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Effect of acute atrial fibrillation on phasic coronary blood flow pattern and flow reserve in humans
G E Kochiadakis1, E I Skalidis, M D Kalebubas
1Cardiology Department, University Hospital of Heraklion, Crete, Greece.
Insights
Experimentally induced atrial fibrillation (AF) increases coronary blood flow in humans. However, this increase is insufficient to meet the heart muscle's heightened oxygen needs due to irregular ventricular rhythm during AF.
Area of Science:
- Cardiology
- Human Physiology
Background:
- Atrial fibrillation (AF) is a common arrhythmia affecting cardiac function.
- Understanding the impact of AF on coronary circulation is crucial for patient management.
Purpose of the Study:
- To evaluate the effect of experimentally induced atrial fibrillation on human coronary blood flow.
- To compare coronary flow during atrial fibrillation with sinus rhythm and right atrial pacing.
Main Methods:
- Coronary blood flow velocity was measured using an intracoronary Doppler wire in patients.
- Measurements were taken during sinus rhythm, induced atrial fibrillation, and right atrial pacing.
- Data were analyzed to assess changes in coronary flow velocity integral per minute.
Main Results:
- Coronary flow velocity integral per minute significantly increased during both atrial fibrillation and right atrial pacing compared to sinus rhythm.
- The increase in coronary flow was greater during right atrial pacing than during atrial fibrillation.
- In patients with complete atrioventricular block, induced atrial fibrillation did not significantly alter coronary flow velocity.
Conclusions:
- Acute atrial fibrillation in humans leads to increased coronary blood flow.
- This augmented flow is inadequate to meet the elevated myocardial oxygen demand, primarily due to ventricular rhythm irregularity.
- The findings highlight the complex hemodynamic consequences of atrial fibrillation on the heart.
Aims:
To assess the effect of experimentally induced atrial fibrillation on coronary flow in humans.
Methods And Results:
In 16 patients (10 men, mean age 43+/-13 years) with normal coronary vessels, baseline and hyperaemic blood pressure and Doppler phasic coronary flow velocity were measured, using a 0.014 inch intracoronary Doppler flow wire, during sinus rhythm, experimentally induced atrial fibrillation, and right atrial pacing at a similar heart rate to that during atrial fibrillation. Coronary flow velocity integral per minute increased significantly during both right atrial pacing and atrial fibrillation compared to sinus rhythm, but during right atrial pacing the increase was greater (85+/-43% vs 52+/-25%, P<0.001). This difference persisted even after correction for the product of heart rate and blood pressure (1.15+/-0.51 vs 0.97+/-0.46, respectively, P<0.02). In a further 12 paced patients (seven men, mean age 54+/-10 years) with complete atrioventricular block the induction of atrial fibrillation (atrial fibrillation with regular RR interval) caused no significant changes in coronary flow velocity variables.
Conclusions:
Acute atrial fibrillation in humans causes an increase in coronary flow that is, however, insufficient to compensate for the augmented myocardial oxygen demand, mainly because of the irregularity in the ventricular rhythm that exists during atrial fibrillation.
