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The normal sequence of right and left atrial contraction
G Barletta1, R Del Bene, F Fantini
1Department of Cardiology, Careggi Hospital, University of Florence, Italy. g.barletta@dfc.unifi.it
Summary
Interatrial electromechanical delay (IEmD) varies significantly in healthy individuals during sinus rhythm. This delay, influenced by the sinus impulse origin, impacts ventricular filling dynamics.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Physiology
Background:
- Atrial activation sequence and interatrial electromechanical delay (IEmD) are crucial for understanding cardiac function.
- Noninvasive assessment of these parameters in healthy subjects during sinus rhythm (SR) provides a baseline for comparison.
Purpose of the Study:
- To investigate the sequence of atrial activation.
- To measure interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR).
Main Methods:
- Vectorcardiography was used to analyze P-wave activation in 66 healthy subjects in SR.
- Atrial contraction timing was measured using Doppler inflows (P-A intervals).
- IEmD was calculated as the difference between left and right atrial contraction timings (P-A(m) - P-A(t)).
Main Results:
- Vectorcardiographic P-loop orientation varied (anteroposterior, anterior, posterior).
- Mean IEmD was 17 ± 8 ms, directly related to R-R and P-R intervals.
- IEmD was significantly shorter in subjects with anterior and posterior P-loops compared to typical anteroposterior P-loops.
Conclusions:
- Interatrial electromechanical delay (IEmD) exhibits wide variability in SR.
- The origin site of the sinus impulse influences IEmD.
- Sinus impulse origin independently affects ventricular filling dynamics.