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Left atrial appendage dysfunction: a cause of thrombosis? Evidence by transesophageal echocardiography-Doppler
M Pozzoli1, O Febo, A Torbicki
1Divisione di Cardiologia, Fondazione Clinica del Lavoro, Centro Medico di Montescano, (Pavia), Italy.
Insights
Reduced blood flow velocity in the left atrial appendage is a key factor for thrombosis. This finding helps explain cardioembolic events in patients with normal heart rhythms.
Area of Science:
- Cardiology
- Echocardiography
- Vascular Medicine
Background:
- The left atrial appendage (LAA) is a common source of cardioembolic events.
- Understanding LAA blood flow dynamics is crucial for predicting thromboembolic risk.
Purpose of the Study:
- To investigate the relationship between atrial rhythm, LAA blood flow patterns, and the presence of thrombus or spontaneous echocardiographic contrast.
- To identify predictors of thrombosis within the LAA.
Main Methods:
- Transesophageal color flow imaging and pulsed Doppler echocardiography were used in 84 patients.
- Patients were categorized by atrial rhythm: sinus rhythm, atrial fibrillation, and atrial flutter.
- Blood flow velocity patterns were analyzed in relation to LAA content (thrombus/spontaneous contrast).
Main Results:
- Abnormal blood flow patterns were observed in patients with atrial fibrillation and atrial flutter.
- Absent or significantly reduced blood flow velocity was detected in 20 patients with LAA thrombus or spontaneous contrast.
- Isolated LAA dysfunction was noted in four patients during sinus rhythm, associated with thrombosis.
Conclusions:
- Absent or low LAA blood flow velocity is a significant predisposing factor for thrombosis.
- LAA dysfunction, even during sinus rhythm, can lead to thrombus formation and cardioembolic events.
- This study provides insights into the mechanisms of cardioembolism in patients with seemingly normal cardiac function.
Abstract:
The blood flow velocity patterns within the left atrial appendage were studied by transesophageal color flow imaging and pulsed Doppler in 84 patients. At the time of the study, 57 of the patients were in sinus rhythm, 25 were in atrial fibrillation, and two were in atrial flutter. The relationships between atrial rhythm, blood flow pattern and the presence/absence of spontaneous echocardiographic contrast or thrombus within the appendage were investigated. Transesophageal echocardiography allowed recording of blood flow velocities in 81 of the 84 patients studied. In 51 of the 55 patients in sinus rhythm the pulsed Doppler study showed a biphasic blood flow pattern, whereas a multiphasic pattern was found in the two patients with atrial flutter and in 14 patients with atrial fibrillation. In four patients with sinus rhythm and 10 patients with atrial fibrillation, no significant blood flow velocity could be detected. Thrombus or spontaneous echocardiographic contrast were found within the left atrial appendage in 20 patients, and in all these patients blood flow was either absent or significantly reduced. Our findings indicate that an absent or low blood flow velocity within the left atrial appendage represents a predisposing factor for thrombosis. Isolated left atrial appendage dysfunction has been documented in four patients during sinus rhythm, which may lead to thrombosis. This observation may offer an explanation for cardioembolic events that occur occasionally in patients without apparent heart disease and sinus rhythm.