Anatomical Basis for the Cardiac Interventional Electrophysiologist

Figure 15

(a) This bovine heart shows the left bundle branch and Purkinje network after Indian ink injection. (b) Histological section stained with Masson’s trichrome in a human heart showing Purkinje fibers at the level of the subendocardium of the left ventricle. (c) Histological section of a false tendon in a human heart which presents within Purkinje fibers, myocytes, and connective tissue in green colour. (d) Histological section of the pulmonary valve shows how the hinge of the valvar leaflet is attached to the ventricular myocardium well proximal to the anatomic ventriculoarterial junction. (e, f) Histologic sagittal sections of the right ventricular infundibulum, pulmonary valve root, left ventricle outflow tract, and aortic root. Note the differences in length of the right ventricular outflow tract infundibulum and in the contact area between both outflow tracts (red dotted lines) depending on the level of the section: at the right posterior pulmonary leaflet (e) or left posterior pulmonary leaflet (f). The subendocardial fibers in the infundibulum run longitudinally. At subendocardial levels of the left ventricular outflow tract, the orientation is mainly spiral and circumferential. Note that there are connections (asterisks) between myocytes in the contact area between both outflow tracts. (g) Histologic cross section of infundibulum of pulmonary valve stained with Masson’s trichrome. In right ventricle, fibers orientation is different in infundibulum and at subendocardial () and subepicardial (arrow) levels of pulmonary valve. (h) Histologic sagittal section of the aortic valve root at the level of right coronary leaflet. Note the relationship of the aortic valve with the conduction tissue and right atrium. (i) Endocardial view of right ventricular outflow tract (RVOT) is shown (d). Note that endocardial infundibular sleeve consists of septoparietal trabeculations () arising from septomarginal trabeculation (SMT). Note crossing architecture pattern of myocardial strands between septomarginal trabeculation with septoparietal trabeculations and supraventricular crest below pulmonary valve. (j) Histological section of the pulmonary valve stained with Masson’s trichrome shows the attachment of the pulmonary leaflet. Note the myocardial extension above the sinotubular junction (arrow). L = the left aortic sinus, LCA = left coronary artery, M = myocyte, MV = mitral valve, N = noncoronary aortic sinus, LP = left posterior pulmonary sinus, PF = Purkinje fiber, PT = pulmonary trunk, R = right aortic sinus, RA = right atrium, RCA = right coronary artery, RP = right posterior pulmonary sinus, RVOT = right ventricle outflow tract, SC = supraventricular crest, SCV = superior cava vein, SMT = septomarginal trabeculation, and SPM = septal papillary muscle.

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