持续性房颤患者左房球形指数与左房自发显影的相关性

目的 探讨持续性房颤患者发生左房自发显影的临床特征,分析其与反映左房球形化的左房球形指数之间的相关性。方法 回顾性分析首都医科大学附属北京同仁医院2021年8月至2022年12月收治的96例非瓣膜性持续性房颤患者的临床资料。根据经食道心脏超声有无左房自发显影表现,将患者分为左房自发显影组(54例)及对照组(42例)。对2组患者合并症、实验室检查结果、心脏超声参数及左房球形指数进行比较。采用SPSS 22.0统计软件进行数据分析。根据数据类型,分别采用t检验、Mann-Whitney U检验或χ²检验进行组间比较。应用Pearson相关分析左房球形指数与合并症及心脏超声参数的相关性。采用logistic回归分析左房自发显影的危险因素。结果 左房自发显影组患者女性患者比例、CHA2DS2-VASc评分、D-二聚体水平、氨基末端B型钠尿肽前体(NT-proBNP)水平、左房前后径与横径、左房球形指数均高于对照组,差异有统计学意义(P<0.05)。左房球形指数与体质量指数(BMI)、心力衰竭、左室舒张末内径(r=0.236,0.272,0.212;P<0.05...     

Prevalence and clinical significance of left atrial spontaneous echo contrast detected by transesophageal echocardiography

The prevalence and clinical significance of left atrial spontaneous echo contrast (SEC) were studied in patients undergoing transesophageal echocardiography (TEE). The study group included 290 consecutive patients (186 male and 104 female, aged 17-86 years, mean age 56.1 +/- 12.8 years). Left atrial SEC was found in 50 (17.2%) patients, and was significantly associated with atrial fibrillation, mitral stenosis, absence of mitral regurgitation, and left atrial dimension. Atrial fibrillation was recorded in 44 (88%) patients, mitral stenosis or mitral valve replacement in 21 (42%) patients, and left atrial thrombus or previous embolism in 23 (46%) patients with SEC. Univariate analysis showed a significant association between the presence of SEC and atrial fibrillation, mitral stenosis or mitral valve replacement, and left atrial size. Multivariate analysis showed the presence of left atrial SEC and atrial fibrillation to be independent factors for thrombus formation and/or thromboembolism. Since left atrial SEC associated with atrial fibrillation, left atrial enlargement, mitral stenosis, or mitral valve prosthesis was found in 17.2% of patients undergoing TEE, it might be considered a marker of left atrial thrombus or previous thromboembolism.     

Transesophageal Echocardiographic Correlates of Clinical Risk of Thromboembolism in Nonvalvular Atrial Fibrillation

Objectives. This study explored the mechanisms linking clinical and precordial echocardiographic predictors to thromboembolism in atrial fibrillation (AF) by assessing transesophageal echocardiographic (TEE) correlations.

Background. Clinical predictors of thromboembolism in patients with nonvalvular AF have been identified, but their mechanistic links remain unclear. TEE provides imaging of the left atrium, its appendage and the proximal thoracic aorta, potentially clarifying stroke mechanisms in patients with AF.

Methods. Cross-sectional analysis of TEE features correlated with low, moderate and high thromboembolic risk during aspirin therapy among 786 participants undergoing TEE on entry into the Stroke Prevention in Atrial Fibrillation III trial.

Results. TEE features independently associated with increased thromboembolic risk were appendage thrombi (relative risk [RR] 2.5, p = 0.04), dense spontaneous echo contrast (RR 3.7, p < 0.001), left atrial appendage peak flow velocities ≤20 cm/s (RR 1.7, p = 0.008) and complex aortic plaque (RR 2.1, p < 0.001). Patients with AF with a history of hypertension (conferring moderate risk) more frequently had atrial appendage thrombi (RR 2.6, p < 0.001) and reduced flow velocity (RR 1.8, p = 0.003) than low risk patients. Among low risk patients, those with intermittent AF had similar TEE features to those with constant AF.

Conclusions. TEE findings indicative of atrial stasis or thrombosis and of aortic atheroma were independently associated with high thromboembolic risk in patients with AF. The increased stroke risk associated with a history of hypertension in AF appears to be mediated primarily through left atrial stasis and thrombi. The presence of complex aortic plaque distinguished patients with AF at high risk from those at moderate risk of thromboembolism.     

The effect of transient balloon occlusion of the mitral valve on left atrial appendage blood flow velocity and spontaneous echo contrast

BACKGROUND: Spontaneous echo contrast (SEC) is a phenomenon that is commonly seen in areas of blood stasis. It is a slowly moving, cloud-like swirling pattern of "smoke" or increased echogenicity recorded on echocardiography. SEC is commonly seen in the left atrium of patients with mitral stenosis or atrial fibrillation. The presence of SEC has been shown to be a marker of increased thromboembolic risk. HYPOTHESIS: By using transesophageal echocardiography during percutaneous balloon mitral valvotomy (PBMV), the study investigated the relationship between SEC and varying left atrial appendage (LAA) blood flow velocity in the human heart. METHODS: Thirty-five patients with rheumatic mitral stenosis underwent percutaneous balloon mitral valvotomy with intraoperative transesophageal echocardiography monitoring. We alternatively measured LAA velocities and observed the left atrium for various grades of SEC (0 = none to 4 = severe) before and after each balloon inflation. RESULTS: Left atrial appendage maximal ejection velocity was reduced from 35 +/- 14 to 6 +/- 2 mm/s at peak balloon inflation and increased to 40 +/- 16 mm/s after balloon deflation. In comparison with the values before balloon inflation and after balloon deflation, LAA velocities were significantly lower (p < 0.001). New or increased SEC grade was observed during 54 of 61 (88%) inflations and unchanged in 7 (12%) inflations at peak balloon inflation. Spontaneous echo contrast became lower in grade after 55 balloon deflations (90%), completely disappeared after 18 deflations (30%), and remained unchanged after 6 deflations (10%). The mean time to achieve maximal SEC grade (2.5 +/- 1.2 s) coincided with the mean time to trough LAA velocities (2.3 +/- 1.1 s) after balloon inflation. Upon deflation, the mean time to lowest SEC grade (2.9 +/- 1.8 s) coincided with mean time to achieve maximal LAA velocities (2.7 +/- 1.6 s). CONCLUSION: During balloon inflation, the severity of SEC was enhanced with corresponding reduction in LAA flow velocity. Upon balloon deflation, SEC lightens or disappears with increase in LAA flow velocity.     

Clinical and echocardiographic risk factors for embolization in the presence of left atrial thrombus

AIMS: The aim of our study was to evaluate the factors leading to embolization in patients with left atrial thrombi (LAT). With this purpose, we retrospectively analyzed clinical, transthoracic, transesophageal echocardiographic data of patients with LAT in the transesophageal echocardiographic evaluation. METHODS AND RESULTS: One hundred ninety-two patients with LAT not on anticoagulant therapy were divided into two groups according to the presence of prior ischemic stroke. The group with ischemic stroke included more patients with sinus rhythm and less patients with mitral stenosis. They had smaller left atrial diameter, more left atrial appendage spontaneous echo-contrast, higher appendage ejection fraction, and emptying velocity. CONCLUSION: Once the thrombus has been formed, cerebral embolization seems to be higher in patients with relatively preserved appendage ejection fraction and emptying velocity. Presence of atrial appendage spontaneous echo-contrast also favor embolization. Factors leading to embolization seem to differ in some respects from the causes of thrombus formation.     

The role of echocardiography in the evaluation of cardiac source of embolism: left atrial spontaneous echo contrast

Left atrial (LA) spontaneous echo contrast, also known as "smoke," is a frequent transesophageal echocardiographic finding characterized by swirling, smokelike echoes in the LA cavity or appendage. LA smoke is associated with conditions favoring stasis of LA blood, including atrial fibrillation, mitral stenosis, the absence of mitral regurgitation, and LA enlargement. LA spontaneous echo contrast is a marker of previous embolic events in patients with atrial fibrillation, mitral stenosis, or mitral valve replacement. Most LA thrombi are accompanied by smoke. Recent studies show that LA spontaneous echo contrast is also associated with increased fibrinogen, hematocrit, and blood viscosity, indicating a relatively hypercoagulable state in addition to stasis. These findings suggest that LA spontaneous echo contrast is a manifestation of erythrocyte aggregation, and that hematologic factors may contribute to the association between spontaneous echo contrast and thromboembolism.     

A novel finding of the atrial substrate properties and long-term results of catheter ablation in chronic atrial fibrillation patients with left atrial spontaneous echo contrast

Atrial Substrate Properties in Chronic AF Patients with LASEC. Background: The atrial substrate in chronic atrial fibrillation (AF) patients with a left atrial spontaneous echo contrast (LASEC) has not been previously reported. The aim of this study was to investigate the atrial substrate properties and long‐term follow‐up results in the patients who received catheter ablation of chronic AF. Methods: Of 36 consecutive patients with chronic AF who received a stepwise ablation approach, 18 patients with an LASEC (group I) were compared with 18 age‐gender‐left atrial volume matched patients without an LASEC (group II). The atrial substrate properties including the weighted peak‐to‐peak voltage, total activation time during sinus rhythm (SR), dominant frequency (DF), and complex fractionated electrograms (CFEs) during AF in the bi‐atria were evaluated. Result: The left atrial weighted bipolar peak‐to‐peak voltage (1.0 ± 0.6 vs 1.6 ± 0.7 mV, P = 0.04), total activation time (119 ± 20 vs 103 ± 13 ms, P < 0.001) and DF (7.3 ± 1.3 vs 6.6 ± 0.7 Hz, P < 0.001) differed between group I and group II, respectively. Those parameters did not differ in the right atrium. The bi‐atrial CFEs (left atrium: 89 ± 24 vs 92 ± 25, P = 0.8; right atrium: 92 ± 25 vs 102 ± 3, P = 0.9) did not differ between group I and group II, respectively. After a mean follow‐up of 30 ± 13 month, there were significant differences in the antiarrhythmic drugs (1.1 ± 0.3 vs 0.7 ± 0.5, P = 0.02) needed after ablation, and recurrence as persistent AF (92% vs 50%, P = 0.03) between group I and group II, respectively. After multiple procedures, there were more group II patients that remained in SR, when compared with group I (78% vs 44%, P = 0.04). Conclusion: There was a poorer atrial substrate, lesser SR maintenance after catheter ablation and need for more antiarrhythmic drugs in the chronic AF patients with an LASEC when compared with those without an LASEC. (J Cardiovasc Electrophysiol, Vol. pp. 1‐8)     

Left atrial appendage function and pulmonary venous flow in patients with nonrheumatic atrial fibrillation and their relation to spontaneous echo contrast

This study analyzed the relation between frequency of left atrial appendage (LAA) contractions, pulmonary venous flow (PVF) parameters, and spontaneous echo contrast (SEC). Thirty-six patients (22 male, 14 female, mean age 61 plus minus 11 years) with nonrheumatic atrial fibrillation undergoing transesophageal echocardiography were studied. Doppler flow was obtained from both the LAA and the left upper pulmonary vein. Fourier analysis was applied to the LAA signal that exhibited the frequency of LAA contractions. LAA emptying velocity and PVF parameters were determined. There was no relation between velocity and frequency of LAA flow (r = 0.256, P = ns). Among LAA and PVF parameters, patients with left atrial SEC (n = 17) had a lower LAA velocity (16.8 +/- 10.8 cm/sec vs 35.6 +/- 13.2 cm/sec, P < 0.001), a larger LAA area (4.8 +/- 2.2 cm(2) vs 3.0 +/- 1.3 cm(2), P = 0.008), and a reduced systolic velocity time integral of PVF (3.4 +/- 2.2 cm vs 5.4 +/- 2.2 cm, P = 0.017) when compared with patients without SEC. Frequency of LAA contractions was similar between both groups (6.8 +/- 0.4 Hz vs 6.8 +/- 1.0 Hz, P = ns). In conclusion, the rate of LAA contraction does not correlate with LAA flow velocity and SEC. A low left atrial flow expressed by low LAA flow velocity and a reduction in systolic PVF is a major hemodynamic determinant for the occurrence of SEC.     

Annular systolic velocity predicts the presence of spontaneous echo contrast in mitral stenosis patients with sinus rhythm

OBJECTIVES: Thromboembolism is the major cause of morbidity and mortality in mitral stenosis (MS), even in sinus rhythm (SR). Spontaneous echo contrast (SEC) is the strongest predictor of thromboembolism. The aim of the study was to investigate if the annular velocities obtained with tissue Doppler imaging can predict the presence of SEC in MS patients with SR. METHODS: One hundred and five MS patients and 100 controls were included. Annular velocities were recorded. All patients underwent transesophageal echocardiography. Subjects were divided into three groups as controls (Group I), the patients without SEC (Group II) and the patients with SEC (Group III). RESULTS: Group III patients had lower ejection fraction, annular systolic velocity, smaller mitral valve area, higher transmitral gradient and larger left atrial size. The annular systolic velocity was the only independent predictor for SEC. The cutoff values of annular systolic velocity for prediction of the presence of any SEC and dense SEC were 13.5 and 11.8 cm/s, respectively. CONCLUSION: The annular systolic velocity is an independent predictor for SEC in MS patients with SR.     

Relationship between left atrial spontaneous echo contrast and the features of middle cerebral artery territory in nonvalvular atrial fibrillation

Summary We investigated the relationship between left atrial spontaneous echo contrast (SEC) and cerebrovascular features in nonvalvular atrial fibrillation (NVAF). Few reports have been published to compare cardiac and cerebrovascular imaging in patients with NVAF. Forty-four patients with NVAF were studied using transesophageal echocardiography and noninvasive imaging including magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and transcranial color Doppler imaging (TCD) in the middle cerebral artery (MCA) territory. The symptomatic severity was divided into asymptomatic, transient ischemic attack (TIA), and stroke. The severity of the MRI findings was divided into normal, small, and large infarcts. The severity of the MRA findings was divided into normal, attenuation, and occlusion. MCA was bilaterally scanned and a side-to-side asymmetry ratio of pulsatility index (PI) was measured. The severity of SEC was divided into normal, SEC, and thrombi. Five patients with other thromboembolic risk or poor results of TCD were excluded. SEC and thrombi were detected in 12 (30%) and in 3 patients (5%), respectively. TIA and stroke were detected in 8 (21%) and in 17 patients (44%), respectively. Small and large infarcts were detected in 9 (23%) and in 18 patients (46%), respectively, on MRI. Attenuation and occlusion were detected in 14 (36%) and in 8 patients (21%), respectively, on MRA. PI ratio was 1.21 ± 0.25. SEC severity was highly associated with PI ratio and MRA severity in monovariate analysis (P < 0.005),P < 0.01, respectively). SEC severity was highly associated with PI ratio and MRA severity in stepwise multiple regression analysis (P = 0.0001,r = 0.630,n = 39). In patients with NVAF, left atrial SEC was highly related to attenuation or occlusion on MRA and imbalance of cerebral blood flow on TCD in the MCA territory.     

非瓣膜性心房颤动患者C反应蛋白与左心房自发显影的关系

目的探讨高敏C反应蛋白(hs-CRP)与非瓣膜性心房颤动(房颤)患者左心房自发显影(LASEC)的关系。方法连续入选自2018年1月1日至6月30日于首都医科大学附属北京安贞医院心内科病房首次行射频消融术的非瓣膜性房颤患者490例,根据术前经食管超声心动图检查结果将研究人群分为无LASEC组(n=338)和LASEC组(n=152)。采用胶乳增强免疫比浊法测定hs-CRP;用单因素及多因素logistic分析探讨非瓣膜性房颤患者hs-CRP与LASEC的相关性。结果490例患者中有152例(31%)检测到LASEC。LASEC组的年龄、房颤类型、既往栓塞事件、纤维蛋白原定量、D-二聚体、左心房前后径及CHA2DS2VASc评分与无LASEC组比较,差异均有统计学意义(P均<0.05),LASEC组hs-CRP水平明显高于无LASEC组[3.16(1.30,5.23)mg/L比0.67(0.37,1.48)mg/L,P<0.001]。多因素logistic回归分析发现hs-CRP(OR=1.136,95%CI 1.060~1.217,P<0.001)和D-二聚体(OR=1.040,95%CI 1.011~1.070,P=0.007)是LASEC的独立相关因素。结论hs-CRP升高是非瓣膜性房颤患者LASEC的独立相关因素,炎症反应可能参与非瓣膜性房颤血栓前状态的形成。     

Roles of Transesophageal Echocardiography and Cardiac Computed Tomography for Evaluation of Left Atrial Thrombus and Associated Pathology: A Review and Critical Analysis

Evaluation of the left atrium and left atrial appendage for the presence of thrombus prior to cardioversion and pulmonary vein isolation, and of the entire heart for embolic sources in the setting of cryptogenic stroke, has long been standard medical care. Guidelines have uniformly recommended transesophageal echocardiography (TEE) to accomplish these goals. In recent years, computed tomographic angiography has demonstrated diagnostic accuracy similar to that of TEE for the detection of thrombus. Analysis of the pertinent data and relative merits of the 2 technologies leads to the conclusions that: 1) both modalities have some unique, nonoverlapping capabilities that may dictate their use in specific situations; 2) computed tomographic angiography is a reasonable alternative to TEE when the primary aim is to exclude left atrial and left atrial appendage thrombus and in patients in whom the risks associated with TEE outweigh the benefits; and 3) both options should be discussed with the patient in the setting of shared decision making.     

Multisite pacing for prevention of atrial tachyarrhythmias: potential mechanisms

OBJECTIVES

To determine the effects of single-, dual-, triple- and quadruple-site atrial pacing on atrial activation and refractoriness in normal canine hearts.

BACKGROUND

Multisite pacing has been suggested to be superior to single-site pacing for prevention of atrial tachyarrhythmias. However, the underlying electrophysiological mechanisms are undetermined at the moment, as is the rationale for the selection of pacing locations and the number of pacing sites.

METHODS

In 13 normal beagle dogs, an epicardial multielectrode (128 bipoles) and a multiplexer mapping system were used to reconstruct epicardial atrial activation patterns obtained during simultaneous stimulation from up to four electrodes located in the high and low right and left atrium, respectively. For all pacing modes (single-, dual-, triple- and quadruple-site pacing), total activation times and local effective refractory periods at eight randomly selected sites as well as local recovery intervals were determined. In a subgroup of five dogs, total epicardial activation times were also obtained during single-site septal stimulation (septal group).

RESULTS

Activation times and local recovery intervals were minimized by triple-site stimulation, whereas a fourth site did not produce further shortening. Septal stimulation produced epicardial activation times comparable to quadruple-site stimulation. Local refractory periods and their dispersion always remained unaffected. Functional conduction blocks apparent during single-site were found to resolve during multisite stimulation.

CONCLUSIONS

Multisite pacing can prevent functional conduction blocks by multidirectional excitation and a reduction in total activation time. Triple-site and, possibly, septal pacing modes are expected to be most efficient because both minimize total activation times and maximize the multidirectionality of excitation. In spite of unaffected local refractory periods, the shortening of local recovery intervals might homogenize atrial repolarization and, thus, contribute to the preventive effects of multisite pacing.