High Acuity Therapy Variation Across Pediatric Acute Care Cardiology Units: Results from the Pediatric Acute Care Cardiology Collaborative Hospital Surveys

We utilized the multicenter Pediatric Acute Care Cardiology Collaborative (PAC³) 2017 and 2019 surveys to describe practice variation in therapy availability and changes over a 2-year period. A high acuity therapies (ATs) score was derived (1 point per positive response) from 44 survey questions and scores were compared to center surgical volume. Of 31 centers that completed the 2017 survey, 26 also completed the 2019 survey. Scores ranged from 11 to 34 in 2017 and 11 to 35 in 2019. AT scores in 2019 were not statistically different from 2017 scores (29/44, IQR 27-32.5 vs. 29.5/44, IQR 27-31, p = 0.9). In 2019, more centers reported initiation of continuous positive airway pressure (CPAP) and Bi-level positive airway pressure (BiPAP) in Acute Care Cardiology Unit (ACCU) (19/26 vs. 4/26, p < 0.001) and permitting continuous CPAP/BiPAP (22/26 vs. 14/26, p = 0.034) compared to 2017. Scores in both survey years were significantly higher in the highest surgical volume group compared to the lowest, 33 ± 1.5 versus 25 ± 8.5, p = 0.046 and 32 ± 1.7 versus 23 ± 5.5, p = 0.009, respectively. Variation in therapy within the ACCUs participating in PAC³ presents an opportunity for shared learning across the collaborative. Experience with PAC³ was associated with increasing available respiratory therapies from 2017 to 2019. Whether AT scores impact the quality and outcomes of pediatric acute cardiac care will be the subject of further investigation using a comprehensive registry launched in early 2019.

Is Clinic Visit Frequency Associated with Weight Gain During the Interstage Period? A Report from the Joint Council on Congenital Heart Disease National Pediatric Cardiology Quality Improvement Collaborative (JCCHD-NPCQIC)

Growth problems are prevalent among infants with congenital heart disease. We sought to determine whether frequency of outpatient clinic visits correlated with weight gain in patients with hypoplastic left heart syndrome or variant during the interstage period between discharge from stage I palliation and presentation for stage II palliation (SIIP). Using prospectively collected data from the JCCHD NPC-QIC database from June 2008 to July 2013, we performed a retrospective cohort study assessing the association of days between clinic visits (DBV) with the change in weight-for-age z-score (WAZ) during the interstage period. Eligible subjects were those who survived to a SIIP performed at <270 days of age and had at least two outpatient clinic visits. There were 561 patients from 49 centers who fulfilled inclusion criteria. The average interstage change in WAZ was +0.22. The mean number of DBV was 16.1 days, and the average number of clinic visits was six. There was no correlation of change in WAZ with either DBV (r = 0.02, P = 0.62) or the number of visits (r = 0.03, P = 0.44). Subjects within this cohort are seen about every 2 weeks averaged over the interstage period. There is no correlation between interstage visit frequency and change in WAZ in this patient population. Further research is needed to describe differences in visit frequency as the patient progresses through the interstage period and to elucidate whether patient factors such as growth velocity are influencing visit frequency. The optimal visit frequency remains unknown.

Longitudinal assessment of growth in hypoplastic left heart syndrome: results from the single ventricle reconstruction trial

BACKGROUND

We sought to characterize growth between birth and age 3 years in infants with hypoplastic left heart syndrome who underwent the Norwood procedure.

METHODS AND RESULTS

We performed a secondary analysis using the Single Ventricle Reconstruction Trial database after excluding patients <37 weeks gestation (N=498). We determined length-for-age z score (LAZ) and weight-for-age z score (WAZ) at birth and age 3 years and change in WAZ over 4 clinically relevant time periods. We identified correlates of change in WAZ and LAZ using multivariable linear regression with bootstrapping. Mean WAZ and LAZ were below average relative to the general population at birth (P<0.001, P=0.05, respectively) and age 3 years (P<0.001 each). The largest decrease in WAZ occurred between birth and Norwood discharge; the greatest gain occurred between stage II and 14 months. At age 3 years, WAZ and LAZ were <-2 in 6% and 18%, respectively. Factors associated with change in WAZ differed among time periods. Shunt type was associated with change in WAZ only in the Norwood discharge to stage II period; subjects with a Blalock-Taussig shunt had a greater decline in WAZ than those with a right ventricle-pulmonary artery shunt (P=0.002).

CONCLUSIONS

WAZ changed over time and the predictors of change in WAZ varied among time periods. By age 3 years, subjects remained small and three times as many children were short as were underweight (>2 SD below normal). Failure to find consistent risk factors supports the strategy of tailoring nutritional therapies to patient- and stage-specific targets.

CLINICAL TRIAL REGISTRATION URL

http://clinicaltrials.gov/. Unique identifier: NCT00115934.

Heterotaxy syndrome and malrotation: does isomerism influence risk and decision to treat

PURPOSE

Controversy remains regarding the management of the asymptomatic heterotaxy syndrome (HS) patient with suspected intestinal rotational abnormalities. We evaluated the outcomes for our HS population to identify frequency of malrotation and identify characteristics of children who might benefit from expectant management.

METHODS

After IRB approval, a retrospective review of all patients treated for HS at a large tertiary care children's hospital between January 2008 and June 2012 was performed. For the purpose of this paper, malrotation was defined as an operative note that described the presence of Ladd's bands and a narrow mesentery.

RESULTS

Thirty-eight patients with HS were identified, including 18 who underwent abdominal exploration. Left atrial isomerisation (LAI) was identified in 13 individuals, and right atrial isomerisation (RAI) was noted in 25. The rate of surgical intervention did not vary between the 2 groups (54%). Malrotation was found in 8 patients: one with LAI and 7 with RAI. This difference in incidence was statistically significant (p=0.04).

CONCLUSION

These data suggest that the direction of atrial isomerisation influences the likelihood of true malrotation, where RAI patients are more likely to be malrotated. Given the inherent risk of surgery on this medically fragile patient population, surgeons should consider expectant management for asymptomatic LAI patients.

Variation in feeding practices following the Norwood procedure

OBJECTIVES

To assess variation in feeding practice at hospital discharge after the Norwood procedure, factors associated with tube feeding, and associations among site, feeding mode, and growth before stage II.

STUDY DESIGN

From May 2005 to July 2008, 555 subjects from 15 centers were enrolled in the Pediatric Heart Network Single Ventricle Reconstruction Trial; 432 survivors with feeding data at hospital discharge after the Norwood procedure were analyzed.

RESULTS

Demographic and clinical variables were compared among 4 feeding modes: oral only (n = 140), oral/tube (n = 195), nasogastric tube (N-tube) only (n = 40), and gastrostomy tube (G-tube) only (n = 57). There was significant variation in feeding mode among sites (oral only 0%-81% and G-tube only 0%-56%, P < .01). After adjusting for site, multivariable modeling showed G-tube feeding at discharge was associated with longer hospitalization, and N-tube feeding was associated with greater number of discharge medications (R(2) = 0.65, P < .01). After adjusting for site, mean pre-stage II weight-for-age z-score was significantly higher in the oral-only group (-1.4) vs the N-tube-only (-2.2) and G-tube-only (-2.1) groups (P = .04 and .02, respectively).

CONCLUSIONS

Feeding mode at hospital discharge after the Norwood procedure varied among sites. Prolonged hospitalization and greater number of medications at the time of discharge were associated with tube feeding. Infants exclusively fed orally had a higher weight-for-age z score pre-stage II than those fed exclusively by tube. Exploring strategies to prevent morbidities and promote oral feeding in this highest risk population is warranted.

Interstage mortality after the Norwood procedure: Results of the multicenter Single Ventricle Reconstruction trial

OBJECTIVE

For infants with single ventricle malformations undergoing staged repair, interstage mortality is reported at 2% to 20%. The Single Ventricle Reconstruction trial randomized subjects with a single morphologic right ventricle undergoing a Norwood procedure to a modified Blalock-Taussig shunt (MBTS) or a right ventricle-to-pulmonary artery shunt (RVPAS). The aim of this analysis was to explore the associations of interstage mortality and shunt type, and demographic, anatomic, and perioperative factors.

METHODS

Participants in the Single Ventricle Reconstruction trial who survived to discharge after the Norwood procedure were included (n = 426). Interstage mortality was defined as death postdischarge after the Norwood procedure and before the stage II procedure. Univariate analysis and multivariable logistic regression were performed adjusting for site.

RESULTS

Overall interstage mortality was 50 of 426 (12%)-13 of 225 (6%) for RVPAS and 37 of 201 (18%) for MBTS (odds ratio [OR] for MBTS, 3.4; P < .001). When moderate to severe postoperative atrioventricular valve regurgitation (AVVR) was present, interstage mortality was similar between shunt types. Interstage mortality was independently associated with gestational age less than 37 weeks (OR, 3.9; P = .008), Hispanic ethnicity (OR, 2.6; P = .04), aortic atresia/mitral atresia (OR, 2.3; P = .03), greater number of post-Norwood complications (OR, 1.2; P = .006), census block poverty level (P = .003), and MBTS in subjects with no or mild postoperative AVVR (OR, 9.7; P < .001).

CONCLUSIONS

Interstage mortality remains high at 12% and is increased with the MBTS compared with the RVPAS if postoperative AVVR is absent or mild. Preterm delivery, anatomic, and socioeconomic factors are also important. Avoiding preterm delivery when possible and close surveillance after Norwood hospitalization for infants with identified risk factors may reduce interstage mortality.

Association of feeding modality with interstage mortality after single-ventricle palliation

OBJECTIVE

Interstage mortality has been reported in 10% to 25% of hospital survivors after single-ventricle palliation. The purpose of this study was to examine the impact of feeding modality at discharge after single-ventricle palliation on interstage mortality.

METHODS

We conducted a retrospective review of all neonates undergoing single-ventricle palliation from January 2003 to January 2010. A total of 334 patients (90%) survived to hospital discharge, comprising the study group. Preoperative, operative, and postoperative variables were examined, including feeding method at discharge. Multivariate Poisson regression models were constructed to estimate the relative risk of interstage mortality.

RESULTS

Of 334 patients, 56 (17%) underwent gastrostomy tube ± Nissen. There was a statistically significant increase in interstage mortality for patients who underwent gastrostomy tube ± Nissen compared with patients who did not (relative risk, 2.38; 95% confidence interval, 1.05-5.40; P = .04]). Of the 278 patients who were not fed via a gastrostomy tube ± Nissen, 190 (68%) were fed with nasogastric feedings and 88 (32%) were fed entirely by mouth. There was no difference in interstage mortality between these 2 groups (relative risk, 0.92; 95% confidence interval, 0.31-2.73; P = .89).

CONCLUSIONS

Neonates undergoing single-ventricle palliation who require gastrostomy tube ± Nissen are at an increased risk of interstage mortality. The need for gastrostomy tube ± Nissen in this population may be a marker for other unmeasured comorbidities that place them at an increased risk of interstage mortality. Discharge with nasogastric feeds does not increase the risk of interstage mortality.

Gastric fundoplication is effective in promoting weight gain in children with severe congenital heart defects

AIM

The aim of this study was to determine outcomes, including weight gain, morbidity, and mortality, of children with severe congenital heart disease who underwent fundoplication (FP) for gastroesophageal reflux disease.

METHODS

An institutional review board-approved retrospective review was conducted on all children with congenital heart disease who underwent FP from 1999 to 2005. Preoperative age, weight, cardiac procedures, postoperative weight, and mortality were extracted from medical records. The Wilcoxon signed rank, Wilcoxon rank sum, and log-rank tests were used; P value less than .05 was significant. All procedures were performed with dedicated cardiac anesthesia personnel with recovery in a cardiac intensive care unit.

RESULTS

Of 112 subjects identified, 37 (33%) had single ventricle (SV) physiology. The most frequent cardiac procedures performed were Norwood (33), pulmonary artery band (11), and systemic pulmonary artery shunt (11). A total of 104 laparoscopic FPs (with 2 conversions to open) and 8 open FPs were performed. The median preoperative age was 3 months, and weight percentile was 1.5%. From baseline, postoperative median weight percentiles increased to 4% at 3 months (P < .001) and to 20% at 5 years postoperatively (P = .004). Single ventricle physiology had no significant effect on outcomes. Postoperative mortality (< or =30 days) was 4.5% (5/112); 5-year survival was 74% (83/112). Five-year survival of SV subjects (59%) was significantly lower (P = .03) than that of the other subjects (81%). No significant difference in survival was seen between SV subjects with FP and all SV patients seen at our center during the study period. Only one death was directly related to antireflux surgery (SV subject). There were 8 patients who had recurrent gastroesophageal reflux disease: 4 were treated with reoperation, and 4 were treated medically.

CONCLUSION

Weight gain in this high-risk population can be expected after antireflux surgery. Mortality is high because of intrinsic disease, especially in the SV population. Fundoplications performed with the assistance of dedicated pediatric cardiac anesthesia personnel followed by recovery in a cardiac intensive care unit is possible with acceptable postoperative morbidity and mortality.

Routine Immunizations and Adverse Events in Infants With Single-Ventricle Physiology

BACKGROUND

Infants with single-ventricle congenital heart defects are at risk of sudden unexpected death. In an effort to decrease the risk of sudden death, some centers have advocated that routine immunizations be deferred in this population. However, it is not known if an association exists between immunizations and adverse events.

METHODS

The present study examined the relationship of routine immunizations with adverse events, which were defined as sudden death or hospital readmission. The diphtheria-tetanus-acellular pertussis (DTaP) vaccine was considered in the analysis. The patient population consisted of infants younger than 9 months old who resided locally and had not yet undergone bidirectional cavopulmonary anastomosis (BCPA). Immunization data were obtained from a mandatory statewide database.

RESULTS

During a 35-month period, 137 patients with single-ventricle physiology were discharged home after neonatal surgery or directly from the newborn nursery. Hypoplastic left heart syndrome (HLHS) was the diagnosis in 58 patients (42%) and was the most common. In the entire cohort, there were four sudden deaths (3%), and 53 patients (38%) had at least one interval hospital admission. Immunization within 48 hours was not associated with adverse events (odds ratio, 1.48; 95% confidence interval, 0.73 to 2.90; p = 0.31). No sudden death events occurred within 48 hours of immunization.

CONCLUSIONS

No association could be identified between routine immunizations and adverse events in infants with single-ventricle physiology. As such, the proposal to alter the immunization regimen in this population does not appear justified.

Retinoid X receptor alpha represses GATA-4-mediated transcription via a retinoid-dependent interaction with the cardiac-enriched repressor FOG-2

Dietary vitamin A and its derivatives, retinoids, regulate cardiac growth and development. To delineate mechanisms involved in retinoid-mediated control of cardiac gene expression, the regulatory effects of the retinoid X receptor alpha (RXR alpha) on atrial naturietic factor (ANF) gene transcription was investigated. The transcriptional activity of an ANF promoter-reporter in rat neonatal ventricular myocytes was repressed by RXR alpha in the presence of 9-cis-RA and by the constitutively active mutant RXR alpha F318A indicating that liganded RXR confers the regulatory effect. The RXR alpha-mediated repression mapped to the proximal 147 bp of the rat ANF promoter, a region lacking a consensus retinoid response element but containing several known cardiogenic cis elements including a well characterized GATA response element. Glutathione S-transferase "pull-down" assays revealed that RXR alpha interacts directly with GATA-4, in a ligand-independent manner, via the DNA binding domain of RXR alpha and the second zinc finger of GATA-4. Liganded RXR alpha repressed the activity of a heterologous promoter-reporter construct containing GATA-response element recognition sites in cardiac myocytes but not in several other cell types, suggesting that additional cardiac-enriched factors participate in the repression complex. Co-transfection of liganded RXR alpha and the known cardiac-enriched GATA-4 repressor, FOG-2, resulted in additive repression of GATA-4 activity in ventricular myocytes. In addition, RXR alpha was found to bind FOG-2, in a 9-cis-RA-dependent manner. These data reveal a novel mechanism by which retinoids regulate cardiogenic gene expression through direct interaction with GATA-4 and its co-repressor, FOG-2.

Evidence for a novel cardiac-enriched retinoid X receptor partner

Recent studies indicate that retinoid-mediated pathways play a pivotal role in cardiac morphogenesis and function. To identify proteins that serve as interacting partners of the retinoid X receptor alpha (RXRalpha) in heart, DNA-protein binding studies were performed with an RXR-responsive element (NRRE-1) derived from the medium chain acyl-CoA dehydrogenase gene promoter and nuclear protein extracts prepared from adult rat heart. NRRE-1 is a pleiotropic RXR-responsive element comprised of three potential recognition sites for class II members of the nuclear receptor superfamily. Gel mobility shift assays performed with an NRRE-1 probe in the absence or presence of bacterially overproduced RXRalpha and nuclear protein extracts prepared from adult rat heart, liver, or brain identified a cardiac-specific, RXR-dependent DNA-protein interaction. The NRRE-1-RXR.cardiac-enriched RXR-interacting protein (CERIP) complex exhibited a distinct mobility compared with NRRE-1-RXR.peroxisome proliferator-activated receptor, NRRE-1-RXR.retinoic acid receptor, or NRRE-1-RXR.thyroid receptor complexes. Mutational analysis demonstrated that two of the three potential binding half-sites of NRRE-1 (an everted repeat separated by an 8-base pair spacer) are required for the NRRE-1-RXR. CERIP interaction. Gel mobility shift assays demonstrated that CERIP interacted with RXRalpha and RXRgamma but not with RXRbeta, indicating a receptor subtypespecific binding preference and suggesting an RXR AB region-dependent interaction. The RXR.CERIP complex did not form on NRRE-1 when a mutant GST-RXRalpha fusion protein lacking the NH(2)-terminal AB region (but containing the receptor dimerization domain) of RXRalpha was added in place of the full-length RXRalpha, confirming a role for the AB region in the RXR. CERIP interaction. DNA-protein cross-linking studies demonstrated that CERIP is a DNA-binding protein of approximately 110 kDa. These results provide evidence for the existence of a cardiac-enriched DNA-binding protein that interacts with RXRalpha via the AB region and suggest a mechanism whereby cardiac retinoid signaling is controlled in an RXR subtype-specific manner.

Hemodynamic data and survival in children with pulmonary hypertension

OBJECTIVES

Using data from a multi-institutional data base, we sought to determine whether hemodynamic data predict duration of survival in children with primary or secondary pulmonary hypertension.

BACKGROUND

Lung transplantation is a therapeutic option for children with pulmonary hypertension. Appropriate timing of lung transplantation requires reliable methods of predicting duration of survival in potential candidates.

METHODS

A regional data base was used to obtain cardiac catheterization data on 50 children with mean pulmonary artery pressure (mPAP) > 25 mm Hg and indexed pulmonary resistance (Rp) > 4.5 Wood units. Data on survival were obtained from the participating centers.

RESULTS

There were 15 patients without congenital heart disease (group 1) and 35 patients with congenital heart disease (group 2) for analysis. Actuarial survival at 1, 2 and 5 years was 86%, 69% and 69% in group 1 and 88% and 77% in group 2, respectively (p = NS). Hemodynamic variables that predicted survival on univariate analysis were mean right atrial pressure (mRAP) (p < 0.0001), mPAP (p = 0.034), Rp (p < 0.0001) and pulmonary flow (p = 0.003), as well as a variable that we generated-mRAP x Rp (p < 0.0001). On multivariate stepwise logistic regression analysis, mRAP x Rp was independently related to survival. A model using mRAP x Rp allows for the estimation of probability of death at 1 and 2 years after catheterization.

CONCLUSIONS

Hemodynamic variables can predict survival in children with pulmonary hypertension in the presence or absence of congenital heart defects. This information can be used to determine the optimal timing of listing for lung transplantation.

Characterization of a T-lymphocyte Epstein-Barr virus/C3d receptor (CD21)

The Epstein-Barr virus/C3d receptor (EBVR-CR2) was detected on three T-lymphoblastoid cell lines. The apparent Mrs of purified EBVR-CR2 of T-cell and B-cell origin were identical. The N-terminal amino acid sequence from the T-cell EBVR-CR2 confirmed the placement of this receptor in a multigene family of complement regulatory proteins. All EBVR-CR2-positive T-cell lines were T6 and T4-T8 antigen positive.

Characterization of the cell surface heterodimer VLA-4 and related peptides

A monoclonal antibody (B-5G10) was produced which specifically recognizes the Mr 150,000/130,000 VLA-4 complex on the surface of human cells. Cross-linking studies indicated that the Mr 150,000 alpha 4 subunit of VLA-4 is in noncovalent 1:1 association with the Mr 130,000 VLA beta subunit. In the absence of cross-linking, the VLA-4 alpha 4 beta subunit complex was easily dissociated, especially in Nonidet P-40 detergent, or at elevated pH (above 8.0). Studies of dissociated subunits showed that B-5G10 recognizes an epitope on the Mr 150,000 alpha 4 subunit of VLA-4, whereas the beta subunit is immunologically identical to the Mr 130,000 beta subunit common to all VLA heterodimers. VLA-4 is widely distributed on hematopoietic cells, including thymocytes, peripheral blood lymphocytes, monocytes, activated T cells, T and B lymphoblastoid cell lines, and myeloid cell lines. However, VLA-4 is only weakly expressed on most adherent cell lines tested. Immunoprecipitates of VLA-4 often contain additional proteins of Mr 80,000 and Mr 70,000. These are probably derived from the Mr 150,000 alpha 4 subunit because: 1) they are both recognized by anti-alpha 4 sera, but not anti-beta sera; 2) the sum of their sizes is equal to the size of alpha 4; 3) they are selectively coexpressed with alpha 4 and not other VLA alpha subunits; 4) the Mr 80,000 protein has an identical NH2-terminal sequence to alpha 4; 5) like alpha 4, the Mr 70,000 and 80,000 peptides can variably associate with the VLA beta subunit; and 6) trypsin appears to cleave the Mr 150,000 alpha 4 subunit into products of Mr 70,000 and 80,000.

Isolation of complementary DNA clones encoding the human lymphocyte glycoprotein T1/Leu-1

The T1/Leu-1/CD5 molecule, a human T-cell surface glycoprotein of relative molecular mass (Mr) 67,000, has been implicated in the proliferative response of activated T cells and in T-cell helper function. A similar involvement in T-cell proliferation has been reported for Ly-1, the murine homologue of T1. Here we report the complete amino-acid sequence of the T1 precursor molecule deduced from complementary DNA clones. The protein contains a classical signal peptide; a 347-amino-acid extracellular segment; a transmembrane region; and a 93-amino-acid intracellular segment. The extracellular segment contains many cysteine residues and is composed of two related structural domains separated by a proline/threonine-rich region. The T1 molecule has structural features characteristic of other receptor molecules.