Serum Bile Acids in Repaired Tetralogy of Fallot: A Marker for Liver and Heart?

Deoxycholic Acid, a Secondary Bile Acid, Increases Cardiac Output and Blood Pressure in Rats

BACKGROUND

Deoxycholic acid (DCA) is a secondary bile acid produced by gut bacteria. Elevated serum concentrations of DCA are observed in cardiovascular disease (CVD). We hypothesized that DCA might influence hemodynamic parameters in rats.

METHODS

The concentration of DCA in systemic blood was measured with liquid chromatography coupled with mass spectrometry. Arterial blood pressure (BP), heart rate (HR) and echocardiographic parameters were evaluated in anesthetized, male, 3-4-month-old Sprague-Dawley rats administered intravenously (IV) or intracerebroventricularly (ICV) with investigated compounds. Mesenteric artery (MA) reactivity was tested ex vivo.

RESULTS

The baseline plasma concentration of DCA was 0.24 ± 0.03 mg/L. The oral antibiotic treatment produced a large decrease in the concentration. Administered IV, the compound increased BP and HR in a dose-dependent manner. DCA also increased heart contractility and cardiac output. None of the tested compounds-prazosin (an alpha-blocker), propranolol (beta-adrenolytic), atropine (muscarinic receptor antagonist), glibenclamide (K-ATP inhibitor) or DY 268 (FXR antagonist), glycyrrhetinic acid (11HSD2 inhibitor)-significantly diminished the DCA-induced pressor effect. ICV infusion did not exert significant HR or BP changes. DCA relaxed MAs. Systemic vascular resistance did not change significantly.

CONCLUSIONS

DCA elevates BP primarily by augmenting cardiac output. As a metabolite derived from gut bacteria, DCA potentially serves as a mediator in the interaction between the gut microbiota and the host's circulatory system.

From heart to gut: Exploring the gut microbiome in congenital heart disease

Congenital heart disease (CHD) is a prevalent birth defect and a significant contributor to childhood mortality. The major characteristics of CHD include cardiovascular malformations and hemodynamical disorders. However, the impact of CHD extends beyond the circulatory system. Evidence has identified dysbiosis of the gut microbiome in patients with CHD. Chronic hypoxia and inflammation associated with CHD affect the gut microbiome, leading to alterations in its number, abundance, and composition. The gut microbiome, aside from providing essential nutrients, engages in direct interactions with the host immune system and indirect interactions via metabolites. The abnormal gut microbiome or its products can translocate into the bloodstream through an impaired gut barrier, leading to an inflammatory state. Metabolites of the gut microbiome, such as short-chain fatty acids and trimethylamine N-oxide, also play important roles in the development, treatment, and prognosis of CHD. This review discusses the role of the gut microbiome in immunity, gut barrier, neurodevelopment, and perioperative period in CHD. By fostering a better understanding of the cross-talk between CHD and the gut microbiome, this review aims to contribute to improve clinical management and outcomes for CHD patients.

Disorders of gut microbiota in children with Tetralogy of Fallot

BACKGROUND

Gut microbiota plays an important role in cardiovascular health and disease, including congenital heart disease (CHD). Tetralogy of Fallot (TOF) is the most common form of cyanotic CHD characterized by systemic chronic hypoxia and sustained pressure overload of the right ventricle. It is well-known that hypoxia and pressure overload can affect gut microbiota. However, the effects of TOF on the gut microbiota remain little understood. This study explored the profile of the gut microbiota in children with unrepaired TOF.

METHODS

A total of 12 pediatric patients diagnosed with TOF and 9 healthy age- and gender-matched children were enrolled in this study. Fecal samples were collected from every participant and subjected to 16S rDNA gene sequencing. The raw sequencing data were processed using the Quantitative Insights Into Microbial Ecology pipeline.

RESULTS

A comparison of the gut microbiota revealed that pediatric patients with TOF had developed dysbiosis as reflected by the altered taxonomic composition and impaired functional profile. A total of 14 indicative bacterial genera were identified as differential biomarkers capable of distinguishing between healthy children and TOF patients. Furthermore, functional annotations revealed that the gut microbiota in TOF patients was characterized by increased levels of inflammatory, oxidative, and immune responses, and decreased activities of adaptation, synthesis, and metabolism.

CONCLUSIONS

Pediatric patients with unrepaired TOF have intestinal dysbacteriosis that is characterized by altered taxonomic composition and impaired functional profile. These findings suggested that the interplay between gut microbiota and the host may be dysregulated in patients with TOF.

Heart and bile acids - Clinical consequences of altered bile acid metabolism

Cardiac dysfunction has an increased prevalence in diseases complicated by liver cirrhosis such as primary biliary cholangitis and primary sclerosing cholangitis. This observation has led to research into the association between abnormalities in bile acid metabolism and cardiac pathology. Approximately 50% of liver cirrhosis cases develop cirrhotic cardiomyopathy. Bile acids are directly implicated in this, causing QT interval prolongation, cardiac hypertrophy, cardiomyocyte apoptosis and abnormal haemodynamics of the heart. Elevated maternal serum bile acids in intrahepatic cholestasis of pregnancy, a disorder which causes an impaired feto-maternal bile acid gradient, have been associated with fatal fetal arrhythmias. The hydrophobicity of individual bile acids in the serum bile acid pool is of relevance, with relatively lipophilic bile acids having a more harmful effect on the heart. Ursodeoxycholic acid can reverse or protect against these detrimental cardiac effects of elevated bile acids.