Investigation Of Histology And Electrophysiology Of Ligament Of Marshall

Ligament of marshall is relict of left primitive vein, and was re garded as a structure of pericardium without any function for a long time. It located at posterior left auricle, advancing toward left superior pulmonary vein, and vein of Marshall, then extend as the first atrial branche of coronary sinu. In 1972, Scherlag et, al recorded close bipolar eletrograms consisting of two deflections along the ligament of Marshall in the posterior left atrium during sinus rhythm, the first deflections was designated as a left atrial muscle potential and the second as a Marshall bundle potential. The cardiac sympathetic nerve stimulation induce independent rhythm and two deflections reverse. According to study in human, the sequence of activation in the second potential in the ligament of Marshall was from proximal to distal, the interval of two deflections and duration of second deflection in distal are similar to left superior pulmonary vein potential, the fuse of two potential located in the area where ligament of Marshall connect coronary or left atria. The study of canine ligament of Marshall implied that the spontaneous activity with cycle length exceed 1300ms was recored in ligament, and automatic rhythm was induced during isoproterenol infusion, the transition from rapid automatic activity to multiple wavelet atrial fibrillation were observed. Immunohistochemy demonstrate the majority of the nerve bundles around Marshall bundle stained positive for tyrosine hydroxylase (adrenergic nerve). Ablation of the ligament of Marshall terminated the spontaneous activity and prevented atrial fibrillation. The studys mentioned above indicate that the ligament of Marshall is richly innervated by sympathetic nerves and serves as a source of isoproterenol-sensitive focal automatic activity in normal canine atrium. A radiofrequency lesion placed in the posterolateral left atrium between the Marshall bundle insertion and the ostium of the left inferior pulmonary vein resulted in successful treatment of the focal AF. This finding suggests that the trigger of the focal AF episodes resides not within the pulmonary veins, but in the Marshall bundl.Atrial fibrillation is one of the most common persistent arrhythmia in clinic, which induce disorder of hemodynamics and increase incidence rate of cerebral apoplexy obviously. On account of complexity of mechanisms of occurrence and maintenance, we lack ideal management of atrial fibrillation. Numerous evidence directe that actuation of ectopic focus, sing circuit reentry and multi-wavelets reentry all participate in occurrence and maintenance of atrial fibrillation.Recently, there are two hypothesis of atrial fibrillation: one is hypothesis of reconstitution which supposed that reentry exist in normal atrium, it can terminate automatically and do not cause atrial fibrillation, the rapid pacing can cause structural and electrical remodeling reconstitution, which are the bace of occurrence and maintenance of atrial fibrillation. The lectrical remodeling, which in favour of reentry sustain, include marked alteration of characteristic of ion channel and increase of anisotropy of ion channel function in space. Another is hypothesis of thoracic vein. The rapid actuation from thoracic vein is basic to either trigger or maintenance atrial fibrillation. According to this hypothesis, structural and electrical remodeling are not important to atrial fibrillation, and elimination of the rapid activity origivated from thoracic vein can cure atrial fibrillation. Recently clinical research comfirm that elimination of the rapid activity of thoracic vein, such as the rapid activity from coronary sinu, ligament of Marshall, pulmonary vein and vena cava, can terminate atrial fibrillation immediately, and prevent recurrence in a long period.As one of focal source of atrial fibrillation, the histology and electrophysiology characters of ligament of Marshall are unknown. We investigate the effect of ligament of Marshll on atrial fibrillation occurrence and maintenance from histology, electrophysiology and...