These included recent congestive heart failure, history of hypertension, previous thromboembolism, left ventricular dysfunction from 2-D echocardiograms, and increased size of the left atrium from M-mode echocardiograms. Given its association with LAA SEC, the low LAA blood flow pattern described herein may become another useful echocardiographic predictor for future systemic embolism in risk stratification in patients with nonrheumatic AF. Such a possibility is worthy of further study.
In the current study, 5 of the 29 (17 percent) patients had mild or moderate mitral regurgitation that was assessed quantitatively by TEE according to the criteria developed by Yoshida et al. The mitral regurgitation may have some influence on the LAA flow Doppler measurement, and this influence needs to be clarified by further investigations. The other problem is the translocation of the LAA during the cardiac cycles. This should be carefully excluded during the determination of the LAA areas, and the simultaneous use of pulsed Doppler recording may be of great help in solving this problem. canadian health&care mall
Although the true pathophysiologic mechanisms underlying the different LAA flow patterns in nonrheumatic AF have not been defined, several factors of potential importance should be mentioned. First, the left atrial size was found to be larger in patients with lower LAA blood flow. As an integral part of the left atrium, the LAA movement may be functionally compromised by left atrial dilatation. However, this still needs further confirmation. Second, LAA dilatation was found to be associated with low LAA blood flow and poor LAA function in previous reports. In the current study, however, we found no such association. The LAA maximal area was not different between the two groups. The reason for these differing results is uncertain, but it may be related to the exclusion of patients with rheumatic AF from our study. Thus, LAA size may not be an important factor in determining LAA flow and function in patients with nonrheumatic AF. my canadian pharmacy phone number
The reported prevalence of TEE-detected left atrial SEC in patients with nonrheumatic AF ranged from 24.3 percent to 47 percent. The prevalence of left atrium and/or LAA thrombus was about 6.8 percent to 19 percent. In the current study, 31 percent of patients with nonrheumatic AF were found to have left atrium LAA/SEC and 10.3 percent patients had LAA thrombus. The different prevalence rates of reported series in comparison to ours may be related to the different patient selection.
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
All the patients were divided into two groups based on the differences in LAA flow patterns. In patients in group 1 (n = 17), irregular but well-defined LAA emptying and filling Doppler flow signals could be recorded (Fig 2). Patients in group 2 (n = 12), there were very low flow signals and, sometimes, no blood flow signal could be detected in the LAA (Fig 3). The baseline variables of patients in these two groups are listed in Table 1. There were no significant differences in age, sex, mean duration of AF, left ventricular end-diastolic dimension, left ventricular ejection fraction, or current use of anticoagulant or antiplatelet agents between these two groups. However, the left atrial diameter was significantly larger in group 2 patients (42.8 ±4.2 mm vs 36.6 ± 8.8 mm; p < 0.05). canadian neightbor pharmacy
The LAA size and LAA function in these two groups of patients were compared in Table 2. No significant difference was found in LAA maximal area between these two groups (5.2 ±2.1 cm2 vs 5.0 ± 1.9 cm2; p = NS). However, patients in group 1 tended to have better LAA ejection fraction (42.6 ±14.1 vs 26.4 ±15.2; p < 0.05) and higher LAA peak emptying velocity (0.36 ±0.16 vs 0.13 ±0.03; p< 0.001).
All the patients received transthoracic echocardiography and TEE. The transthoracic echocardiography was performed with a 2.5- or 3.75-MHz phased-array transducer connected to an ultrasound system (Aloka SSD-870 Aloka Co, Ltd, Tokyo, Japan). All the transthoracic echocardiography measurements were obtained according to the standards of American Society of Echocardiography. Left ventricular ejection fraction was calculated by the method of Teichholz et al.n Transesophageal echocardiography was performed according to previously described methods with a 5-MHz phased-arrav biplane transesophageal transducer connected to the same ultrasound system. After topical pharyngeal anesthesia with lidocaine spray, the patient was placed in the left lateral position, and the gastroscope was advanced into the esophagus. The LAA was observed from the basal short axis view in transverse scan.
In recent years, nonrheumatic atrial fibrillation (AF) has received much attention because it is associated with an increased risk of thromboembolic complications. The incidence of ischemic stroke is about five times higher in patients with nonrheumatic AF than is the case in patients with sinus rhythm. This increased risk of stroke was presumably due to cardiogenic embolism. With the advent of transesophageal echocardiography (TEE), cardiac source of emboli, particularly the left atrial appendage (LAA) thrombi now can be detected with much greater sensitivity. Jordan et al reported that LAA thrombus could be found in 34 of 40 patients (85 percent) with mitral stenosis. Because of the high incidence of thrombus formation in LAA, the LAA function and its blood flow have recently come under increased scrutiny. Few studies, however, have dealt with the LAA function in patients with nonrheumatic AF. The present study was directed at assessing the LAA function and its blood flow by means of TEE in patients with nonrheumatic AF and identified the subgroup of patients with higher incidence of LAA spontaneous echocardiographic contrast (SEC) or thrombus formation. canada health and care mall