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.
A cardiac rhythm management system includes a method of applying anti-tachyarrhythmia therapy to a heart in a patient. In one form of the cardiac rhythm management system, a first ventricular electrode is disposed in a ventricle of the heart. A first supraventricular electrode is disposed in a supraventricular region of the heart. The system monitors atrial heart activity for atrial tachyarrhythmia activity indicative of a need for the anti-tachyarrhythmia therapy. Anti-tachyarrhythmia therapy is applied through the first supraventricular and first ventricular electrodes if atrial tachyarrhythmia activity needing anti-tachyarrhythmia therapy is detected.
In another form of the cardiac rhythm management system, an implantable cardioverter-defibrillator (ICD) is disposed in a patient, such as in a pectoral region. The ICD includes an ICD housing electrode. A first supraventricular electrode is disposed in a supraventricular region of the heart. The system monitors atrial heart activity for atrial tachyarrhythmia activity indicative of a need for the anti-tachyarrhythmia therapy. Anti-tachyarrhythmia therapy is applied through the first supraventricular electrode and the ICD housing electrode if atrial tachyarrhythmia activity needing anti-tachyarrhythmia therapy is detected.
In one embodiment, the implantable cardiac rhythm management system includes a first supraventricular electrode, proportioned for disposition within a supraventricular region of the heart. A first ventricular electrode is proportioned for disposition within a ventricle of the heart. An ICD device is electrically coupled for delivering the anti-tachyarrhythmia therapy through the first supraventricular and first ventricular electrodes in response to atrial heart activity indicating a need for anti-tachyarrhythmia therapy.
In another embodiment, the implantable cardiac rhythm management system includes a first supraventricular electrode, proportioned for disposition within a supraventricular region of the heart. An ICD device is electrically coupled to the first supraventricular electrode. An ICD housing electrode is included, carried on a housing of the ICD device and coupled to the ICD device. The ICD device delivers anti-tachyarrhythmia therapy through the ICD housing electrode and the first supraventricular electrode in response to atrial heart activity indicating a need for anti-tachyarrhythmia therapy.
Thus, the cardiac rhythm management system provides either atrial or both atrial and ventricular anti-tachyarrhythmia therapy through a single endocardial lead, although a separate lead may also be used, such as for sensing heart activity. In addition to providing dual-chamber anti-tachyarrhythmia therapy through a single endocardial lead, the cardiac rhythm management system avoids the need for the difficult placement of an electrode in the coronary sinus/great vein region. As a result, the convenience of the lead placement procedure by the implanting physician is greatly increased.