Lynn F. Peng

Hypoplastic Left Heart Syndrome : Current Considerations and Expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Outcomes After Stent Implantation for the Treatment of Congenital and Postoperative Pulmonary Vein Stenosis in Children

Background— Pulmonary vein stenosis (PVS) is a rare condition that can lead to worsening pulmonary hypertension and cardiac failure in children, and it is frequently lethal. Surgical and transcatheter approaches are acutely successful but restenosis is common and rapid. Methods and Results— We reviewed outcomes among patients who underwent transcatheter pulmonary vein stent implantation for congenital or postoperative PVS at <18 years of age. A total of 74 pulmonary veins were stented with bare metal, drug-eluting, or covered stents in 47 patients. Primary diagnoses included PVS associated with anomalous venous return in 51%, PVS associated with other congenital cardiovascular defects in 36%, and congenital (“de novo”) PVS in 13% of patients. Median age at the time of pulmonary vein stent implantation was 1.4 years. During a median cross-sectional follow-up of 3.1 years, 21 patients died. Estimated survival was 62±8% at 1 year and 50±8% at 5 years after pulmonary vein stent implantation. Stent placement acutely relieved focal obstruction in all veins. Of the 54 stents reexamined with catheterization, 32 underwent reintervention. Freedom from reintervention was 62±7% at 6 months and 42±7% at 1 year. Stent occlusion was documented in 9 cases and significant in-stent stenosis in 17 cases. Stent implantation diameter ≥7 mm was associated with longer freedom from reintervention (hazard ratio, 0.32; P=0.015) and from significant in-stent stenosis (hazard ratio, 0.14; P=0.002). Major acute complications occurred in 5 cases. Conclusions— Transcatheter stent implantation can acutely relieve PVS in children, but reintervention is common. Larger stent lumen size at implantation is associated with longer stent patency and a lower risk of reintervention.

Evaluation of Pediatric Near-Infrared Cerebral Oximeter for Cardiac Disease

BACKGROUND Cerebral hypoxia-ischemia remains a complication in children with congenital heart disease. Near-infrared spectroscopy can be utilized at the bedside to detect cerebral hypoxia-ischemia. This study aimed to calibrate and validate an advanced technology near-infrared cerebral oximeter for use in children with congenital heart disease. METHODS After institutional review board approval and parental consent, 100 children less than 12 years and less than 40 kg were enrolled. Phase I (calibration) measured arterial and jugular venous saturation (SaO(2), SjO(2)) by co-oximetry simultaneously with device signals to calibrate an algorithm to determine regional cerebral saturation against a weighted average cerebral saturation (0.7 SjO(2) + 0.3 SaO(2)). Phase II (validation) evaluated regional cerebral saturation from the algorithm against the weighted average cerebral saturation by correlation, bias, precision, and A(Root Mean Square) assessed by linear regression and Bland-Altman analysis. RESULTS Of 100 patients, 86 were evaluable consisting of 7 neonates, 44 infants, and 35 children of whom 55% were female, 79% Caucasian, and 41% with cyanotic disease. The SaO(2) and regional cerebral saturation ranged from 34% to 100% and 34% to 91%, respectively. There were no significant differences in subject characteristics between phases. For the entire cohort, A(RMS), bias, precision, and correlation coefficient were 5.4%, 0.5%, 5.39%, and 0.88, respectively. Age, skin color, and hematocrit did not affect these values. CONCLUSIONS This cerebral oximeter accurately measures the absolute value of cerebral saturation in children over a wide range of oxygenation and subject characteristics, offering advantages in assessment of cerebral hypoxia-ischemia in congenital heart disease.

Hemodynamic assessment after complete repair of pulmonary atresia with major aortopulmonary collaterals.

BACKGROUND Pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals (PA/VSD/MAPCAs) is a complex form of congenital heart defect. There are limited data regarding late hemodynamics of patients after repair of PA/VSD/MAPCAs. This study evaluated the hemodynamics of patients who underwent complete repair of PA/VSD/MAPCSs and subsequently returned for a conduit change. METHODS This was a retrospective review of 80 children undergoing a right ventricle (RV)-to-pulmonary artery conduit replacement after complete repair of PA/VSD/MAPCAs. All patients underwent preoperative cardiac catheterization to define the cardiac physiology. Patients were an average age of 6.5±1.2 years, and the average interval between complete repair and conduit change was 4.5±1.1 years. RESULTS The preoperative cardiac catheterization demonstrated an average RV right peak systolic pressure of 70±22 mm Hg and pulmonary artery pressure of 38±14 mm Hg. This pressure gradient of 32 mm Hg reflects the presence of conduit obstruction. After conduit change, the intraoperative RV systolic pressure was 34±8 mm Hg, similar to 36±9 mm Hg at the conclusion of the previous complete repair. The corresponding RV/aortic pressure ratios were 0.36±0.07 and 0.39±0.09, respectively. CONCLUSIONS The data demonstrate that patients who underwent complete repair of PA/VSD/MAPCAs had nearly identical pulmonary artery pressures when they returned for conduit change some 4.5 years later. This finding indicates that the growth and development of the unifocalized pulmonary vascular bed is commensurate with visceral growth. We would hypothesize that complete repair, along with low RV pressures, will confer a long-term survival advantage.

Melody® pulmonary valve bacterial endocarditis: Experience in four pediatric patients and a review of the literature

The objectives of this manuscript are two‐fold: (a) to describe the clinical characteristics and management of four pediatric patients with bacterial endocarditis (BE) after Melody® pulmonary valve implantation (MPVI); and (b) to review the literature regarding Melody® pulmonary valve endocarditis.

Late Outcomes in Patients Undergoing Aortopulmonary Window for Pulmonary Atresia/Stenosis and Major Aortopulmonary Collaterals

BACKGROUND Pulmonary atresia with ventricular septal defect (PA/VSD) and major aortopulmonary collateral arteries (MAPCAs) is a complex form of congenital heart defect. One identifiable subset has small (<2.5 mm) intrapericardial branch pulmonary arteries that are (1) confluent, (2) have normal arborization, and (3) have dual-supplied collateral vessels. When this anatomy is associated with limited pulmonary blood flow, the patients are candidates for creation of an aortopulmonary window to stimulate growth of the pulmonary arteries. The purpose of this study was to review our experience with creation of an aortopulmonary window as the initial palliative procedure. METHODS This was a retrospective review of our surgical experience with 35 children undergoing aortopulmonary window creation from 2002 to 2011. Patients were identified by preoperative cardiac catheterization to define the cardiac and pulmonary artery anatomy. RESULTS There was no mortality in 35 patients undergoing aortopulmonary window creation. These patients have subsequently undergone 78 cardiac procedures (with 2 operative mortalities). Eighteen of these patients have achieved complete repair, 4 patients in a second procedure, 6 patients in a third procedure, 5 patients in a fourth procedure, and 3 patients in a fifth procedure. CONCLUSIONS The data demonstrate that patients can undergo creation of an aortopulmonary window with excellent early results. Few patients were amenable to complete repair at the second operation, and most required multiple reoperations to recruit sufficient arborization. We interpret these counterintuitive results to suggest that hypoplastic central pulmonary arteries and diminished pulmonary blood flow are markers for a less well developed pulmonary vascular bed.

Programmatic Approach to Management of Tetralogy of Fallot With Major Aortopulmonary Collateral Arteries: A 15-Year Experience With 458 Patients

Background— Tetralogy of Fallot with major aortopulmonary collateral arteries is a complex and heterogeneous condition. Our institutional approach to this lesion emphasizes early complete repair with the incorporation of all lung segments and extensive lobar and segmental pulmonary artery reconstruction. Methods and Results— We reviewed all patients who underwent surgical intervention for tetralogy of Fallot and major aortopulmonary collateral arteries at Lucile Packard Children’s Hospital Stanford (LPCHS) since November 2001. A total of 458 patients underwent surgery, 291 (64%) of whom underwent their initial procedure at LPCHS. Patients were followed for a median of 2.7 years (mean 4.3 years) after the first LPCHS surgery, with an estimated survival of 85% at 5 years after first surgical intervention. Factors associated with worse survival included first LPCHS surgery type other than complete repair and Alagille syndrome. Of the overall cohort, 402 patients achieved complete unifocalization and repair, either as a single-stage procedure (n=186), after initial palliation at our center (n=74), or after surgery elsewhere followed by repair/revision at LPCHS (n=142). The median right ventricle:aortic pressure ratio after repair was 0.35. Estimated survival after repair was 92.5% at 10 years and was shorter in patients with chromosomal anomalies, older age, a greater number of collaterals unifocalized, and higher postrepair right ventricle pressure. Conclusions— Using an approach that emphasizes early complete unifocalization and repair with incorporation of all pulmonary vascular supply, we have achieved excellent results in patients with both native and previously operated tetralogy of Fallot and major aortopulmonary collateral arteries.

Hemodynamic Effects of Phenylephrine, Vasopressin, and Epinephrine in Children With Pulmonary Hypertension: A Pilot Study.

Objectives: During a pulmonary hypertensive crisis, the marked increase in pulmonary vascular resistance can result in acute right ventricular failure and death. Currently, there are no therapeutic guidelines for managing an acute crisis. This pilot study examined the hemodynamic effects of phenylephrine, arginine vasopressin, and epinephrine in pediatric patients with pulmonary hypertension. Design: In this prospective, open-label, nonrandomized pilot study, we enrolled pediatric patients previously diagnosed with pulmonary hypertensive who were scheduled electively for cardiac catheterization. Primary outcome was a change in the ratio of pulmonary-to-systemic vascular resistance. Baseline hemodynamic data were collected before and after the study drug was administered. Patients: Eleven of 15 participants were women, median age was 9.2 years (range, 1.7–14.9 yr), and median weight was 26.8 kg (range, 8.5–55.2 kg). Baseline mean pulmonary artery pressure was 49 ± 19 mm Hg, and mean indexed pulmonary vascular resistance was 10 ± 5.4 Wood units. Etiology of pulmonary hypertensive varied, and all were on systemic pulmonary hypertensive medications. Interventions: Patients 1–5 received phenylephrine 1 &mgr;g/kg; patients 6–10 received arginine vasopressin 0.03 U/kg; and patients 11–15 received epinephrine 1 &mgr;g/kg. Hemodynamics was measured continuously for up to 10 minutes following study drug administration. Measurements and Main Results: After study drug administration, the ratio of pulmonary-to-systemic vascular resistance decreased in three of five patients receiving phenylephrine, five of five patients receiving arginine vasopressin, and three of five patients receiving epinephrine. Although all three medications resulted in an increase in aortic pressure, only arginine vasopressin consistently resulted in a decrease in the ratio of systolic pulmonary artery-to-aortic pressure. Conclusions: This prospective pilot study of phenylephrine, arginine vasopressin, and epinephrine in pediatric patients with pulmonary hypertensive showed an increase in aortic pressure with all drugs although only vasopressin resulted in a consistent decrease in the ratio of pulmonary-to-systemic vascular resistance. Studies with more subjects are warranted to define optimal dosing strategies of these medications in an acute pulmonary hypertensive crisis.

Reperfusion pulmonary edema in children with tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries undergoing unifocalization procedures: A pilot study examining potential pathophysiologic mechanisms and clinical significance.

OBJECTIVE Children with tetralogy of Fallot (TOF), pulmonary atresia (PA), and major aortopulmonary collateral arteries (MAPCAs) are at risk for reperfusion pulmonary edema (RPE) after unifocalization procedures to reconstruct the central pulmonary arteries. The purpose of this study was to determine the incidence of RPE, describe the clinical course of patients with RPE, and explore the mechanism of RPE in this population by measuring plasma biomarkers of alveolar epithelial and endothelial injury and lung inflammation. METHODS Levels of plasma receptor for advanced glycation end products (RAGE), intercellular adhesion molecule 1 (ICAM-1), and interleukin 6 (IL-6) were measured at baseline and postoperative day (POD) 0, 1, and 2 after unifocalization. A pediatric radiologist reviewed chest radiographs from the same time points and scored each lung segment for the degree of pulmonary edema. A pediatric interventional cardiologist reviewed the preoperative angiograms for each patient and determined the degree of stenosis for each aortopulmonary collateral vessel. RPE was defined as localized pulmonary edema with a pulmonary edema score of at least 2 occurring in the lung segment demonstrating the greatest degree of angiographic stenosis within the first 48 hours after surgery and with resolution by discharge. RESULTS Thirty-five patients who underwent 37 unifocalization procedures were enrolled, and 32 patients were included in the analysis. Of these, 16 of 32 (50%) demonstrated evidence of RPE based on our defined criteria. There was no significant difference in RAGE (P=.60), ICAM-1 (P=.34), or IL-6 (P=.31) levels between those with and without RPE at any time point. The mean duration of mechanical ventilation in patients with RPE versus those without was not significantly different (5.1±4.2 vs 5.6±4.5 days, respectively; P=.57). CONCLUSIONS Fifty percent of children with TOF/PA/MAPCAs undergoing unifocalization surgery developed RPE. Levels of plasma biomarkers of alveolar epithelial and endothelial injury and lung inflammation were not increased in patients with RPE compared with those without RPE. The presence of RPE did not affect the duration of respiratory failure and mechanical ventilation. The process of RPE is clinically self-limited and seems unlikely to be associated with vascular changes.

Percutaneous transcatheter pulmonary valve replacement in children weighing less than 20 kg

Since FDA approval of the Melody valve, transcatheter pulmonary valve replacement (TPVR) has been offered to an expanding population. Limited data exist regarding the safety and feasibility of TPVR in smaller patients.