Automatic beat-to-beat left heart AV normalization: is it possible?

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Optimizing right heart AV interval programming can be challenging due to interatrial and interventricular conduction delays, potentially impairing cardiac performance.
• Existing AV normalization methods may be invalidated by pacing mode changes during rest or exercise.
• Accurate assessment of left heart AV timing is crucial for effective cardiac pacing.

Purpose of the Study:

• To evaluate the feasibility of a mode-independent pacemaker algorithm for automatic beat-to-beat left AV normalization.
• To establish normal reference values for the AfVa interval, a mechanical surrogate of left AV timing.
• To determine interatrial electromechanical delay (IAEMD) values and the impact of right atrial pacing.

Main Methods:

• Utilized diagnostic echo Doppler studies in 84 subjects across control, cardiac pathology, and DDD-paced groups.
• Collected data on interatrial electromechanical delays (IAEMDs) and atrial-paced IAEMDs (IAEMDp).
• Tested a novel algorithm (RAV = N + IAEMD - IVD) via computer simulation under various pacing modes and rates.

Main Results:

• Established normal AfVa interval in controls as 85 ± 15 ms (range 52-110 ms).
• Determined mean IAEMDs across all subjects to be 84 ± 16 ms.
• Demonstrated that atrial pacing significantly prolonged IAEMDs by 57 ± 18 ms (P < 0.0001).
• Computer simulations validated the algorithm's ability to normalize left AV timing across different modes and rates.

Conclusions:

• An automatic, beat-to-beat left AV normalization algorithm is feasible for maintaining a normal AfVa interval without hemodynamic sensors.
• The established normal AfVa value of 85 ± 15 ms provides a critical reference for pacing optimization.
• This algorithm holds potential for improving cardiac performance in paced patients by addressing conduction delays.