| Aim: To study mechanism of paroxysmal atrial fibrillation(PAF) by mapping origins and re-entrant circuits of PAF with non-contact mapping system(EnSite3000).Materials and methods: There were eleven male patients in total suffering from PAF who were mapped with EnSite 3000. They were 50 ± 12(30-74) years old with a history of PAF for 9.0 ± 1 l(4months to 20 years) years, among which there were five patients with left atrial enlargement(34, 36, 38, 41 and 45mm respectively),one patient with sick sinus syndrome(SSS) and the others without any associated cardiac diseases. Endomyocardial non-contact mapping methods were as follows :①Routine Endomyocardial electrophysiological examination was performed to distinguish the origins arising from left atrium from those arising from right atrium.②Mapping balloon was positioned in an appropriate site of left atrium by transseptal puncture by use of standard techniques to construct a three-dimensional simulant shape of left atrium.③ Mapping balloon was positioned in an appropriate site of right atrium to construct a three-dimensional simulant shape of right atrium. ④To map origins of premature atrial beats(PAB) and re-entrant circuits of PAF precisely in the three-dimensional simulant shape of atrium with EnSite3000.Results: In the eleven cases of PAF, there were six cases arising from left atrium and seven arising from right atrium, among which there were two cases from both left and right atria. Origins of PAB which initiating PAF from left atrium and re-entrieswere as follows: there were six initiating foci in total( all of them had one origin)which were all located in the body of left atrium, among which there were three cases in the anterior wall( two cases in the upper part, one case in the middle part), three in the posterior wall of left atrium(one cases in the upper part, two case in the middle part).Re-entries of PAF arising from left atrium were located in pulmonary veins( mainly in the superior pulmonary veins) and the body of left atrium. There were two re-entrant patterns in pulmonary vein including the pulmonary vein is the component of re-entrant circuit of PAF and the re-entrant circuit passed through the pulmonary vein and/or the pulmonary vein is the obstocle zone of conduction and the re-entrant circuit is surrounding the orifice of pulmonary vein. Origins of PAB which initiating PAF from right atrium and re-entries were as follows: there were eight initiating foci in total( six cases had one origin,one had two origins) and there were two cases located in superior vena cava(SVC), two in orifices of superior vena cava(SVCO), two in crista terminalis(CT), one in isthmus(IS) and one in inferior vena cava(IVC) respectively. PABs which initiated PAF from right atrium were mainly located in the upper part of right atrium. Re-entries of PAF arising from right atrium were mainly located in vena cava (including vena cava is the component of re-entrant circuit of PAF and the re-entrant circuit passed through the vena cava and/or the SVC is the obstocle zone of conduction and the re-entrant circuit is surrounding the SVCO) especially in SVC, CT and IS,and all of them passed through the common border of the posterior wall of SVC and right atrium,and conducted towards CT.Discussion: We found that the PABs initiating PAF from left atrium all were located in the middle and upper parts of the anterior and posterior walls of the left atrium with EnSite3000, we did not found that the PAB arising from pulmonary vein initiated PAF, it did not coincide with the report recently that most of the PABs initiating PAF from left atrium were located in pulmonary veins. It was probably associated with different mapping condition and/or different choices of the patients. The lowest frequency of activation the EnSite3000 catched can reach to 0.1 Hz,while what routine electrophysiologic examination can only reach to higher than20Hz.EnSite 3000 system can map a three-dimensional and dynamical circuit of the activation origins and a complete course of activati...
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