Zeppellini R, Erbel R, Schön F, Gheno G, Cucchini F
Divisione di Cardiologia, Ospedale Civile, Bassano del Grappa, VI.
G Ital Cardiol. 1995 Aug;25(8):1055-65.
In the past, the left atrial appendage has been considered a "useless" structure but associated to thromboembolic complications; its physiologic role is still undefined. Owing to its great distensibility, left atrial appendage positively influences atrial compliance and left ventricular performances. In addition this structure seems to play an important role in circulatory homeostasis by the release of atrial natriuretic factor in response to volume loading and atrial stretch. Transesophageal echocardiography provides a detailed anatomical characterization of this structure and, by means of Doppler flow velocities recordings, supplies relevant functional data. Despite their anatomical contiguity, the left atrium and atrial appendage result from a separate embryonic development; likewise, their function may differentiate. In the left atrial appendage a quadriphasic flow pattern has been described in subjects with sinus rhythm; however, as we reported, in some patients a more complex Doppler pattern can be observed, with an additional systolic forward flow wave which is presumably due to reflection phenomena. In patients with atrial fibrillation, an irregular flow pattern has been detected, which is mostly dependent on the duration of the arrhythmia, the underlying heart disease and the left atrial pressure. By transesophageal echocardiography a clear correlation has been established between the left atrial appendage slow flow and the occurrence of thromboembolic events; however, while waiting data from large studies, stratification of patients according to thromboembolic risk and decisions about anticoagulant prophylaxis should be performed by clinical information and transthoracic echocardiographic findings. No clinical or echocardiographic parameter has been found to be predictive of the thromboembolic events after cardioversion; in this setting the exclusion of atrial or atrial appendage thrombi by transesophageal echocardiography does not rule out the need for anticoagulation in patients with atrial fibrillation undergoing electrical or pharmacological cardioversion.
过去，左心耳一直被认为是一个“无用”的结构，但与血栓栓塞并发症相关；其生理作用仍不明确。由于其具有很大的扩张性，左心耳对心房顺应性和左心室功能有积极影响。此外，该结构似乎通过在容量负荷和心房牵张时释放心房利钠因子，在循环稳态中发挥重要作用。经食管超声心动图可对该结构进行详细的解剖学特征描述，并通过记录多普勒流速提供相关功能数据。尽管左心房和心耳在解剖学上相邻，但它们是由不同的胚胎发育形成的；同样，它们的功能也可能不同。在窦性心律的受试者中，左心耳已被描述为具有四相血流模式；然而，正如我们所报道的，在一些患者中可以观察到更复杂的多普勒模式，伴有一个额外的收缩期正向血流波，这可能是由于反射现象所致。在房颤患者中，检测到不规则的血流模式，这主要取决于心律失常的持续时间、基础心脏病和左心房压力。经食管超声心动图已明确证实左心耳缓慢血流与血栓栓塞事件的发生之间存在关联；然而，在等待大型研究数据的同时，应根据临床信息和经胸超声心动图检查结果对患者进行血栓栓塞风险分层，并决定是否进行抗凝预防。尚未发现任何临床或超声心动图参数可预测复律后的血栓栓塞事件；在这种情况下，经食管超声心动图排除心房或心耳血栓并不排除房颤患者在进行电复律或药物复律时需要抗凝的必要性。
