Association Between Hemodynamic Parameters and Gut Microbiota in Fontan Circulation: A Cross-Sectional Study.

Fontan patients exhibited distinct gut dysbiosis compared with age- and sex-matched healthy controls, with lower evenness and significant shifts in beta-diversity.

• Cross-sectional study enrolled 23 Fontan patients and 23 matched controls
• Gut microbiota profiles were analyzed using 16S rRNA gene sequencing
• Lower evenness (not richness) was the specific alpha-diversity measure that differed between groups
• Beta-diversity showed significant compositional shifts between Fontan patients and controls

Fontan patients had higher relative abundances of inflammation-associated taxa and lower abundances of short-chain fatty acid-producing or commensal genera compared with controls.

• Inflammation-associated taxa were enriched in Fontan patients relative to healthy controls
• Short-chain fatty acid-producing genera were depleted in Fontan patients
• Commensal genera were also found at lower relative abundances in Fontan patients
• Specific bacteria were identified as potential microbial biomarkers for identifying higher-risk patients

Higher catheter-measured pulmonary and Fontan-circuit pressures and greater transpulmonary gradients were associated with lower microbial diversity and depletion of several beneficial taxa.

• Hemodynamic parameters were obtained via cardiac catheterization
• Both pulmonary pressures and Fontan-circuit pressures were treated as continuous variables to reveal graded associations
• Greater transpulmonary gradients correlated with depletion of beneficial taxa
• These associations support a hemodynamic contribution to gut dysbiosis in Fontan physiology

Better liver status reflected by higher serum albumin coincided with more favorable gut microbial profiles in Fontan patients.

• Serum albumin was used as a liver-related parameter reflecting hepatic status
• Higher serum albumin was associated with more favorable microbial profiles
• This finding links hepatic burden to the degree of gut dysbiosis
• Results support a hemodynamic-gut-liver axis in Fontan physiology

Treating Fontan-related pressures as continuous variables revealed graded associations among circulatory congestion, liver involvement, and gut dysbiosis.

• Continuous rather than categorical treatment of hemodynamic variables was used to characterize dose-response relationships
• Graded associations were identified among circulatory congestion, liver involvement, and gut dysbiosis
• These associations support the concept of a hemodynamic-gut-liver axis specific to Fontan physiology
• The study design was cross-sectional, limiting causal inference

Fontan patients underwent cardiovascular assessments including cardiac catheterization as part of the study protocol.

• All 23 Fontan patients underwent cardiovascular assessments including catheter-measured hemodynamic parameters
• Stool samples were collected from all 23 Fontan patients and all 23 matched controls
• The study was cross-sectional in design
• Participants were age- and sex-matched between Fontan and control groups