Gut microbiota community and metabolic profiles in direct total cavopulmonary connection and Fontan circulation: a cross-sectional study in the single center

Background

This study aimed to evaluate the impact of the direct total cavopulmonary connection (dTCPC) procedure on the gut microbiome and metabolome. It also sought to elucidate the features of the gut microbiota community and metabolic profiles in Fontan circulation.

Methods

We randomly recruited 45 participants above 14 years old undergoing Fontan procedure by typical extracardiac conduit (TCPC group, n = 15), direct total cavopulmonary connection (dTCPC group, n = 16) procedure and healthy control (control group, n = 14) in our institution between May 2023 and October 2023. 16S rRNA amplicon sequencing and untargeted metabolites measurement were performed on their fecal sample.

Results

The four alpha diversity indexes showed no statistical significance between the dTCPC and TCPC groups (p > 0.05). Orthogonal partial least squares discriminant analysis (OPLS-DA) followed by permutation testing indicated an overfitting effect in the model between the dTCPC and TCPC groups. We observed significant differences in the Chao1 index (p = 0.0236), the ACE index (p = 0.0236), and the unweighted beta diversity (p = 0.0099) between the Fontan group and healthy control group. Strains of Fusobacterium were significantly overrepresented in the Fontan group [with linear discriminant analysis (LDA) scores exceeding (log10) >3]. Functional enrichment analysis revealed a significant overrepresentation of several metabolic pathways. These pathways predominantly included those related to amino acid metabolism, such as histidine metabolism, glycine, serine, and threonine metabolism, and cysteine and methionine metabolism. Additionally, the biosynthesis of unsaturated fatty acids was also notably enriched.

Conclusion

The dTCPC procedure demonstrated similar gut microbiota composition and metabolic profiles to the traditional ECC procedure in Fontan patients. Notably, the increased abundance of Fusobacterium, reduced microbial biodiversity, and altered metabolic profiles of amino acids and unsaturated fatty acids in the alimentary canal may serve as distinctive characteristics of patients who have undergone Fontan circulation. These findings provide valuable insights into the long-term physiological consequences of Fontan procedure and may inform future clinical management strategies.

A case of gaucher disease with a rare complication of gaucheroma and protein-losing enteropathy

This case report describes a patient initially diagnosed with Gaucher disease (GD) with type I with homozygous mutation c.1448T > C p. (Leu483Pro) at age of 2, presenting with hepatosplenomegaly and cytopenia. Imiglucerase replacement therapy was initiated. At age 17, bilateral hearing loss developed, with subsequent Cranial MRI revealing thalamic damage, leading to a reclassification as type 3 GD. By age of 20, the patient presented with a range of symptoms, including abdominal pain, diarrhea, hypoproteinemia, multiple lymphadenopathy, edema, and Gaucher cell infiltration in the lymph nodes. Comprehensive diagnosis identifies Gaucher tumor and protein-losing enteropathy. Imiglucerase therapy at 90-120 U/kg every 2 weeks significantly improved clinical symptoms, emphasizing the importance of tailored interventions for managing GD manifestations.

Dysbiosis of gut microbiota in patients with protein-losing enteropathy after the Fontan procedure

BACKGROUND

There is a lack of predictive biomarkers for the onset or activity of protein-losing enteropathy (PLE), a Fontan procedure-associated complication. Here, we aimed to identify the gut microbiota composition of patients with active PLE and investigate its relationship with PLE activity.

METHODS

This multicenter case-control study involved patients who developed PLE (n = 16) after the Fontan procedure and those who did not (non-PLE; n = 20). Patients with PLE who maintained a serum albumin level of ≥3 g/dL for >1 year were included in the remissive-stage-PLE group (n = 9) and those who did not maintain this level were included in the active-PLE group (n = 7). 16S rRNA gene sequencing analysis of fecal samples was performed using QIIME2 pipeline. Alpha (Shannon and Faith's phylogenetic diversity indices) and beta diversity was assessed using principal coordinate analysis based on unweighted UniFrac distances.

RESULTS

Shannon and Faith's phylogenetic diversity indices were lower in the active-PLE group than in the remissive-stage- (q = 0.028 and 0.025, respectively) and non-PLE (q = 0.028 and 0.017, respectively) groups. Analysis of beta diversity revealed a difference in the microbiota composition between the active-PLE and the other two groups. Linear discriminant effect size analysis demonstrated differences in the relative abundance of Bifidobacterium and Granulicatella spp., and Ruminococcus torques between patients with active- and those with remissive-stage-PLE.

CONCLUSIONS

Gut microbiota dysbiosis was observed in patients with active PLE. Changes in the bacterial composition of the gut microbiota and decreased diversity may be associated with the severity of PLE.

Current diagnostic and therapeutic strategies for the management of lymphatic insufficiency in patients with hypoplastic left heart syndrome

Children with hypoplastic left heart syndrome share unique hemodynamic features that alter lymphatic integrity at all stages of palliation. Lymphatic congestion is almost universal in this patient group to some extent. It may lead to reversal of lymphatic flow, the development of abnormal lymphatic channels and ultimately decompression and loss of protein rich lymphatic fluid into extra lymphatic compartments in prone individuals. Some of the most devastating complications that are associated with single ventricle physiology, notably plastic bronchitis and protein losing enteropathy, have now been proven to be lymphatic in origin. Based on the new pathophysiologic concept new diagnostic and therapeutic strategies have recently been developed. Dynamic contrast magnetic resonance lymphangiography is now mainstay in diagnosis of lymphatic insufficiency and allows a thorough assessment of anatomy and function of the main lymphatic compartments through intranodal, intrahepatic and intramesenteric lymphatic imaging. Contrast enhanced ultrasound can evaluate thoracic duct patency and conventional fluoroscopic lymphangiography has been refined for evaluation of patients where magnetic resonance imaging cannot be performed. Novel lymphatic interventional techniques, such as thoracic duct embolization, selective lymphatic duct embolization and liver lymphatic embolization allow to seal abnormal lymphatic networks minimally invasive and have shown to resolve symptoms. Innominate vein turn-down procedures, whether surgical or interventional, have been designed to reduce lymphatic afterload and increase systemic preload effectively in the failing Fontan circulation. Outflow obstruction can now be managed with new microsurgical techniques that create lympho-venous anastomosis. Short term results for all of these new approaches are overall promising but evidence is sparse and long-term outcome still has to be defined. This review article aims to summarize current concepts of lymphatic flow disorders in single ventricle patients, discuss new emerging diagnostic and therapeutic strategies and point out lacks in evidence and needs for further research on this rapidly growing topic.

Protein-losing enteropathy in Fontan circulation: Pathophysiology, outcome and treatment options of a complex condition

Protein-losing enteropathy (PLE) represents a rare but severe and potentially life-threatening complication following Fontan operation in patients with a functional single ventricle. PLE is characterized by enteric protein loss, leading to devastating multiorgan involvement with increased morbidity and mortality. In spite of remarkable advances in the care of congenital heart disease in recent years, treatment of PLE is still one of the most challenging tasks due to limited understanding of the underlying mechanisms and lack of high-quality evidence from large scale, controlled studies to test the real efficacy of the several treatment strategies, which have been proposed. For this reason, we herewith aim to discuss the pathogenesis and diagnosis of PLE in Fontan patients as well as provide a comprehensive overview on potential advantages and disadvantages of the currently available therapeutic strategies, in order to propose a stepwise approach for the management of this unique condition.

Protein losing enteropathy after the Fontan operation

The Fontan or Fontan Kreutzer procedure is the culmination of staged, surgical palliation of functional single ventricle congenital heart disease, offering the potential for survival and good quality of life well into adulthood. As more patients with Fontan circulation age, a variety of complications involving almost every organ system may occur. Protein-losing enteropathy is a major cause of morbidity and mortality after the Fontan operation, occurring more often in patients with adverse hemodynamics and presenting weeks to years after Fontan surgery. The causes are not well understood, but likely include a combination of lymphatic insufficiency, high central venous pressure, loss of heparan sulfate from intestinal epithelial cells, abnormal mesenteric circulation, and intestinal inflammation. A comprehensive evaluation including multimodality imaging and cardiac catheterization is necessary to diagnose and treat any reversible causes. In advanced cases, early referral for heart transplantation evaluation or lymphatic decompression procedures (if the single ventricle function remains adequate) is indicated. Despite the improvement in detection and management options, the mortality remains high. Standardization of protein-losing enteropathy definition and management strategies will help facilitate interpretation of research and clinical experience, potentially fostering the identification of new therapies. Based on the published data, this review suggests a standardized approach to diagnosis and treatment.

Management of circulatory failure after Fontan surgery

With improvement in survival after Fontan surgery resulting in an increasing number of older survivors, there are more patients with a Fontan circulation experiencing circulatory failure each year. Fontan circulatory failure may have a number of underlying etiologies. Once Fontan failure manifests, prognosis is poor, with patient freedom from death or transplant at 10 years of only about 40%. Medical treatments used include traditional heart failure medications such as renin-angiotensin-aldosterone system blockers and beta-blockers, diuretics for symptomatic management, antiarrhythmics for rhythm control, and phosphodiesterase-5 inhibitors to decrease PVR and improve preload. These oral medical therapies are typically not very effective and have little data demonstrating benefit; if there are no surgical or catheter-based interventions to improve the Fontan circulation, patients with severe symptoms often require inotropic medications or mechanical circulatory support. Mechanical circulatory support benefits patients with ventricular dysfunction but may not be as useful in patients with other forms of Fontan failure. Transplant remains the definitive treatment for circulatory failure after Fontan, but patients with a Fontan circulation face many challenges both before and after transplant. There remains significant room and urgent need for improvement in the management and outcomes of patients with circulatory failure after Fontan surgery.

Diagnosis and Management of Lymphatic Disorders in Congenital Heart Disease

Purpose of Review

Lymphatic disorders have received an increasing amount of attention over the last decade. Sparked primarily by improved imaging modalities and the dawn of lymphatic interventions, understanding, diagnostics, and treatment of lymphatic complications have undergone considerable improvements. Thus, the current review aims to summarize understanding, diagnostics, and treatment of lymphatic complications in individuals with congenital heart disease.

Recent Findings

The altered hemodynamics of individuals with congenital heart disease has been found to profoundly affect morphology and function of the lymphatic system, rendering this population especially prone to the development of lymphatic complications such as chylous and serous effusions, protein-losing enteropathy and plastic bronchitis.

Summary

Although improved, a full understanding of the pathophysiology and targeted treatment for lymphatic complications is still wanting. Future research into pharmacological improvement of lymphatic function and continued implementation of lymphatic imaging and interventions may improve knowledge, treatment options, and outcome for affected individuals.

Protein Losing Enteropathy After Fontan Operation: Glimpses of Clarity Through the Lifting Fog

Fontan-associated protein losing enteropathy is a challenge to treat and is a major contributor to morbidity and mortality in patients with palliated single ventricle. Numerous strategies for management have been proposed, with confusion as to how best to stratify and implement care among the many treatments available. Medical management can be helpful in some, while novel lymphatic interventions hold potential for remission with good results. We review our institutional approach to protein losing enteropathy after Fontan operation and provide a suggested algorithm and pathway for effective care.