Hemodynamic Consequence of Different Pacing Modes after Aortic Valve Replacement.

Area of Science:

• Cardiology
• Biomedical Engineering
• Cardiac Electrophysiology

Background:

• Left ventricular hypertrophy (LVH) following aortic valve replacement (AVR) can impair hemodynamic function.
• Diastolic dysfunction is common in these patients, complicating optimal heart rate selection for cardiac output.
• The ideal pacing strategy to maximize stroke volume (SV) and cardiac index (CI) in LVH post-AVR remains unclear.

Purpose of the Study:

• To identify the optimal pacemaker stimulation mode and heart rate for maximizing stroke volume (SV) and cardiac index (CI) in patients with LVH post-AVR.
• To evaluate the hemodynamic effects of various pacing modes and rates in this specific patient population.

Main Methods:

• Hemodynamic parameters, including SV and cardiac output, were assessed using pulse curve analysis in 48 patients with severe LVH post-AVR.
• Four pacing modes (atrial (AAI), right ventricular (DDDright), left ventricular (DDDleft), and biventricular (DDDbi)) were tested at five heart rates (60, 80, 100, 120, 140 bpm).
• Measurements were taken intraoperatively and at 3 and 24 hours postoperatively.

Main Results:

• The highest cardiac index (CI) was observed across a range of heart rates from 60 to 140 bpm.
• Atrial pacing (AAI) was the most effective mode in most patients (35%), but other modes were superior in some cases.
• Stroke volume (SV) exhibited a U-shaped trend, peaking at a heart rate of 100 bpm.

Conclusions:

• Increasing heart rate up to 100 bpm can enhance cardiac output in LVH patients post-AVR without a significant drop in SV.
• A universally optimal pacemaker stimulation mode for maximizing hemodynamic parameters could not be determined.
• Individualized assessment of pacing modes and rates is recommended for patients with LVH post-AVR.