How can the rate-adaptive atrioventricular delay be programmed in atrioventricular block pacing?

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Rate-adaptive atrioventricular (AV) delay programming aims to optimize cardiac function in patients with pacemakers.
• Understanding the components influencing optimal AV delay, such as interatrial conduction time (IACT) and electromechanical action durations, is crucial.

Purpose of the Study:

• To optimize recommendations for programming the rate-adaptive atrioventricular (AV) delay in patients with atrioventricular block (AVB).
• To investigate the impact of exercise on the components determining optimal AV delay.

Main Methods:

• Twenty patients with third-degree AV block and preserved ejection fraction (EF >45%) receiving DDD pacemakers were studied.
• Measurements of interatrial conduction time (IACT), left-atrial electromechanical action duration (LA-EAC(long)), and left-ventricular latency (S(V)-EAC(short)) were performed at rest and during submaximal exercise.
• Optimal AV delay (AVD(opt)) was calculated using the formula: AVD(opt) = IACT + LA-EAC(long) - S(V)-EAC(short).

Main Results:

• No significant differences were observed in the components of optimal AV delay or the final AVD(opt) between rest and exercise conditions.
• Variations in IACT, S(V)-EAC(short), and AVD(opt) were minimal across different pacing modes (VDD and DDD) and during rate changes.
• The greatest variation was observed in LA-EAC(long), but overall rate-dependent variations in AVD(opt) were not substantial enough for definitive programming recommendations.

Conclusions:

• A definitive recommendation for programming rate-adaptive AV delay in atrioventricular block patients cannot be provided based on current findings.
• The study highlights the complexity and limited rate-dependency of the factors influencing optimal AV delay programming in this patient group.