56 results about "Ventricular depolarization" patented technology

A method and apparatus for detecting and treating atrial fibrillation. In response to detecting atrial fibrillation, the device derives an escape interval based on one or more preceding intervals between ventricular depolarizations. The escape interval is initiated in response to a ventricular depolarization, and in response to the expiration of the escape interval, an atrial cardioversion pulse is delivered. In one embodiment of the invention, the cardioverting pulse is delivered immediately upon expiration of the derived escape interval. In a second embodiment of the invention, a ventricular pacing pulse is delivered on expiration of the escape interval, with an atrial cardioversion pulse following after a short delay.

Methods and systems of noise detection and response for use when monitoring for arrhythmias are described herein. At least two electrodes are used to obtain a signal indicative of cardiac electrical activity. The signal is bandpass filtered to obtain a filtered signal. Ventricular depolarizations are monitored for based on comparisons of the filtered signal to a first threshold. Arrhythmias are monitored for based on ventricular depolarization detections that occur as a result of monitoring for ventricular depolarizations. During one or more noise detection windows, noise is monitored for and a likelihood that monitoring for arrhythmias is adversely affected by noise is determined based on results thereof. Whether and/or how the monitoring for arrhythmias is performed is modified when it is determined that monitoring for arrhythmias is likely adversely affected by noise.

According to the present invention a sensing means is provided for chronically measuring and/or sensing contractions of a right ventricle (RV) and/or a left ventricle (LV). The sensing means can include a tensiometric sensor, a single or a multiple axis accelerometer to measure peak endocardial acceleration due to atrial and ventricular depolarizations. For example, a tensiometric stylet, disposed within a portion of the coronary sinus, great vein, or branches of the great vein, simultaneously senses atrial contractions, RV contractions and LV contractions and provides an output signal related thereto. When an atrial contraction occurs, pacing stimulation is delivered to the LV upon expiration of a predetermined A-LV delay interval. The A-LV delay interval for the pacing therapy is adjusted so as to avoid delay between the respective contractions of RV and LV, respectively, and thereby promote ventricular synchrony.

An implantable cardioverter defibrillator (ICD) senses ventricular depolarizations (R-waves) in an electrogram signal to detect a ventricular tachycardia or fibrillation episodes. The EGM signal is also monitored in real time for characteristics that uniquely identify instances of T-wave oversensing. The ICD determines whether detection of a tachycardia or fibrillation episode is appropriate based upon counts of each of the unique characteristics evidencing T-wave oversensing.

Systems and methods for pacing the heart using resynchronization pacing delays that achieve improvement of cardiac function are described. An early activation pacing interval is calculated based on an optimal AV delay and an atrial to early ventricular activation interval between an atrial event and early activation of a ventricular depolarization. The early activation pacing interval for the ventricle is calculated by subtracting the measured AV_EA from the calculated optimal AV delay. The early activation pacing interval is initiated responsive to sensing early activation of the ventricle and pacing is delivered relative to expiration of the early activation pacing interval.

The invention is directed to techniques for providing cardiac resynchronization therapy by synchronizing delivery of pacing pulses to the left ventricle with intrinsic right ventricular depolarizations. An implantable medical device measures an interval between an atrial depolarization and an intrinsic ventricular depolarization is measured. In various embodiments, the intrinsic ventricular depolarization may be an intrinsic right or left ventricular depolarization. The implantable medical device delivers pacing pulses to the left ventricle to test a plurality of pacing intervals. The pacing intervals tested may be within a range around the measured interval between the atrial depolarization and the intrinsic ventricular depolarization. One of the pacing intervals is selected based on a measured characteristic of an electrogram that indicates ventricular synchrony. For example, the pacing interval may be selected based on measured QRS complex widths and/or Q-T intervals. The implantable medical device paces the left ventricle based on the selected pacing interval.

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device operates to promote intrinsic conduction by providing elongated AV intervals or operating in an atrial based pacing mode. Conduction checks to determine if AV conduction is present are performed on a graduated or progressive scale to facilitate intrinsic emergence.

A dual chamber cardiac pacemaker has a pulse controller for delivering stimulation pulses to the ventricle of a heart, a ventricular sensor for sensing ventricular depolarization, and a unit for identifying a beginning of an A-V interval of the heart. The pulse controller causes a ventricular stimulation pulse to be generated at a predetermined energy level after the expiration of a predetermined A-V interval. The controller prolongs the A-V interval under certain circumstances. Upon the expiration of the prolonged A-V interval, the pulse controller causes the ventricular pulse generator to emit a ventricular stimulation pulse at a higher energy level than the predetermined energy level to evoke a response in the ventricle. This allows the intrinsic heart activity to be detected and utilized, while ensuring safe pacing, as well as successful and reliable stimulation and maintaining a low power consumption during normal operation.

A method and apparatus for preventing atrial fibrillation arising from a premature atrial contraction. Upon detection of a premature atrial contraction, a pace is delivered to a ventricle at a specified AV interval selected as either a late-pace or early-pace value. The resulting ventricular depolarization then occurs during a time when the atria are not vulnerable to the triggering of fibrillation.

In some embodiments, a method for operating a cardiac rhythm management device may include one or more of the following steps: (a) sensing atrial depolarizations through an implanted atrial electrode, (b) administering a sequential CRT pacing therapy in a sequential CRT pacing mode to a left and right ventricle of a heart of a patient via implanted ventricular electrodes in a sequential bi-ventricular fashion, (c) switching from the sequential CRT pacing mode to a simultaneous CRT pacing mode, (d) administering a simultaneous CRT pacing therapy in the simultaneous CRT pacing mode to the left and right ventricle in a simultaneous bi-ventricular fashion, (e) analyzing the sensed atrial depolarizations to detect the presence of an atrial arrhythmia, (f) analyzing the sensed atrial depolarizations while in the sequential CRT pacing mode to detect the presence of atrial arrhythmia, and (g) sensing ventricular depolarizations of the left and the right ventricle.

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. When a cardiac rate exceeds a predetermined threshold, the implantable medical device modifies the pacing protocol parameters to promote AV synchrony.

An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. The medical device determines a course of action based upon the presence or absence of sensed ventricular activity. The device further determines whether that activity is properly conducted or the result of a PVC or nodal rhythm.

This invention is directed to methods for controlling the duration of the depolarization and repolarization of the cardiac ventricle and therefore the QT interval, in therapeutically useful ways in a subject, comprising administering to the subject in need thereof a therapeutically effective amount of a compound selected from the group consisting of Formula (I) and Formula (II), or a pharmaceutically acceptable salt or ester thereof:

wherein phenyl is substituted at X with one to five halogen atoms selected from the group consisting of fluorine, chlorine, bromine and iodine; and, R₁, R₂, R₃, R₄, R₅ and R₆ are independently selected from the group consisting of hydrogen and C₁-C₄ alkyl; wherein C₁-C₄ alkyl is optionally substituted with phenyl, wherein phenyl is optionally substituted with substituents independently selected from the group consisting of halogen, C₁-C₄ alkyl, C₁-C₄ alkoxy, amino, nitro and cyano.