| Method and apparatus for classifying and localizing heart arrhythmias -> Monitor Keywords |
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  Method and apparatus for classifying and localizing heart arrhythmiasUSPTO Application #: 20070021679Title: Method and apparatus for classifying and localizing heart arrhythmias Abstract: Analyzes surface electrocardiographic and intracardiac signals to identify and separate electrical activity corresponding to distinct but superimposed events in the heart. Assesses the spatial phase, temporal phase, rate, spectrum and reproducibility of each event to determine uniformity of activation in all spatial dimensions. Uses numerical indices derived from these analyses to diagnose arrhythmias. Uses these indices to determine the location of an arrhythmia circuit, and to direct the movement of an electrode catheter to this location for ablation or permanent catheter positioning. Subsequently, uses these indices to determine whether ablation has successfully eliminated the circuit. Uses variability in these indices from the surface electrocardiogram to indicate subtle beat-to-beat fluctuations which reflect the tendency towards atrial and ventricular arrhythmias. (end of abstract)
Agent: Stout, Uxa, Buyan & Mullins LLP - Irvine, CA, US Inventors: Sanjiv Mathur Narayan, Valmik Bhargava USPTO Applicaton #: 20070021679 - Class: 600518000 (USPTO) Related Patent Categories: Surgery, Diagnostic Testing, Cardiovascular, Heart, Detecting Heartbeat Electric Signal, Detecting Arrhythmia, Tachycardia Or Fibrillation Detected The Patent Description & Claims data below is from USPTO Patent Application 20070021679. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application is a continuation of U.S. application Ser. No. 10/323,423, filed Jun. 3, 2003, which claims the benefit of U.S. Provisional Application No. 60/412,148, filed Sep. 19, 2002. The entire contents of both applications are incorporated herein by reference. BACKGROUND OF INVENTION [0002] 1. Field of the Invention [0003] This invention relates generally to the field of heart rhythm disorders and more specifically to systems and methods for analyzing the electrocardiogram, pacing and mapping the heart for the diagnosis and treatment of cardiac conditions. [0004] 2. History of Technology [0005] A normal heartbeat consists of an organized sequence of conduction and orderly myocardial contraction. Normal (sinus) rhythm begins when the sinoatrial node (or "SA node") generates a depolarization wavefront in atrium. The impulse causes adjacent atrial cells to depolarize in a spreading wavefront, resulting in the "P-wave" on the Electrocardiogram (ECG), which causes the atria to contract and empty blood into the ventricles. Next, the impulse is delivered via the atrioventricular node (or "AV node") and the bundle of His to myocardial tissue cells of the ventricle. Depolarization propagates similarly across ventricular cells, resulting in the "QRS" complex on the ECG, causing the ventricles to contract and eject blood into the lungs and the systemic circulation. [0006] Unfortunately, several important and common diseases result when aberrant conductive pathways develop and disrupt the normal paths of atrial or ventricular depolarization. In general, anatomic barriers (known as "conduction blocks") can develop and disorganize the electrical impulse into wavelets that circulate around the barrier. In addition, localized regions of scarred or ischemic tissue may propagate depolarization slower than normal tissue, causing "slow conduction zones" (SCZ) which facilitate the wavelets to create errant, circular propagation patterns. The "reentry" or "circus motion" resulting from these effects disrupts normal depolarization and contraction of the atria or ventricles, and can lead to abnormal rhythms ("arrhythmias"). [0007] Arrhythmias cause significant mortality and morbidity in the United States. Arrhythmias can include fast rhythms ("tachycardias") and slow rhythms ("bradycardias"). Both can be life-threatening or cause symptoms such as shortness of breath, chest pain, dizziness, loss of consciousness or stroke. Ventricular arrhythmias are the most common cause of sudden death, causing over 300,000 deaths per year. Ventricular arrhythmias include ventricular tachycardia (VT) and fibrillation (VF). Atrial arrhythmias are very common and cause many symptoms. They include atrial fibrillation (AF), the most common arrhythmia in the U.S., affecting up to 5% of the population, atrial tachycardia (AT) and atrial flutter (AFL). [0008] Accurate and precise diagnosis of the arrhythmia is critical in customizing medication therapy for the patient, and to provide accurate advice on the likely outcomes of therapy for that patient. In addition, many arrhythmias are cured nowadays by precisely destroying tissue (known as "ablation") responsible for aberrant conduction using a specialized electrical probe (or "catheter"). For example, typical atrial flutter, in which the circuit involves the sub-eustachian isthmus of the right atrium, is successfully cured in this way. However, other rhythms that may appear similar on the surface ECG, such as atypical AFL, may involve circuits that vary between successive beats and may not consistently involve the isthmus. These rhythms are less successfully ablated. The precise diagnosis and localization of the tissue responsible for an arrhythmia is clearly important for successful ablation. 1. Diagnosis [0009] Current techniques for precise heart rhythm diagnosis are sub optimal and cumbersome. Although the electrocardiogram (ECG) recorded from the body surface forms the cornerstone of diagnosis, current interpretation methods often cannot determine the arrhythmia diagnosis. Invasive electrophysiologic study is then required to confirm the diagnosis and decide upon treatment, although this involves discomfort and risk to the patient. For example, the ECG often cannot separate typical and atypical AFL. However, this distinction is important since typical AFL is best treated by ablation while atypical AFL is more difficult to ablate and is often treated with medications. Thus, invasive electrophysiologic study may be performed, only to find atypical AFL and recommend drug treatment. There is a pressing need to improve upon the prior art and allow accurate diagnosis from the standard 12-lead body surface ECG of the various forms of AFL, other atrial arrhythmias and forms of VT. 2. Arrhythmia Localization, Catheter Guidance and Determination of Ablation Success [0010] For successful ablation, destructive energy is typically targeted and delivered using a catheter positioned in contact with tissue integral to the circuit. The first pass at arrhythmia localization is made using the ECG. However, current methods of analyzing the ECG are often inadequate even to determine if the rhythm originates in the atria or ventricle (such as "wide complex tachycardias"), or whether it primarily involves the left or right side of the heart (such as atypical AFL). However, these distinctions are important since they determine the recommendation for medical or invasive therapy, and the type of invasive therapy (including ablation or surgery). There is a real need for methods to improve arrhythmia localization from the ECG, to help avoid electrophysiologic study in some patients while guiding the study in others. [0011] More precise arrhythmia localization is usually performed during invasive electrophysiologic study. These methods generally involve placing a catheter close to the arrhythmia circuit. This is indicated when the signals after stimulating the heart ("pacing") match those during the actual arrhythmia. However, this requires considerable skill and is often cumbersome even for practitioners skilled in the prior art. All methods require the physician to assimilate and compare the shape and relative timing of multiple (often 10-15) complex signals from the ECG and inside the heart ("intracardiac"), during each pacing episode. This is a field in which numerical and computer processing should have led to increased precision and efficiency. However, the prior art has yet to fill this void; most practitioners use their expert knowledge to process information in much the same way as they did a decade ago. [0012] Once a catheter is maneuvered to the located arrhythmia circuit, it is used to deliver destructive energy ("ablation"). Determining whether ablation is successful is also sub optimal. It requires the physician to be unable to re-induce the arrhythmia. However, this is not foolproof since many arrhythmia circuits are induced on a sporadic basis in the first place. There is clearly a need for quantitative methods to reproducibly determine if activation of the arrhythmia circuit has been eliminated by ablation. 3. Pacemaker and Defibrillator Lead Positioning [0013] The leads of pacemakers and implantable defibrillators are required to pace or deliver high-voltage energy to ("defibrillate") a heart chamber. This purpose is best served by placing leads close to arrhythmia circuits. However, this customization for each patient is not performed, and leads are generally placed in standard anatomic locations. This is because current methods for arrhythmia localization are difficult to implement when implanting a lead. Therefore, even though an atrial lead would better terminate AFL, for example, if placed in the right atrial isthmus, it is usually placed in the right atrial appendage. Similarly, the ventricular lead of an implantable cardiac defibrillator is rarely targeted to a site of VT, even though pacing and defibrillating rhythms emanating from that site may be the main function of that device. [0014] A method to quickly and systematically localize an arrhythmia circuit during implantation of a pacer or defibrillator lead would significantly advance the performance of each of these frequently implanted devices. 4. Arrhythmia Risk Stratification [0015] The prediction of whether a patient will develop an arrhythmia in the future is becoming increasingly important. This is particularly true for VT and VF, where the first occurrence may cause death, but is also important for AF and other arrhythmias. However, the current art is sub optimal in this "risk stratification" since it is rarely able to detect substrates until the patient has a documented arrhythmia. Although there are several methods to determine the risk for VT or VF, none are very accurate and they have not entered routine clinical practice. The prior art for predicting AF, AFL and other atrial arrhythmias is even more rudimentary. [0016] There is a very real need to improve risk stratification for these arrhythmias. Waiting for VT or VF to occur puts the patient at an unacceptable risk (a third or more will not survive), but if identified ahead of time they may receive proven life-saving treatment such an implantable cardioverter defibrillator. Similarly, waiting for AF or AFL to occur delays treatment, while earlier diagnosis and treatment makes them less likely to progress and reduces the risk for stroke and other complications. PRIOR TECHNOLOGY [0017] This section will describe prior technology in each of the areas covered by the invention. 1. Diagnosis Continue reading... Full patent description for Method and apparatus for classifying and localizing heart arrhythmias Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for classifying and localizing heart arrhythmias patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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