Clinical Implications of Left Atrial Appendage Flow Patterns in Nonrheumatic Atrial Fibrillation: Discussion

LAA Flow Patterns and Contractile Function
The LAA has long been known to be a predilection site for thrombus formation. However, because LAA cannot be observed clearly by transthoracic echocardiography, little has been known about the blood flow and contractile function of the LAA before. Pollick and Taylor first evaluated the LAA blood flow and function by TEE. In 19 patients with AF due to rheumatic and nonrheumatic etiologies, LAA appeared as a static pouch in 7 of 8 with LAA thrombus and in 2 of 11 without LAA thrombus. Seven patients had been studied for LAA blood flow in their report. Four of them had the typical rapid minimal emptying and filling fibrillatory contractions. Others had either prolonged low-velocity outflow or no recordable velocity contour. Although there were only small AF case numbers in the report of Pollick and Taylor, the result implied that different LAA flow patterns did exist in AF. Recently, Garcia-Fernandez et al defined the LAA flow patterns more clearly. In their study, three different LAA flow patterns could be identified by Doppler testing within the LAA cavity. sildenafil citrate pink

In patients with sinus rhythm, biphasic filling and emptying blood flow was found. In patients with AF, two kinds of flow patterns were noted. Some patients had irregular but well-defined emptying and filling waves; others had no identifiable flow waves. The patients with no identifiable LAA blood flow waves predisposed to LAA SEC and thrombus formation. They concluded that AF was associated with two distinct LAA flow patterns and this difference had influence on atrial blood stasis and thrombus development. However, most of their patients were sent for TEE study because of rheumatic valvular disease or prosthetic valve evaluation (31 of 39; 79 percent). Only a few patients with nonrheumatic AF were assessed. In the present study, we tried to identify the LAA blood flow pattern specific for patients with nonrheumatic AF. In the 29 patients we studied, 2 different LAA blood flow patterns existed. The patients either had well-defined emptying and filling waves (group 1) or very low, even no recordable blood flow waves (group 2). In patients with very low LAA blood flow, we found a trend for a lower LAA ejection fraction and lower LAA peak emptying velocity. This phenomenon is similar to the results previously described.

This entry was posted in Nonrheumatic Atrial Fibrillation and tagged echocardiography, ejection fraction, thromboembolism, thrombus.