Advanced Imaging Guidance for Ductus Venosus Stenting in Obstructed Total Anomalous Pulmonary Venous Return.

Obstructed infracardiac total anomalous pulmonary venous return is nearly always a surgical emergency in which infants present in severe cardiopulmonary distress. Ductal venosus stenting can provide a temporizing option for premature, low birth weight infants with high risk for surgical complications. In challenging anatomic cases, virtual reality, 3D-printed models, and fusion image guidance can aid in procedural planning and provide support for successful intervention.

Regional Arch Measurements Differ Between Imaging Modalities in Infants With Aortic Coarctation.

BACKGROUND: Aortic arch measurements provide a framework for surgical decision-making in neonatal aortic coarctation, specifically in the determination of approach for arch repair by lateral thoracotomy vs median sternotomy. The purpose of this study was to evaluate our experience with transthoracic echocardiography (TTE) and computed tomography angiography (CTA) in the preoperative evaluation of infants with aortic coarctation, specifically comparing arch dimensions as a function of imaging modality. METHODS: Imaging data were reviewed for all infants undergoing surgical repair of aortic coarctation at our institution from 2012 to 2022. Infants with both TTE and CTA evaluations were included. Aortic measurements were compared at predefined anatomic regions including ascending aorta, proximal arch, distal arch, and isthmus. RESULTS: During the study period, 372 infants underwent surgical coarctation repair; 72 (19.4%) infants had TTE and CTA arch evaluations preoperatively. Significant discrepancies between imaging modalities were defined by poor correlation coefficients and absolute measurement differences and were most prominent in the proximal aortic arch (R2 = 0.23 [-4.4 to 3.2 mm]) and isthmus regions (R2 = 0.11 [-4.2 to 1.7 mm]). Improved correlation was demonstrated in the ascending aorta (R2 = 0.63) and distal aortic arch (R2 = 0.54). CONCLUSIONS: Significant variability exists between TTE- and CTA-derived aortic measurements in infants with coarctation, with proximal arch measurements demonstrating the poorest correlation. This anatomic location represents a commonly used arch region for the determination of approach for repair of neonatal aortic coarctation. Thus, these findings have important implications for current preoperative surgical decision-making paradigms and future prospective study to minimize the risk of residual or recurrent arch obstruction.

Complement Cross Talks With H-K-ATPase to Upregulate Runx2 in Human Aortic Valve Interstitial Cells.

INTRODUCTION: Calcific aortic valve disease (CAVD) is a slowly progressive fibro-calcific valve leaflet disorder. The underlying pathophysiology is complex and not yet well understood. Complement is known to play a role in the pathogenesis of CAVD by upregulating Runx2 to induce profibrogenic change in human aortic valve interstitial cells (AVICs). Furthermore, H-K-ATPase has independently been shown to induce tissue calcification. Therefore, we hypothesized that complement cross talks with H-K-ATPase to upregulate Runx2 in human AVICs. MATERIALS AND METHODS: Human AVICs were isolated from normal and calcified aortic valves. Cells were treated with a variation of complement, H-K-ATPase, or ERK1/2 inhibitors. H-K-ATPase and its association with complement in AVICs were investigated by reverse transcriptase-polymerase chain reaction, immunofluorescence, and Western blot. RESULTS: Calcified human AVICs expressed significantly higher H-K-ATPase level than normal human AVICs. Presence of complement C3 with H-K-ATPase is found in AVICs after complement treatment. Complement induced both H-K-ATPase and Runx2 expression in AVICs, which was associated with increased phosphorylation of ERK1/2 and its downstream molecule p-70 S6. Pharmacological inhibition of either H-K-ATPase or Erk1/2 abolished complement-induced Runx2 expression. CONCLUSIONS: These findings indicate that complement cross talks with H-K-ATPase to upregulate Runx2 in human AVICs by activation of ERK1/2 signaling pathways. The study revealed the potential role of H-K-ATPase in the pathogenesis of CAVD and therapeutically targeting either complement system or H-K-ATPase may limit the development of CAVD.

Two-Stage Biventricular Repair of Complex Aortic Atresia.

We describe the successful 2-stage treatment of an infant with double-outlet right ventricle, aortic valve atresia, normally related great vessels, muscular outlet ventricular septal defect, and ductal arch origin of the cephalic vessels using a hybrid ductal stent and branch pulmonary artery banding followed by a comprehensive Yasui-type biventricular repair.

Open Chest Duration Following Congenital Cardiac Surgery Increases Risk for Surgical Site Infection.

Surgical site infections (SSI) following congenital heart surgery (CHS) remain a significant source of morbidity. Delayed sternal closure (DSC) is often required to minimize the potential for hemodynamic instability. The purpose of this study was to determine the incidence of SSI among patients undergoing DSC versus primary chest closure (PCC) and to define a potential inflection point for increased risk of SSI as a function of open chest duration (OCD).A retrospective review of our institutional Society of Thoracic Surgeons dataset is to identify patients undergoing CHS at our institution between 2015 and 2020. Incidences of SSI were compared between DSC and PCC patients. DSC patients were evaluated to determine the association of OCD and the incidence of SSI.2582 operations were performed at our institution between 2015 and 2020, including 195 DSC and 2387 PCC cases. The incidence of SSI within the cohort was 1.8% (47/2,582). DSC patients had significantly higher incidences of SSI (17/195, 8.7%) than PCC patients (30/2387, 1.3%, p < 0.001). Further, patients with an OCD of four or more days had a significantly higher incidence of SSI (11/62, 17.7%, p = 0.006) than patients with an OCD less than 4 days (6/115, 5.3%).The incidence of SSI following CHS is higher in DSC patients compared to PCC patients. Prolonged OCD of 4 days or more significantly increases the risk of SSI and represents a potentially modifiable risk factor for SSI predisposition. These data support dedicated, daily post-operative assessment of candidacy for chest closure to minimize the risk of SSI.

Computed Tomographic Angiography Provides Reliable Coronary Artery Evaluation in Infants With Pulmonary Atresia Intact Ventricular Septum.

Evaluate the use of coronary CTA as an initial assessment for determining Right Ventricle Dependent Coronary Circulation (RVDCC) in neonates with Pulmonary Atresia with Intact Ventricular Septum (PA IVS). Retrospective review of cases with coronary CTA and compare with available catheter angiography, pathology, surgical reports, and outcomes from Mar 2015 to May 2022. In our cohort of 16 patients, 3 were positive for RVDCC, confirmed by pathologic evaluation, and there was concordance for presence or absence of RVDCC with catheter angiography in 5 patients (4 negatives for RVDCC, 1 positive). Clinical follow up for the 8 patients that underwent RV decompression had no clinical evidence of myocardial ischemia. Our findings suggest that coronary CTA is reliable as first-line imaging for determination of RVDCC in neonates with PA IVS. These findings, if supported by further prospective study, may reserve invasive coronary angiography for cases with diagnostic uncertainty or at the time of necessary transcatheter interventions.

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury.

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R2 = 0.93, Q2 = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

Monitoring and evaluation of the surgical Potts shunt physiology using 4-dimensional flow magnetic resonance imaging.

OBJECTIVE: The reversed Potts shunt is an increasingly applied mode of surgical palliation of severe pulmonary hypertension (PH). However, the long-term flow hemodynamic effect of the Potts shunt physiology and desirable long-term hemodynamic end points are not defined. The purpose of this descriptive study was to analyze a series of pediatric patients who underwent surgical Potts shunt as a part of end-stage PH palliation using 4-dimensional (4D)-flow magnetic resonance imaging (MRI) to (1) quantitate the flow through the anastomosis, (2) correlate the shunting pattern with phases of cardiac cycle and PH comorbidities, and (3) describe chronologic changes in shunting pattern. METHODS: This was a 2-center study evaluating 4 patients seen in the Pulmonary Hypertension Clinic at Children's Hospital Colorado who were evaluated and selected to undergo surgical reverse Potts shunt at Washington University School of Medicine and were serially followed using comprehensive imaging including cardiac MRI and 4D-flow MRI. RESULTS: After the procedure, each child underwent 2 4D-flow MRI evaluations. Pulmonary pressure offload was evident in all patients, as demonstrated by positive systolic right-to-left flow across the Potts shunt. All patients experienced some degree of the flow reversal, which occurs primarily in diastole. Interventricular dyssynchrony further contributed to flow reversal across the Potts shunt. Lastly, systemic and pulmonary blood mixing in the descending aorta results in secondary helical flow persisting throughout the diastole. CONCLUSIONS: 4D-flow MRI demonstrates that children who have undergone a Potts shunt for severe PH can experience shunt flow reversal. Cumulatively, this left-to-right pulmonary shunt adds to right ventricular volume overload. We speculate that a valved conduit may decrease the left to right shunting and improve overall cardiac output.

Diastolic inflow is associated with inefficient ventricular flow dynamics in Fontan patients.

OBJECTIVE: This study used cardiac magnetic resonance imaging to evaluate flow characteristics and ventricular hemodynamics for children with single right (hypoplastic left heart syndrome) and single left (hypoplastic right heart syndrome) systemic ventricle anatomy after Fontan palliation compared with normal biventricular controls. METHODS: Twenty children with single ventricle anatomy (hypoplastic left heart syndrome, n = 10; hypoplastic right heart syndrome, n = 10) underwent standardized 4-dimensional flow cardiac magnetic resonance and were compared with age-matched controls (n = 10). End-diastolic volume was partitioned into 4 defined components of variable kinetic energy (direct flow, retained inflow, delayed ejection, and residual volume) and compared between groups. Further, volumetric and functional parameters as defined by cardiac magnetic resonance were evaluated. RESULTS: Children with hypoplastic left heart syndrome had significantly increased indexed end-diastolic and end-systolic volumes compared with both hypoplastic right heart syndrome and control groups. Flow component analysis demonstrated diastolic inefficiency in both hypoplastic left heart syndrome and hypoplastic right heart syndrome groups compared with controls as defined by decreased direct flow and increased residual volumes. Decreased direct flow correlated with decreased ejection fraction and increased end-diastolic and end-systolic volume indices. Increased residual volume correlated with decreased ejection fraction and increased end-systolic volume index. CONCLUSIONS: Fontan-palliated patients with single ventricle physiology (hypoplastic left heart syndrome and hypoplastic right heart syndrome) demonstrate altered and inefficient flow patterns in the systemic ventricle as defined by 4-dimensional flow cardiac magnetic resonance compared with normal biventricular controls. Decreased direct flow and increased residual volume indicate that diastolic ventricular dysfunction is prevalent after Fontan palliation. This study provides a foundation for future predictive modeling and cardiac magnetic resonance flow diagnostic studies in this high-risk patient population.

Generation of functional human thymic cells from induced pluripotent stem cells.

BACKGROUND: The thymus is a glandular organ that is essential for the formation of the adaptive immune system by educating developing T cells. The thymus is most active during childhood and involutes around the time of adolescence, resulting in a severe reduction or absence of naive T-cell output. The ability to generate a patient-derived human thymus would provide an attractive research platform and enable the development of novel cell therapies. OBJECTIVES: This study sought to systematically evaluate signaling pathways to develop a refined direct differentiation protocol that generates patient-derived thymic epithelial progenitor cells from multiple induced pluripotent stem cells (iPSCs) that can further differentiate into functional patient-derived thymic epithelial cells on transplantation into athymic nude mice. METHODS: Directed differentiation of iPSC generated TEPs that were transplanted into nude mice. Between 14 and 19 weeks posttransplantation, grafts were removed and analyzed by flow cytometry, quantitative PCR, bulk RNA sequencing, and single-cell RNA sequencing for markers of thymic-cell and T-cell development. RESULTS: A direct differentiation protocol that allows the generation of patient-derived thymic epithelial progenitor cells from multiple iPSC lines is described. On transplantation into athymic nude mice, patient-derived thymic epithelial progenitor cells further differentiate into functional patient-derived thymic epithelial cells that can facilitate the development of T cells. Single-cell RNA sequencing analysis of iPSC-derived grafts shows characteristic thymic subpopulations and patient-derived thymic epithelial cell populations that are indistinguishable from TECs present in primary neonatal thymus tissue. CONCLUSIONS: These findings provide important insights and resources for researchers focusing on human thymus biology.

Endocarditis Caused by Candida parapsilosis Presenting With Severe Thrombocytopenia in a Patient With Tetralogy of Fallot.

Infective endocarditis (IE) occurs more frequently in individuals living with congenital heart disease, often with high morbidity and mortality. Although gram-positive bacterial infections commonly cause IE, prosthetic valves are a known risk factor for fungal IE. We report a case of prosthetic pulmonary valve Candida parapsilosis IE in a 58-year-old male with repaired tetralogy of Fallot. He presented with fatigue, petechiae, and hematochezia. He had severe thrombocytopenia from idiopathic/immune thrombocytopenia purpura, which resolved with steroids and immunoglobulin. Treatment with antifungals as well as a surgical pulmonary valve replacement resulted in recovery without relapse at greater than a year.

Regional lung metabolic profile in a piglet model of cardiopulmonary bypass with circulatory arrest.

INTRODUCTION: Acute lung injury is common following cardiopulmonary bypass and deep hypothermic circulatory arrest for congenital heart surgery with the most severe injury in the dorsocaudal lung. Metabolomics offers promise in deducing mechanisms of disease states, providing risk stratification, and understanding therapeutic responses in regards to CPB/DHCA related organ injury. OBJECTIVES: Using an infant porcine model, we sought to determine the individual and additive effects of CPB/DHCA and lung region on the metabolic fingerprint, metabolic pathways, and individual metabolites in lung tissue. METHODS: Twenty-seven infant piglets were divided into two groups: mechanical ventilation + CPB/DHCA (n = 20) and mechanical ventilation only (n = 7). Lung tissue was obtained from dorsocaudal and ventral regions. Targeted analysis of 235 metabolites was performed using HPLC/MS-MS. Data was analyzed using Principal Component Analysis (PCA), Partial Least Square Discriminant Analysis (PLS-DA), ANOVA, and pathway analysis. RESULTS: Profound metabolic differences were found in dorsocaudal compared to ventral lung zones by PCA and PLS-DA (R2 = 0.7; Q2 = 0.59; p < 0.0005). While overshadowed by the regional differences, some differences by exposure to CPB/DHCA were seen as well. Seventy-four metabolites differed among groups and pathway analysis revealed 20 differential metabolic pathways. CONCLUSION: Our results demonstrate significant metabolic disturbances between dorsocaudal and ventral lung regions during supine mechanical ventilation with or without CPB/DHCA. CPB/DHCA also leads to metabolic differences and may have additive effects to the regional disturbances. Most pathways driving this pathology are involved in energy metabolism and the metabolism of amino acids, carbohydrates, and reduction-oxidation pathways.

Validation of Point-of-Care Ultrasound to Measure Perioperative Edema in Infants With Congenital Heart Disease.

Purpose: Fluid overload is a common post-operative issue in children following cardiac surgery and is associated with increased morbidity and mortality. There is currently no gold standard for evaluating fluid status. We sought to validate the use of point-of-care ultrasound to measure skin edema in infants and assess the intra- and inter-user variability. Methods: Prospective cohort study of neonates (≤30 d/o) and infants (31 d/o to 12 m/o) undergoing cardiac surgery and neonatal controls. Skin ultrasound was performed on four body sites at baseline and daily post-operatively through post-operative day (POD) 3. Subcutaneous tissue depth was manually measured. Intra- and inter-user variability was assessed using intraclass correlation coefficient (ICC). Results: Fifty control and 22 surgical subjects underwent skin ultrasound. There was no difference between baseline surgical and control neonates. Subcutaneous tissue increased in neonates starting POD 1 with minimal improvement by POD 3. In infants, this pattern was less pronounced with near resolution by POD 3. Intra-user variability was excellent (ICC 0.95). Inter-user variability was very good (ICC 0.82). Conclusion: Point-of-care skin ultrasound is a reproducible and reliable method to measure subcutaneous tissue in infants with and without congenital heart disease. Acute increases in subcutaneous tissue suggests development of skin edema, consistent with extravascular fluid overload. There is evidence of skin edema starting POD 1 in all subjects with no substantial improvement by POD 3 in neonates. Point-of-care ultrasound could be an objective way to measure extravascular fluid overload in infants. Further research is needed to determine how extravascular fluid overload correlates to clinical outcomes.

Neonatal heart transplant outcomes: A single institutional experience.

OBJECTIVE: Neonatal orthotopic heart transplantation was introduced in the 1980s as a treatment for complex congenital heart disease. Progress in single-ventricle palliation and biventricular correction has resulted in a decline in neonatal heart transplant volume. However, limited reports on neonatal heart transplants have demonstrated favorable outcomes. We report the long-term outcomes of patients with neonatal heart transplants at our institution spanning nearly 30 years. METHODS: A retrospective analysis of neonatal heart transplants and neonates listed for transplant was performed at Children's Hospital Colorado. Primary outcomes were early and late survival. Secondary outcomes were rejection episodes, retransplantation, and development of cardiac allograft vasculopathy or post-transplant lymphoproliferative disease. RESULTS: A total of 21 neonates underwent orthotopic heart transplantation at our institution. Among these, 10 neonates were transplanted from 1991 to 2000, 8 neonates were transplanted from 2001 to 2010, and 3 neonates were transplanted from 2011 to 2020. The average age of these patients was 17 days, and the average weight was 3.43 kg. Early survival was 95.2%. Survival at 1 and 5 years was 85.7% (confidence interval [CI], 61.9%-95.2%) and 75% (CI, 45.6%-85.5%), respectively. Of eligible patients, the 10-year and 20-year survival was 72.2% (CI, 45.1%-85.3%) and 50% (CI, 25.9%-70.1%), respectively. CONCLUSIONS: Our institution reports favorable outcomes of neonatal heart transplantation. These results should be considered within the context of outcomes for patients awaiting transplant and the limited donor availability. However, the successful nature of these procedures suggest it may be necessary to reevaluate the indications for neonatal heart transplantation, particularly where risk of mortality and morbidity with palliative or corrective surgery is high.

Serum metabolic profile of postoperative acute kidney injury following infant cardiac surgery with cardiopulmonary bypass.

BACKGROUND: We sought to determine differences in the circulating metabolic profile of infants with or without acute kidney injury (AKI) following cardiothoracic surgery with cardiopulmonary bypass (CPB). METHODS: We performed a secondary analysis of preoperative and 24-h postoperative serum samples from infants ≤ 120 days old undergoing CPB. Metabolic profiling of the serum samples was performed by targeted analysis of 165 serum metabolites via tandem mass spectrometry. We then compared infants who did or did not develop AKI in the first 72 h postoperatively to determine global differences in the preoperative and 24-h metabolic profiles in addition to specific differences in individual metabolites. RESULTS: A total of 57 infants were included in the study. Six infants (11%) developed KDIGO stage 2/3 AKI and 13 (23%) developed stage 1 AKI. The preoperative metabolic profile did not differentiate between infants with or without AKI. Infants with severe AKI could be moderately distinguished from infants without AKI by their 24-h metabolic profile, while infants with stage 1 AKI segregated into two groups, overlapping with either the no AKI or severe AKI groups. Differences in these 24-h metabolic profiles were driven by 21 metabolites significant at an adjusted false discovery rate of < 0.05. Prominently altered pathways include purine, methionine, and kynurenine/nicotinamide metabolism. CONCLUSION: Moderate-to-severe AKI after infant cardiac surgery is associated with changes in the serum metabolome, including prominent changes to purine, methionine, and kynurenine/nicotinamide metabolism. A portion of infants with mild AKI demonstrated similar metabolic changes, suggesting a potential role for metabolic analysis in the evaluation of lower stage injury.

High-degree Norwood neoaortic tapering is associated with abnormal flow conduction and elevated flow-mediated energy loss.

OBJECTIVE: The Norwood neoaortic arch biomechanical properties are abnormal due to reduced vessel wall compliance and abnormal geometry. Others have previously described neoaortic geometric distortion by the degree of diameter reduction (tapering) and associated this with mismatched ventricular-neoaortic coupling, abnormal flow hemodynamic parameters, and worse patient outcome. Our purposes were to investigate the influence of neoaortic tapering (ie, diameter reduction) on flow-mediated viscous energy loss (EL') in post-Norwood palliated hypoplastic left heart syndrome patients, and correlate flow-geometry with single ventricle power generation. METHODS: Twenty-six palliated hypoplastic left heart syndrome patients underwent comprehensive cardiac evaluation with 4-dimensional-flow magnetic resonance imaging. Patients were grouped into high- (group H, n = 13) and low- (group L, n = 13) degree neoaortic tapering using the median cutoff value of neoaortic diameter variance. EL' was calculated along standardized segments using 4-dimensional-flow magnetic resonance imaging. Flow-mediated power loss as a percentage of total power generated by the single ventricle was determined. RESULTS: Group H had a higher prevalence of abnormal recirculating flow in the neoaorta and elevated neoaortic EL' in the ascending aorta (1.0 vs 0.6 mW; P = .004). Group H EL' was increased across the entire thoracic aorta (2.6 vs 1.3 mW; P = .002) and accounted for 0.7% of generated ventricular power versus 0.3% in group L (P = .024). EL' directly correlated with the degree of ascending aortic dilation (R = 0.49; P = .012). CONCLUSIONS: Patients with high degree neoaortic tapering have more perturbed flow through the neoaorta and increased EL'. Flow-mediated energy loss due to abnormal flow represents irreversibly wasted power generated by the single right ventricle. In patients with high-degree neoaortic tapering, EL' was more than 2-fold greater than low-degree tapering patients. These data suggest that oversizing the Norwood neoaortic reconstruction should be avoided and that patients with distorted neoaortic geometry may warrant increased surveillance for single-ventricle deterioration.

Complement Upregulates Runx-2 to Induce Profibrogenic Change in Aortic Valve Interstitial Cells.

BACKGROUND: Calcium accumulation and fibrotic activities are principal mechanisms for calcific aortic valve disease (CAVD). Active complement products are observed in human stenotic aortic valves. Runt-related transcription factor 2 (Runx-2) is involved in tissue calcification. We hypothesized that complement upregulates Runx-2 to induce profibrogenic change in human aortic valve interstitial cells (AVICs). METHODS: AVICs were isolated from 6 normal and 6 CAVD donor valves. Cells were treated with complement cocktails. Profibrogenic activities and associated signaling molecules were analyzed by Western blot assay and collagen staining. RESULTS: Complement time and dose dependently enhanced profibrogenic activities in AVICs, and complement exposure also induced total collagen deposition in AVICs. Complement-induced profibrogenic responses were associated with increased Runx-2 expression and phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2). Genetic silencing of Runx-2 decreased both matrix metalloproteinase 9 (MMP-9) and collagen I levels. Pharmacological inhibition of ERK1/2 decreased complement-mediated MMP-9, collagen I, and Runx-2 expression as well as total collagen deposition in human AVICs. Further, treating AVICs with heat-deactivated complement resulted in reduced MMP-9, collagen I, and Runx-2 levels compared with active complement treatment. CONCLUSIONS: Complement induced profibrogenic activities in AVICs by activation of ERK1/2-mediated Runx-2 signaling pathways. This study demonstrates a potential role for complement-mediated CAVD pathogenesis, establishing a possible therapeutic target to limit CAVD progression.