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AN IMPROVEMENT OF AN ASYNCHRONIZED METHOD OF ATRIAL THRESHOLD TESTING

IP.com Disclosure Number: IPCOM000085378D
Publication Date: 2005-Mar-02
Document File: 5 page(s) / 150K

Publishing Venue

The IP.com Prior Art Database

Abstract

A process that enables evaluation of atrial capture threshold for consecutive beats while maintaining lower rate ventricular support involves asynchronous atrial pacing at a rate above the sinus rhythm to determine the atrial capture threshold while minimizing the interference from the native ventricular rhythm. Atrial capture or loss of capture can be evaluated through the presence or absence of a P-wave.

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An Improvement of an Asynchronized Method

of Atrial Threshold Testing

                    Conventional modes for atrial threshold testing include AAI mode “overdrive pacing” if the AV node is intact, and DDD mode with extended AV delay (300 msec.) for AV block points.  The AAI mode for atrial threshold testing can be problematic for patients with atrial arrhythmias, a high degree of heart blockage, or ablated AV node.  In the DDD mode with ventricular pacing, even with an extended AV delay, confusion may arise because a P-wave can be lost in the ventricular complex.  This makes atrial threshold testing difficult for pacemaker dependent patients. 

                    A process that enables evaluation of atrial capture threshold for consecutive beats while maintaining lower rate ventricular support involves asynchronous atrial pacing at a rate above the sinus rhythm to determine the atrial capture threshold while minimizing the interference from the native ventricular rhythm.  Atrial capture or loss of capture can be evaluated through the presence or absence of a P-wave.

                    In one example of this process, asynchronous pacing is performed with AAI and VVI pacing at a different rate, e.g., AAI pacing at a rate of 90 ppm, or higher than the patient’s intrinsic sinus rate at the time of testing, along with backup VVI pacing at a rate of 50 ppm.  The atrial pacing output automatically steps-down after a programmable number of pulses, e.g., every 3 pulses.  This automatic step-down can be fixed or programmable. 

                    The process may be initiated through the use of a device programmer having a Diagnostic Evaluation/ Threshold Test screen with additional selection buttons (Atrium and Asynch) for chamber test selection.  Two additional selection windows may be utilized to allow the clinician to enter an independent atrial test rate and a ventricular backup rate when the Atrium, Asynch buttons are selected.  Similarly, when the Atrium, Asynch buttons are selected, a parameter input window can popup for input of additional parameters such as AAI lower rate limit, atrial amplitude (used to step down), pulse width, and VVI backup rate, amplitude and pulse width.

                    Using AAI with VVI backup pacing allows asynchronous pacing to facilitate atrial threshold measurements.  The methods illustrated by the examples above can be used in dual-chamber devices and in bi-ventricular devices.  The methods can be extended to additional test modes including RV threshold measurements with LV backup, LV threshold measurements with RV backup.  Further, the methods may be utilized in a permanent AAI pacing mode with VVI backup. 

                    Figure 1 illustrates an example process that may be utilized for non-synchronized atrial threshold testing with ventricular backup pacing.  The threshold test process may begin 110, for example, by the clinician selecting an appropriate button o...