[Doppler echocardiography determination of systolic and diastolic function in sequential and ventricular stimulation]

Area of Science:

• Cardiology
• Biomedical Engineering
• Echocardiography

Background:

• Sequential pacing is used in patients with impaired left-ventricular function.
• The atrioventricular (AV) interval significantly influences cardiac hemodynamics.

Purpose of the Study:

• To investigate the impact of varying AV intervals during sequential pacing on valvular flow and cardiac output.
• To determine if echocardiographic parameters can predict the hemodynamic benefits of sequential pacing.

Main Methods:

• Doppler echocardiography was used to study mitral and aortic valve flow in 16 patients.
• Heart rate was maintained at 70/min, with measurements taken at different AV intervals.

Main Results:

• Diastolic filling parameters (time-velocity integral, filling fraction, filling time) were significantly dependent on the AV interval (p < 0.001).
• Maximum stroke volume (85.6 ± 28.4 ml) occurred at a 200 ms AV interval.
• Stroke volume during VOO pacing was 17% lower than optimal sequential pacing (p < 0.003).
• No correlation was found between stroke volume increase and M-mode or Doppler parameters.

Conclusions:

• Echocardiography cannot predict the hemodynamic benefits of sequential pacing.
• Doppler echocardiography is valuable for identifying the AV interval that maximizes cardiac output at rest.
• The influence of the AV interval on diastolic filling must be considered in echocardiographic assessments of left-ventricular function.