What is the optimum A-V interval in D.D.D. pacing?

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Pacemakers utilize programmable parameters like the atrio-ventricular (A-V) interval to optimize cardiac function.
• Determining the ideal A-V interval is crucial for enhancing patient outcomes and device efficacy.

Purpose of the Study:

• To investigate the optimal atrio-ventricular (A-V) interval for maximizing left ventricular function in patients with pacemakers.
• To assess the impact of different A-V intervals on cardiac output and ejection fraction.

Main Methods:

• Utilized multigated radionuclide scans to evaluate left ventricular function in 14 patients at a resting heart rate of 70 bpm.
• Compared cardiac performance metrics at A-V intervals of 150 ms and 250 ms, with a focus on patients exhibiting reduced ejection fraction (<50%).

Main Results:

• Left ventricular ejection fraction, relative cardiac output, and end-diastolic counts were significantly higher at a 250 ms A-V interval compared to 150 ms.
• Patients with poor left ventricular function showed a 27% greater relative cardiac output at 250 ms A-V delay versus 150 ms.
• No significant relationship was found between A-V interval and ejection rate or end-systolic counts.

Conclusions:

• An optimal atrio-ventricular (A-V) interval of 250 milliseconds is recommended for maximizing left ventricular function.
• This interval provides particular benefit for patients with impaired left ventricular function, enhancing cardiac output.