Biomimetic superabsorbent hydrogel acts as a gut protective dynamic exoskeleton improving metabolic parameters and expanding A. muciniphila

The rising prevalence of obesity and metabolic disorders worldwide highlights the urgent need to find new long-term and clinically meaningful weight-loss therapies. Here, we evaluate the therapeutic potential and the mechanism of action of a biomimetic cellulose-based oral superabsorbent hydrogel (OSH). Treatment with OSH exerts effects on intestinal tissue and gut microbiota composition, functioning like a protective dynamic exoskeleton. It protects from gut barrier permeability disruption and induces rapid and consistent changes in the gut microbiota composition, specifically fostering Akkermansia muciniphila expansion. The mechanobiological, physical, and chemical structures of the gel are required for A. muciniphila growth. OSH treatment induces weight loss and reduces fat accumulation, in both preventative and therapeutic settings. OSH usage also prevents liver steatosis, immune infiltration, and fibrosis, limiting the progression of non-alcoholic fatty liver disease. Our work shows the potential of using OSH as a non-systemic mechanobiological approach to treat metabolic syndrome and its comorbidities.

Mucosal Overexpression of Thymic Stromal Lymphopoietin and Proinflammatory Cytokines in Patients With Autoimmune Atrophic Gastritis

INTRODUCTION

The immune mechanisms underlying human autoimmune atrophic gastritis (AAG) are poorly understood. We sought to assess immune mucosal alterations in patients with AAG.

METHODS

In 2017-2021, we collected gastric corpus biopsies from 24 patients with AAG (median age 62 years, interquartile range 56-67, 14 women), 26 age-matched and sex-matched healthy controls (HCs), and 14 patients with Helicobacter pylori infection (HP). We investigated the lamina propria mononuclear cell (LPMC) populations and the mucosal expression of thymic stromal lymphopoietin (TSLP) and nicotinamide phosphoribosyltransferase (NAMPT). Ex vivo cytokine production by organ culture biopsies, under different stimuli (short TSLP and zinc-l-carnosine), and the gastric vascular barrier through plasmalemma vesicle-associated protein-1 (PV1) were also assessed.

RESULTS

In the subset of CD19+ LPMC, CD38+ cells (plasma cells) were significantly higher in AAG compared with HC. Ex vivo production of tumor necrosis factor (TNF)-α, interleukin (IL)-15, and transforming growth factor β1 was significantly higher in AAG compared with HC. At immunofluorescence, both IL-7R and TSLP were more expressed in AAG compared with HC and HP, and short TSLP transcripts were significantly increased in AAG compared with HC. In the supernatants of AAG corpus mucosa, short TSLP significantly reduced TNF-α, while zinc-l-carnosine significantly reduced interferon-γ, TNF-α, IL-21, IL-6, and IL-15. NAMPT transcripts were significantly increased in AAG compared with HC. PV1 was almost absent in AAG, mildly expressed in HC, and overexpressed in HP.

DISCUSSION

Plasma cells, proinflammatory cytokines, and altered gastric vascular barrier may play a major role in AAG. TSLP and NAMPT may represent potential therapeutic targets, while zinc-l-carnosine may dampen mucosal inflammation.

BNT162b2 vaccine induces antibody release in saliva: a possible role for mucosal viral protection?

Vaccination against an airborne pathogen is very effective if it induces also the development of mucosal antibodies that can protect against infection. The mRNA‐based vaccine‐encoding SARS‐CoV‐2 full‐length spike protein (BNT162b2, Pfizer/BioNTech) protects also against infection despite being administered systemically. Here, we show that upon vaccination, cognate IgG molecules are also found in the saliva and are more abundant in SARS‐CoV‐2 previously exposed subjects, paralleling the development of plasma IgG. The antibodies titer declines at 3 months from vaccination. We identified a concentration of specific IgG in the plasma above which the relevant IgG can be detected in the saliva. Regarding IgA antibodies, we found only protease‐susceptible IgA1 antibodies in plasma while they were present at very low levels in the saliva over the course of vaccination of SARS‐CoV‐2‐naïve subjects. Thus, in response to BNT162b2 vaccine, plasma IgG can permeate into mucosal sites and participate in viral protection. It is not clear why IgA1 are detected in low amount, they may be proteolytically cleaved.

A 'Multiomic' Approach of Saliva Metabolomics, Microbiota, and Serum Biomarkers to Assess the Need of Hospitalization in Coronavirus Disease 2019

BACKGROUND AND AIMS

The SARS-CoV-2 pandemic has overwhelmed the treatment capacity of the health care systems during the highest viral diffusion rate. Patients reaching the emergency department had to be either hospitalized (inpatients) or discharged (outpatients). Still, the decision was taken based on the individual assessment of the actual clinical condition, without specific biomarkers to predict future improvement or deterioration, and discharged patients often returned to the hospital for aggravation of their condition. Here, we have developed a new combined approach of omics to identify factors that could distinguish coronavirus disease 19 (COVID-19) inpatients from outpatients.

METHODS

Saliva and blood samples were collected over the course of two observational cohort studies. By using machine learning approaches, we compared salivary metabolome of 50 COVID-19 patients with that of 270 healthy individuals having previously been exposed or not to SARS-CoV-2. We then correlated the salivary metabolites that allowed separating COVID-19 inpatients from outpatients with serum biomarkers and salivary microbiota taxa differentially represented in the two groups of patients.

RESULTS

We identified nine salivary metabolites that allowed assessing the need of hospitalization. When combined with serum biomarkers, just two salivary metabolites (myo-inositol and 2-pyrrolidineacetic acid) and one serum protein, chitinase 3-like-1 (CHI3L1), were sufficient to separate inpatients from outpatients completely and correlated with modulated microbiota taxa. In particular, we found Corynebacterium 1 to be overrepresented in inpatients, whereas Actinomycetaceae F0332, Candidatus Saccharimonas, and Haemophilus were all underrepresented in the hospitalized population.

CONCLUSION

This is a proof of concept that a combined omic analysis can be used to stratify patients independently from COVID-19.

Isoproterenol Disrupts Intestinal Barriers Activating Gut-Liver-Axis: Effects on Intestinal Mucus and Vascular Barrier as Entry Sites

BACKGROUND

The gut-liver-axis presents the pathophysiological hallmark for multiple liver diseases and has been proposed to be modulated during stress and shock. Access to the gut-liver-axis needs crossing of the mucus and gut-vascular barrier. The role of β-adrenoreceptor-activation for both barriers has not been defined and is characterized here.

METHODS

Splanchnic β-adrenergic stimulation was achieved by chronic intraperitoneal application of isoproterenol via alzet-pump in vivo. The intestinal permeability and gut-vascular barrier function was assessed in ileal loop experiments. The extravasation of predefined sizes of fluorescence isothiocyanate (FITC)-dextran molecules in ileal microcirculation was evaluated by intravital confocal laser endomicroscopy in vivo. Mucus parameters thickness, goblet cell count and mucin-expression were assessed by stereomicroscopy, immunostaining and RNA-sequencing respectively. Ileal lamina propria (LP) as well as mesenteric lymph node mononuclear cells was assessed by FACS.

RESULTS

Healthy mice lack translocation of 4 kDa-FITC-dextran from the small intestine to the liver, whereas isoproterenol-treated mice demonstrate pathological translocation (PBT). Mucus layer is reduced in thickness with loss of goblet-cells and mucin-2-staining and -expression in isoproterenol-treated animals under standardized gnotobiotic conditions. Isoproterenol disrupts the gut vascular barrier displaying Ileal extravasation of large-sized 70- and 150 kDa-FITC-dextran. This pathological endothelial permeability and accessibility induced by isoproterenol associates with an augmented expression of plasmalemmal-vesicle-associated-protein-1 in intestinal vessel. Ileal LP after isoproterenol treatment contains more CD11c+-dendritic cells (DC) with increased appearance of CCR7+ DC in mesenteric lymph nodes.

CONCLUSIONS

Isoproterenol impairs the intestinal muco-epithelial and endothelial-vascular barrier promoting PBT to the liver. This barrier dysfunction on multiple levels potentially can contribute to liver injury induced by catecholamines during states of increased β-adrenergic drive.

Gut vascular barrier impairment leads to intestinal bacteria dissemination and colorectal cancer metastasis to liver

Metastasis is facilitated by the formation of a "premetastatic niche," which is fostered by primary tumor-derived factors. Colorectal cancer (CRC) metastasizes mainly to the liver. We show that the premetastatic niche in the liver is induced by bacteria dissemination from primary CRC. We report that tumor-resident bacteria Escherichia coli disrupt the gut vascular barrier (GVB), an anatomical structure controlling bacterial dissemination along the gut-liver axis, depending on the virulence regulator VirF. Upon GVB impairment, bacteria disseminate to the liver, boost the formation of a premetastatic niche, and favor the recruitment of metastatic cells. In training and validation cohorts of CRC patients, we find that the increased levels of PV-1, a marker of impaired GVB, is associated with liver bacteria dissemination and metachronous distant metastases. Thus, PV-1 is a prognostic marker for CRC distant recurrence and vascular impairment, leading to liver metastases.

The role of gut vascular barrier in experimental alcoholic liver disease and A. muciniphila supplementation

The translocation of bacterial components from the intestinal lumen into the portal circulation is crucial in the pathogenesis of alcoholic liver disease (ALD). Recently the important role of the gut vascular barrier (GVB) was elucidated in alcoholic liver disease. Here we report about the influence of A. muciniphila supplementation in experimental ALD on the GVB. Ethanol feeding was associated with increased Pv-1, indicating altered endothelial barrier function, whereas A. muciniphila administration tended to restore GVB. To further investigate GVB in experimental ALD, β-catenin gain-of-function mice, which display an enhanced GVB, were ethanol-fed. β-catenin gain-of-function mice were not protected from ethanol-induced liver injury, suggest an alternative mechanism of ethanol-induced GVB disruption. The description of the GVB in ALD could pave the way for new therapeutic options in the future.

Endogenous murine microbiota member Faecalibaculum rodentium and its human homologue protect from intestinal tumour growth

The microbiota has been shown to promote intestinal tumourigenesis, but a possible anti-tumourigenic effect has also been postulated. Here, we demonstrate that changes in the microbiota and mucus composition are concomitant with tumourigenesis. We identified two anti-tumourigenic strains of the microbiota-Faecalibaculum rodentium and its human homologue, Holdemanella biformis-that are strongly under-represented during tumourigenesis. Reconstitution of ApcMin/+ or azoxymethane- and dextran sulfate sodium-treated mice with an isolate of F. rodentium (F. PB1) or its metabolic products reduced tumour growth. Both F. PB1 and H. biformis produced short-chain fatty acids that contributed to control protein acetylation and tumour cell proliferation by inhibiting calcineurin and NFATc3 activation in mouse and human settings. We have thus identified endogenous anti-tumourigenic bacterial strains with strong diagnostic, therapeutic and translational potential.

Microbiota-driven gut vascular barrier disruption is a prerequisite for non-alcoholic steatohepatitis development

BACKGROUND & AIMS

Fatty liver disease, including non-alcoholic fatty liver (NAFLD) and steatohepatitis (NASH), has been associated with increased intestinal barrier permeability and translocation of bacteria or bacterial products into the blood circulation. In this study, we aimed to unravel the role of both intestinal barrier integrity and microbiota in NAFLD/NASH development.

METHODS

C57BL/6J mice were fed with high-fat diet (HFD) or methionine-choline-deficient diet for 1 week or longer to recapitulate aspects of NASH (steatosis, inflammation, insulin resistance). Genetic and pharmacological strategies were then used to modulate intestinal barrier integrity.

RESULTS

We show that disruption of the intestinal epithelial barrier and gut vascular barrier (GVB) are early events in NASH pathogenesis. Mice fed HFD for only 1 week undergo a diet-induced dysbiosis that drives GVB damage and bacterial translocation into the liver. Fecal microbiota transplantation from HFD-fed mice into specific pathogen-free recipients induces GVB damage and epididymal adipose tissue enlargement. GVB disruption depends on interference with the WNT/β-catenin signaling pathway, as shown by genetic intervention driving β-catenin activation only in endothelial cells, preventing GVB disruption and NASH development. The bile acid analogue and farnesoid X receptor agonist obeticholic acid (OCA) drives β-catenin activation in endothelial cells. Accordingly, pharmacologic intervention with OCA protects against GVB disruption, both as a preventive and therapeutic agent. Importantly, we found upregulation of the GVB leakage marker in the colon of patients with NASH.

CONCLUSIONS

We have identified a new player in NASH development, the GVB, whose damage leads to bacteria or bacterial product translocation into the blood circulation. Treatment aimed at restoring β-catenin activation in endothelial cells, such as administration of OCA, protects against GVB damage and NASH development.

LAY SUMMARY

The incidence of fatty liver disease is reaching epidemic levels in the USA, with more than 30% of adults having NAFLD (non-alcoholic fatty liver disease), which can progress to more severe non-alcoholic steatohepatitis (NASH). Herein, we show that disruption of the intestinal epithelial barrier and gut vascular barrier are early events in the development of NASH. We show that the drug obeticholic acid protects against barrier disruption and thereby prevents the development of NASH, providing further evidence for its use in the prevention or treatment of NASH.

FXR modulates the gut-vascular barrier by regulating the entry sites for bacterial translocation in experimental cirrhosis

BACKGROUND & AIMS

Pathological bacterial translocation (PBT) in cirrhosis is the hallmark of spontaneous bacterial infections, increasing mortality several-fold. Increased intestinal permeability is known to contribute to PBT in cirrhosis, although the role of the mucus layer has not been addressed in detail. A clear route of translocation for luminal intestinal bacteria is yet to be defined, but we hypothesize that the recently described gut-vascular barrier (GVB) is impaired in experimental portal hypertension, leading to increased accessibility of the vascular compartment for translocating bacteria.

MATERIALS

Cirrhosis was induced in mouse models using bile-duct ligation (BDL) and CCl₄. Pre-hepatic portal-hypertension was induced by partial portal vein ligation (PPVL). Intestinal permeability was compared in these mice after GFP-Escherichia coli or different sized FITC-dextrans were injected into the intestine.

RESULTS

Healthy and pre-hepatic portal-hypertensive (PPVL) mice lack translocation of FITC-dextran and GFP-E. coli from the small intestine to the liver, whereas BDL and CCl₄-induced cirrhotic mice demonstrate pathological translocation, which is not altered by prior thoracic-duct ligation. The mucus layer is reduced in thickness, with loss of goblet cells and Muc2-staining and expression in cirrhotic but not PPVL mice. These changes are associated with bacterial overgrowth in the inner mucus layer and pathological translocation of GFP-E. coli through the ileal epithelium. GVB is profoundly altered in BDL and CCl₄-mice with Ileal extravasation of large-sized 150 kDa-FITC-dextran, but only slightly altered in PPVL mice. This pathological endothelial permeability and accessibility in cirrhotic mice is associated with augmented expression of PV1 in intestinal vessels. OCA but not fexaramine stabilizes the GVB, whereas both FXR-agonists ameliorate gut to liver translocation of GFP-E. coli.

CONCLUSIONS

Cirrhosis, but not portal hypertension per se, grossly impairs the endothelial and muco-epithelial barriers, promoting PBT to the portal-venous circulation. Both barriers appear to be FXR-modulated, with FXR-agonists reducing PBT via the portal-venous route.

LAY SUMMARY

For intestinal bacteria to enter the systemic circulation, they must cross the mucus and epithelial layer, as well as the gut-vascular barrier. Cirrhosis disrupts all 3 of these barriers, giving bacteria access to the portal-venous circulation and thus, the gut-liver axis. Diminished luminal bile acid availability, cirrhosis and the associated reduction in farnesoid x receptor (FXR) signaling seem, at least partly, to mediate these changes, as FXR-agonists reduce bacterial translocation via the portal-venous route to the liver in cirrhosis.

Organ-specific protection mediated by cooperation between vascular and epithelial barriers

Immune privilege is a complex process that protects organs from immune-mediated attack and damage. It is accomplished by a series of cellular barriers that both control immune cell entry and promote the development of tolerogenic immune cells. In this Review, we describe the vascular endothelial and epithelial barriers in organs that are commonly considered to be immune privileged, such as the brain and the eye. We compare these classical barriers with barriers in the intestine, which share features with barriers of immune-privileged organs, such as the capacity to induce tolerance and to protect from external insults. We suggest that when intestinal barriers break down, disruption of other barriers at distant sites can ensue, and this may underlie the development of various neurological, metabolic and intestinal disorders.

Gene expression profile of endothelial cells during perturbation of the gut vascular barrier

It has been widely demonstrated that tolerance against gut microbiota is compartmentalized to mucosal sites where microbes mostly reside. How the commensal bacteria are excluded from the entrance into the blood stream via intestinal capillaries that are located beneath the gut epithelium was not clear. We recently described the existence of a new anatomical structure, the 'gut vascular barrier' (GVB), both in murine and human intestines that plays a fundamental role in avoiding indiscriminate trafficking of bacteria from the gut into the blood circulation. The vascular barrier integrity could be altered by Salmonella typhimurium, a pathogen capable of systemic dissemination, through the modulation of the Wnt/β-catenin signaling pathway. Here we have analyzed the differences in gut endothelial gene expression profiles during Salmonella infection and have identified some interesting characteristics of endothelial to mesenchymal transition. These findings add new insights in the gut-liver axis.

A gut-vascular barrier controls the systemic dissemination of bacteria

In healthy individuals, the intestinal microbiota cannot access the liver, spleen, or other peripheral tissues. Some pathogenic bacteria can reach these sites, however, and can induce a systemic immune response. How such compartmentalization is achieved is unknown. We identify a gut-vascular barrier (GVB) in mice and humans that controls the translocation of antigens into the blood stream and prohibits entry of the microbiota. Salmonella typhimurium can penetrate the GVB in a manner dependent on its pathogenicity island (Spi) 2-encoded type III secretion system and on decreased β-catenin-dependent signaling in gut endothelial cells. The GVB is modified in celiac disease patients with elevated serum transaminases, which indicates that GVB dismantling may be responsible for liver damage in these patients. Understanding the GVB may provide new insights into the regulation of the gut-liver axis.

Human intestinal epithelial cells promote the differentiation of tolerogenic dendritic cells

OBJECTIVE

In mice, a subpopulation of gut dendritic cells (DCs) expressing CD103 drives the development of regulatory T (T(reg)) cells. Further, it was recently described that the cross-talk between human intestinal epithelial cells (IECs) and DCs helps in maintaining gut immune homeostasis via the induction of non-inflammatory DCs. In this study, an analysis was carried out to determine whether IECs could promote the differentiation of CD103+ tolerogenic DCs, and the function of primary CD103+ DCs isolated from human mesenteric lymph nodes (MLNs) was evaluated.

METHODS

Monocyte-derived DCs (MoDCs) and circulating CD1c+ DCs were conditioned or not with supernatants from Caco-2 cells or IECs isolated from healthy donors or donors with Crohn's disease and analysed for their ability to induce T(reg) cell differentiation. In some cases, transforming growth factor beta (TGFbeta), retinoic acid (RA) or thymic stromal lymphopoietin (TSLP) were neutralised before conditioning. CD103+ and CD103- DCs were sorted by fluorescence-activated cell sorting (FACS) from MLNs and used in T(reg) cell differentiation experiments.

RESULTS

It was found that human IECs promoted the differentiation of tolerogenic DCs able to drive the development of adaptive Foxp3+ T(reg) cells. This control was lost in patients with Crohn's disease and paralleled a reduced expression of tolerogenic factors by primary IECs. MoDCs differentiated with RA or IEC supernatant upregulated the expression of CD103. Consistently, human primary CD103+ DCs isolated from MLNs were endowed with the ability to drive T(reg) cell differentiation. This subset of DCs expressed CCR7 and probably represents a lamina propria-derived migratory population.

CONCLUSIONS

A population of tolerogenic CD103+ DCs was identified in the human gut that probably differentiate in response to IEC-derived factors and drive T(reg) cell development.

Dyspnoea and hypoxaemia after lung surgery: the role of interatrial right-to-left shunt

After lung surgery, some patients complain of unexplained increased dyspnoea associated with hypoxaemia. This clinical presentation may be due to an interatrial right-to-left shunt despite normal right heart pressure. Some of these patients show postural dependency of hypoxaemia, whereas others do not. In this article, the pathogenesis and mechanisms involved in this post-surgical complication are discussed, and the techniques used for confirmation and localisation of shunt are reported. An invasive technique, such as right heart catheterisation with angiography, was often used in the past as the diagnostic procedure for the visualisation of interatrial shunt. As to noninvasive techniques, a perfusion lung scan may be used as the first approach as it may detect the effect of the right-to-left shunt by visualising an extrapulmonary distribution of the radioactive tracer. The 100% oxygen breathing test could also be used to quantify the amount of right-to-left shunt. Particular emphasis is given to newer imaging modalities, such as transoesophageal echocardiography, which is minimally invasive but highly sensitive in clearly visualising the atrial septum anatomy. Finally, the approach to closure of the foramen ovale or atrial septal defect is discussed. Open thoracotomy was the traditional approach in the past. Percutaneous closure has now become the most used and effective technique for the repair of the interatrial anatomical malformation.

Transcatheter closure of atrial septal defects with the STARFlex device: early results and follow-up

BACKGROUND

The STARFlex (SF) device is a CardioSEAL (CS) double-umbrella device that has been modified by the addition of a self-centering mechanism comprised of nitinol springs connected between the two umbrellas and a flexible core wire with a pin-pivoting connection. This paper compares the results of atrial septal defect (ASD) closure with CardioSEAL and STARFlex devices.

PATIENTS AND METHODS

Between December 1996 and March 2000, 117 patients underwent ASD closure with CardioSEAL (n = 79) and STARFlex (n = 38). The mean age (17 years), weight (49 kg), and ASD size (15 mm) were similar in the two groups. The procedures were performed under general anesthesia with both fluoroscopic and transesophageal echocardiographic monitoring.

IMMEDIATE RESULTS

The devices were successfully implanted in all patients. Ten patients had multiple ASDs. A single device was used in four patients (CardioSEAL in three, STARFlex in one), while a simultaneous placement of two CardioSEAL (one patient) or two STARFlex (five patients) were performed in six patients. The results are summarized as follows: [table: see text] Follow-Up Results: On follow-up clinical exam, electrocardiograms, chest X-rays, and echocardiograms were obtained at 1, 6, and 12 months. [table: see text] During follow-up there were no deaths, endocarditis, rhythm disturbances, or other complications. Arm fractures were observed almost exclusively with large CardioSEAL devices (40 mm, less frequently with 33 mm), and only in one 33-mm STARFlex device. There were no clinical complications related to fractures.

CONCLUSIONS

The STARFlex device seems to offer better results than the CardioSEAL, with significantly lower rates of residual shunts and arm fractures.

Repair of hemitruncus with autologous arterial ring and valved bioconduit

We present a technical variant to reconstruct the right outflow tract in truncus type A3 (single pulmonary artery branch originating from the ascending aorta with common arterial valve and ventricular septal defect) with interposition of a ring of autologous arterial tissue and a bioconduit between the right ventricular infundibulum and the pulmonary artery branches. The final result is shown by postoperative angiogram which demonstrates an anatomically adequate reconstruction of the right ventricular outflow tract.

Long-term follow-up of stents implanted to relieve peripheral pulmonary arterial stenosis: hemodynamic findings and results of lung perfusion scanning

In recent years, percutaneous placement of stents has been used as an alternative to surgery or balloon angioplasty for the treatment of adults with peripheral pulmonary arterial stenosis. This therapy has also been proposed for children, but questions still remain about its indications in this group of patients. We describe here the results of intravascular placement of stents in a group of 29 patients, with a mean age of 12+/-7 (range 3-31) years and weighing 35+/-19 (range 11-74) kg. All were affected by postsurgical or congenital isolated pulmonary arterial stenosis, and have now been followed for 38+/-19 (range 6-65) months. The early hemodynamic results have been excellent, with a significant reduction of the pulmonary arterial systolic pressure, the systolic pressure gradient, and the ratio of systolic pressures in the pulmonary and systemic circuits, and with a significant increase of the diameter of the stented vessels in all the patients. Of the 29 patients, 24 have been recatheterized 18+/-10 months after the procedure, demonstrating the stability of the results, with a low incidence of late restenosis, this seen in only 1 patient (2%). Lung perfusion scanning, performed in 17 patients each year after the follow-up catheterization, has showed that the results are maintained at long-term follow-up (51+/-9 months).

[Radiofrequency perforation in pulmonary valve atresia and intact ventricular septum]

METHODS

Four neonates with Pulmonary Atresia and intact Ventricular Septum underwent Radiofrequency Valvotomy in our institution from October 1994 to June 1995. All patients had "membranous" atresia with confluent and normal size pulmonary branches; one of them had abnormal tricuspid tensor apparatus and severe right ventricular outflow tract hypertrophy. The right ventricle was considered of sufficient size to support biventricular circulation in all cases. In three patients the pulmonary arteries were supplied by the arterial duct maintained open with intravenous infusion of Prostaglandins. The other patient had previously undergone a modified left Blalock Taussig shunt in another institution. The cardiac catheterization was performed by the femoral venous and arterial routes, under general anesthesia. After delineating the atretic valve with angiography, a 5 French right Judkins catheter was placed in the right ventricular outflow tract just beneath the membrane. A 2 french radiofrequency catheter (Cerablate PA 120 Osypka) was then passed through the right Judkins; with a mean energy of 5-10 watts over 3-5 seconds the valve was perforated. After a predilation with a 2,5 mm balloon catheter (New Probe USCI or Cobra SCIMED), the valve was dilated with balloon catheters 20 to 30% larger than the anulus (Cristal Balloon BALT).

RESULTS

In all cases the procedure was successful without any complication; a significant decrease of right ventricular pressure and an excellent antegrade flow across the valve were achieved. Two patients were weaned from prostaglandins by sixth and eighth day after the procedure. The patient with previous Bialock Taussig shunt showed a complete recovery of the right ventricle, but four months later underwent surgery for shunt closure and enlargement of the left pulmonary branch. These three patients are well at latest follow-up (5-10 months), with normal biventricular circulation. The other patient remained duct-dependent and was operated on of outflow patch and shunt nine days after the procedure, with good result; he unfortunately died the tenth postoperative day for complications of hemopericardium related to epicardial wires removal.

CONCLUSIONS

In our opinion radiofrequency valvotomy is the first choice procedure in cases suitable for biventricular repair. In selected patients it may represent a definitive treatment.

Balloon aortic valvuloplasty in the first year of life

Between February 1988 and September 1993 balloon aortic valvuloplasty was attempted in 33 consecutive patients in the first year of life: 20 patients (61%) were younger than 1 month. Major associated anomalies such as mitral stenosis, coarctation, and hypoplastic left ventricle were found in 11 cases (33%). The balloon dilation of the aortic valve was accomplished through the right carotid cut-down approach in neonates and patients with body weight < 5 kg, through a percutaneous femoral approach in the others; the procedure was completed in all. The peak systolic gradient across the aortic valve measured at catheterization fell from 80 +/- 33 mmHg (range 25-165) before the dilation to 27 +/- 17 mmHg (range 0-65), afterwards (p < 0.0001). The left ventricular ejection fraction increased from 44% +/- 26% to 61% +/- 17%, 24-48 hours after the procedure (p < 0.0001). Aortic insufficiency developed in 17 cases, being moderate in 2, mild in 6, and trivial in 9. Seven patients (21%), all in the first month of life, died within 30 days from the valvuloplasty; major associated anomalies were present in six; the death was due to a procedure related complication in one. No mortality was observed among the patients undergoing valvuloplasty beyond the first month of life. On follow-up (6 months to 6 years) aortic restenosis occurred in 3 cases; 1 was treated by surgical valvotomy, 2 by repeat balloon valvatomy; in another 2 cases, a subvalvular aortic obstruction developed and was relieved by surgical resection. There was no late mortality. Thus, balloon valvuloplasty appears to be an effective palliation for critical aortic stenosis in infancy. Early mortality is mainly related to associated anomalies.

[Pulmonary valvuloplasty]

The aim of this study was to present the experience of 2 Institutions (Department of Cardiology in Bergamo and Department of Pediatric Cardiology, Apuano Pediatric Hospital in Massa) in performing the balloon dilatation of the pulmonary valve. From January 1985 to August 1993 the balloon pulmonary valvuloplasty was performed in 220 patients, age ranging from 1 day to 60 years (mean age 5 years), 55 (25%) in the first year of life, 17 (8%) in the first week of life. The systolic gradient across the pulmonary valve fell from 78 +/- 31 mmHg (range 40-160) to 20 +/- 16 mmHg (range 0-70) immediately after the procedure (p < 0.001). In-hospital mortality happened in 3 cases (1.3%); 2 of them were neonates with critical pulmonary stenosis. In 7 cases (3%) the balloon valvuloplasty was repeated afterwards, because of inadequate relief of the gradient after the first dilatation. During the mean follow-up period of 4 years the other 210 patients (95%) did not need any further treatment and remain in stable clinical conditions. The balloon valvuloplasty gives excellent early and intermediate term results and should be considered the first choice procedure in the treatment of pulmonary stenosis at all ages.

[The closure with a double-umbrella prosthesis of recanalized ducts after surgical ligation]

Four patients of 5, 27, 27 and 62 years of age, who previously underwent surgical ligation of ductus arteriosus (respectively 3, 17, 19 and 17 years before), came to our observation because of recanalization of the duct. In three cases the duct was an isolated finding, whereas in the oldest patient the duct ligation had been accompanied by implantation of a Starr prosthesis in aortic position. The diagnosis of residual shunt was based on the auscultation of a continuous murmur at the left subclavicular space and on typical signs of patent ductus evidenced by Doppler interrogation. In all cases the diagnosis was confirmed by angiography; the minimal diameter of the ducts varied between 2.5 and 4 mm. Three umbrellas of 17 mm and one of 12 mm diameter were employed for the closure of the residual shunt. The implantation of the double-umbrella device was obtained with the routine transfemoral venous approach. In the youngest patient, in order to facilitate the progression of the transseptal catheter through the duct, it was necessary to create a circuit with the guide wire from the femoral vein to the contralateral femoral artery. In all four patients the shunt was completely abolished. The oldest patient underwent replacement of a malfunctioning aortic prosthesis three days after implantation of the double-umbrella device; the surgical approach was this way significantly simplified. The implantation of a Rashkind double-umbrella device is the method of choice for closure of residual shunts through the duct after surgical ligation.