paced heart cycle;
means for measuring blood pressure within the heart chamber during a paced heart cycle and providing a reference blood pressure value;
means for establishing an extrasystolic escape interval;
means operable following provision of the reference blood pressure value for (i) timing the extrasystolic escape interval from a previously generated and applied pacing pulse;
(ii) selectively generating and applying electrical stimuli to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
(iii) measuring blood pressure within the heart chamber during the heart cycle in which the electrical stimuli is applied and providing an extrasystolic blood pressure value;
(iv) processing the extrasystolic blood pressure value with said reference systolic blood pressure value to determine a plotted data point of the mechanical restitution parameter of the heart chamber correlated to the extrasystolic interval;
(v) incrementing the extrasystolic escape interval; and
(vi) repeating operations (i) through (v) a predetermined number of times to obtain a plurality of plotted data points from the extrasystolic blood pressure values at the plurality of extrasystolic escape intervals comprising the mechanical restitution parameter; and
therapy delivery means responsive to a determined mechanical restitution parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. In an implantable medical device, a method of monitoring the state of heart failure as a function of the mechanical restitution of the heart of a heart failure patient and delivering a therapy comprising the steps of:
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(a) determining a stable heart rate of a heart chamber having a heart cycle escape interval;
(b) determining an extrasystolic escape interval;
(c) timing out the extrasystolic escape interval during the heart cycle escape interval;
(d) selectively generating and applying an extrasystolic electrical stimulus to the heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
(e) measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
(f) repeating steps (b)-(e) for a predetermined series of heart cycles, each time changing the extrasystolic escape interval in step (b), to accumulate a series of blood pressure measurements in step (e);
(g) determining a mechanical restitution parameter of the heart chamber from the accumulated series of blood pressure measurements representing the mechanical response of the heart chamber to the electrical stimuli applied to the heart chamber prematurely at differing extrasystolic escape intervals during the plurality of heart cycles; and
(h) in response to a determined mechanical restitution parameter, providing a therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (38, 39, 42, 43, 44)
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40. In an implantable medical device, a method of monitoring the state of heart failure as a function of the recirculation fraction of the heart of a heart failure patient and delivering a therapy comprising the steps of:
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determining a stable heart rate of a heart chamber having a heart cycle escape interval;
determining an extrasystolic escape interval;
timing out the extrasystolic escape interval during the heart cycle escape interval;
selectively generating and applying an extrasystolic electrical stimulus to the heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
during a series of heart cycles following the application of the extrasystolic electrical stimulus to the heart chamber, measuring an index of the strength of contraction of the heart chamber over at least a portion of a heart cycle and providing a strength of contraction value;
determining a recirculation fraction parameter of the heart chamber from the accumulated series of strength of contraction values representing the mechanical response of the heart chamber to the electrical stimuli applied to the heart chamber prematurely at expiration of the extrasystolic escape interval; and
in response to a determined mechanical restitution parameter, providing a therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (41)
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45. In an implantable medical device, apparatus for monitoring the state of heart failure as a function of the recirculation fraction of the heart of a heart failure patient and delivering a therapy comprising:
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means for determining a stable heart rate of a heart chamber having a heart cycle escape interval;
means for determining an extrasystolic escape interval;
means for timing out the extrasystolic escape interval during the heart cycle escape interval;
means for selectively generating and applying an extrasystolic electrical stimulus to the heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
means operable during a series of heart cycles following the application of the extrasystolic electrical stimulus to the heart chamber for measuring an index of the strength of contraction of the heart chamber over at least a portion of a heart cycle and providing a strength of contraction value;
means for determining a recirculation fraction parameter of the heart chamber from the accumulated series of strength of contraction values representing the mechanical response of the heart chamber to the electrical stimuli applied to the heart chamber prematurely at expiration of the extrasystolic escape interval; and
blood pressure, volume or geometry change, acceleration if an accelerometertherapy delivery means operable in response to a determined mechanical restitution parameter for providing a therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (46, 47)
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48. In an implantable medical device, a system for monitoring the state of heart failure as a function of the recirculation fraction of the heart of a heart failure patient and delivering a therapy comprising:
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pacing pulse generating means for selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber commencing a paced heart cycle;
extrasystolic escape interval timing means for timing an extrasystolic escape interval from a previously generated and applied pacing pulse;
extrasystolic stimuli generating means for selectively generating and applying an electrical stimulus to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing measured blood pressure values;
recirculation fraction parameter deriving means for selectively enabling operation of said pacing pulse generating means to generate and apply pacing pulses to the heart chamber, said extrasystolic escape interval timing means to time out a predetermined extrasystolic escape interval following an applied pacing pulse, said extrasystolic stimuli generating means to generate and apply an extrasystolic stimulus to the heart chamber at the time out of the extrasystolic escape interval, and said blood pressure measuring means to determine a recirculation fraction blood pressure value representing the force of contraction of the heart chamber in the heart cycle in which the extrasystolic stimuli is applied and in a predetermined number of heart cycles following the heart cycle in which the extrasystolic stimuli is applied, whereby a data set of such determined blood pressure values is derived that represents the recirculation fraction parameter of the heart chamber; and
therapy delivery means responsive to a determined recirculation fraction parameter for operating said pulse generating means in a burst pacing therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (49, 50)
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51. In an implantable medical device, a method of monitoring the state of heart failure as a function of the recirculation fraction of the heart of a heart failure patient and delivering a therapy comprising the steps-of:
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selectively generating and applying a pacing pulse to at least one heart chamber to effect a contraction of the heart chamber commencing a paced heart cycle;
timing an exfrasystotic escape interval from a previously generated and applied pacing pulse;
selectively generating and applying an electrical stimulus to the at least one heart chamber at the time out of the extrasystolic escape interval to induce post-extrasystolic potentiation increasing the strength of contraction of the heart chamber;
measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing measured blood pressure values to determine a recirculation fraction blood pressure value representing the force of contraction of the heart chamber in the heart cycle in which the extrasystolic stimuli is applied and in a predetermined number of heart cycles following the heart cycle in which the extrasystolic stimuli is applied, whereby a data set of such determined blood pressure values is derived that represents the recirculation fraction parameter of the heart chamber; and
in response to a determined mechanical recirculation fraction parameter, providing a burst pacing therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (52, 53, 54)
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55. In an implantable medical device, a system for monitoring the state of heart failure as a function of the relaxation time constant (tau) of the heart of a heart failure patient during a heart cycle and providing a therapy comprising:
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blood pressure measuring means for periodically measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a set of measured blood pressure values including blood pressure (P) and rate of change of blood pressure (dP/dt);
means for determining the minimum value of the rate of change of blood pressure among the set of rate of change of blood pressure values;
means for determining the time in the measured heart cycle of the determined minimum value of the rate of change of blood pressure;
means for deriving a tau parameter as a function of a set of samples of blood pressure values within a time window measured from the determined time in the measured heart cycle of the determined minimum value of the rate of change of blood pressure;
pulse generating means for delivering electrical stimulation to he patient'"'"'s heart; and
therapy delivery means responsive to a determined tau parameter for operating said pulse generating means in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (56, 57, 58, 59)
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60. In an implantable medical device, a method of monitoring the state of heart failure as a function of the relaxation time constant (tau) of the heart of a heart failure patient over a heart cycle and delivering a therapy comprising the steps of:
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periodically measuring blood pressure within a heart chamber over at least a portion of the heart cycle and providing a set of measured blood pressure values including blood pressure (P) and rate of change of blood pressure (dP/dt);
determining the minimum value of the rate of change of blood pressure among the set of rate of change of blood pressure values;
determining the time in the measured heart cycle of the determined minimum value of the rate of change of blood pressure;
deriving a tau parameter as a function of a set of samples of blood pressure values within a time window measured from the determined time in the measured heart cycle of the determined minimum value of the rate of change of blood pressure; and
in response to a determined tau parameter, providing a pacing therapy during a heart cycle to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (61, 62, 63, 64)
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65. In an implantable medical device, a system for monitoring the state of heart failure of the heart of a patient as a function of the elastance of the heart and providing a therapy comprising:
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means for defining a heart cycle;
heart chamber volume measuring means for measuring the volume of a heart chamber over at least a portion of a heart cycle and providing a chamber volume value;
blood pressure measuring means for measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value;
elastance parameter deriving means for deriving an elastance parameter representing the slope of plotted sets of end systolic blood pressure versus end systolic chamber volume over a plurality of heart cycles further comprising;
(a) means for operating said blood pressure measuring means and said heart chamber volume measuring means to make N blood pressure (P) measurements and N volume (V) measurements of the heart chamber at a predetermined sample rate over a series of heart cycles following a natural, intrinsic, or paced depolarization of the heart chamber;
(b) means for selecting the end systolic blood pressure (PES) measurements and end systolic volume (VES) measurements at the end systolic point in each heart cycle;
(c) means for establishing a threshold correlation coefficient R2;
(d) means for accumulating n sets of end systolic [PES, VES] data points;
(e) means for performing a linear regression of the “
n”
sets of [PES, VES] data points to derive the slope of the sampled data set, a sample correlation coefficient R and a sample squared correlation coefficient R2;
(f) means for comparing the sample squared correlation coefficient R2 to the threshold squared correlation coefficient R2; and
(g) means for storing the derived slope as the end systolic elastance if the sample squared correlation coefficient R2 exceeds the threshold squared correlation coefficient R2; and
therapy delivery means responsive to a determined end systolic elastance parameter for operating the implantable medical device in a therapy delivery mode to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (66, 67, 68, 69, 70, 71)
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72. In an implantable medical device, a method of monitoring the state of heart failure of the heart of a patient as a function of the elastance of the heart and providing a therapy comprising the steps of:
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defining a heart cycle;
measuring the volume of a heart chamber over at least a portion of a heart cycle and providing a chamber volume value;
measuring blood pressure within a heart chamber over at least a portion of a heart cycle and providing a blood pressure value; and
deriving an elastance parameter representing the slope of plotted sets of end systolic blood pressure versus end systolic chamber volume over a plurality of heart cycles further comprising the steps of;
(a) operating said blood pressure measuring means and said heart chamber volume measuring means to make N blood pressure (P) measurements and N volume (V) measurements of the heart chamber at a predetermined sample rate over a series of heart cycles following a natural, intrinsic, or paced depolarization of the heart chamber;
(b) selecting the end systolic blood pressure (PES) measurements and end systolic volume (VES) measurements at the end systolic point in each heart cycle;
(c) establishing a threshold correlation coefficient R2;
(d) accumulating n sets of end systolic [PES, VES] data points;
(e) performing a linear regression of the “
n”
sets of [PES, VES] data points to derive the slope of the sampled data set, a sample correlation coefficient R and a sample squared correlation coefficient R2;
(f) comparing the sample squared correlation coefficient R2 to the threshold squared correlation coefficient R2; and
(g) storing the derived slope as the end systolic elastance if the sample squared correlation coefficient R2 exceeds the threshold squared correlation coefficient R2; and
in response to a determined end systolic elastance parameter, providing a therapy to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (73, 74, 75, 76, 77, 78)
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79. In an implantable medical device having pacing means for delivering a pacing pulse to the heart and means for sensing a heart signal and providing a sensed event in response thereto, a method of providing a therapy to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state comprising the steps of:
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establishing a therapy delay timed from a pacing pulse or sensed event that lapses within the refractory period of the heart but outside the vulnerable period of the heart, a therapy burst pulse number X, and a therapy pulse separation interval between each pulse of a therapy burst of X pulses;
timing out the therapy delay and triggering the delivery of one or more burst pacing pulse within the refractory period; and
timing out the pulse separation interval for each of the remaining burst pacing pulses and triggering the delivery of at least one burst pacing pulse after the refractory period ends to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state. - View Dependent Claims (80, 81, 82)
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83. An implantable medical device for providing a therapy to increase the strength of contraction of the patient'"'"'s heart and improve the heart failure state comprising:
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pacing pulse generator means for delivering a pacing pulse to the heart;
means for sensing a heart signal and providing a sensed event in response thereto means for timing out a therapy delay from a pacing pulse or sensed event that lapses within the refractory period of the heart but outside the vulnerable period of the heart; and
means for operating said pacing pulse generator means to deliver a therapy burst of X electrical pulses during a therapy delivery period starting upon time out of the therapy delay and ending after the vulnerable period of the heart, whereby the delivery of at least one burst pacing pulse occurs during the refractory period and is ineffective to capture the heart and at least one pulse is delivered after the refractory period ends, the delivered therapy burst increasing the strength of contraction of the patient'"'"'s heart. - View Dependent Claims (84, 85, 86)
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Specification