By the means of computer simulation, the polypeptide antigen conformational structure that initiates the immunodominant epitope of the 2nd extracellular loop of β1-adrenoreceptor has been built. A linear 25-member peptide corresponding to the calculated sequence was synthesized by means of the solid-phase method using Fmoc-technology, then by means of the closure of disulfide bridges, the original bicyclic polypeptide was obtained corresponding to the proposed structure of the conformational antigen. With the help of high-resolution NMR spectroscopy, the 3D structure of synthetic conformational antigen was investigated. It was shown, that the structure of bicyclic polypeptide is similar to that of the computer model. Bicyclic conformational antigen was suitable for the detection of autoantibodies in the blood serum of patients with rhythm and conductivity violation without evidence of organic disease of the cardiovascular system. © Pleiades Publishing, Ltd., 2013.