Objective In this research we established rapid atrial pacing rabbit models, to investigate the effects of simvastatin on changes of early atrial effective refractory period (AERP) and protein expression of atrial α1c sub-unit of L-type calcium channel on atrial remodeling. Methods 42 rabbits were randomly divided into 3 groups:control group,rapid pacing group and simvastatin group,simvastatin 5 mg/( kg·d) was given intragastrically daily for two weeks before electrophysiology study in simvastatin group, normal saline was given intragastrically in control and rapid pacing group instead. Control group with no pacing, in simvastatin group and rapid pacing group, right atrium was paced at 800 beats/min for 8 hours to establish acute atrial fibrillation models, right atrial effective re-fractory period(AERP)was measured at the basic cycle length of 200 ms and 150 ms before pacing and 1,2,4,6, and 8 hours after the onset of the pacing, the changes of rate adaptation of AERP (AERP200-AERP150) were ana-lyzed . Right atrium tissue was obtained for measurement of protein expression of atrialα1 c subunit of L-type calcium channel by Western blot. Simultaneously,lipid levels in each group was examined. Results No significant differ-ence in lipid levels among three groups was observed. The AERP was shortened and the rate adaptation of AERP (AERP200-AERP150) disappeared during pacing compared with those before pacing(P<0.05). The shortening of AERP was reversed and AERP200-AERP150 was maintained in simvastatin group. Compared with the control group,the protein expression levels of atrial α1c subunit of L-type calcium channel decreased significantly after 8 hours pacing in rapid pacing group(P<0.01). The protein expression levels of simvastatin group decreased insig-nificantly . Conclusion Atrial rapid pacing can induce the shortening of the AERP and the losing of adaptability to the frequency of AERP,pretreatment with simvastatin can improve the degree significantly and maintain the adapta-bility to frequence basically. The protein expression levels of atrial α1c subunit of L-type calcium channel de-creased significantly after 8 hours pacing,pretreatment with simvastatin can prevent this change without lowering the lipid levels,thus contributing to the ionic mechanism of simvastatin for antiarrhythmia.

Objective To evaluate the results of acromioclavicukr crook plate in treatment of acromioclavicular joint dislocation and distal clavicular fracture and discuss causes for complications and preventive measures.Methods From September 2003 to April 2007,open reduction and acromiocla vicular crook plate fixation was done on 38 patients with acromioclavicular joint dislocation and distal clavicular fracture including 17 with acromioclavicular dislocation and 12 with distal clavicle fractures.Postoperative rehabilitation began early.Results Of all,27 patients were followed up for mean 21 months (3-37 months) and obtained bone healing.The internal fixation was removed at 6-8 months postoperatively and the outcome was evaluated with Karlsson rating system,which showed 22 patients at grade A,four at grade B and one at grade C.There was no dislocation or fracture after the internal fixation was removed ranging.Three patients with limited abduct motion <90° during certain movements got better after plate removal.One patient had acromio clavicular erosion.Conclusions The application of acromioclavicular crook plate provides accurate anatomical reduction and early rehabilitation and enables fast functional recovery.Technically,the implant needs to be used precisely.It is better to get appropriate early exercise and remove plate as early as possible.