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Cardiac performance early after cardioversion from atrial fibrillation
R J Raymond1, A J Lee, F C Messineo
1Cardiology Division of the University of Connecticut School of Medicine, Farmington, USA.
American Heart Journal
|September 15, 1998
Summary
Cardioversion rapidly improves cardiac function by increasing stroke volume and ejection fraction. This enhancement is primarily due to better diastolic filling and restored atrial function, not changes in intrinsic contractility.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Cardiovascular Physiology
Background:
- The precise mechanisms driving the immediate improvement in cardiac function following cardioversion from atrial fibrillation remain incompletely understood.
- Atrial fibrillation (AF) is a common arrhythmia affecting cardiac performance.
Purpose of the Study:
- To investigate the changes in ventricular volumes and load-independent cardiac contractility shortly after cardioversion from atrial fibrillation to normal sinus rhythm.
- To elucidate the underlying mechanisms responsible for early functional recovery post-cardioversion.
Main Methods:
- Ventricular volumes and load-independent contractility were assessed in 15 adult patients during atrial fibrillation and within 24 hours after successful cardioversion.
- Measurements included ejection fraction, stroke volume, mean cycle length, and cardiac contractility indices (Vcfc/ESWS).
Main Results:
- Left ventricular ejection fraction significantly increased from 51% to 61% (P=.001) and stroke volume rose from 57 mL to 76 mL (P < .001) post-cardioversion.
- Mean cardiac cycle length increased, indicating improved ventricular filling time.
- Intrinsic cardiac contractility (Vcfc/ESWS) remained largely unchanged in most patients, suggesting preserved inotropic state.
Conclusions:
- Immediate post-cardioversion increases in stroke volume and ejection fraction are observed.
- The primary drivers appear to be enhanced left ventricular diastolic filling, facilitated by increased cycle length and the restoration of left atrial mechanical function.
- Intrinsic contractility does not significantly change in the early period after restoring sinus rhythm.