Over the past three decades, numerous studies have shown a strong connection between matrix metalloproteinase 9 (MMP-9) levels and myocardial infarction (MI) mortality and left ventricle remodeling and dysfunction. Despite this fact, clinical trials using MMP-9 inhibitors have been disappointing. This review focuses on the roles of MMP-9 in MI wound healing. Infiltrating leukocytes, cardiomyocytes, fibroblasts, and endothelial cells secrete MMP-9 during all phases of cardiac repair. MMP-9 both exacerbates the inflammatory response and aids in inflammation resolution by stimulating the pro-inflammatory to reparative cell transition. In addition, MMP-9 has a dual effect on neovascularization and prevents an overly stiff scar. Here, we review the complex role of MMP-9 in cardiac wound healing, and highlight the importance of targeting MMP-9 only for its detrimental actions. Therefore, delineating signaling pathways downstream of MMP-9 is critical.

• Little is understood regarding the connection between congenital heart disease, the intestinal Microbiome, and how this could influence systemic inflammation. • To date, no study has evaluated the microbiome in congenital heart disease and the effects of cardiopulmonary bypass. • There is significant dysbiosis in patients with congenital heart disease and this is exacerbated following cardiopulmonary bypass. • Cardiopulmonary bypass induces intestinal barrier dysfunction which was not seen in control surgeries. • This data improves our understanding of intestinal dysbiosis, intestinal barrier dysfunction, and intestinal inflammatory eicosanoids and their interactions with cardiopulmonary bypass.

The intestinal barrier orchestrates selective permeability to nutrients and metabolites while excluding noxious stimuli. Recent scientific advances establishing a causal role for the gut microbiota in human health outcomes have generated a resurgent interest toward intestinal permeability. Considering the well-established role of the gut barrier in protection against foreign antigens, there is mounting evidence for a causal link between gut permeability and the microbiome in regulating human health. However, an understanding of the dynamic host–microbiota interactions that govern intestinal barrier functions remains poorly defined. Furthermore, the system-level mechanisms by which microbiome-targeted therapies, such as probiotics and prebiotics, simultaneously promote intestinal barrier function and host health remain an area of active investigation. This review summarizes the recent advances in understanding the dynamics of intestinal permeability in human health and its integration with gut microbiota. We further summarize mechanisms by which probiotics/prebiotics influence the gut microbiota and intestinal barrier functions.

The intestinal microbiome is essential to human health and homeostasis, and is implicated in the pathophysiology of disease, including congenital heart disease and cardiac surgery. Improving the microbiome and reducing inflammatory metabolites may reduce systemic inflammation following cardiac surgery with cardiopulmonary bypass (CPB) to expedite recovery post-operatively. Limited research exists in this area and identifying animal models that can replicate changes in the human intestinal microbiome after CPB is necessary. We used a piglet model of CPB with two groups, CPB (n=5) and a control group with mechanical ventilation (n=7), to evaluate changes to the microbiome, intestinal barrier dysfunction and intestinal metabolites with inflammation after CPB. We identified significant changes to the microbiome, barrier dysfunction, intestinal short-chain fatty acids and eicosanoids, and elevated cytokines in the CPB/deep hypothermic circulatory arrest group compared to the control group at just 4 h after intervention. This piglet model of CPB replicates known human changes to intestinal flora and metabolite profiles, and can be used to evaluate gut interventions aimed at reducing downstream inflammation after cardiac surgery with CPB.

Feeding intolerance contributes to postoperative morbidity following pediatric cardiac surgery. The intestinal microbiome and milieu play a vital role in gut function. Short-chain fatty acids are gut and cardioprotective metabolites produced by commensal bacteria and help maintain appropriate barrier function. Depletion of these metabolites and barrier dysfunction contribute to postoperative feeding intolerance following cardiac surgery. Identifying mechanistic targets to improve the intestinal milieu with the goal of improved nutrition and clinical outcomes is critical.

Calcium channel blocker ingestions remain one of the leading causes of death related to cardiovascular medication ingestion in both adults and pediatric patients. We report a case of a 17-year-old, 103 kg female presenting after an intentional polypharmacy ingestion, including 500 to 550 mg of amlodipine. She presented with profound vasoplegia and cardiovascular collapse requiring high-dose inotropes and eventual life support with extracorporeal membrane oxygenation (ECMO). Current available treatments, designed for adults, including lipid emulsion and methylene blue, provided no sustained clinical improvement. This resulted in the initiation of single-pass albumin dialysis (SPAD). We aim to describe the clinical implications, amlodipine toxic dose effects, and clinical challenges associated with large pediatric patients and high-dose medications. We also discuss several challenges encountered related to dosing and concentration of medications, which led to fluid overload. Given the ongoing obesity epidemic, we routinely see pediatric patients of adult size. This will continue to challenge pediatric use of adult dosing and concentrations to avoid excessive fluid administration for high-dose medications, such as insulin and vasoactive agents. To our knowledge, this is the first successful case of using SPAD in conjunction with ECMO for salvage therapy after refractory life-threatening calcium channel blocker toxicity.