Patent Issued for System and Method for Cardiac Resynchronization Therapy Control Parameter Generation Using Ventricular Activation Simulation and Surface ECG Registration
The patent's inventor is Sweeney, Michael O. (
This patent was filed on
From the background information supplied by the inventors, news correspondents obtained the following quote: "The field of the invention is systems and methods for cardiac rhythm management. More particularly, the invention relates to systems and methods for performing cardiac resynchronization therapy in which adjustments to pacing control parameters are automatically made in relation to simulated and derived models of cardiac electrical activity, such as simulated and derived models of global cardiac electrical activity.
"Left ventricular conduction delay due to bundle branch block causes regional heterogeneity in contraction and stretch, or asynchrony, which reduces pump function and stimulates negative left ventricular remodeling, such as increased chamber volumes. Experimental models have demonstrated a direct linkage between left ventricular electrical activation, cardiac mechanics, and remodeling. The conceptual basis of multisite pacing, which is also referred to as cardiac resynchronization therapy ('CRT') or biventricular pacing, for asynchronous heart failure is to minimize ventricular conduction delay, which reduces contractile asynchrony and improves chamber mechanics. Resynchronization of electromechanical activation induces so-called 'reverse' remodeling, characterized by ventricular volume reductions, and improved pump function, characterized by increased ventricular ejection fraction. Reverse remodeling is associated with reduced heart failure morbidity and mortality. However, up to one-third of patients do not improve following CRT.
"The translational mechanism for reverse volumetric remodeling in response to multisite pacing for asynchronous heart failure is ventricular activation wavefront fusion, which is evident on the paced 12-lead surface ECG. Presence of ventricular activation wavefront fusion predicts increased probability of reverse remodeling, whereas absence of wavefront fusion predicts reduced probability of remodeling, regardless of baseline substrate conditions.
"Unfavorable substrate conditions, such as high myocardial scar volume or small amounts of ventricular conduction delay, cannot be modified by pacing techniques. In contrast, pacing strategies can be readily adapted to modify ventricular activation, and such instructions can be implemented automatically in the fully ambulatory patient having a cardiac implantable electrical device ('CIED'). Recent experimental evidence indicates that only two-thirds of CIED patients have paced surface ECG evidence of ventricular activation wavefront fusion during conventional CRT. This implies that failure to correct ventricular conduction delay, despite conventional CRT pacing, contributes significantly to volumetric remodeling non-response.
"The limitation of existing CIED approaches to automatic or semi-automatic adjustment of pacing control systems for CRT is that they rely solely on limited device-based measurements that have not been correlated with improvement in any clinical outcome measure, most notably, reverse volumetric remodeling.
"It would therefore be desirable to provide a system and method for generating patient-specific cardiac resynchronization therapy pacing control parameters that more accurately result in ventricular activation wavefront fusion as characterized by global ventricular activation patterns."
Supplementing the background information on this patent, NewsRx reporters also obtained the inventor's summary information for this patent: "The present invention overcomes the aforementioned drawbacks by providing a system and method for cardiac resynchronization therapy ('CRT') in which a model of baseline cardiac electrical activity, such as a model of global baseline cardiac electrical activity derived from various surface electrocardiograph ('ECG') signals, is utilized to automatically adjust pacing control parameters of a cardiac implantable electrical device ('CIED') are provided. The baseline model is modified with simulated pacing control parameters in an iterative fashion until ventricular electrical asynchrony is minimized. The simulated pacing control parameters resulting in the minimum ventricular electrical asynchrony are used to generate an updated model of ventricular activation, and this updated model is used to generate control parameters for the CIED using a QRS glyph morphological framework.
"It is an aspect of the invention to provide a method for delivering cardiac resynchronization therapy to a patient's heart with a cardiac rhythm management ('CRM') device. Signals representing baseline cardiac electrical activity in the patient's heart are acquired using electrocardiograph surface-lead electrodes, and a baseline model of ventricular conduction is formed using these signals. The baseline model is iteratively modified in order to minimize ventricular electrical asynchrony. From this iteratively modified baseline model, an updated model of global ventricular conduction that is indicative of ventricular activation wavefront fusion is generated. This updated model is then converted into pacing control parameters for the CRM device using a QRS hieroglyph morphological framework.
"It is another aspect of the invention to provide a cardiac implantable electrical device ('CIED') for delivering cardiac resynchronization therapy to a patient's heart. The CIED includes an input for receiving signals indicative of baseline cardiac electrical activity in the heart from electrocardiography surface leads, an impulse delivery system for delivering electrical impulses to the heart in order to provide cardiac resynchronization therapy to the heart, a memory for storing pacing control parameters, and a processor in communication with the memory. The processor is configured to receive the signals representing baseline cardiac electrical activity in the patient's heart, form a baseline model of ventricular conduction using the received signals, iteratively modify the baseline model to minimize ventricular electrical asynchrony, generate an updated model of global ventricular conduction that is indicative of ventricular activation wavefront fusion using the iteratively modified baseline model, convert the updated model into pacing control parameters using a QRS hieroglyph morphological framework, and communicate with the impulse delivery system to provide cardiac resynchronization therapy to the heart in accordance with the pacing control parameters.
"It is yet another aspect of the invention that real-time patient-specific simulations of cardiac electrical activation during multisite pacing may be used to identify the optimal conditions for generating maximum evidence of ventricular activation wavefront fusion.
"It is yet another aspect of the invention that the aforementioned simulations rely on models of cardiac electrical activation that can be related to specific electrocardiography ('ECG') registrations on the body surface ('forward solution').
"It is yet another aspect of the invention that body surface ECG signals can be related to cardiac electrical activation ('inverse solution').
"It is yet another aspect of the invention that, using an 'inverse solution,' the baseline ventricular activation sequence is duplicated to form a baseline model of ventricular conduction.
"It is yet another aspect of the invention that this baseline ventricular activation sequence model may be iteratively modified with pacing simulations of cardiac resynchronization therapy ('CRT') to generate maximum evidence of ventricular activation wavefront fusion.
"It is yet another aspect of the invention that the final best-fit activation wavefront fusion simulation may be used to generate a 'forward solution' for the corresponding unique surface ECG registration of global ventricular activation.
"It is yet another aspect of the invention that the patient-specific simulation and modeling process is conducted in real-time by linking the simulation software and surface ECG to the CIED programmer.
"It is yet another aspect of the invention that the final parameters of the inverse solution for baseline ventricular activation are stored in a registry on the CIED and/or CIED programmer.
"It is yet another aspect of the invention that a registry of critical timing parameters, such as monochamber ventricular timing, cross-chamber ventricular timing, cross-chamber atrial-ventricular timing, varying stimulation strength and pulse duration, and others known to those skilled in the art, corresponding to each forward solution pacing simulation are automatically stored in a registry on the CIED and/or CIED programmer.
"It is yet another aspect of the invention that these registries can be subsequently retrieved so that any desired set of critical timing control parameters generated by the simulations can be recalled, modified and implemented at a later date without necessarily recreating the inverse and forward solution processes.
"It is yet another aspect of the invention that, in the event that the QRS glyph signature for ventricular activation fusion generated by the forward solution process cannot be suitably duplicated by CIED-based EGM surrogates, CIED operation could be instructed by implementing the critical timing parameters that generated activation wavefront fusion derived from the forward solution, which are stored in the settings registry. In this case, periodic automatic updates to critical control parameters could be achieved by repeating the inverse and forward solution simulation processes, rather than automatically using CIED-based EGM surrogates.
"It is yet another aspect of the invention that the corresponding surface ECG registration can be transferred to CIED-based surface ECG surrogates in the form of multiple, complementary intracardiac, far-field (including body surface) EGM QRS glyphs, and the resulting CIED EGM QRS glyph template patterns can be used to continuously adapt pacing control parameters to guarantee optimal global ventricular activation wavefront fusion on a continuous (e.g., beat-to-beat) or nearly continuous basis.
"It is yet another aspect of the invention that these enhancements provide additional advantages including patient-specific real-time ventricular activation sequencing; the ability to specifically model the effects of different pacing stimulation sites, timing relationships, and substrate conditions on ventricular activation sequencing; the ability to anticipate timing requirements necessary for achieving maximum evidence of ventricular activation wavefront fusion; the ability to directly transfer to body surface ECG registration facilitating identification and selection of pivotal CIED QRS glyph template patterns used to automatically adapt and update critical pacing control parameters to guarantee global ventricular activation wavefront fusion; and the ability to supplement and/or eliminate the conventional 12-lead surface ECG for ventricular activation sequencing analysis.
"It is another aspect of the invention to provide a method for delivering cardiac resynchronization therapy to a patient's heart with a CIED for CRM. Pacing control and timing parameters used to direct the therapy are continuously and automatically adjusted using a model of cardiac electrical activity, such as a model of global cardiac electrical activity that is derived from baseline and paced surface electrocardiography signals. Exemplary timing parameters include atrioventricular intervals ('AVIs'), such as intrinsic AVIs ('iAVI'), pacemaker AVIs ('pAVI'), and effective AVIs ('eAVI').
"It is yet another aspect of the invention to provide a method for automatically increasing atrial sensitivity of a CIED to overcome failure to achieve maximum evidence of ventricular activation wavefront fusion during multisite pacing and to reduce the risk of left ventricular filling abnormalities, such as diastolic dysfunction, without compromising maximal evidence of ventricular activation wavefront fusion.
"The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention."
For the URL and additional information on this patent, see: Sweeney, Michael O.. System and Method for Cardiac Resynchronization Therapy Control Parameter Generation Using Ventricular Activation Simulation and Surface ECG Registration. U.S. Patent Number 8805504, filed
Keywords for this news article include: Therapy, Cardiology, Heart Disease, Heart Failure, Cardiovascular Diseases, Brigham and
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