The autonomic nerves around the vein of Marshall: a postmortem study with clinical implications.

This study aims to analyze the vein of Marshall (VOM) in human autopsy hearts and its correlation with clinical data to elucidate the morphological substrates of atrial fibrillation (AF) and other cardiac diseases. Twenty-three adult autopsy hearts were studied, assessing autonomic nerves by immunohistochemistry with tyrosine hydroxylase (sympathetic nerves), choline acetyltransferase (parasympathetic nerves), growth-associated protein 43 (neural growth), and S100 (general neural marker) antibodies. Interstitial fibrosis was assessed by Masson trichrome staining. Measurements were conducted via morphometric software. The results were correlated with clinical data. Sympathetic innervation was abundant in all VOM-adjacent regions. Subjects with a history of AF, cardiovascular cause of death, and histologically verified myocardial infarction had increased sympathetic innervation and neural growth around the VOM at the mitral isthmus. Interstitial fibrosis increased with age and heart weight was associated with AF and cardiovascular cause of death. This study increases our understanding of the cardiac autonomic innervation in the VOM area in various diseases, offering implications for the development of new therapeutic approaches targeting the autonomic nervous system.

Detailed study of collagen, vasculature, and innervation in the human cardiac conduction system.

BACKGROUND: The cardiac conduction system (CCS) creates and propagates electrical signals generating the heartbeat. This study aimed to assess the collagen content, vasculature, and innervation in the human sinoatrial and atrioventricular CCS, and surrounding tissue. MATERIALS AND METHODS: Ten sinoatrial and 17 atrioventricular CCS samples were collected from 17 adult human autopsied hearts. Masson trichrome stain was used to examine collagen, cardiomyocytes, and fat proportions. Immunohistochemically, vessels and lymphatics were studied by CD31 (pan-endothelial marker) and D2-40 (lymphatic endothelium marker) antibodies. General nerve densities were assessed by S100, while sympathetic nerves were studied using tyrosine hydroxylase, parasympathetic nerves with choline acetyltransferase, and GAP43 (neural growth marker) antibodies looked at these components. All components were quantified with QuPath software (Queens University, Belfast, Northern Ireland). RESULTS: Interstitial collagen was more than two times higher in the sinoatrial vs. atrioventricular CCS (55% vs. 22%). The fat content was 6.3% in the sinoatrial CCS and 6.5% in the atrioventricular CCS. The lymphatic vessel density was increased in the sinoatrial and atrioventricular CCS compared to the surrounding tissue and was lower in the sinoatrial vs. atrioventricular CCS (P=.043). The overall vasculature density did not differ between the SA and AV CCS. The overall innervation and neural growth densities were significantly increased in the CCS compared to the surrounding tissue. The overall innervation was higher in the atrial vs. ventricular CCS (P=.018). The neural growth was higher in the atrial vs. ventricular CCS (P=.018). The sympathetic neural supply was dominant in all the studied regions with the highest density in the sinoatrial CCS. CONCLUSIONS: Our results provide new insights into the unique morphology of the human CCS collagen, fat, vasculature, and innervation. A deeper understanding of the CCS anatomical components and morphologic substrates' role will help in elucidating the causes of cardiac arrhythmias and provide a basis for further therapeutic interventions.

Human Pulmonary Vein Myocardial Sleeve Autonomic Neural Density and Cardiovascular Mortality.

Myocardial sleeves around pulmonary veins (PVs) are highly innervated structures with heterogeneous morphological and electrophysiological characteristics. Autonomic nerve dysfunction in the myocardium may be associated with an increased risk of cardiovascular morbidity and mortality. This article studied autonomic neural remodeling in myocardial sleeves around PVs and atrial-PV ostia with immunohistochemical and morphometric methods with clinicopathological correlations. PVs were collected from 37 and atrial-PV ostia from 17 human autopsy hearts. Immunohistochemical analysis was performed using antibodies against tyrosine hydroxylase (TH), choline acetyltransferase (CHAT), and growth-associated protein 43 (GAP43). In the PV cohort, subjects with immediate cardiovascular cause of death had significantly decreased sympathetic nerve density in fibro-fatty tissue vs those with non-cardiovascular cause of death (1624.53 vs 2522.05 µm2/mm2, p=0.038). In the atrial-PV ostia cohort, parasympathetic nerve density in myocardial sleeves was significantly increased in subjects with underlying cardiovascular cause of death (19.48 µm2/mm2) than subjects with underlying non-cardiovascular cause of death with no parasympathetic nerves detected (p=0.034). Neural growth regionally varied in sympathetic nerves and was present in most of the parasympathetic nerves. Heterogeneous autonomic nerve distribution and growth around PVs and atrial-PV ostia might play a role in cardiovascular morbidity and mortality. No association in nerve density was found with atrial fibrillation.

Autonomic nerves in myocardial sleeves around caval veins: Potential role in cardiovascular mortality?

BACKGROUND: Quantitative changes in the cardiac autonomic nervous system may play an important role in the pathogenesis of various cardiovascular diseases. In the present morphological analysis, we aimed to study autonomic nerve density in myocardial sleeves and surrounding fibro-fatty tissue around caval veins. We correlated the nerve distribution with cardiovascular mortality and a history of atrial fibrillation. MATERIALS AND METHODS: A total of 24 autopsied adult hearts were excised together with the superior and inferior vena cava and grouped according to the immediate and underlying causes of death (cardiovascular vs. non-cardiovascular), and documented heart rhythm history (atrial fibrillation vs. sinus rhythm). The density of autonomic nerves was quantified by measuring the area of immunohistochemical staining for sympathetic (tyrosine hydroxylase, TH) and parasympathetic (choline acetyltransferase, CHAT) nerves and ganglia. Growth-associated protein 43 (GAP43) was used as a neural growth marker. RESULTS: The mean density of TH-positive nerves in the superior vena cava myocardial sleeves was significantly decreased between groups with documented underlying cardiovascular vs. non-cardiovascular cause of death (mean density ± standard deviation (SD): 704.81±1016.41 µm2/mm2 vs. 2391.01±1841.37 µm2/mm2; P = .008). Similarly, the nerve density of GAP43-positive nerves in the superior vena cava myocardial sleeves was significantly lower in subjects with documented underlying cardiovascular cause of death (mean density ± SD: 884.74±1240.16 µm2/mm2 vs. 2132.89±1845.89 µm2/mm2; P = .040). The mean age was significantly higher in subjects with documented underlying cardiovascular vs. non-cardiovascular cause of death (mean age ± SD: 69.2±11.9 years, vs. 57.5±11.2 years, P = .016). No differences were found in nerve densities of TH-positive (953.01±1042.93 µm2/mm2 vs. 919.26±1677.58 µm2/mm2), CHAT-positive (180.8±532.9 µm2/mm2 vs. 374.22±894.76 µm2/mm2), and GAP43-positive nerves (593.58±507.97 µm2/mm2 vs. 1337.34±1747.69 µm2/mm2) in myocardial sleeves around the inferior vena cava between groups with documented immediate cardiovascular vs. non-cardiovascular cause of death. Similarly, no differences were found between groups with documented underlying cardiovascular vs. non-cardiovascular cause of death (TH: 717.23±887.31 µm2/mm2 vs. 1365.51±2149.10 µm2/mm2; CHAT: 256.18±666.86 µm2/mm2 vs. 368.53±959.47 µm2/mm2; GAP43: 661.21±839.51 µm2/mm2 vs. 1759.90±2008.80 µm2/mm2). Moreover, there was no association found in nerve densities between subjects with documented atrial fibrillation vs. sinus rhythm (TH: 235.07±425.69 µm2/mm2 vs. 1166.08±1563.84 µm2/mm2; CHAT: 648.59±1017.33 µm2/mm2 vs. 175.31±641.65 µm2/mm2; GAP43: 990.17±1315.18 µm2/mm2 vs. 1039.86±1467.23 µm2/mm2). CONCLUSIONS: Decrease of superior vena cava myocardial sleeve sympathetic nerves may be associated with cardiovascular mortality and/or aging. No difference in autonomic innervation was found between subjects with documented atrial fibrillation vs. sinus rhythm.