Mitral Valve Replacement in Infants and Children: Five Year Outcomes of the HALO Clinical Trial.

BACKGROUND: Repair is preferable for children with mitral valve disease, but mitral valve replacement (MVR) is occasionally necessary. This report presents the results of a multiinstitutional Investigational Device Exemption trial of the 15-mm St Jude (SJM) mechanical mitral valve (Abbott Structural Heart). METHODS: From May 2015 to March 2017, 23 children aged 0.4 to 27.4 months (mean, 7.8 months; 85% <1 year) weighing 2.9 to 10.9 kg (mean, 5.5 kg) at 15 centers underwent MVR with a 15-mm SJM mechanical mitral valve (intraannular, 45%; supraannular, 55%). A total of 21 (91%) of the children had undergone previous cardiac operations. Follow-up until death, valve explantation, or 5 years postoperatively was 100% complete. RESULTS: There were 6 deaths, all in the first 12 months; no death was valve related. Four patients required a pacemaker (2 supraannular, 2 intraannular). Three patients had thrombosis requiring valve explantation at 13, 21, and 35 days postoperatively. Two of these 3 patients were receiving low-molecular-weight heparin for anticoagulation, and the third had factor V Leiden deficiency. There were 5 nonfatal bleeding complications within 4 months of MVR (1-year freedom from bleeding, 71.0%). The 1- and 5-year freedom from death or valve explantation was 71.0%. CONCLUSIONS: In small children with severe mitral valve disease requiring MVR, the 15-mm SJM mechanical mitral valve provides satisfactory hemodynamics. Mortality and complications in these patients are not trivial. Low-molecular-weight heparin likely should be avoided as primary anticoagulation. Eventual valve replacement is inevitable.

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.

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.

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.

Coronary Artery Reimplantation and Berlin Heart EXCOR Rescue for Left Coronary Artery Atresia With Severe Ischemic Cardiomyopathy.

We describe a successful bridge to recovery by coronary reimplantation and Berlin Heart EXCOR left ventricular assist device in a child with left main coronary artery ostial atresia and severe ischemic cardiomyopathy.

Slide Tracheoplasty for Tracheal Cartilaginous Sleeve in a Patient With Apert Syndrome.

Apert syndrome is a form of acrocephalosyndactyly involving craniosynostosis, syndactyly, and less commonly, tracheal cartilaginous sleeve (TCS), a potential cause of tracheal stenosis. Slide tracheoplasty is performed in children with tracheal stenosis. No reports exist for its application in stenosis related to TCS. We present a case in which slide tracheoplasty was used for the expansion of long segment tracheal stenosis owing to TCS in a newborn with Apert syndrome. Using this technique, a safe and durable airway was achieved without tracheostomy.

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.

Increased Aortic Stiffness and Left Ventricular Dysfunction Exist After Truncus Arteriosus Repair.

BACKGROUND: The purpose of this study was to determine whether aortic biomechanical properties are abnormal in children with repaired truncus arteriosus (TA) and to concurrently evaluate left ventricular (LV) function post-repair utilizing a novel platform for regional ventricular function. METHODS: Cardiac magnetic resonance (CMR) studies from 26 children (mean age: 15.6 ± 7.2 years) post-TA repair were compared with 20 normal controls (mean age: 14.7 ± 2.6 years). Parameters of aortic stiffness (pulse wave velocity and relative area change) were measured. Flow hemodynamic metrics (aortic regurgitant fraction, peak systolic flow, and peak systolic velocity) and LV function (volumetric data, ejection fraction, regional wall strain) were also compared. RESULTS: Ascending aortic pulse wave velocity was elevated and relative area change was decreased in TA patients compared with controls. Patients post-TA repair demonstrated elevated end diastolic and end systolic volumes in addition to decreased regional wall strain and increased mechanical dyssynchrony. LV functional changes were independent of aortic biomechanical properties. CONCLUSIONS: Children with repaired TA have increased ascending aortic stiffness and altered LV function as measured by CMR imaging. Longitudinal studies and advanced CMR assessments are warranted to better determine the long-term potential for late aortic complications and to optimize both the medical and surgical management of these patients after TA repair.

Native Aortic Root Thrombosis After Norwood Palliation for Hypoplastic Left Heart Syndrome.

BACKGROUND: Norwood palliation for hypoplastic left heart syndrome typically results in retrograde perfusion of the native aortic root. This may predispose to native aortic root thrombosis (NART). METHODS: Patients who underwent stage 1 Norwood palliation at Children's Hospital Colorado between 2003 and 2019 were retrospectively reviewed for NART. Additional patients were identified by a systematic literature review. Patient factors, operative details, presentation, diagnostic methods, treatments, and outcomes were analyzed. RESULTS: Three patients with NART were identified among 241 patients who had undergone stage 1 Norwood palliation at Children's Hospital Colorado (mean follow-up, 48 months). A fourth patient identified at Children's Hospital Colorado had undergone stage 1 palliation elsewhere. The systematic literature review identified 12 additional patients. Among the 16 patients, patients presented with new arrhythmias (38% [n = 6]), evidence of ischemia (31% [n = 5]), incidentally (19% [n = 3]), inability to wean from postoperative support (6% [n = 1]), and cardiac arrest (6% [n = 1). The diagnosis was made by transthoracic echocardiography (TTE) in 50% (n = 8), transesophageal echocardiography in 19% (n = 3), cardiac catheterization in 25% (n = 4), and cardiac computed tomography in 6% (n = 1). Importantly, 44% (n = 7) of patients were missed by TTE and subsequently diagnosed by other methods. Treatment strategies were surgical thrombectomy in 38% (n = 6), anticoagulation alone in 38% (n = 6), direct catheter thrombolysis in 19% (n = 3), and systemic thrombolysis in 6% (n = 1). The rate of mortality or transplant listing was 44% (n = 7). CONCLUSIONS: NART is an underappreciated complication of Norwood palliation with high mortality. There should be a high index of suspicion for NART in patients after Norwood palliation with an unexplained complicated clinical course. Importantly, NART is frequently missed by TTE.

Proteomic profiling identifies key differences between inter-stage infants with single ventricle heart disease and healthy controls.

Despite significant morbidity among infants with single ventricle heart disease (SVHD), clinical monitoring is limited by poor understanding of the underlying pathobiology. Proteomics can identify novel biomarkers and important pathways in complex disease. No prior study has evaluated whether the proteome of SVHD infants differs from healthy controls, how it shifts after stage 2 palliation, or whether differences can predict post-operative outcomes. We present a prospective cohort study of cardiovascular proteomic phenotyping in infants with SVHD undergoing stage 2 palliation. Twenty-nine pre-stage-2 SVHD infants and 25 healthy controls were enrolled. Outcomes included postoperative hypoxemia and endotracheal intubation time. Serum samples were drawn pre-operatively (systemic and pulmonary vein) and at 24 hours postoperation. Targeted cardiovascular proteomic analysis included 184 proteins. Partial least squares discriminant analysis distinguished cases from controls (Accuracy = 0.98, R2 = 0.93, Q2 = 0.81) with decreased inflammatory mediators and increased modulators of vascular tone. Partial least squares discriminant analysis also distinguished cases pre-operation vs. post-operation (Accuracy=0.98, R2=0.99, Q2 = 0.92) with postoperative increase in both inflammatory and vascular tone mediators. Pre-operation pulmonary vein tissue inhibitor of metalloproteinase-1 (1.8x-fold, p=1.6 × 10-4) and nidogen-1 (1.5x-fold, p=1.7 × 10-4) were higher in subjects with longer endotracheal intubation time. Postoperation matrix metalloproteinase 7 levels were higher in subjects with greater postoperative hypoxemia (1.5x-fold, P= 1.97 × 10-5). Proteomic analysis identifies significant changes among SVHD infants pre- and post-stage 2, and healthy controls. Tissue inhibitor of metalloproteinase-1, nidogen-1, and matrix metalloproteinase 7 levels are higher in SVHD cases with greater morbidity suggesting an important role for regulation of extracellular matrix production. Proteomic profiling may identify high-risk SVHD infants.

Type B Aortic Dissection Complicating Stage 1 Norwood Procedure.

We present a rare case of iatrogenic type B aortic dissection due to ductal cannulation during stage 1 Norwood procedure.

Activation of kynurenine pathway of tryptophan metabolism after infant cardiac surgery with cardiopulmonary bypass: a prospective cohort study.

BACKGROUND: Serum kynurenic acid is associated with poor outcomes after infant cardiopulmonary bypass (CPB), but comprehensive mapping of the kynurenine pathway (KP) after CPB has yet to be performed. AIMS: To map changes in the KP induced by infant CPB. METHODS: Compared changes in serum KP metabolites through 48hrs post-op with liquid-chromatography-tandem mass spectrometry. RESULTS: Infant CPB results in marked increase in proximal, but not distal metabolites of the KP. CONCLUSIONS: Infant CPB leads to accumulation of circulating KP metabolites, which have important neurologic and immunologic activities. Thus, further exploration of the KP is warranted in these high-risk infants.

Abnormal left ventricular flow organization following repair of tetralogy of Fallot.

BACKGROUND: Left ventricular intracavitary flow (LVICF) characteristics reflect diastolic function. Right ventricular (RV) volume overload due to pulmonary regurgitation (PR) adversely impacts interventricular interactions and left ventricular (LV) function. This aimed to determine whether patients with PR and mild to moderate RV dilation after repair of tetralogy of Fallot (TOF) repair have abnormal LVICF, and to determine whether RV dilation and biventricular function correlate with LVICF abnormalities. METHODS: Patients with repaired TOF with PR (n = 11) and controls (n = 11) underwent LVICF analysis. LV end-diastolic volume was partitioned into 4 flow components: direct flow, retained inflow, delayed ejection flow, and residual volume. Flow components were correlated with indexed biventricular size, function, and LV strain. RESULTS: The TOF patients had reduced direct flow (35% vs 25%; P = .004) and increased residual volume (15% vs 24%; P = .026) compared with controls. Retained inflow and delayed ejection flow did not differ. Reduced direct flow correlated with increased RV end-diastolic volume index (R = 0.44; P = .042), RV end-systolic volume index (R = -0.46; P = .032), reduced RV ejection fraction (R = 0.45; P = .036), and reduced LV circumferential strain (R = 0.52; P = .014). Increased residual volume correlated with increased RV end-systolic volume index (R = 0.52; P = .013), reduced LV ejection fraction (R = -0.54; P = .010), and reduced LV circumferential strain (R = -0.44; P = .040). CONCLUSIONS: Patients with repaired TOF with mild to moderate RV dilation have abnormal LV diastolic direct flow and increased recirculating residual volume. These changes correlate with the degree of RV dilation and impaired LV function.

Abnormal aortic flow conduction is associated with increased viscous energy loss in patients with repaired tetralogy of Fallot.

OBJECTIVES: Aortopathy in tetralogy of Fallot (TOF) is characterized by increased aortic stiffness, dilation and reduced left ventricular (LV) function. Repair in infancy normalizes aortic dimensions in early childhood. Our prior work demonstrated that early TOF repair does not normalize aortic compliance and that abnormal ascending aortic flow patterns are prevalent. The objectives of this study were to: (i) determine whether proximal aortic flow-mediated viscous energy loss (EL') is elevated in patients with early TOF repair compared with healthy controls, and (ii) determine whether the degree of EL' is associated with LV function. METHODS: Forty-one patients post TOF repair with normalized aortic size and 15 healthy controls underwent 4-dimenisonal-flow magnetic resonance imaging flow analysis and EL' assessment. Correlations between EL', aortic size, and LV function were assessed. RESULTS: The TOF group had increased peak systolic thoracic aorta EL' (3.8 vs 1.5 mW, P = 0.004) and increased averaged EL' throughout the cardiac cycle (1.2 vs 0.5 mW, P = 0.003). Peak and mean systolic EL' in the ascending aorta was increased 2-fold in the TOF group compared with control (peak: 2.0 vs 0.9 mW, P = 0.007). Peak EL' measured along the entire thoracic aortic length correlated with LV ejection fraction (R = -0.45, P = 0.009), indexed LV end-systolic volume (R = -0.40, P = 0.010), and right ventricular end-systolic volume (R = -0.37, P = 0.034). CONCLUSIONS: Patients with repaired TOF exhibit abnormal aortic flow associated with increased EL' in the thoracic aorta. The magnitude of EL' is associated with LV function and volumes. Increased aortic EL' in TOF is likely due to inherently abnormal LV outflow geometry and or right ventricular interaction. Reduced aortic flow efficiency in TOF increases cardiac work and may be an important factor in long-term cardiac performance.