ABSTRACT
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Subject(s)
Humans , Male , Female , Adult , Prosthesis Implantation/methods , Pulmonary Valve/innervation , Heart Defects, Congenital/surgery , Aortic Valve Insufficiency/complications , Magnetic Resonance Imaging/methods , Pulmonary Valve/physiopathology , Pulmonary Valve , Catheter Ablation , Aortic Stenosis, Subvalvular/complications , Aortic Stenosis, Subvalvular , Aortic Valve StenosisABSTRACT
To determine the innervation of human semilunar valves, we examined the pulmonary and aortic valves of the normal autopsied hearts of 3 men (53 to 71 years old). Whole valve tissues with the aorta or pulmonary trunk were stained for acetylcholinesterase by a histochemical method. Acetylcholinesterase-positive nerve fibers with a diameter of 2 to 20 mm were located on the ventricular side of the semilunar valves. Innervation of the semilunar valves was extremely sparse compared with that of the atrioventricular valves and that of the aortic or pulmonary arterial wall. The nerves originated from the subendocardium of the ventricles and the adventitia of the arterial walls. The nerves were more distributed in the basal site than in the marginal site of the semilunar valve. The nerve fibers formed a network in basal two-thirds of the leaflet. Thick nerves ramified in the thin nerve plexus. The thick nerves had a varicose-like structure. Thin nerves had a dot- and brush-like ending. The nerves in human semilunar valves may play a role in valve motion.
Subject(s)
Aortic Valve/innervation , Pulmonary Valve/innervation , Vagus Nerve/cytology , Aged , Histocytochemistry , Humans , Male , Middle AgedABSTRACT
We evaluated the distribution of the nerves in valve tissue of humans to clarify the relationship between mitral valve prolapse and autonomic nerve dysfunction. We studied 15 autopsy specimens of normal mitral valve, 10 prolapsed mitral valves, five each of normal tricuspid, aortic, and pulmonary valves, and three prolapsed mitral valves obtained at cardiac surgery. Immunohistochemical studies utilized the avidinbiotin peroxidase complex (ABC) method and several nerve-related antigens: 1) S-100 protein, glial fibrillary acidic protein (GFAP), and neurofilament protein (NFP) as markers of glial and Schwann cells of the nervous system; 2) choline acetyltransferase (ChAT) to identify cholinergic nerve endings; 3) neuropeptide Y (NPY), a neuropeptide that is distributed in accordance with sympathetic nerves; and 4) calcitonin gene-related peptide (CGRP), a neuropeptide that is distributed in accordance with afferent nerves. Distribution of adrenergic nerve fibers was also examined by fluorescence method. Morphology of nerve endings of the normal mitral valve was studied by electron microscopy. In normal valves, distributions of S-100 protein, GFAP, and NFP immunoreactivities were clearly visible along the subendocardial site on the coaptation aspect of the base-to-body portion of each valve, regardless of the kind of valve. In contrast, there was only a scanty distribution of these reactivities on the physiologic coaptation area of the tip. In prolapsed mitral valves, there was no distribution of S-100-positive protein or other nerve-related antigens in areas of the valve with myxomatous degeneration. Distribution of CGRP, ChAT, and NPY immunoreactivities, and adrenergic fluorescence, were the same as those of the nerve-related antigens in both normal and prolapsed mitral valves. Electron microscopic study of the atrial aspect of normal mitral valves revealed numerous small axons with aggregations of small clear vesicles, indicating cholinergic features. The results suggest that the subendocardial site on the atrial aspect at the middle portion of the mitral valve is rich in nerve endings, including the afferent nerves, and that mechanical stimuli from this area caused by abnormal coaptation in mitral valve prolapse may produce an improper circuit in autonomic nerve function between the central and mitral valve nervous systems.
Subject(s)
Aortic Valve/innervation , Mitral Valve Prolapse/pathology , Mitral Valve/innervation , Pulmonary Valve/innervation , Tricuspid Valve/innervation , Adult , Aged , Aortic Valve/chemistry , Aortic Valve/pathology , Choline O-Acetyltransferase/analysis , Glial Fibrillary Acidic Protein/analysis , Humans , Immunohistochemistry , Microscopy, Electron , Middle Aged , Mitral Valve/chemistry , Mitral Valve/pathology , Mitral Valve Prolapse/metabolism , Neurofilament Proteins/analysis , Neuropeptide Y/analysis , Pulmonary Valve/chemistry , Pulmonary Valve/pathology , S100 Proteins/analysis , Sensitivity and Specificity , Tricuspid Valve/chemistry , Tricuspid Valve/pathologyABSTRACT
In order to provide additional information on the morphology and the functional performance of semilunar valves, the presence of nerve fibers was investigated in the aortic and pulmonary leaflets by AChE techniques, formaldehyde-induced fluorescence methods, en block silver nitrate and gold chloride impregnation and electron microscopy. The results show that AChE positive and adrenergic nerve fibers are constantly present in every leaflet of all the animals examined. The pattern of innervation is similar in aortic and pulmonary valves and no differences exist between coronary and non coronary aortic leaflets. Nerve networks extend over the inferior two-thirds of the leaflets: they are composed of myelinated and non-myelinated axons and are mainly located in the ventricular side of the leaflets. Structures resembling free sensory endings can be shown both by light and electron microscopy. The presence in the leaflets of blood vessels and of an intrinsic smooth muscle system suggests that these two components are the most probable targets of the nerve fibers.
