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Left atrial appendage blood flow determined by transesophageal echocardiography in patients with complete
1Department of Internal Medicine, National Taiwan University Hospital, Taipei, ROC.
Insights
Left atrial appendage (LAA) flow is higher during ventricular diastole in patients with complete atrioventricular block. This finding may impact understanding of LAA thrombus formation in left ventricular dysfunction.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Left atrial appendage (LAA) function is crucial for predicting thrombus formation in nonrheumatic atrial fibrillation.
- LAA flow patterns in patients with complete atrioventricular (AV) block are not well understood.
Purpose of the Study:
- To investigate the characteristics of LAA flow in patients with complete AV block and pacemaker implantation.
- To explore the relationship between LAA flow dynamics and ventricular phases.
Main Methods:
- Transesophageal echocardiography was used to study 21 patients with complete AV block and VVI/VVIR pacemakers.
- LAA outflow and inflow velocities and velocity time integrals were measured during ventricular systolic and diastolic phases.
Main Results:
- LAA outflow velocity was significantly higher during ventricular diastole (41.5 cm/s) versus systole (34.9 cm/s).
- LAA inflow velocity was also significantly higher during diastole (29.9 cm/s) versus systole (26.4 cm/s).
- Velocity time integrals for both LAA outflow and inflow were significantly greater during diastole.
Conclusions:
- Ventricular diastolic function appears to influence LAA flow, potentially through active atrial contraction and early diastolic flow.
- These findings may have implications for the pathogenesis of LAA thrombi in patients with left ventricular dysfunction.
Abstract:
Function of the left atrial appendage (LAA) represented by LAA outflow is an important predictor for thrombus formation in patients with nonrheumatic atrial fibrillation, but the pattern of LAA flow in patients with complete atrioventricular (AV) block has rarely been studied. Twenty-one patients with complete AV block and an implanted VVI or VVIR pacemaker were studied with transesophageal echocardiography. The LAA outflow velocity obtained during the ventricular diastolic phase was significantly higher than that obtained during the ventricular systolic phase (41.5 +/- 6.0 vs. 34.9 +/- 9.7 cm/s; p < 0.001). The LAA inflow velocity obtained during the ventricular diastolic phase was also significantly higher that that obtained during the ventricular systolic phase (29.9 +/- 7.8 vs. 26.4 +/- 5.3 cm/s; p < 0.01). In addition, the LAA outflow and inflow velocity time integrals during the ventricular diastolic phase were significantly higher than those during the ventricular systolic phase (4.66 +/- 0.96 vs. 4.08 +/- 1.05 cm, p < 0.01, and 2.81 +/- 0.77 vs. 2.56 +/- 0.65 cm, p < 0.05, respectively). Thus, due to both diastolic augmentation of the LAA flow related to active atrial contraction and minor early diastolic LAA flow formation, left ventricle diastolic function might have some influence on LAA flow. Thus may have implications for the pathogenesis of LAA thrombi in left ventricular dysfunction.