| Background Sudden cardiac death (SCD) refers to the sudden loss of consciousness withcardiac causes and is characterized by rapid natural death, occupying the first place insudden death cases reported at home and abroad, and is the emphasis and difficulty offorensic pathology’s research and practice. Malignant arrhythmia is considered to be animportant reason that leads to sudden cardiac death. Although most cases can be found fataldieases or fatal injury in the actual prosecution, a small part of the cases are absent ofreasons by forensic pathological examine, which is called negative autopsy (negativeautopsy). To negative autopsy cases, most scholars believe that the fatal arrhythmia causessudden cardiac death. Genetic studies have confirmed the relevance between fatalarrhythmias and mutations in the gene encoding the corresponding ion channels, resultingin abnormal expression and distribution of the ion channel p rotein.The cardiac conduction system are special cardiocytes which start and conductelectrocardiac activities and control the heart rhythm, including sinuatrial node(SAN),internodal tracts, atrioventricular node(AVN), and His bundle(HB), Purkinje network, etc.Checkouting the SAN, AVN and His bundle is the main method in the practice of forensicscience, the pathological changes of them could lead to the disorder of cardiac electrical activity, namly arrhythmia.Ryanodine Receptor2(RyR2) is the main calcium release channel in sarcoplasmicreticulum of cardiocytes, mainly involved in the process of cardiac mechanical contraction.RyR2is influenced by many factors, the calcium leak caused by its dysfunction is thepathological basis of heart failure and fatal arrhythmia and sudden cardiac death. Thepresent studies focus on the gene mution and the expression of the gene and correspondingprotein, but the uncertainty of the samples in the practice of forensic science limits itsapplication widely. Immunohistochemical techniqune has been very mature, withing highsensitivity and specificity, has broad application prospeccts in the forensic pathologicaldiagnosis. However, no studies have been reported of the expression of RyR2in the cardiacconduction system between men with sudden cardiac death and non–sudden cardiac deathassociated with aging at home and abroad utill now.Objectives After HE and immunohistochemically staining of the collected and sliced tissuewax of cardiac conduction system, observing the pathological changes and the expressionof RyR2in sinoauricular node, atrioventricular node and His bundle between the SCD andnon-SCD, and finding out the difference between the two groups associated with aging.Material and Methods All the samples came from the autopsies at the Teaching andResearch Section of Forensic Pathology, Forensic Medicine Department, Tongji MedicalCollege, HUST was sorted out to be2groups according to the grouping conditions, SCDgroup(37samples) and non-SCD group(40samples). Tissue from SAN, AVN, His bundle inthe cardiac conduction system would be sliced and then disposed with HE staining andimmunohistochemical staining of RyR2. And then a comparison of pathological change andgraphical semi-quantitative analysis of immunohistochemical staining of the cardiacconduction system cardiocytes was made between the two groups.Results The rate of pathological changes in cardiac conduction system in SCD group wasmuch higher than in non-SCD. The expression of RyR2in the two groups both decressedassociated with aging, and the expression of RyR2in the same location in SCD group was much lower than in non-SCD in the same age group.Conclusions The expression of RyR2in SAN, AVN, His in SCD and non-SCD bothdecressed associated with aging. The expression of RyR2in SCD group was much lowerthan in non-SCD. The conclusion implied that the mechanism of arrhythmia of SCD mightbe associated with the abnormal Ca2regulation of cardiac conduction system. The IHC ofRyR2in cardiac conduction system might contribute to the diagnosis of SCD in forensicdiagnosis. |
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