Hot Topics in Tetralogy of Fallot Villafañe, Juan, MD; Feinstein, Jeffrey A., MD; Jenkins, Kathy J., MD, MPH ...
Journal of the American College of Cardiology,
12/2013, Volume:
62, Issue:
23
Journal Article
Peer reviewed
Open access
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. We explore “hot topics” to highlight areas of emerging science for clinicians and scientists in moving toward a better ...understanding of the long-term management of patients with repaired TOF. From a genetic perspective, the etiology of TOF is multifactorial, with a familial recurrence risk of 3%. Cardiac magnetic resonance is the gold standard assessment tool based on its superior imaging of the right ventricular (RV) outflow tract, pulmonary arteries, aorta, and aortopulmonary collaterals, and on its ability to quantify biventricular size and function, pulmonary regurgitation (PR), and myocardial viability. Atrial re-entrant tachycardia will develop in more than 30% of patients, and high-grade ventricular arrhythmias will be seen in about 10% of patients. The overall incidence of sudden cardiac death is estimated at 0.2%/yr. Risk stratification, even with electrophysiologic testing and cardiac magnetic resonance, remains imperfect. Drug therapy has largely been abandoned, and defibrillator placement, despite its high risks for complications and inappropriate discharges, is often recommended for patients at higher risk. Definitive information about optimal surgical strategies for primary repair to preserve RV function, reduce arrhythmia, and optimize functional status is lacking. Post-operative lesions are often amenable to transcatheter intervention. In selected cases, PR may be treated with transcatheter valve insertion. Ongoing surveillance of RV function is a crucial component of clinical assessment. Except for resynchronization with biventricular pacing, no medical therapies have been shown to be effective after RV dysfunction occurs. In patients with significant PR with RV dilation, optimal timing of pulmonary valve replacement remains uncertain, although accepted criteria are emerging.
Objectives To compare registry and electronic health record (EHR) data mining approaches for cohort ascertainment in patients with pediatric pulmonary hypertension (PH) in an effort to overcome some ...of the limitations of registry enrollment alone in identifying patients with particular disease phenotypes. Study design This study was a single-center retrospective analysis of EHR and registry data at Boston Children's Hospital. The local Informatics for Integrating Biology and the Bedside (i2b2) data warehouse was queried for billing codes, prescriptions, and narrative data related to pediatric PH. Computable phenotype algorithms were developed by fitting penalized logistic regression models to a physician-annotated training set. Algorithms were applied to a candidate patient cohort, and performance was evaluated using a separate set of 136 records and 179 registry patients. We compared clinical and demographic characteristics of patients identified by computable phenotype and the registry. Results The computable phenotype had an area under the receiver operating characteristics curve of 90% (95% CI, 85%-95%), a positive predictive value of 85% (95% CI, 77%-93%), and identified 413 patients (an additional 231%) with pediatric PH who were not enrolled in the registry. Patients identified by the computable phenotype were clinically distinct from registry patients, with a greater prevalence of diagnoses related to perinatal distress and left heart disease. Conclusions Mining of EHRs using computable phenotypes identified a large cohort of patients not recruited using a classic registry. Fusion of EHR and registry data can improve cohort ascertainment for the study of rare diseases. Trial registration ClinicalTrials.gov : NCT02249923.
Objective The aims of our study are to describe the incidence, clinical profile, and risk factors for pulmonary reperfusion injury after the unifocalization procedure for tetralogy of Fallot, ...pulmonary atresia, and major aortopulmonary collateral arteries. We hypothesized the following: (1) Pulmonary reperfusion injury is more likely to occur after unifocalization procedures in which a septated circulation is not achieved, (2) pulmonary reperfusion injury is directly related to the severity of stenosis in major aortopulmonary collateral arteries, and (3) pulmonary reperfusion injury leads to longer intubation time and longer hospitalization. Methods Consecutive patients with tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries who underwent unifocalization procedures over a 5-year period were identified in our institutional database. Chest radiographs before the unifocalization procedure, from postoperative days 0 to 4, and from 2 weeks after the unifocalization procedure or at discharge were evaluated by a pediatric radiologist for localized pulmonary edema. Determination of stenosis severity was based on review of preoperative angiograms. Statistical analyses using multivariate repeated-measures analyses were performed with generalized estimating equations. Results Pulmonary reperfusion injury was present after 42 of 65 (65%) unifocalization procedures. In 36 of 42 cases of reperfusion injury, unilateral injury was present. Risk factors for the development of reperfusion injury included bilateral unifocalization ( P = .01) and degree of stenosis ( P = .03). We did not identify an association between pulmonary reperfusion injury and time to tracheal extubation or hospital discharge. Conclusions Pulmonary reperfusion injury is common after the unifocalization procedure for tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries. Severity of stenosis and bilateral unifocalization are associated with the development of reperfusion injury.
Objectives In this study, with the use of computational fluid dynamics, we evaluate the postoperative hemodynamic performance of the first cohort of patients undergoing a handcrafted Y-graft Fontan ...procedure and validate simulation predictions of hepatic blood flow distribution against in vivo clinical data. Methods An 18-12 × 2–mm handcrafted Y-graft modification of the Fontan procedure was performed in 6 patients. Early (at the time of discharge) and 6-month postoperative 3-dimensional magnetic resonance imaging data were collected. Patient-specific models were constructed for flow simulations. Results Hepatic blood flow distribution varied among patients. Lung perfusion data (n = 3) showed good agreement with simulations. Postoperative asymmetry in hepatic blood flow distribution was reduced 6 months postoperatively. In 1 patient, low wall shear stress was found in the left limb of the Y-graft, corresponding to the location of subsequent thrombosis in the patient. Conclusions The credibility and accuracy of simulation-based predictions of postoperative hepatic flow distribution for the Fontan surgery have been validated by in vivo lung perfusion data. The performance of the Y-graft design is highly patient-specific. The anastomosis location is likely the most important factor influencing hepatic blood flow distribution. Although the development of thrombosis is multifactorial, the occurrence in 1 patient suggests that simulations should not solely consider the hepatic blood flow distribution but also aim to avoid low wall shear stress in the limbs.
Objectives A novel Y-shaped baffle has been proposed for the Fontan operation with promising initial results. However, previous studies have relied either on idealized models or a single ...patient-specific model. The objective of this study is to comprehensively compare the hemodynamic performance and hepatic blood flow distribution of the Y-graft Fontan baffle with 2 current designs using multiple patient-specific models. Methods Y-shaped and tube-shaped grafts were virtually implanted into 5 patient-specific Glenn models forming 3 types of Fontan geometries: Y-graft, T-junction, and offset. Unsteady flow simulations were performed at rest and at varying exercise conditions. The hepatic flow distribution between the right and left lungs was carefully quantified using a particle tracking method. Other physiologically relevant parameters such as energy dissipation, superior vena cava pressure, and wall shear stress were evaluated. Results The Fontan geometry significantly influences the hepatic flow distribution. The Y-graft design improves the hepatic flow distribution effectively in 4 of 5 patients, whereas the T-junction and offset designs may skew as much as 97% of hepatic flow to 1 lung in 2 cases. Sensitivity studies show that changes in pulmonary flow split can affect the hepatic flow distribution dramatically but that some Y-graft and T-junction designs are relatively less sensitive than offset designs. The Y-graft design offers moderate improvements over the traditional designs in power loss and superior vena cava pressure in all patients. Conclusions The Y-graft Fontan design achieves overall superior hemodynamic performance compared with traditional designs. However, the results emphasize that no one-size-fits-all solution is available that will universally benefit all patients and that designs should be customized for individual patients before clinical application.
The Adult Congenital and Pediatric Cardiology Section Martin, Gerard R., MD; Mitchell, Stephanie, BPh; Beekman, Robert H., MD ...
Journal of the American College of Cardiology,
01/2012, Volume:
59, Issue:
1
Journal Article
Peer reviewed
Open access
The Adult Congenital and Pediatric Cardiology (AC/PC) Section was established to develop a clear voice within the American College of Cardiology and address the myriad issues facing the congenital ...heart disease profession. The Section is governed by the AC/PC Council, which includes pediatric cardiologists, adult congenital cardiologists, a cardiac care associate, and a fellow-in-training member. The Council is responsible for bidirectional communication between the College's Board of Trustees and the AC/PC Section members. Since its founding in 2004, Section objectives have been defined by the College's mission: to advocate for quality cardiovascular care through education, research promotion, and the development and application of standards and guidelines and to influence health care policy. The pillars of the College—advocacy, quality, education, and member engagement—serve as the defining template for the Section's strategy. The Section has developed work groups in advocacy, clinical practice, education and training, quality, and publications. A separate leadership group has been developed for adult congenital heart disease. Work groups are open to all Section members. Recognition of the importance of lifelong care in congenital heart disease led Section leaders to incorporate pediatric cardiology and adult congenital heart disease content into each of the work groups. There are more than 1,200 Section members, with nearly 400 members actively contributing to Section activities. This article outlines Section efforts to date and highlights significant successes to date.
Objectives To demonstrate the technical feasibility and describe intermediate outcomes for the initial patients undergoing handcrafted, area-preserving, Y-graft modification of the Fontan procedure. ...Methods A retrospective review of a pilot study was undertaken to describe preoperative, intraoperative, and postoperative results. Results Six patients underwent successful procedures and remain alive 3 to 4 years later. The median age at operation was 3.3 years, and median weight was 13.2 kg. Five operations were done without cardiopulmonary bypass and no intraoperative pressure gradients were found. Five patients were extubated by postoperative day 1, Fontan pressures were 12 to 14 mm Hg, transpulmonary gradients were 6 to 8 mm Hg, and no renal or hepatic function abnormalities were found. Length of stay was 10 to 64 days. One patient required venovenous extracorporeal membrane oxygenation for previously undiagnosed plastic bronchitis (64-day stay); another required reoperation for an incidentally diagnosed aortic thrombus (44-day stay). One patient had occlusion of a Y-graft limb noted on magnetic resonance imaging follow-up at 3 months. Catheterization showed excellent hemodynamic parameters and no Fontan obstruction. Occlusion was believed to be due to right-sided pulmonary arteriovenous malformations and widely discrepant flow (80%) to the right lung leading to low flow in the left limb. Conclusions The area-preserving, bifurcated Y-graft Fontan modification is technically feasible and shows excellent intermediate outcomes. Additional study is required to determine whether the advantages seen in the computational models will be realized in patients over the long-term, and to optimize patient selection for each of the various Fontan options now available.
The assessment of pulmonary vascular resistance (PVR) plays an important role in the diagnosis and management of pulmonary arterial hypertension (PAH). The main objective of this study was to ...determine whether the noninvasive index of systolic pulmonary arterial pressure (SPAP) to heart rate (HR) times the right ventricular outflow tract time-velocity integral (TVI(RVOT)) (SPAP/HR x TVI(RVOT)) provides clinically useful estimations of PVR in PAH.
Doppler echocardiography and right-heart catheterization were performed in 51 consecutive patients with established PAH. The ratio of SPAP/(HR x TVI(RVOT)) was then correlated with invasive indexed PVR (PVRI) using regression and Bland-Altman analysis. Using receiver operating characteristic curve analysis, a cutoff value for the Doppler equation was generated to identify patients with PVRI > or = 15 Wood units (WU)/m2.
The mean pulmonary arterial pressure was 52 +/- 15 mm Hg, the mean cardiac index was 2.2 +/- 0.6 L/min/m2, and the mean PVRI was 20.5 +/- 9.6 WU/m2. The ratio of SPAP/(HR x TVI(RVOT)) correlated very well with invasive PVRI measurements (r = 0.860; 95% confidence interval, 0.759-0.920). A cutoff value of 0.076 provided well-balanced sensitivity (86%) and specificity (82%) to determine PVRI > 15 WU/m2. A cutoff value of 0.057 increased sensitivity to 97% and decreased specificity to 65%.
The novel index of SPAP/(HR x TVI(RVOT)) provides useful estimations of PVRI in patients with PAH.
Pulmonary vascular resistance (PVR) is a critical parameter in the assessment and treatment of patients with pulmonary hypertension, regardless of origin. Noninvasive estimation of PVR could be ...helpful.
Consecutive patients with known or suggested pulmonary hypertension referred for cardiac catheterization were evaluated prospectively and the PVR was calculated invasively. Subsequently, the tricuspid regurgitation velocity (TRV), the velocity-time integral (mean of 3 measurements) of the right ventricular outflow tract (VTIm), and the right ventricular outflow tract diameter were recorded noninvasively.
The TRV/VTIm ratio and the TRV/VTIm corrected for the indexed RVOT diameter correlated well with the PVR at catheterization with R(2) = 0.711 and R(2) = 0.731, respectively, including patients with very high values of PVR. A TRV/VTI(RVOT) value of 38 provided a specificity of 100% for a PVR of 8 Woods units.
Noninvasive estimation is feasible over a broad range of PVR values and could be a useful tool to estimate and longitudinally tracked changes in PVR.
Pulmonary arterial capacitance (PAC) has been associated with right ventricular (RV) workload and mortality in pulmonary hypertension, but is not routinely evaluated in children. We investigated ...whether PAC can be estimated noninvasively by echocardiography.
We retrospectively determined PAC in 31 children with pulmonary hypertension, using echocardiography, and compared the results with those obtained at cardiac catheterization.
PAC derived from echocardiography was similar to that derived from catheterization (mean +/- SD 1.16 +/- 1.0 vs 1.10 +/- 0.95 mL(3) x mm Hg(-1), P = not significant) and the two correlated well (r = 0.74, P < .0001). There was a highly significant polynomial relationship between PAC and RV anterior wall thickness indexed to body surface area (R(2) = 0.54, P < .0001), but not between pulmonary vascular resistance and RV wall thickness. Pulmonary vascular resistance and PAC did not correlate.
Echocardiography can reliably estimate PAC, which strongly correlates with RV hypertrophy, a surrogate for RV work.
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