Atrial and ventricular implantable cardioverter-defibrillator and lead system

#This invention relates generally to cardiac rhythm management systems, and more particularly to an implantable cardioverter-defibrillator and lead system for treating atrial tachyarrhythmias or treating both atrial and ventricular tachyarrhythmias.

#Atrial tachyarrhythmias are quite common, and occur even in patients who are not acutely ill. One such atrial tachyarrhythmia, atrial fibrillation, does not usually pose an immediate threat to the patient's life, but since prolonged atrial fibrillation can compromise patient hemodynamics, its treatment is highly desirable. For patients having episodes of atrial fibrillation that do not respond to drug therapy, an electrical countershock delivered by an implantable cardioverter-defibrillator (ICD) may be used to convert the atrial tachyarrhythmia into a normal heart rhythm.

#One method of delivering an electrical countershock to treat atrial fibrillation is illustrated in the Bardy U.S. Pat. No. 5,314,430. The Bardy patent describes a lead system having a coronary sinus/great vein electrode and a subcutaneous left pectoral plate electrode such as on a surface of a defibrillator housing. The Bardy lead system optionally includes a superior vena cava and/or ventricular electrode. The Bardy lead system can be employed in a device that is intended to perform atrial cardioversion or defibrillation only, or in a device that also performs ventricular cardioversion or defibrillation. However, placing the electrode in the coronary/sinus great vein portion of the heart is an extremely difficult procedure for the implanting physician. Moreover, in the case where both atrial cardioversion and ventricular defibrillation are desired, a separate ventricular lead is required. Therefore, there is a need in the art for a more convenient system for performing either atrial cardioversion or both atrial cardioversion and ventricular defibrillation.

#In the drawings, like numerals describe substantially similar components throughout the several views.

#FIG. 1 is a schematic/block diagram illustrating generally one embodiment of a cardiac rhythm management system in relation to a heart to which it delivers therapy.

#FIG. 2 is a flow chart illustrating generally one embodiment of a method of applying anti-tachyarrhythmia therapy.

#In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. In the accompanying drawings, like numerals describe substantially similar components throughout the several views.

#The present invention relates to applying anti-tachyarrhythmia therapy to a heart, including to an atrium of the heart. In this application, atrial tachyarrhythmias (ATs) are understood to comprise any atrial tachyarrhythmia including, but not limited to: sinus tachycardia, atrial flutter, atrial tachycardia, atrial fibrillation, AV nodal reentrant tachycardia. Ventricular tachyarrhythmias (VTs) are understood to comprise any ventricular tachyarrhythmia including, but not limited to, ventricular tachycardia, and ventricular fibrillation (VF). Cardioversion and defibrillation are understood to refer generally to any treatment of a cardiac arrhythmia by an electrical countershock. Cardioverter and defibrillator are understood to refer generally to any device capable of treating a cardiac arrhythmia through an electrical countershock, though pacing or other therapy may also be included. Anti-tachyarrhythmia therapy is understood to comprise treatment of atrial tachyarrhythmia by electrical countershock, anti-tachyarrhythmia drugs, or anti-tachycardia pacing.

#The present invention provides a system for delivering anti-tachyarrhythmia therapy, such as an implantable cardioverter-defibrillator (ICD) delivering an electrical countershock through a lead system that is convenient to implant. In one embodiment, a countershock is delivered to an atrium needing anti-tachyarrhythmia therapy. In another embodiment, a countershock is delivered to either an atrium needing anti-tachyarrhythmia therapy or to a ventricle needing anti-tachyarrhythmia therapy.