System and method for discriminating acute and chronic heart failure using an implantable medical device
First Claim
1. A method for evaluating heart failure within a patient using an implantable medical device, the method comprising:
- detecting changes, if any, in cardiac electrical signals indicative of heart failure within the patient;
detecting changes, if any, in transthoracic impedance values indicative of heart failure within the patient; and
distinguishing between acute and chronic heart failure, if occurring within the patient, based on detected changes in the cardiac electrical signals and the transthoracic impedance values, wherein acute heart failure is relatively short term as compared to chronic heart failure;
wherein distinguishing between acute and chronic heart failure within the patient includes (a) generating an indication of acute heart failure if the cardiac signals indicate the presence of heart failure whereas the impedance values exhibit little or no net change in value and (b) generating an indication of chronic heart failure if the impedance values indicate the presence of heart failure whereas the cardiac signals exhibit little or no net change in value.
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Abstract
Techniques are provided for evaluating heart failure within a patient. In one example, the implantable device detects a decrease, if any, in selected morphological parameters derived from the intracardiac electrogram (IEGM) that are indicative of possible heart failure, such as paced depolarization integrals (PDI) or peak-to-peak amplitudes of QRS-complexes. The device also detects a decrease, if any, in transthoracic impedance, which is also indicative of possible heart failure. Acute heart failure is indicated if there is a decrease in the morphological IEGM parameters but no significant decrease in transthoracic impedance. Chronic heart failure is indicated if there is a decrease in transthoracic impedance but no significant decrease in the morphological IEGM parameters. If both transthoracic impedance and the morphological IEGM parameters are found to be decreasing significantly, the device issues a warning of severe heart failure.
74 Citations
17 Claims
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1. A method for evaluating heart failure within a patient using an implantable medical device, the method comprising:
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detecting changes, if any, in cardiac electrical signals indicative of heart failure within the patient; detecting changes, if any, in transthoracic impedance values indicative of heart failure within the patient; and distinguishing between acute and chronic heart failure, if occurring within the patient, based on detected changes in the cardiac electrical signals and the transthoracic impedance values, wherein acute heart failure is relatively short term as compared to chronic heart failure; wherein distinguishing between acute and chronic heart failure within the patient includes (a) generating an indication of acute heart failure if the cardiac signals indicate the presence of heart failure whereas the impedance values exhibit little or no net change in value and (b) generating an indication of chronic heart failure if the impedance values indicate the presence of heart failure whereas the cardiac signals exhibit little or no net change in value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for evaluating heart failure within a patient for use with an implantable medical device, comprising:
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an IEGM-based heart failure detection unit adapted to detect heart failure within the patient based on changes, if any, in IEGM signals; an impedance-based heart failure detection unit adapted to detect heart failure within the patient based on changes, if any, in thoracic impedance; and a heart failure discrimination unit adapted to distinguish between acute and chronic heart failure within the patient based on output signals provided by the IEGM-based heart failure detection unit and the impedance-based heart failure detection unit, wherein acute heart failure is relatively short term as compared to chronic heart failure;
wherein the heart failure discrimination unit is adapted to (a) generate an indication of acute heart failure if the cardiac signals indicate the presence of heart failure whereas the impedance values exhibit little or no net change in value, and to (b) generate an indication of chronic heart failure if the impedance values indicate the presence of heart failure whereas the cardiac signals exhibit little or no net change in value. - View Dependent Claims (15)
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16. A system for evaluating heart failure within a patient for use with an implantable medical device, comprising:
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means for detecting changes, if any, in cardiac electrical signals indicative of heart failure within the patient; means for detecting changes, if any, in transthoracic impedance values indicative of heart failure within the patient; and means for distinguishing between acute and chronic heart failure within the patient based on detected changes in the cardiac electrical signals and the transthoracic impedance values, wherein acute heart failure is relatively short term as compared to chronic heart failure;
wherein the means for distinguishing between acute and chronic heart failure within the patient includes (a) means for generating an indication of acute heart failure if the cardiac signals indicate the presence of heart failure whereas the impedance values exhibit little or no net change in value and (b) means for generating an indication of chronic heart failure if the impedance values indicate the presence of heart failure whereas the cardiac signals exhibit little or no net change in value.
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17. A method for evaluating heart failure within a patient using an implantable medical device, the method comprising:
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detecting changes, if any, in cardiac electrical signals indicative of heart failure within the patient; detecting changes, if any, in transthoracic impedance values indicative of heart failure within the patient; generating an indication of acute heart failure if the cardiac signals indicate the presence of heart failure whereas the impedance values exhibit little or no net change in value; generating an indication of chronic heart failure if the impedance values indicate the presence of heart failure whereas the cardiac signals exhibit little or no net change in value, wherein acute heart failure is relatively short term as compared to chronic heart failure; and evaluating the severity of heart failure within the patient based on the impedance values and the cardiac signals.
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Specification