Identification of abnormal cardiac substrate during left-ventricular pacing
Inventors
Grenz, Nathan A. • Atwater, Brett • Beshai, John F.
Assignees
Medtronic Inc • US Department of Veterans Affairs
Publication Number
US-9289145-B2
Publication Date
2016-03-22
Expiration Date
2033-12-05
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Abstract
Techniques for identifying abnormal cardiac substrate, e.g., scar substrate, may be implemented, as an example, during implantation of a left-ventricular (LV) lead, e.g., for cardiac resynchronization therapy (CRT), which may enable placement of the LV lead to avoid the abnormal cardiac substrate. An example system for identifying abnormal cardiac substrate comprises at least one implantable LV lead comprising at least one bipolar electrode pair configured to sense a LV bipolar cardiac electrogram signal of LV tissue proximate the bipolar electrode pair. The system delivers cardiac pacing pulses to a left ventricle via at least one electrodes of the LV lead, which may be different then the electrodes of the bipolar pair, and which may be spaced at least a threshold distance from the bipolar pair of electrodes. The amplitude of paced depolarizations in the bipolar electrogram indicates whether tissue proximate the bipolar electrode pair comprises abnormal cardiac substrate.
Core Innovation
The invention is directed to devices, systems and techniques for identifying abnormal cardiac substrate, such as scar substrate, of the left ventricle during left-ventricular (LV) pacing. It employs an LV lead implanted on the left ventricle that includes a bipolar electrode pair configured to sense an LV bipolar cardiac electrogram signal of LV tissue proximate the electrodes. The system determines whether the tissue near the bipolar electrode pair is abnormal based on the amplitude of LV-paced depolarizations within the bipolar electrogram signal, where pacing is delivered via an electrode different from the sensing bipolar pair and spaced at least a threshold distance away.
The background identifies the problem that the effectiveness of cardiac resynchronization therapy (CRT) can be compromised when the LV pacing electrode is proximate to abnormal or scar tissue, as such tissue may not depolarize or propagate depolarization effectively. Existing LV mapping uses bipolar electrode pairs during intrinsic conduction to identify scar substrate before lead implantation, but the methodology and thresholds used during intrinsic conduction may not be effective during LV pacing. Therefore, there is a need for techniques to identify abnormal cardiac substrate during LV pacing, particularly during LV lead implantation, to allow optimal placement of the lead to improve therapy effectiveness.
Claims Coverage
The patent claims cover several inventive features related to systems and methods for identifying abnormal cardiac substrate using an LV lead with specific electrode configurations and analysis modules.
Use of an implantable LV lead with a bipolar electrode pair sensing electrogram signal proximate tissue
The system includes at least one implantable left-ventricular (LV) lead having multiple electrodes, including at least one bipolar electrode pair configured to sense an LV bipolar cardiac electrogram signal in tissue near that pair.
Delivery of cardiac pacing pulses spaced from sensing bipolar pair
A signal generator delivers cardiac pacing pulses to the left ventricle via at least one electrode spaced from the bipolar sensing pair by at least approximately ten millimeters, ensuring the pacing electrode does not include electrodes of the sensing pair.
Determination of depolarization amplitude to identify abnormal substrate
A cardiac tissue analysis module determines an amplitude of a depolarization within the sensed LV bipolar cardiac electrogram signal, resulting from pacing pulses, where the amplitude indicates whether the proximate tissue comprises abnormal cardiac substrate.
Comparison of amplitude to a threshold to provide substrate indication
The cardiac tissue analysis module compares the depolarization amplitude to a threshold and, if below the threshold, provides an indication that the tissue proximate the bipolar pair comprises abnormal substrate such as scar.
Bipolar electrode pair with short inter-electrode spacing
The bipolar electrode pair used for sensing comprises an inter-electrode spacing less than or equal to approximately five millimeters, with examples down to approximately 1.3 millimeters or two millimeters.
User interface provision of substrate indication
The system provides an indication to a user via a user interface whether the tissue proximate the bipolar electrode pair is abnormal.
Integration with implantable medical devices and external computing devices
The system may include an implantable medical device that delivers the pacing and/or an external computing device that communicates with the implantable device and presents substrate indications to the user, with either device incorporating the analysis module.
Method claims reflecting sensing, pacing, amplitude determination, and indication
Method claims cover sensing an LV bipolar electrogram via a bipolar pair, delivering pacing pulses spaced from the sensing pair, determining depolarization amplitude, comparing to a threshold, and providing an indication of abnormal substrate based on the amplitude.
Further steps such as moving lead or modifying tissue in response to indications
Methods include moving the LV lead to a different implantation site upon indication of abnormal substrate, and modifying the tissue, such as ablating, based on the substrate indication.
Computer-readable storage medium with instructions for signal reception, amplitude determination, and indication
Claims include non-transitory computer-readable media storing instructions executed by a processor to receive bipolar cardiac electrogram signals during pacing, determine depolarization amplitude, and provide substrate indication based on the amplitude and electrode spacing criteria.
The claims collectively cover a system and method featuring an implantable LV lead with a bipolar sensing electrode pair and a pacing electrode spaced at least approximately ten millimeters apart, a module determining depolarization amplitude during LV pacing to identify abnormal cardiac substrate, and providing indications to clinicians, along with specific electrode spacing and threshold criteria for substrate identification.
Stated Advantages
Allows identification of abnormal cardiac substrate, such as scar tissue, during left-ventricular pacing, which may improve lead placement during implantation.
Enables real-time mapping of cardiac tissue abnormalities without requiring separate mapping catheters.
Facilitates avoidance of pacing at sites proximate abnormal substrate, potentially improving the effectiveness of cardiac resynchronization therapy.
Improves discrimination of scar from normal tissue during pacing by using pacing electrodes spaced at least a threshold distance from sensing electrodes.
Documented Applications
Implantation of left-ventricular leads for cardiac resynchronization therapy (CRT).
Mapping and identification of left ventricular scar or abnormal substrate during LV pacing to guide lead placement or ablation procedures.
Use with implantable medical devices such as pacemakers or defibrillators equipped with LV leads having multiple electrodes.
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