Study Of The Electrophysiological Characteristics Of The Ligament Of Marshall

Objective The aim of this study is to research the electrophysiological characteristics of the ligament of Marshall.Methods Fifteen mongrel dogs were studied. An electrode catheter was positioned over the ligament of Marshall (LOM) to record the Marshall potential during sinus rhythm and different protocols of atrial appendage pacing. Histological examination was performed to determine if histological connections between the Marshall bundle (MB) and left atrium (LA) were presented in these 10 dogs, which were divided into 2 groups based on histological connection or no histological connection. Ablation of the LOM was performed in rest five dogs.Results In first ten dogs, six of them had no histological connection between LA and MB (Group 1), and the other four had the histological connections between LA and MB (Group 2). The Marshall potentials were recorded in five dogs under sinus rhythm in Group 1, and the atrial-Marshall potential (AM) intervals were prolonged significantly by left atrium appendage (LAA) pacing at 350 ms[(125±9) ms vs (80±6) ms, P = 0.043,P<0.001] and at 450 ms[(126±9)ms vs (80±6) ms, P = 0.044], but not prolonged during RAA pacing( P>0.05). In rest one dog of Group 1, the Marshall potential was not recorded separately under sinus rhythm or under right atrium appendage (RAA) pacing but could be separated from LA electrograms by LAA pacing; The Marshall potentials were recorded in two dogs under sinus rhythm In Group 2, AM interval could be prolonged or shortened by LAA pacing. In addition, the AM interval wasn't changed significantly during RAA pacing. In the rest two dogs of Group 2, the Marshall potential wasn't seen under sinus rhythm or during RAA pacing but could be separated from LA electrogram during LAA pacing; The Marshall potentials were recorded in three dogs under sinus rhythm and two dogs under LAA pacing in Group 3. All Marshall potentials recorded in Group 3 were eliminated by LOM ablation.Conclusion Marshall potential has different electrograms including the prolonged AM interval, which would be presented by LAA pacing. This might be useful in LOM ablation.