Hensey Mark, O'Neill Louisa, Mahon Ciara, Keane Stephen, Fabre Aurelie, Keane David
Saint Vincent's University Hospital, Dublin.
J Atr Fibrillation. 2018 Apr 30;10(6):1650. doi: 10.4022/jafib.1650. eCollection 2018 Apr.
The left atrial appendage (LAA) has a key role in the embolic complications of atrial fibrillation (AF). It has been studied extensively, from recent interest in the thrombotic implications of various LAA morphologies to LAA occlusion and ablation. We collected eleven post-mortem LAA samples for visual analysis, two were not included due to poor sample quality. On examination of the nine remaining samples, several common patterns of pectinate muscle orientation were noted. The LAA samples were noted to have a smooth circumferential neck of muscular tissue giving rise to a dominant singular smooth trunk of papillary muscle in 6 cases and two trunks in 3 cases. These trunks were either shallow (5 samples) or more muscular and raised (4 samples). Shallow trunks tended to be wider than the raised trunks and may even be circumferential (2 samples). The main trunk arborized to give off papillary muscle branches down to third or fourth order branches. The samples were visually assessed for the percentage of smooth papillary muscle versus non-papillary recesses and were found to have ≤50% smooth muscle in 3 samples, 50-75% in 3 samples and >75% in 3 samples. We performed histological analysis of further LAA samples collected during cardiac surgery in a parallel study. We identified a distinct pattern of myocyte orientation from the neck, mid-section and apical section of the LAA demonstrating arborization of myocyte fibers with minimal communication in distal segments of the LAA. We feel that this information may help understanding of the issues surrounding LAA ablation strategies.
左心耳（LAA）在心房颤动（AF）的栓塞并发症中起关键作用。从近期对各种LAA形态的血栓形成影响到LAA封堵和消融，它都得到了广泛研究。我们收集了11个尸检LAA样本用于视觉分析，由于样本质量差，2个样本未纳入。在检查其余9个样本时，注意到梳状肌方向的几种常见模式。LAA样本有一个光滑的环形肌肉组织颈部，6例产生一个占主导的单一光滑乳头肌主干，3例产生两个主干。这些主干要么较浅（5个样本），要么肌肉更丰富且隆起（4个样本）。浅主干往往比隆起主干更宽，甚至可能是环形的（2个样本）。主树干分支形成乳头肌分支，直至三级或四级分支。对样本进行视觉评估，以确定光滑乳头肌与非乳头隐窝的百分比，发现3个样本的平滑肌≤50%，3个样本为50 - 75%，3个样本>75%。在一项平行研究中，我们对心脏手术期间收集的更多LAA样本进行了组织学分析。我们从LAA的颈部、中部和顶端部分确定了一种独特的心肌细胞方向模式，显示心肌纤维分支，在LAA的远端节段中沟通极少。我们认为这些信息可能有助于理解围绕LAA消融策略的问题。
