Systems and methods for cardiac pacing are provided, where a pacing lead is placed at or near the bundle of His. A method for pacing a heart of a patient comprises: introducing a sheath to vasculature of the patient; steering the sheath within a coronary sinus in the heart to lodge a distal end of the sheath to a target location proximal to the bundle of His above a septum separating a left ventricle and a right ventricle of the heart; advancing a pacing lead through a lumen of the sheath to the target location; coupling the pacing lead to cardiac tissue at the target location; removing the sheath; and electrically pacing the bundle of His using the pacing lead.

A medical device is configured to detect an atrial tachyarrhythmia episode. The device senses a cardiac signal, identifies R-waves in the cardiac signal attendant ventricular depolarizations and determines classification factors from the R-waves identified over a predetermined time period. The device classifies the predetermined time period as one of unclassified, atrial tachyarrhythmia and non-atrial tachyarrhythmia by comparing the determined classification factors to classification criteria. A classification criterion is adjusted from a first classification criterion to a second classification criterion after at least one time period being classified as atrial tachyarrhythmia. An atrial tachyarrhythmia episode is detected by the device in response to at least one subsequent time period being classified as atrial tachyarrhythmia based on the adjusted classification criterion.

Implantable medical devices (IMD), such as but not limited to leadless cardiac pacemakers (LCP), subcutaneous implantable cardioverter defibrillators (SICD), transvenous implantable cardioverter defibrillators, neuro-stimulators (NS), implantable monitors (IM), may be configured to communicate with each other. In some cases, a first IMD may transmit instructions to a second IMD. In order to improve the chances of a successfully received transmission, the first IMD may transmit the instructions several times during a particular time frame, such as during a single heartbeat. If the second IMD receives the message more than once, the second IMD recognizes that the messages were redundant and acts accordingly.

Wearable devices are provided herein including wearable defibrillators, wearable devices for diagnosing symptoms associated with sleep apnea, and wearable devices for diagnosing symptoms associated with heart failure. The wearable external defibrillators can include a plurality of ECG sensing electrodes and a first defibrillator electrode pad and a second defibrillator electrode pad. The ECG sensing electrodes and the defibrillator electrode pads are configured for long term wear. Methods are also provided for using the wearable external defibrillators to analyze cardiac signals of the wearer and to provide an electrical shock if a treatable arrhythmia is detected. Methods are also disclosed for refurbishing wearable defibrillators. Methods of using wearable devices for diagnosing symptoms associated with sleep apnea and for diagnosing symptoms associated with heart failure are also provided.

An object of the present invention is to provide a new electric device for defibrillation and a method for generating a defibrillation signal. The electric device for defibrillation includes an electrocardiogram waveform input unit; and an enable signal generating unit, wherein the electric device for defibrillation is configured to generate an enable signal from the enable signal generating unit after a peak of an event is surpassed and when or after condition 1 is satisfied, the event being estimated to be an R-wave of an electrocardiogram waveform, the electrocardiogram waveform being obtained from a human body and inputted from the electrocardiogram waveform input unit, and the condition 1 is that a differential value in a differentiated waveform generated based on the electrocardiogram waveform, which corresponds to the event estimated to be the R-wave, is a negative constant C.sub.3 value or less.

A computer implemented method and system are provided for detecting premature ventricular contractions (PVCs) in cardiac activity. The method and system obtain cardiac activity (CA) signals for a series of beats, and, for at least a portion of the series of beats, calculate QRS scores for corresponding QRS complex segments from the CA signals. The method and system calculate a variability metric for QRS scores across the series of beats, calculate a QRS complex template using QRS segments from the series of beats, calculate correlation coefficients between the QRS complex template and the QRS complex segments, compare the variability metric to a variability threshold and the correlation coefficients to a correlation threshold, and designate the CA signals to include a predetermined level of PVC burden based on the determining.

Techniques and devices for implementing the techniques for adjusting atrial arrhythmia detection based on analysis of one or more P-wave sensing windows associated with one or more R-waves. An implantable medical device may determine signal characteristics of the cardiac signal within the P-wave sensing window, determine whether the cardiac signal within the sensing window corresponds to a P-wave based on the determined signal characteristics, determine a signal to noise ratio of the cardiac signal within the sensing window, update the arrhythmia score when the P-wave is identified in the sensing window and the determined signal to noise ratio satisfies a signal to noise threshold.

Techniques and devices for implementing the techniques for adjusting atrial arrhythmia detection based on analysis of one or more P-wave sensing windows associated with one or more R-waves. An implantable medical device may determine signal characteristics of the cardiac signal within the P-wave sensing window, determine whether the cardiac signal within the sensing window corresponds to a P-wave based on the determined signal characteristics, determine a signal to noise ratio of the cardiac signal within the sensing window, update the arrhythmia score when the P-wave is identified in the sensing window and the determined signal to noise ratio satisfies a signal to noise threshold.

Various techniques related to post-treatment parameters of patients are described. An example method includes identifying a segment of an electrocardiogram (ECG) of an individual, wherein the segment is detected during a time interval that begins when an electrical shock is output to the individual's heart. The method further includes identifying a parameter of the electrical shock and generating a report including the segment of the ECG and indicating the parameter of the electrical shock. The report is output or transmitted to an external device.

A method for treatment of cardiac problems includes performing modulation of a cardiac rhythm of a patient by increasing a number of heart beats the patient during time interval with high pleural pressure relative to the number during low (negative) pleural pressure, wherein an amplitude of the modulation of the cardiac rhythm between these segments is determined by severity of a respiratory effort and lung congestion of the patient.