Cardiac rhythm management system with defibrillation threshold prediction
First Claim
1. A method including:
- delivering a nondefibrillating and nonfibrillation-inducing test energy to a heart;
detecting a resulting output signal based on the test energy and a heart characteristic; and
estimating a defibrillation threshold, based on the output signal, for a portion of the heart to be defibrillated.
2 Assignments
0 Petitions
Accused Products
Abstract
A cardiac rhythm management device predicts defibrillation thresholds without any need to apply defibrillation shocks or subjecting the patient to fibrillation. Intravascular defibrillation electrodes are implanted in a heart. By applying a small test energy, an electric field near one of the defibrillation electrodes is determined by measuring a voltage at a sensing electrode offset from the defibrillation electrode by a known distance. A desired predetermined minimum value of electric field at the periphery of the heart is established. A distance between one of the defibrillation electrodes and the heart periphery is measured, either fluoroscopically or by measuring a voltage at an electrode located at or near the heart periphery. Using the measured electric field and the measured distance to the periphery of the heart, the defibrillation energy needed to obtain the desired electric field at the heart periphery is estimated. This estimation is based on an elliptical model of the electric field distribution around the dipole foci formed by the defibrillation electrodes, or other suitable electric field model.
19 Citations
49 Claims
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1. A method including:
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delivering a nondefibrillating and nonfibrillation-inducing test energy to a heart;
detecting a resulting output signal based on the test energy and a heart characteristic; and
estimating a defibrillation threshold, based on the output signal, for a portion of the heart to be defibrillated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of determining a defibrillation threshold energy, the method including:
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positioning a first electrode near a heart at a predetermined distance, d1, from a second electrode near the heart;
providing a predetermined nondefibrillating and nonfibrillation-inducing test energy, in a heart between the first electrode and a third electrode;
detecting a resulting first response, V1, between the first and second electrodes;
detecting a resulting second response, V2, between the first and third electrodes;
determining an electric field near the second electrode based on V1 and V2;
measuring a distance, d2, between the second electrode and a distal portion of the heart tissue to be defibrillated; and
estimating the defibrillation threshold energy, based on a predetermined required defibrillation electric field at the distal portion of the heart tissue to be defibrillated, d2, and the electric field near the second electrode. - View Dependent Claims (22, 23, 24, 25, 27, 28, 29, 30)
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26. A method of determining a defibrillation threshold energy, the method including:
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positioning a right ventricular (RV) tip electrode in a heart at a predetermined distance, d1, from an RV shock electrode in the heart;
positioning a superior vena cava (SVC) electrode in or near the heart;
providing a nondefibrillating and nonfibrillation-inducing predetermined test current in a heart between the RV shock electrode and a cardiac rhythm management device housing electrode that is electrically connected in common with the SVC electrode;
detecting a resulting first voltage, V1, between the RV tip electrode and the RV shock electrode;
detecting a resulting second voltage, V2, between the RV tip electrode and the commonly connected SVC and housing electrodes;
determining a fractional tip voltage parameter as V2/(V1+V2);
measuring a distance, d2, between the RV shock electrode and a left ventricular apical heart periphery; and
estimating the defibrillation threshold energy, based on a predetermined required defibrillation electric field at the left ventricular apical heart periphery, d2, and the fractional tip voltage parameter and an elliptical model of dipolar electric field distribution having the RV shock and SVC electrodes as its foci.
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31. A system including:
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first and second electrodes configured for association with a heart;
a test energy module, coupled to the second electrode, for delivering a nondefibrillating and nonfibrillation-inducing test energy to the heart;
a response signal module, coupled to the first and second electrodes for detecting responses to the test energy; and
a controller, coupled to the response signal module, the controller including a module estimating a defibrillation threshold energy based on a predetermined desired defibrillation electric field at a distal portion of the heart tissue to be defibrillated and a distance from the second electrode to the distal portion of the heart tissue, and an indication of the electric field near the second electrode. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 49)
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46. A system including:
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first, second, and third electrodes configured for association with a heart, in which the first and second electrodes are separated by a predetermined distance;
a test energy module, coupled to the second and third electrodes, for delivering therebetween a nondefibrillating and nonfibrillation-inducing test energy to the heart;
a response signal module, coupled to the first and second electrodes for detecting responses to the test energy; and
a defibrillation threshold energy estimation module, coupled to the response signal module, and estimating a defibrillation threshold energy based on a predetermined desired defibrillation electric field at a distal portion of the heart tissue to be defibrillated, a distance from the second electrode to the distal portion of the heart tissue, and an indication of the electric field near the second electrode obtained by measuring the response signal at the first and second electrodes and by using the predetermined separation between the first and second electrodes.
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47. A system including:
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first, second, and third electrodes configured for association with a heart, in which the first and second electrodes are separated by a predetermined distance;
a test energy module, coupled to the second and third electrodes, for delivering therebetween a nondefibrillating and nonfibrillation-inducing test energy to the heart;
a response signal module, coupled to the first and second electrodes for detecting responses to the test energy; and
means, coupled to the response signal module, for performing the function of estimating the defibrillation threshold energy.
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48. A cardiac rhythm management system including:
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a first right ventricular (RV) electrode, a second RV electrode, a superior vena cava (SVC) electrode, and a housing electrode, configured for association with a heart; and
a cardiac rhythm management (CRM) device, coupled to the electrodes, the CRM device including;
a test energy module, delivering a nondefibrillating and nonfibrillation-inducing test energy to the heart;
a response signal module, coupled to the first and second RV electrodes for detecting a response to the test energy; and
a defibrillation threshold energy estimation module, coupled to the response signal module, and estimating a defibrillation threshold energy based on;
(a) a predetermined desired defibrillation electric field at portion of the heart tissue to be defibrillated that is distal to the second RV electrode;
(b) a distance from the second electrode to the distal portion of the heart tissue;
(c) an indication of the electric field near the second electrode obtained by measuring the response signal at the first and second electrodes and by using the predetermined separation between the first and second electrodes.
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Specification