Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart. The atrial defibrillator includes a first detector for sensing depolarization activation waves at a first area of the heart and producing a first signal, a second detector for sensing depolarization activation waves at a second area of the heart and producing a second signal, an analyzing circuit for determining if the first signal satisfies a first criterion and if the second signal satisfies a second criterion. The atrial defibrillator includes a third detector for sensing activity of the heart in at least one of the atria of the heart and an atrial fibrillation detector for determining when the atria of the heart are in need of cardioversion.

Abstract: A defibrillator system includes an implantable defibrillator and a non-implantable external receiver. The implantable defibrillator includes a first sense channel for generating a first electrogram and a second sense channel for generating a second electrogram. The defibrillator further includes a cardioverter for applying cardioverting electrical energy to the heart and a transmitter for transmitting the first and second electrograms. The non-implantable receiver includes a display for simultaneously displaying the first and second electrograms. The implantable defibrillator may further include an event detector having a threshold for detecting cardiac events in one of the electrograms and an event marker generator for generating an event marker for each detected cardiac event. The transmitter transmits the event detection markers and the display displays the event detection markers and the thresholds with the corresponding electrogram.

Abstract: An implantable atrial defibrillator includes at least one lead for sensing electrical activity of a heart, a synchronizing stage for providing a synchronizing signal upon detection of an R wave, a timer for timing time intervals between immediately successive R waves, and a cardiovertor for cardioverting the heart when a cardiac interval is greater than a determined minimum time interval and in timed relation to a synchronizing signal. The defibrillator further includes first and second R wave detection channels, the first R wave detection channel providing the synchronizing stage with specific R wave detection, and the second R wave detection channel providing the timer with sensitive R wave detection.

Abstract: An atrial defibrillator applies cardioverting electrical energy to the atria of a heart when in need of cardioversion. The atrial defibrillator includes an atrial fibrillation detector for determining if the atria of a heart are in need of cardioversion, and a therapy sequencer for performing a therapy sequence to apply cardioverting electrical energy to the atria when the atria are in need of cardioversion. The therapy sequence is terminated when the atrial fibrillation detector fails at least twice in succession to determine that the atria are in need of cardioversion. As a result, a greater atrial fibrillation detection sensitivity is employed for terminating a therapy sequence as is employed for initiating the therapy sequence.

Abstract: An atrial cardiovertor/defibrillator provides therapy to the atria corresponding to the type of atrial arrhythmia occurring in the atria of the heart. The atrial cardiovertor/defibrillator includes a memory for storing respective different criteria for each of different types of atrial arrhythmia, a sensor for sensing activity of at least one of the atria of the heart to provide an electrogram signal, and a cardiovertor for providing a corresponding therapy to the heart for each of the different types of atrial arrhythmia. The cardiovertor/defibrillator further includes an atrial arrhythmia detector responsive to the electrogram signal and the stored criteria for identifying one of the types of atrial arrhythmia to cause the cardiovertor to provide therapy to the heart corresponding to the identified atrial arrhythmia.

Abstract: An atrial defibrillator coordinates atrial cardioversion with ischemia detection. The defibrillator includes a plurality of sense amplifiers for sensing electrical activity of a heart. An ischemia detector is responsive to the sensed electrical activity of the heart for detecting ischemia of the heart. An atrial fibrillation detector is responsive to the sensed electrical activity of the heart for determining if the atria are in need of cardioversion, and a cardiovertor applies cardioverting electrical energy to the atria of the heart if the atria of the heart are in need of cardioversion and if the ischemia detector fails to detect ischemia of the heart.

Abstract: A lead is provided which assists in the implantation of the lead within an artery or vein of a human heart. The lead includes a lead body having a distal end and a proximal end and at least one electrode carried by the lead body intermediate the distal end and the proximal end. The lead includes a guide tip carried by the lead body which extends distally from the lead body distal end. The guide tip includes a distal tip end and a tapered portion forming the distal tip end. The tapered portion is curved in a direction of curvature to offset the distal tip end in a direction from the longitudinal center axis of the lead body. The guide tip may further include tines or fibrotic tissue ingrowth sites for retaining the lead in place after implantation.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion and thereafter paces the heart in a demand mode. The atrial defibrillator includes a first detector for detecting atrial activity of the heart, an atrial fibrillation detector responsive to the atrial activity detected by the first detector for determining when the atria of the heart are in need of cardioversion, and a cardiovertor responsive to the atrial fibrillation detector for applying the cardioverting electrical energy to the atria of the heart when the atria are in need of cardioversion.

Abstract: An atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion. The defibrillator includes an electrode pair and a sense amplifier associated with the atria of the heart for sensing electrical activity of the heart during a plurality of cardiac cycles to provide a cardiac signal. A detector is responsive to the cardiac signal for detecting cardiac events. During each cardiac cycle of the plurality of cardiac cycles, a time for counting is established wherein each time for counting has a total duration less than the duration of its corresponding cardiac cycle. A counter counts the cardiac events detected by the detector during the time for counting of the plurality of cardiac cycles to provide a cardiac event count. A comparator compares the cardiac event count to a predetermined cardiac event count.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in response to detection of an atrial fibrillation episode and stores selected data associated with the detected atrial fibrillation episode. The atrial defibrillator includes a cardiovertor which provides successive applications of cardioverting electrical energy to the atria of the heart until one of the pulses successfully cardioverts the atria. A memory system stores selected heart activity data in connection with the detected episode including heart activity data related to initial detection of the atrial fibrillation episode and heart activity data occurring from before and until after the application of the cardioverting electrical energy which successfully cardioverts the atria of the heart.

Abstract: An implantable atrial defibrillator provides a pulse of defibrillating electrical energy to the atria of the heart in synchronism with sensed R waves in response to non-coincident sensing of an R wave at first and second areas of the heart. The defibrillating pulse is provided after a predetermined number of consecutive R waves are non-coincidently sensed to assure reliable synchronization. The atrial defibrillator is also operational in a marker mode wherein a number of synchronization marker pulses are delivered to the heart for detection on an externally generated electrocardiogram. The atrial fibrillation detector of the defibrillator is normally disabled and is activated when the sensed ventricular activity indicates a probability of atrial fibrillation to conserve a depletable power source. An endocardial lead is also described which ensures that the delivered atrial defibrillating electrical energy is substantially confined to the atria of the heart.

Abstract: A defibrillator, such as an atrial defibrillator, applies cardioverting electrical energy to the atria of a heart when the atria are in need of cardioversion. The atrial defibrillator includes an atrial sense channel for sensing atrial activity and ventricular sense channels for sensing ventricular activity to generate heart activity data, a memory for storing the heart activity data, and a cardiovertor which applies cardioverting electrical energy to the atria if the heart activity satisfies a predetermined criteria. A storage control causes at least a portion of the heart activity data to be retained in the memory if the heart activity data fails to satisfy the predetermined criteria.

Abstract: An atrial defibrillator implantable beneath the skin of a patient includes an intervention sequencer for performing an intervention sequence. The intervention sequencer includes an atrial fibrillation detector for determining if atrial fibrillation is present in a patient's heart and a cardiovertor for applying cardioverting electrical energy to the atria of the patient's heart if the atrial fibrillation detector determines that atrial fibrillation is present. A sequence initiating stage includes a receiver for receiving a sequence command generated from external to the patient. The sequence initiating stage causes the intervention sequencer to perform the intervention sequence upon receipt of a sequence command.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion after first determining if there is an absence of potential atrial fibrillation. A sensor associated with the atria of the heart senses activity of the heart and generates a cardiac signal and a first detector detects cardiac events from the cardiac signal. A second detector responsive to time spans between immediately successive detected cardiac events which are grater in duration than a preselected interval detects for an absence of potential atrial fibrillation. An atrial fibrillation detector detects for atrial fibrillation if the second detector fails to detect an absence of atrial fibrillation, and a cardiovertor applies cardioverting electrical energy to the atria when the atria are in fibrillation.

Abstract: An atrial defibrillator and method provides cardioverting electrical energy to the atria of a human heart after timing successive R to R intervals. A detector detects ventricular activations of the heart and a timer times intervals between immediately successive ventricular activations. A cardiovertor applies cardioverting electrical energy to the atria of the heart when a second time interval between a third ventricular activation and a second ventricular activation immediately preceding the third ventricular activation satisfies a predetermined criteria with respect to a first time interval between the second ventricular activation and a first ventricular activation immediately preceding the second ventricular activation.

Abstract: An intravenous lead for use with a cardiac device for implantation in the coronary sinus or the coronary sinus and great cardiac vein of the heart provides positive fixation for the lead when implanted in the coronary sinus or the coronary sinus and great vein of the heart. The lead includes a lead body adapted to be fed into the coronary sinus and great vein of the heart of a patient and at least one electrode carried by the lead body and adapted to be coupled to the implantable cardiac device. The lead body includes a preformed section having a resiliently coiled configuration. The coiled section is a left-handed turned coiled section which provides superior positive fixation of the lead as compared to right-handed turned coiled sections for use in the coronary sinus and great cardiac vein.

Abstract: An atrial defibrillator implantable beneath the skin of a patient includes an intervention sequencer for performing an intervention sequence. The intervention sequencer includes an atrial fibrillation detector for determining if atrial fibrillation is present in a patient's heart and a cardiovertor for applying cardioverting electrical energy to the atria of the patient's heart if the atrial fibrillation detector determines that atrial fibrillation is present. A sequence initiating stage includes a receiver for receiving a sequence command generated from external to the patient. The sequence initiating stage causes the intervention sequencer to perform the intervention sequence upon receipt of a sequence command.

Abstract: An implantable atrial defibrillator for applying cardioverting electrical energy to the atria of a human heart. The atrial defibrillator includes a first detector for sensing a depolarization activation wave at a first pair of locations of the heart and generating a first initiation signal and a second detector for sensing the depolarization activation wave between a second pair of locations of the heart and generating a second initiation signal. The atrial defibrillator also includes a timing circuit for timing the time between immediately successive depolarization activation waves of the heart in response to one of the first and the second initiation signals for commencing the timing. The atrial defibrillator also includes a cardioverting circuit for applying the cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion and when the timer times a time greater than a predetermined time interval.

Abstract: An implantable automatic atrial defibrillator powered by a depletable battery power source conserves battery power for extending the predicted life of the defibrillator by intermittently detecting for atrial fibrillation. The atrial defibrillator includes a real time clock which, at spaced apart predetermined times, causes heart activity data to be stored in a memory. Thereafter, a normally deactivated atrial fibrillation detector is activated for processing the stored data to detect for atrial fibrillation.

Abstract: An apparatus reliably detects a depolarization activation wave of the heart. The apparatus includes a sensor in electrical contact with the heart for sensing electrical activity of the heart and including an amplifier for amplifying the sensed electrical activity according to a variable gain and providing a signal corresponding to the depolarization activation wave. The apparatus further includes an output circuit coupled to the sensor for producing an electrical output corresponding to the depolarization activation wave sensed by the sensor when the signal exceeds a threshold. The apparatus still further includes a control circuit coupled to the sensor and the output circuit for varying at least one of the gain and the threshold to maintain a predetermined sense margin between the sensed electrical activity and the gain and the threshold.