Atrial-Synchronized Ventricular Pacing With Selective Tracking
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Solution Overview
Problem
Current cardiac resynchronization therapy (CRT) devices lose AV synchrony during atrial arrhythmias, leading to asynchronous ventricular pacing and reduced hemodynamic flow due to mode switching, which disconnects ventricular paces from intrinsic atrial depolarizations.
Innovation Solution
A modified atrial tracking algorithm that maintains AV synchrony by delivering ventricular pacing pulses at a reduced rate during atrial arrhythmias, using a ratio-based approach such as 4:1 pacing, where a ventricular pulse is provided every fourth atrial depolarization, rather than one-to-one, to synchronize ventricular contractions with atrial activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If mode switching is used to deliver ventricular paces at a reduced rate during atrial arrhythmias, then complete diastolic filling is achieved, but AV synchrony is lost
Solution Approach 1:
The patent applies periodic action by delivering ventricular pacing pulses at regular intervals that are synchronized to every Nth atrial depolarization (e.g., every 4th atrial event). This creates a periodic ventricular pacing pattern that ensures adequate diastolic filling time while maintaining a predictable relationship with atrial activity, thereby preserving AV synchrony during arrhythmias.
Solution Approach 2:
The patent changes the pacing parameters by adjusting the ventricular pacing rate to be a fraction (1/N) of the atrial rate during arrhythmias. This parameter change allows the system to deliver ventricular pulses at a reduced rate that permits complete diastolic filling while maintaining synchrony through the fixed ratio relationship between atrial and ventricular events.
2Reliability
If one-to-one atrial tracking is used during normal sinus rhythm, then AV synchrony is maintained, but ventricular rate becomes too rapid during atrial arrhythmias
Solution Approach 1:
The patent implements periodic action by transitioning from one-to-one tracking to tracking every Nth atrial depolarization during arrhythmias. This creates a periodic ventricular pacing pattern where ventricular pulses are delivered at a reduced frequency (1/N of atrial rate), ensuring adequate filling time while maintaining synchrony through the fixed ratio relationship.
Solution Approach 2:
The patent applies dynamics by making the tracking ratio adjustable and condition-dependent. During normal sinus rhythm, the system uses 1:1 tracking to maintain AV synchrony. During atrial arrhythmias, it dynamically switches to N:1 tracking to reduce ventricular rate. The system can also dynamically adjust the N value based on the detected atrial rate, allowing flexible adaptation to different arrhythmia conditions.
Data Source
AI summary
A device for delivering pacing therapy includes an atrial and ventricular leads, sensing circuitry connected to the leads for detecting depolarizations, and pulse generation circuitry for delivering ventricular pacing pulses based on sensed atrial depolarizations. The device includes control circuitry for controlling the pulse generation circuitry in a first mode in which the pulse generation circuitry delivers atrial synchronized pulses to both the right and left ventricular leads in response to each atrial depolarization sensed. In response to a detected atrial arrhythmia, the control circuitry causes the pulse generation circuitry to deliver atrial synchronized ventricular pacing pulses in response only to selected atrial depolarizations.