Methods and apparatus for estimation of ventricular afterload based on ventricular pressure measurements
First Claim
1. A method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
- obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1.
1 Assignment
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Accused Products
Abstract
A method and system incorporated into an IMD that detects changes in ventricular afterload using the morphology of a ventricular blood pressure wave. A peak positive pressure value Pb, peak positive and peak negative derivative pressures dP/dtPP and dP/dtNP, and a decreasing pressure Pc are determined. The sample times tb, at Pb, ta at dP/dtPP and tc at dP/dtNP are determined. An index α of the relative timing of peak positive pressure Pb in the blood ejection phase is calculated from, α=(tb−ta)/(tc−ta), the severity of ventricular afterload is proportional to the value α in the range between 0 and 1. The slope of the early ejection pressure in the blood ejection phase is calculated from β=(Pc−Pb)/(tc−tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β.
83 Citations
43 Claims
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1. A method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
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obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1. - View Dependent Claims (2, 3, 4)
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5. A method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
. - View Dependent Claims (6, 7)
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8. In an implantable heart monitor adapted to be implanted in a patient'"'"'s body and comprising a pressure sensor coupled with pressure signal processing circuitry and memory for data storage, a method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
operating the pressure sensor to obtain a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1; and
storing the calculated index α
in data storage memory. - View Dependent Claims (9, 10, 11)
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12. In an implantable heart monitor adapted to be implanted in a patient'"'"'s body and comprising a pressure sensor coupled with pressure signal processing circuitry and memory for data storage, a method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
; and
- View Dependent Claims (13, 14, 15)
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16. In an implantable medical device adapted to be implanted in a patient'"'"'s body for delivering a therapy in accordance with adjustable therapy delivery operating modes and parameters comprising a pressure sensor coupled with pressure signal processing circuitry and therapy delivery means for delivering a therapy, a method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1; and
adjusting one of a therapy delivery operating mode or parameter to minimize the value of index α
. - View Dependent Claims (17, 18, 19)
-
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20. In an implantable medical device adapted to be implanted in a patient'"'"'s body for delivering a therapy in accordance with adjustable therapy delivery operating modes and parameters comprising a pressure sensor coupled with pressure signal processing circuitry and therapy delivery means for delivering a therapy, a method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
; and
adjusting one of a therapy delivery operating mode or parameter to minimize the magnitude of index β
. - View Dependent Claims (21, 22)
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23. Apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
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means for obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
means for calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1. - View Dependent Claims (24, 25, 26)
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27. Apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
means for obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values; and
means for calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
. - View Dependent Claims (28, 29)
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30. In an implantable heart monitor adapted to be implanted in a patient'"'"'s body and comprising a pressure sensor coupled with pressure signal processing circuitry and memory for data storage, apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
means for operating the pressure sensor to obtain a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
means for calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1; and
means for storing the calculated index α
in data storage memory. - View Dependent Claims (31, 32, 33)
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34. In an implantable heart monitor adapted to be implanted in a patient'"'"'s body and comprising a pressure sensor coupled with pressure signal processing circuitry and memory for data storage, apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
means for obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
means for calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
; and
means for storing the calculated index β
in data storage memory. - View Dependent Claims (35, 36)
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37. In an implantable medical device adapted to be implanted in a patient'"'"'s body for delivering a therapy in accordance with adjustable therapy delivery operating modes and parameters comprising a pressure sensor coupled with pressure signal processing circuitry and therapy delivery means for delivering a therapy, apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
means for obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak positive derivative pressure dP/dtPP and the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, the sample time ta of the peak positive derivative pressure dP/dtPP, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
means for calculating an index α
of the relative timing of peak positive pressure Pb in the blood ejection phase in accordance with the formula α
=(tb−
ta)/(tc−
ta), wherein the severity of ventricular afterload is proportional to the value of index α
in the range between 0 and 1; and
means for adjusting one of a therapy delivery operating mode or parameter to minimize the value of index α
. - View Dependent Claims (38, 39, 40)
-
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41. In an implantable medical device adapted to be implanted in a patient'"'"'s body for delivering a therapy in accordance with adjustable therapy delivery operating modes and parameters comprising a pressure sensor coupled with pressure signal processing circuitry and therapy delivery means for delivering a therapy, apparatus that derives an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising:
-
means for obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle;
means for determining the peak positive pressure value Pb, the peak negative derivative pressure dP/dtNP, and the decreasing pressure Pc associated with the peak negative derivative pressure dP/dtNP from the set of ventricular pressure values;
means for determining the sample time tb of peak positive pressure, and the sample time tc of the peak negative derivative pressure dP/dtNP from the sample times associated with the set of ventricular pressure values;
means for calculating an index β
of the slope of the early ejection pressure in the blood ejection phase in accordance with the formula β
=(Pc−
Pb)/(tc−
tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index β
; and
means for adjusting one of a therapy delivery operating mode or parameter to minimize the magnitude of index β
. - View Dependent Claims (42, 43)
-
Specification