Longitudinal Trends of Vascular Flow and Growth in Patients Undergoing Fontan Operation.

BACKGROUND: Single ventricle (SV) patients undergo multiple surgeries with subsequent changes in anatomy and hemodynamics. There are little cardiac magnetic resonance (CMR) data on serial changes in these patients. This study aimed to assess longitudinal changes of SV anatomy and hemodynamics in a large cohort. METHODS: Anatomy and flow in SV patients with serial CMRs performed between 2008 and 2019 at a single institution were retrospectively reviewed. Mixed-effects linear regression was used to estimate changes over time at 3 to 9 months, 1 to 5 years, and >5 years after Fontan. RESULTS: A total of 119 patients were included (51% with hypoplastic left heart syndrome; 77% underwent extracardiac Fontan). A total of 88 patients had 3 serial CMRs. Indexed right superior vena cava, inferior vena cava, neoaortic valve, and descending aorta area decreased over time (beta = -0.19, -0.44, and -0.23, respectively; P < .01), as did indexed right superior vena cava, neoaorta and native aorta, and descending aorta flow (beta = -0.49, -0.53, and -0.59, respectively; P < .0001). Inferior vena cava flow and its contribution to total caval flow increased (beta = 0.33; P < .0001). Indexed right and left pulmonary artery flow did not change; however, indexed left pulmonary artery area decreased (beta = -0.16; P = .0014) with time. Systemic-to-pulmonary collateral flow remained unchanged before and early after Fontan (beta = -0.54; P = .42) but decreased with time from Fontan (beta = -0.22; P < .0001). CONCLUSIONS: In this cohort of longitudinally followed SV patients, there are significant trends in vascular size and flow over time from Fontan. These findings can be used as a framework to interpret serial CMR data in the SV and noninvasively identify deviations from expected patterns before the development of clinical symptoms.

Clinical 3D modeling to guide pediatric cardiothoracic surgery and intervention using 3D printed anatomic models, computer aided design and virtual reality.

BACKGROUND: Surgical and catheter-based interventions for congenital heart disease require precise understanding of complex anatomy. The use of three-dimensional (3D) printing and virtual reality to enhance visuospatial understanding has been well documented, but integration of these methods into routine clinical practice has not been well described. We review the growth and development of a clinical 3D modeling service to inform procedural planning within a high-volume pediatric heart center. METHODS: Clinical 3D modeling was performed using cardiac magnetic resonance (CMR) or computed tomography (CT) derived data. Image segmentation and post-processing was performed using FDA-approved software. Patient-specific anatomy was visualized using 3D printed models, digital flat screen models and virtual reality. Surgical repair options were digitally designed using proprietary and open-source computer aided design (CAD) based modeling tools. RESULTS: From 2018 to 2020 there were 112 individual 3D modeling cases performed, 16 for educational purposes and 96 clinically utilized for procedural planning. Over the 3-year period, demand for clinical modeling tripled and in 2020, 3D modeling was requested in more than one-quarter of STAT category 3, 4 and 5 cases. The most common indications for modeling were complex biventricular repair (n = 30, 31%) and repair of multiple ventricular septal defects (VSD) (n = 11, 12%). CONCLUSIONS: Using a multidisciplinary approach, clinical application of 3D modeling can be seamlessly integrated into pre-procedural care for patients with congenital heart disease. Rapid expansion and increased demand for utilization of these tools within a high-volume center demonstrate the high value conferred on these techniques by surgeons and interventionalists alike.

Fontan Geometry and Hemodynamics Are Associated With Quality of Life in Adolescents and Young Adults.

BACKGROUND: Despite favorable short-term outcomes, Fontan palliation is associated with comorbidities and diminished quality of life (QOL) in the years after completion. We hypothesized that poor Fontan hemodynamics and ventricular function are associated with worse QOL. METHODS: This was a single-center study of Fontan survivors aged more than 12 years. Subjects completed a cardiac magnetic resonance scan and QOL questionnaire. Cardiac magnetic resonance-derived variables included Fontan geometry, and hemodynamics. Computational fluid dynamics simulations quantified power loss, pressure drop, and total cavopulmonary connection resistance across the Fontan. Quality of life was assessed by completion of the Pediatric Quality of Life Inventory. Longitudinal and cross-sectional comparisons were made between cardiac magnetic resonance and computational fluid dynamics parameters with patient-reported QOL. RESULTS: We studied 77 Fontan patients, median age 19.7 years (interquartile range, 17.1 to 23.6), median time from Fontan completion 16 years (interquartile range, 13 to 20). Longitudinal data were available for 48 patients; median time between cardiac magnetic resonance and QOL was 8.1 years (interquartile range, 7 to 9.4). Median patient-reported Pediatric Quality of Life Inventory total score was 80 (interquartile range, 67.4 to 88). Greater power loss and smaller left pulmonary artery diameter at baseline were associated with worse QOL at follow-up. Greater pressure drop was associated with worse QOL at the same time point. CONCLUSIONS: For Fontan survivors, measures of computational fluid dynamics hemodynamics and geometry are associated with worse QOL. Interventional strategies targeted at optimizing the Fontan may improve QOL.

Imposition of Fontan physiology: Effects on strain and global measures of ventricular function.

OBJECTIVE: We sought to evaluate contractile function in single-ventricle patients before and after imposition of Fontan physiology. METHODS: Single right ventricle (SRV; n = 38) and single left ventricle (SLV; n = 11) patients underwent cardiac magnetic resonance imaging pre and post Fontan operation. Global radial strain (GRS), global circumferential strain (GCS), and global longitudinal strain were measured along with ejection fraction (EF) and atrioventricular valve regurgitation (AVVR). RESULTS: Age at cardiac magnetic resonance imaging before the Fontan operation was 3.1 ± 1.3 years and after the Fontan procedure was 5.8 ± 2.7 years. There were no significant EF differences between SRV and SLV patients before and after the Fontan procedure, and EF did not deteriorate significantly after the Fontan operation. GRS was significantly lower for SRV patients than for SLV patients before (24.3% vs 32.1%; P = .048) and after (21.8% vs 29.7%; P = .045) the Fontan procedure. GRS and GCS of the SRV patients deteriorated significantly after the Fontan operation (GRS, P = .01; GCS, P = .009). Strains showed positive correlations before and after the Fontan operation with positive correlations among each strain. Within all patients, strains correlated positively with EF. Strains and EF negatively correlated with AVVR (GRS P = .03, r = -0.22; GCS P = .03, r = -0.23; EF P < .001, r = -0.37). CONCLUSIONS: Strains were lower for SRV than for SLV patients before and after the Fontan operation and deteriorated after the Fontan operation. Our study suggests that strain measures might detect ventricular deterioration earlier than EF. Because strains before and after the Fontan operation were positively correlated, and negatively correlated with AVVR, the early institution of myocardial protective therapy including AVVR management, especially for SRV patients, might have benefit.

Pearls and Pitfalls in Pediatric Fontan Operation Imaging.

The Fontan operation or the total cavopulmonary connection is a palliative surgery for single ventricle congenital heart disease where the systemic venous return circumvents a pumping chamber and flows directly into the pulmonary circuit. With surgical and medical advances, there has been improvement in life expectancy of these patients, however, it has also resulted in unique complications from the physiology that requires diligent surveillance. A critical component relies on optimal imaging for diagnosis and treatment of these complications. This article describes the normal anatomy of the Fontan circulation, current imaging modalities and techniques, and frequently encountered complications seen when imaging the patients who have undergone Fontan palliation.

Prevalence and Cause of Early Fontan Complications: Does the Lymphatic Circulation Play a Role?

Background Recent studies suggest that lymphatic congestion plays a role in development of late Fontan complications, such as protein-losing enteropathy. However, the role of the lymphatic circulation in early post-Fontan outcomes is not well defined. Methods and Results This was a retrospective, single-center study of patients undergoing first-time Fontan completion from 2012 to 2017. The primary outcome was early Fontan complication ≤6 months after surgery, a composite of death, Fontan takedown, extracorporeal membrane oxygenation, chest tube drainage >14 days, cardiac catheterization, readmission, or transplant. Complication causes were assigned to 1 of 4 groups: (1) Fontan circuit obstruction, (2) ventricular dysfunction or atrioventricular valve regurgitation, (3) persistent pleural effusions in the absence of Fontan obstruction or ventricular dysfunction, and (4) chylothorax or plastic bronchitis. T2-weighted magnetic resonance imaging sequences were used to assess for lymphatic perfusion abnormality. The cohort consisted of 238 patients. Fifty-eight (24%) developed early complications: 20 of 58 (34.5%) in group 1, 8 of 58 (14%) in group 2, 18 of 58 (31%) in group 3, and 12 of 58 (20%) in group 4. Preoperative T2 imaging was available for 126 (53%) patients. Patients with high-grade lymphatic abnormalities had 6 times greater odds of developing early complications (P=0.001). Conclusions There is substantial morbidity in the early post-Fontan period. Half of those who developed early complications had lymphatic failure or persistent effusions unrelated to structural or functional abnormalities. Preoperative T2 imaging demonstrated that patients with higher-grade lymphatic perfusion abnormalities were significantly more likely to develop early complications. This has implications for risk stratification and optimization of patients before Fontan palliation.

Cross-Sectional Magnetic Resonance and Modeling Comparison From Just After Fontan to the Teen Years.

BACKGROUND: Little is known of baseline anatomic, hemodynamic, and fluid dynamic cardiac magnetic resonance data in single-ventricle patients immediately after Fontan. A comparison from that time point to the teen years can demonstrate clinical course, potentially predict future events, and may shed some light regarding how to optimize outcome. This cross-sectional study is meant to characterize these variables from just after Fontan to the teenage years. METHODS: The anatomy, flows, and computational fluid dynamic modeling of 22 patients 3 to 9 months after Fontan (age 3 ± 1.1 years) and 25 teens (age 16 ± 1.8 years) were compared. Significance was defined as P less than .05. RESULTS: The percentage of Fontan pathway stenosis was greater with cardiac index and fenestration flow while caval return was lower in teens than in younger patients (for Fontan pathway stenosis, 43% vs 21%, P = .009); however, hepatic flow distribution was more evenly distributed in older patients. Pulmonary artery size kept up with somatic growth. In the teen group, indexed power loss (R = .39), percentage of Fontan pathway stenosis (R = .62), and particle resident time (R = .42) deteriorated as time from Fontan increased (P < .04 for all). CONCLUSIONS: There are mostly aspects of deterioration with a few bright spots of stability in anatomy, blood flow, and fluid dynamic variables in Fontan patients from the postoperative period to the teenage years. Most notably, Fontan pathway stenosis increases with decreasing flows while pulmonary artery size and hepatic flow distribution remain stable or improved. These data may be aid in designing improved Fontan reconstruction to optimize clinical outcome and to understand future complications.

Impact of Free-Breathing Phase-Contrast MRI on Decision-Making in Fontan Surgical Planning.

Fontan surgical planning ranks proposed surgical options according to their hemodynamics assessed by computational fluid dynamic (CFD) modeling. CFD commonly utilizes blood flow acquired under breath-holding (BH) conditions. Ignoring the free-breathing (FB) effect on blood flow waveforms may impact the ranking of surgical options. This study investigates such a potential impact by including ten Fontan patients who had blood flow acquisitions under both BH and FB conditions. A virtual surgery platform was used to generate two surgical options for each patient: (1) a traditional Fontan conduit and (2) a Y-graft. These options were ranked based on clinically relevant hemodynamic metrics: power loss (PL) and hepatic flow distribution (HFD). No difference was found in the ranking of options between using FB and BH flow acquisitions. The findings indicated that decision-making is not affected by the types of flow acquisition for Fontan surgical planning.

Multicenter Safety and Practice for Off-Label Diagnostic Use of Ferumoxytol in MRI.

Background Ferumoxytol is approved for use in the treatment of iron deficiency anemia, but it can serve as an alternative to gadolinium-based contrast agents. On the basis of postmarketing surveillance data, the Food and Drug Administration issued a black box warning regarding the risks of rare but serious acute hypersensitivity reactions during fast high-dose injection (510 mg iron in 17 seconds) for therapeutic use. Whereas single-center safety data for diagnostic use have been positive, multicenter data are lacking. Purpose To report multicenter safety data for off-label diagnostic ferumoxytol use. Materials and Methods The multicenter ferumoxytol MRI registry was established as an open-label nonrandomized surveillance databank without industry involvement. Each center monitored all ferumoxytol administrations, classified adverse events (AEs) using the National Cancer Institute Common Terminology Criteria for Adverse Events (grade 1-5), and assessed the relationship of AEs to ferumoxytol administration. AEs related to or possibly related to ferumoxytol injection were considered adverse reactions. The core laboratory adjudicated the AEs and classified them with the American College of Radiology (ACR) classification. Analysis of variance was used to compare vital signs. Results Between January 2003 and October 2018, 3215 patients (median age, 58 years; range, 1 day to 96 years; 1897 male patients) received 4240 ferumoxytol injections for MRI. Ferumoxytol dose ranged from 1 to 11 mg per kilogram of body weight (≤510 mg iron; rate ≤45 mg iron/sec). There were no systematic changes in vital signs after ferumoxytol administration (P > .05). No severe, life-threatening, or fatal AEs occurred. Eighty-three (1.9%) of 4240 AEs were related or possibly related to ferumoxytol infusions (75 mild [1.8%], eight moderate [0.2%]). Thirty-one AEs were classified as allergiclike reactions using ACR criteria but were consistent with minor infusion reactions observed with parenteral iron. Conclusion Diagnostic ferumoxytol use was well tolerated, associated with no serious adverse events, and implicated in few adverse reactions. Registry results indicate a positive safety profile for ferumoxytol use in MRI. © RSNA, 2019 Online supplemental material is available for this article.

MRI Evaluation of Lymphatic Abnormalities in the Neck and Thorax after Fontan Surgery: Relationship with Outcome.

Background The Fontan operation is performed for surgical palliation of single ventricle physiology. This operation is usually preceded by a superior cavopulmonary connection (SCPC); lymphatic abnormalities after SCPC may be demonstrated at MRI and prior to the Fontan operation. Purpose To determine if the degree of neck and thoracic lymphatic abnormalities at T2-weighted MRI in patients after superior cavopulmonary connection (SCPC) correlated with surgical outcomes from the Fontan procedure. Materials and Methods Patients for whom SCPC was performed for palliation of single ventricle disease who underwent chest MRI between July 2012 and May 2015 at a single institution were retrospectively reviewed. T2-weighted images were scored as lymphatic type 1 (little or no T2 mediastinal and supraclavicular signal) to type 4 (T2 signal into both the mediastinum and the lung parenchyma). Fontan takedown, duration of post-Fontan hospitalization and pleural effusion, postoperative plastic bronchitis, need for transplant, and mortality were tabulated. The relationship between lymphatic type and clinical outcomes was evaluated by using analysis of variance (ANOVA), the Kruskal-Wallis H test, and the Fisher exact test. Results A total of 83 patients (mean age, 7.9 years ± 2.6) were evaluated. Among these 83 patients, 53 (64%) were classified with type 1 or 2 lymphatic abnormalities, 17 (20%) with type 3, and 12 (16%) with type 4. The rate of failure of Fontan completion was higher in patients with type 4 than in type 1 or 2 (54% vs 2%, respectively; P = .004). Need for cardiac transplant (one of 13 [8%]) and death (three of 13 [23%]) occurred only in type 4. Median postoperative length of stay was longer for patients with type 4 than for those with types 1 or 2 (29 days vs 9 days, respectively; P < .01). Conclusion Greater MRI-based severity of lymphatic abnormalities in patients prior to planned Fontan procedure was associated with failure of Fontan completion and longer postoperative stay. © RSNA, 2019 Online supplemental material is available for this article.

Relationship of Aortic Stiffness to Exercise and Ventricular Volumes in Single Ventricles.

BACKGROUND: Patients with single ventricle (SV) may often undergo aortic reconstruction that creates a stiff large vessel, increasing afterload and affecting exercise performance. The objective of this study was to determine the relationship of pulse wave velocity (PWV) and distensibility in reconstructed and normal aortic arches after Fontan with exercise variables. METHODS: PWV and distensibility of the descending aorta at the level of the diaphragm (DAo) were calculated with real-time exercise cardiac magnetic resonance in 48 patients with SV after Fontan (18 after aortic reconstruction; 30 without aortic reconstruction) and compared with metabolic exercise stress test variables. RESULTS: PWV was greater in the reconstructed group than in the non-reconstructed group (median 4.4 m/s [range: 2.3 to 9.8 m/s] versus 3.6 [range: 2.6 to 6.3 m/s], respectively, p = 0.003). Statistically significant inverse correlations were found between PWV and end-diastolic, end-systolic, and stroke volumes at rest and at exercise in the reconstructed group. In addition, inverse correlations also existed in the reconstructed group between distensibility of the DAo and the exercise variables such as peak oxygen pulse (R = 0.56, p = 0.02), peak oxygen consumption (R = 0.63, p = 0.008), oxygen consumption at ventilatory anaerobic threshold (R = 0.48, p = 0.04), and peak work (R = 0.54, p = 0.02). Similar correlations were not seen in patients with non-reconstructed aortas. CONCLUSIONS: Patients with SV with reconstructed aortas have increased aortic stiffness, increasing afterload on the ventricle. Native DAo stiffness distal to the reconstruction is inversely correlated with exercise performance, presumably to decrease impedance mismatch to maintain homogeneity of the aortic wall. This information suggests a possible mechanism for decreased exercise performance in patients with SV with aortic reconstructions.

Magnetic Resonance Myocardial Perfusion Imaging: Safety and Indications in Pediatrics and Young Adults.

The purpose of this study was to assess the safety and indications for cardiac magnetic resonance (CMR) with myocardial perfusion imaging (MPI) in a cohort of children and young adults. A retrospective review of 178 children and young adults who underwent CMR with MPI was performed. Studies were categorized based on study protocols as MPI with resting perfusion only, adenosine stress MPI, exercise-induced stress MPI, and MPI for cardiac mass diagnosis. Relevant clinical history, exam indications, and adverse reactions following gadolinium-based contrast agent and adenosine administration were recorded. Studies were reviewed for the presence of myocardial perfusion defects, wall motion abnormalities, and delayed myocardial enhancement. The most common indications from MPI were congenital heart disease (CHD), Kawasaki disease, anomalous coronary artery, or myocardial mass characterization. Of these, 51% were protocoled with adenosine stress, 23% without stress, 6% with exercise stress, and 20% for cardiac mass evaluation. Excluding patients for myocardial mass evaluation, MPI defects were present in 16% (14 with adenosine stress, 1 with exercise stress, 8 on resting studies only). For cardiac mass evaluation, a mass was confirmed in 58%. No adverse reactions occurred with intravenous administration of a gadolinium-based contrast agent. Three self-limited adverse reactions, 2 patients with chest pain, and 1 patient with bradycardia, occurred following adenosine administration. MPI is a safe modality for the evaluation of pediatric and young adults with minimal adverse events. The most common indications for MPI were for the evaluation of CHD, Kawasaki disease, anomalous coronary artery, or myocardial mass characterization.

Cardiac magnetic resonance imaging characterizes stenosis, perfusion, and fibrosis preoperatively and postoperatively in children with anomalous coronary arteries.

OBJECTIVES: Using cardiac magnetic resonance imaging (MRI) with virtual angioscopy, we sought to evaluate coronary anatomy, myocardial injury, and left ventricular function in children with interarterial anomalous aortic origin of coronary artery before and after surgery. METHODS: We prospectively enrolled children 5 to 19 years old with interarterial anomalous coronary artery. Cardiac MRI was performed with respiratory-navigated steady-state free-precession 3-dimensional data set acquisition. Virtual angioscopy was used to evaluate the coronary ostia directly. Surgery consisted of the modified unroofing procedure. RESULTS: We enrolled 9 subjects between February 2009 and May 2015. Subjects were male, with an average age at surgery of 14.1 years. Anomalous coronary was right in 7 patients (77%) and left in 2. In all subjects, the proximal anomalous coronary arose tangential to the aorta with an elliptical, slitlike ostium. Before the operation, the proximal coronary artery was significantly smaller proximally than distally (2 vs 3.1 mm; P < .0001. After the operation, neo-orifices were round and patent in 7 subjects; however, 2 subjects still had narrowed neo-orifices. New postoperative MRI findings included flattened septal wall motion (N = 1), small region of midmyocardial partial-thickness scar (N = 1), and dyskinetic septal wall motion with mild aortic insufficiency (N = 1). Left ventricular function was normal both before and after surgery (P = .85). CONCLUSIONS: Cardiac MRI with virtual angioscopy is an important tool for evaluating anomalous coronary anatomy, myocardial function, and ischemia and should be considered for initial and postoperative assessment of children with anomalous coronary arteries.

Respiratory Effects on Fontan Circulation During Rest and Exercise Using Real-Time Cardiac Magnetic Resonance Imaging.

BACKGROUND: It is known that respiration modulates cavopulmonary flows, but little data compare mean flows under breath-holding and free-breathing conditions to isolate the respiratory effects and effects of exercise on the respiratory modulation. METHODS: Real-time phase-contrast magnetic resonance combined with a novel method to track respiration on the same image acquisition was used to investigate respiratory effects on Fontan caval and aortic flows under breath-holding, free-breathing, and exercise conditions. Respiratory phasicity indices that were based on beat-averaged flow were used to quantify the respiratory effect. RESULTS: Flow during inspiration was substantially higher than expiration under the free-breathing and exercise conditions for both inferior vena cava (inspiration/expiration: 1.6 ± 0.5 and 1.8 ± 0.5, respectively) and superior vena cava (inspiration/expiration: 1.9 ± 0.6 and 2.6 ± 2.0, respectively). Changes from rest to exercise in the respiratory phasicity index for these vessels further showed the impact of respiration. Total systemic venous flow showed no significant statistical difference between the breath-holding and free-breathing conditions. In addition, no substantial difference was found between the descending aorta and inferior vena cava mean flows under either resting or exercise conditions. CONCLUSIONS: This study demonstrated that inferior vena cava and superior vena cava flow time variance is dominated by respiratory effects, which can be detected by the respiratory phasicity index. However, the minimal respiration influence on net flow validates the routine use of breath-holding techniques to measure mean flows in Fontan patients. Moreover, the mean flows in the inferior vena cava and descending aorta are interchangeable.

High-Resolution, Contrast-Enhanced Cardiac Magnetic Resonance Detects an Intracardiac Thrombus in a Fontan Patient.

A 28-year-old male with Fontan physiology presented with chest pain, elevated troponin, regional dyskinesis, and an apical echogenicity in the right-sided morphologically left ventricle (LV) on echocardiogram. Cardiac magnetic resonance (CMR) imaging was performed with a three-dimensional respiratory-navigated inversion recovery FLASH (low flip angle, spoiled gradient echo technique) sequence during slow gadolinium infusion. A hypointense lesion in the LV apex was consistent with thrombus. Gadolinium-delayed enhancement imaging demonstrated increased signal in the mid-inferior LV free wall. In this case, progressive decline in ventricular function was likely followed by an intracardiac thrombus and embolic myocardial infarction. The CMR was instrumental in characterizing the mass and identifying myocardial scar.

Repaired tetralogy of Fallot with coexisting unrepaired partial anomalous pulmonary venous connection is associated with diminished right ventricular ejection fraction and more severe right ventricular dilation.

BACKGROUND: There is an established association between tetralogy of Fallot and partial anomalous pulmonary venous connections. This association is important because surgically repaired tetralogy patients have increased risk of right heart failure. We hypothesize that partial anomalous venous connections increase right ventricular volumes and worsen right ventricular failure. MATERIALS AND METHODS: We reviewed cardiac MRI exams performed at a tertiary pediatric hospital from January 2005 to January 2014. We identified patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection. We used age- and gender-matched repaired tetralogy patients without partial anomalous pulmonary venous connection as controls. We analyzed the MRI results and surgical course and performed comparative statistics to identify group differences. RESULTS: There were eight patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection and 16 controls. In all cases, the partial anomalous pulmonary venous connection was not detected on preoperative echocardiography. There were no significant differences in surgical course and body surface area between the two groups. Repaired tetralogy patients with unrepaired partial anomalous pulmonary venous connection showed significantly higher indexed right ventricular end diastolic volume (149 ± 33 mL/m(2) vs. 118 ± 30 mL/m(2)), right ventricle to left ventricle size ratios (3.1 ± 1.3 vs. 1.9 ± 0.5) and a higher incidence of reduced right ventricular ejection fraction compared to controls (3/8 vs. 0/16). CONCLUSION: Repaired tetralogy of Fallot with unrepaired partial anomalous pulmonary venous connection is associated with reduced right ventricular ejection fraction and more significant right ventricular dilation.

Identifying Abnormal Ostial Morphology in Anomalous Aortic Origin of a Coronary Artery.

BACKGROUND: Anomalous origin of a coronary artery from the contralateral sinus of Valsalva is associated with exercise-induced ischemia and sudden death. That is thought to be due to aortic enlargement in patients with an elliptical ostium. We hypothesize that virtual angioscopy can identify abnormal coronary ostial morphology in these patients. METHODS: We retrospectively analyzed 55 consecutive pediatric coronary artery magnetic resonance imaging studies from January 2006 to January 2010 with the diagnosis of anomalous right (n = 20), or left (n = 7) coronary artery, or normal coronary origins (n = 28). One postmortem heart specimen with anomalous left coronary artery was imaged and analyzed to validate our technique. Virtual angioscopy analysis was used for visualization and measurement of the coronary ostia. RESULTS: Distinct aortic origins of the right and left coronaries were seen in all 55 studies. An elliptical orifice with a longer superior-inferior dimension was seen in all anomalous ostia, in contrast to a circular ostium in all normal origins. That was quantified in anomalous ostia with a long-axis to short-axis ratio of 2.5 ± 0.5 (right) and 2.4 ± 0.5 (left) compared with 1.1 ± 0.2 (right) and 1.0 ± 0.3 (left) in controls (p < 0.001 for right and left ostia comparisons). Ostial morphology was confirmed in all 9 patients who underwent operative repair and in 1 patient at autopsy. CONCLUSIONS: Virtual angioscopy identifies abnormal ostial morphology in anomalous coronary artery patients, which is important for characterizing the diagnosis of patients who may be at risk for sudden death.

Doppler-derived flow pattern in the descending aorta does not predict systemic to pulmonary arterial collateral flow in patients with single ventricle palliation: a cross-sectional study.

BACKGROUND: Children with single ventricle heart disease are at risk for developing systemic to pulmonary arterial collateral vessels that adversely impact short-term outcomes, although the effect on long-term outcomes remains unclear. Collateral flow (CollF) can be quantified using cardiac magnetic resonance (CMR) flow quantification. The velocity-time integral (VTI), obtained from spectral Doppler tracings, has been used in "runoff" lesions like aortic regurgitation to quantify insufficiency. We hypothesized that the VTI ratio of the proximal descending aorta (DAo) after cavopulmonary anastomosis (CPA) would estimate CollF. METHODS: A retrospective cross-sectional study was conducted. Patients who had a superior CPA or total CPA and underwent CMR between April 2008 and December 2012 were included. Those with greater than trivial semilunar valve insufficiency or aortic arch obstruction were excluded. In a subset (n = 88), spectral Doppler tracings of the DAo were analyzed to determine the VTI ratio. In another subset (n = 112), CMR was used to determine the ratio of retrograde to antegrade flow in the DAo. RESULTS: There was no linear correlation between VTI ratio and CollF (r (2) = .006, P = .46). There was a weakly positive correlation with CollF (r (2) = .07, P = .007) and the CMR measured ratio of retrograde to antegrade flow. Holodiastolic flow reversal by echo did not predict higher CollF (P = .40), but those with holodiastolic flow reversal by CMR had significantly higher CollF (P = .04). CONCLUSIONS: The ratio of reverse to forward flow in the DAo as determined by Doppler echo does not accurately reflect CollF in children with single ventricle after CPA.

Relationship of single ventricle filling and preload to total cavopulmonary connection hemodynamics.

BACKGROUND: Single ventricle lesions are associated with gradual attrition after surgical palliation with the total cavopulmonary connection (TCPC). Ventricular dysfunction is frequently noted, particularly impaired diastolic performance. This study seeks to relate TCPC hemodynamic energy losses to single ventricle volumes and filling characteristics. METHODS: Cardiac magnetic resonance (CMR) data were retrospectively analyzed for 30 single ventricle patients at an average age of 12.7 ± 4.8 years. Cine ventricular short-axis scans were semiautomatically segmented for all cardiac phases. Ventricular volumes, ejection fraction, peak filling rate, peak ejection rate, and time to peak filling were calculated. Corresponding patient-specific TCPC geometry was acquired from a stack of transverse CMR images; relevant flow rates were segmented from through-plane phase contrast CMR data at TCPC inlets and outlets. The TCPC indexed power loss was calculated from computational fluid dynamics simulations using a validated custom solver. Time-averaged flow conditions and rigid vessel walls were assumed in all cases. Pearson correlations were used to detect relationships between variables, with p less than 0.05 considered significant. RESULTS: Ventricular end-diastolic (R = -0.48) and stroke volumes (R = -0.37) had significant negative correlations with the natural logarithm of a flow-independent measure of power loss. This power loss measure also had a significant positive relationship to time to peak filling rate (normalized to cycle time; R = 0.67). CONCLUSIONS: Flow-independent TCPC power loss is inversely related with ventricular end-diastolic and stroke volumes. Elevated power losses may contribute to impaired diastolic filling and limited preload reserve in single ventricle patients.

Usefulness of insulin like growth factor 1 as a marker of heart failure in children and young adults after the Fontan palliation procedure.

Growth hormone and its mediator, insulinlike growth factor 1 (IGF-1), are key determinants of growth in children and young adults. As patients with Fontan physiology often experience diminished longitudinal growth, we sought to describe IGF-1 levels in this population and to identify factors associated with IGF-1 deficiency. Forty-one Fontan subjects ≥5 years were evaluated in this cross-sectional study. Age- and gender-specific height Z scores were generated using national data. Laboratory testing included IGF-1 and brain natriuretic peptide (BNP) levels. IGF-1 levels were converted to age-, gender-, and Tanner stage-specific Z scores. BNP levels were log transformed to achieve a normal distribution (log-BNP). Medical records were reviewed for pertinent clinical variables. Predictors of IGF-1 Z score were assessed through the Student t test and Pearson's correlation. Median age was 11.1 years (range 5.1 to 33.5 years), and time from Fontan was 8.2 years (1.1 to 26.7). Mean height Z score was -0.2 ± 0.9 with a mean IGF-1 Z score of -0.1 ± 1.3. There was no association between IGF-1 Z score and height Z score. Longer interval since Fontan (R = -0.32, p = 0.04), higher log-BNP (R = -0.40; p = 0.01), and lower indexed systemic flow on cardiac magnetic resonance (R = 0.55, p = 0.02) were associated with lower IGF-1 Z scores. In conclusion, in this cohort with Fontan physiology, higher BNP and lower systemic flow were associated with lower IGF-1 Z score. Longitudinal studies are needed to determine if these relations represent a mechanistic explanation for diminished growth in children with this physiology and with other forms of congenital heart disease.