Global and regional atrial function after rapid atrial pacing: an echo Doppler study

Area of Science:

• Cardiovascular Physiology
• Echocardiography
• Cardiac Electrophysiology

Background:

• Atrial function is crucial for cardiac output.
• Atrial arrhythmias can significantly impact cardiac hemodynamics.
• Understanding the effects of rapid atrial pacing on atrial function is important for clinical management.

Purpose of the Study:

• To investigate the impact of rapid atrial pacing on diastolic transmitral, left atrial appendage, and pulmonary venous flow velocities.
• To assess changes in left atrial pump and conduit function following rapid atrial pacing.
• To evaluate the effect of rapid atrial pacing on left ventricular systolic function.

Main Methods:

• Utilized transesophageal echocardiography in five dogs.
• Measured pulsed-wave Doppler velocities of transmitral, left atrial appendage, and pulmonary venous flow.
• Assessed left ventricular systolic function using fractional area shortening.
• Compared hemodynamic parameters before and 1 week after rapid atrial pacing (400 beats/min).

Main Results:

• Significant decreases in transmitral, left atrial appendage, and pulmonary vein systolic velocities were observed.
• Increased transmitral and left atrial appendage early-to-late velocity ratios indicated impaired atrial contraction.
• Decreased pulmonary venous systolic-to-diastolic velocity ratio suggested altered pulmonary venous flow dynamics.
• Left ventricular systolic function remained preserved.

Conclusions:

• One week of rapid atrial pacing leads to impaired global and regional atrial pump function.
• Conduit function of the left atrium is enhanced following rapid atrial pacing.
• Left ventricular systolic function is preserved despite altered atrial mechanics.
• Findings may inform anticoagulation strategies in patients with atrial arrhythmias.