Abstract: Systems and methods for providing communications between an external device and first and second leadless pacemakers (LPs) located in a heart are provided. A method includes receiving first and second event messages from the first and second LPs, the first and second event messages received at different points in time at the external device, determining the signal strengths of the first and second event messages, respectively, as received at the external device, adjusting first and second LP discrimination thresholds based on the received signal strengths of the first and second event messages, respectively, and utilizing the first and second LP discrimination thresholds to identify which of the first and second LP transmits subsequent event messages, in order for the external device to independently communicate with the first and second LPs.

Abstract: Techniques are provided for use with an implantable cardiac stimulation device equipped for multi-site left ventricular (MSLV) pacing using a multi-pole LV lead. In one example, MSLV interelectrode conduction delays are determined among the electrodes of the multi-pole LV lead. MSLV interelectrode pacing delays are then set based on the MSLV interelectrode conduction delays for use in delivering MSLV pacing. To this end, various criteria are exploited for determining optimal values for the pacing delays based on the interelectrode conduction delays. MSLV pacing is then controlled using the specified MSLV interelectrode pacing delays. In some examples, the optimization procedure is performed by the implantable device itself. In other examples, the procedure is performed by an external programmer device. In such an embodiment, the external device determines optimal MSLV interelectrode pacing delays and then transmits programming commands to the implantable device to program the device to use the pacing delays.

Abstract: A real-time impedance monitoring system is provided for use with an implantable medical device having an implantable electrical lead. The impedance monitoring system includes components for determining the electrical impedance of the lead as a function of time, with the determination being made substantially in real-time, and components for graphically displaying the electrical impedance of the lead as a function of time, with the display also being generating substantially in real-time. In one specific example described herein, the implantable medical device is a pacemaker and the impedance monitoring system is within an external programmer device separate from the pacemaker. The programmer device includes a computer display screen or a computer printout device for presenting real-time graphical displays of the lead impedance. The programmer may alternatively generate graphical displays of lead impedance as a function of time based upon pre-recorded data.

Abstract: A DC-to-DC converter circuit is disclosed for use in a pacemaker. The DC-to-DC converter circuit is capable of producing a pulse burst and boosting the voltage of the pulse burst up to an effective pacing amplitude, thereby eliminating the need for the multiple pump capacitors and the output capacitor. The DC-to-DC converter circuit uses a transformer to amplify the battery voltage to the required pacing amplitude. By using a transformer, DC leakage current is eliminated without the use of a decoupling capacitor, thereby achieving lower pacing thresholds. Also, each patient may be individually tested to determine their response to high frequency pulse bursts and a "customized" pacing waveshape can be produced by varying the duty cycle, polarity or pulse burst of each stimulation signal. The DC-to-DC converter circuit also reduces the polarization effect of the tissue around the electrodes.