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Beat-to-beat assessment of left ventricular ejection in atrial fibrillation
Insights
In atrial fibrillation, beat-to-beat left ventricular ejection variations are significantly higher than in sinus rhythm. Ejection changes are primarily linked to filling time, not systolic duration.
Area of Science:
- Cardiology
- Physiology
Background:
- Atrial fibrillation (AF) is a common arrhythmia affecting cardiac function.
- Understanding beat-to-beat variations in left ventricular ejection is crucial for assessing cardiac performance.
Purpose of the Study:
- To evaluate beat-to-beat left ventricular ejection dynamics in patients with chronic atrial fibrillation.
- To compare these dynamics with those in patients exhibiting normal sinus rhythm.
Main Methods:
- Utilized a computerized single probe detector to analyze 30 successive cardiac cycles per patient.
- Assessed relative variations in R-R interval, diastolic and systolic time intervals, and ejection amplitude (stroke volume).
- Included 20 patients with atrial fibrillation and 10 healthy controls with sinus rhythm.
Main Results:
- Patients with atrial fibrillation showed significantly greater mean variations in R-R interval (21.9% vs 3.4%) and ejection amplitude (30.5% vs 11.8%) compared to sinus rhythm.
- Diastolic time variations were also markedly higher in AF (37.9% vs 10.4%), while systolic time variations were similar (10.6% vs 8.4%).
- Highly significant correlations (P < 0.001) between R-R intervals and ejection amplitude were observed in 85% of AF patients.
Conclusions:
- Beat-to-beat left ventricular ejection variability in atrial fibrillation is substantially increased.
- Ejection amplitude changes are predominantly influenced by variations in diastolic filling time.
- Findings provide insights into ventricular dynamics beyond average ejection fraction in AF.
Abstract:
Beat-to-beat left ventricular ejection was evaluated in a group of 20 patients with chronic atrial fibrillation using a computerized single probe detector. The reference group consisted of 10 patients with sinus rhythm. For each patient 30 successive cardiac cycles were analyzed and the relative variations of four parameters were assessed: R-R interval, diastolic and systolic time intervals, and ejection amplitude, corresponding to the left ventricular stroke volume. The mean variations were respectively 3.4%, 10.4%, 8.4%, and 11.8% in patients with sinus rhythm, and 21.9%, 37.9%, 10.6% and 30.5% in patients with atrial fibrillation. This demonstrates that changes in ejection are mainly related to the duration of the filling phase, with nearly constant systolic times. Correlations between R-R intervals and systolic ejection amplitudes were highly significant (P less than 0.001) in patients with atrial fibrillation in 85% of cases. This information complements the average ejection fraction obtained from multiple cycle superimposition.