Characteristic structural features of fibrous rings and their connexion with the human cardiac conduction system.

In surgical treatment of acquired defects of mitral, aortic, and tricuspid valves, in many instances severe disturbances of cardiac conduction are observed. With due regard to the individual and typical anatomical features of human heart, the author investigated the structures of fibrous rings and triangles and their interrelationships with the cardiac conduction system. The material studied consisted of 230 hearts obtained from persons aged 20-80 years. The author assumes that within the heart cavity "dangerous zones" have to bbe singled out, whose traumatization in heart surgery may produce a disturbance of elements of the conduction system. The "dangerous zones" are situated at the base of the right-side surface of the interatrial septum above the fibrous ring of the septal cusp of the tricuspid valve, along the base of the membranous segment of the interventricular septum, in front of the posterior fibrous triangle, and at the fibrous ring encircling the bases of the posterior and right aortic semilunar valves.