Cardiac and Vascular Causes of Syncope and Atherosclerosis

Benzo[b]fluoranthene damages coronary artery and affects atherosclerosis markers in mice and umbilical vein endothelial cells

Polycyclic aromatic hydrocarbons (PAHs) exposure is associated with cardiovascular diseases. Toxic effects of PAHs are diverse, while cardiovascular consequences of benzo[b]fluoranthene (B[b]F) are unclear. Here, we reported the impacts of B[b]F on coronary artery and atherosclerosis markers both in mice and umbilical vein endothelial EAhy.926 cells. In mice, we found that B[b]F decreases heart-to-body weight ratio, affects aortic physiology, elevates serum low-density lipoprotein and total cholesterol, increases aortic levels of collagen fiber and atherosclerotic marker vascular cell adhesion molecule-1 (VCAM-1), and downregulates oxidative stress related nuclear factor erythroid 2-related factor 2 (Nrf2). In EAhy.926 cells, we showed that B[b]F inhibits cell proliferation and migration in a dose-dependent manner, induces cell cycle arrest and apoptosis, increases reactive oxygen species, upregulates VCAM-1 level, and suppresses expression of Nrf2. Taken together, our findings reveal that B[b]F exposure may contribute to coronary artery damage and potentially induce atherosclerosis, possibly via the Nrf2-related signaling pathways.

[Syncopes - differential diagnoses and treatment]

Syncope is a sudden loss of consciousness (transient loss of consciousness, TLOC) caused by a lack of cerebral perfusion that resolves spontaneously and completely after a short period of time 1. With a lifetime prevalence of 40% and constituting about 1% of all emergency department admissions, syncope is a common and medically relevant problem 2 3. The underlying causes of syncope are diverse and associated with significantly different prognoses. A structured approach is essential to identify high-risk patients and ensure appropriate treatment. This article aims at providing an overview of the current recommendations for the diagnosis and treatment of syncope.

An Investigation of Metabolic Risk Factors and Gut Microbiota in Unexplained Syncope

BACKGROUND

The pathogenesis of many syncopal episodes remains unexplained. Intestinal dysbiosis could be involved in the pathophysiological mechanisms of syncope due to its connection with the central nervous system via the microbiota-gut-brain axis. This pilot study aimed to explore the specific cardiometabolic risk factors and gut microbiota in unexplained syncope (US), compared to other types of syncope, to assess their similarity or verify their different origins.

METHODS

We studied 86 participants with syncope, who were divided into four groups: an orthostatic syncope group (OH, n = 24), a neuromediated syncope group (NMS, n = 26), a cardiological syncope group (CS, n = 9), and an unexplained syncope group (US, n = 27). We evaluated the anthropometric, clinical, and metabolic characteristics of the four groups; the α- and β-diversity; and the differences in the abundance of the microbial taxa.

RESULTS

The US group had a lower incidence of systolic hypertension at the first visit and a lower frequency of patients with nocturnal hypertension than the CS group. Compared to the OH and NMS groups, the US group had a higher incidence of carotid plaques and greater carotid intima-media thickness, respectively. The microbiota differed significantly between the US and CS groups, but not between the US group and the OH or NMS group.

CONCLUSIONS

We observed significant differences in the gut microbiota between CS and US. Future studies are necessary to evaluate the involvement of the gut microbiota in the complex pathogenesis of syncope and whether its analysis could support the interpretation of the pathophysiological mechasnisms underlying some episodes classifiable as US.