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Background: A subset of patients who develop post-surgical heart block have recovery of atrioventricular node function. Factors predicting recovery are not understood. We investigated our centre’s incidence of post-surgical heart block and examine factors associated with recovery of atrioventricular node function. Methods: We conducted a single-centre retrospective study of patients 0 – 21 years who underwent cardiac surgery between January 2010 and December 2019 and experienced post-operative heart block. Data including patient and clinical characteristics and operative variables were collected and analysed. Results: Of 6333 surgical hospitalisations, 128 (2%) patients developed post-operative heart block. Of the 128 patients, 90 (70%) had return of atrioventricular node function, and 38 (30%) had pacemaker placement. Of the 38 patients who underwent pacemaker placement, 6 (15.8%) had recovery of atrioventricular node function noted on long-term follow-up. Median time from onset of heart block to late atrioventricular node recovery was 13 days (Interquartile range: 5 – 117). Patients with single-ventricle physiology (p = 0.04), greater weight (p = 0.03), and shorter cardiopulmonary bypass time (p = 0.015) were more likely to have recovery. The use of post-operative steroids was similar between all groups (p = 0.445). Infectious or wound complications were similar between pacemaker groups (p = 1). Conclusions: Two per cent of patients who underwent congenital cardiac surgery developed post-operative heart block, and 0.6% underwent pacemaker placement. Early recovery of atrioventricular node was associated with greater weight at the time of surgery, single-ventricle physiology, and shorter cardiopulmonary bypass time. Late recovery of atrioventricular node conduction following pacemaker placement occurred in 15.8% of patients.

Introduction: Absent ductus arteriosus (ADA) is a poorly described feature associated with tetralogy of Fallot (TOF). We compare characteristics and outcomes of neonates with symptomatic TOF (sTOF) with ADA to those with a ductus arteriosus (DA). Hypothesis: We hypothesized: neonates with sTOF and ADA would have similar outcomes to those born with a DA, and a small portion of the ADA cohort would have critically-deficient pulmonary blood flow (CDPBF). Methods: Consecutive neonates with sTOF who underwent intervention during the neonatal period from 2005—2017 were identified from the Congenital Cardiac Research Collaborative. Those with DA on echocardiogram performed on the first day of life or on fetal echocardiogram were identified and compared to those with ADA. ADA neonates who required ECMO or intervention to augment PBF on the first day of life were defined as having CDPBF. Patient characteristics and outcomes were compared between DA and ADA groups. Results: Among 519 neonates, 460 (89%) had a DA and 59 (11%) had ADA. ADA neonates were more likely to carry a genetic or syndromic diagnosis, had smaller branch PA sizes, and were more likely to receive a transannular patch compared to those with a DA. Despite this, reintervention rates were similar (data not shown), and there was only a small difference in mortality that did not reach statistical significance. Of ADA neonates, 7/59 (12%) had CDPBF. Compared to ADA neonates without CDPBF, those with CDPBF had lower baseline oxygen saturation (58 vs 87%, p=0.031) and smaller pulmonary valve (PV) annular z-score (-2.9 vs -2.5, p=0.015) with similar reintervention rates and mortality. Conclusion: ADA is relatively common in sTOF. Despite higher rates of comorbidities, mid-term reintervention rates and mortality are similar to those with DA. CDPBF is a rare, high-risk feature of infants with sTOF and ADA. Smaller PV size may be a marker of CDPBF. Future work should focus on prenatal factors to identify fetuses with TOF, ADA and CDPBF.

Introduction: A subset of patients who develop post-surgical heart block have recovery of atrioventricular-node function. Factors predicting recovery are not understood. We sought to investigate our center’s incidence of post-surgical heart block and examine factors associated with recovery of atrioventricular-node function. Methods: Patients 0 – 21 years who underwent cardiac surgery between January 2010 – December 2019 at a free-standing children’s hospital and experienced postoperative heart block were included. Demographics, clinical and operative variables were analyzed. Results: Of 6333 surgical hospitalizations, 128 (2%) patients were included. Of the 128 patients included, 90 (70%) had return of atrioventricular-node function, and 38 (30%) had permanent pacemaker placement. Of the 38 patients who underwent pacemaker placement, 6 (15.8%) had recovery of atrioventricular-node function noted on long-term follow-up. Median time to from onset of heart block to late atrioventricular-node recovery was 13 days (IQR 5 – 117). Patients with single-ventricle physiology ( p = 0.04), greater weight ( p = 0.03) and shorter cardiopulmonary bypass time ( p =0.015) were more likely to have recovery. The use of postoperative steroids was similar between all groups ( p = 0.445). Infectious or wound complications were similar between pacemaker groups ( p = 1). Conclusions: Two percent of patients who underwent cardiac surgery developed postoperative heart block, and 0.6% underwent pacemaker placement. Early recovery of atrioventricular-node was associated with greater weight at time of surgery, single-ventricle physiology and shorter cardiopulmonary bypass time. Late recovery of atrioventricular-node conduction following pacemaker placement occurred in 15.8% of patients.

Background Pediatric patients with atrioventricular valve disease have limited options for prosthetic valve replacement in sizes15 mm. Based on successful experience with the stented bovine jugular vein graft (Melody valve) in the right ventricular outflow tract, the prosthesis has been modified for surgical valve replacement in pediatric patients with atrioventricular dysfunction with the intention of subsequent valve expansion in the catheterization laboratory as the child grows. Methods and Results A multicenter, retrospective cohort study was performed among patients who underwent atrioventricular valve replacement with Melody valve at 17 participating sites from North America and Europe, including 68 patients with either mitral (n=59) or tricuspid (n=9) replacement at a median age of 8 months (range, 3 days to 13 years). The median size at implantation was 14 mm (range, 9-24 mm). Immediately postoperatively, the valve was competent with low gradients in all patients. Fifteen patients died; 3 patients underwent transplantation. Nineteen patients required reoperation for adverse outcomes, including valve explantation (n=16), left ventricular outflow tract obstruction (n=1), permanent pacemaker implantation (n=1), and paravalvular leak repair (n=1). Twenty-five patients underwent 41 episodes of catheter-based balloon expansion, exhibiting a significant decrease in median gradient ( P0.001) with no significant increase in grade of regurgitation. Twelve months after implantation, cumulative incidence analysis indicated that 55% of the patients would be expected to be free from death, heart transplantation, structural valve deterioration, or valve replacement. Conclusions The Melody valve is a feasible option for surgical atrioventricular valve replacement in patients with hypoplastic annuli. The prosthesis shows acceptable short-term function and is amenable to catheter-based enlargement as the child grows. However, patients remain at risk for mortality and structural valve deterioration, despite adequate early valvular function. Device design and implantation techniques must be refined to reduce complications and extend durability. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT02505074.

To understand the relationship between the dynamics of tropical rain forests and the population processes of individual species, data are needed on the rates at which trees grow, die, and establish. Data on the family Moraceae have been extracted from long-term forestry studies in Sarawak, on the northwest coast of Borneo, an area at the center of species richness of Old World tropical forests. These data can also be combined with forest maps and logging studies to investigate the importance of competition and disturbance in controlling tree growth. Tree populations of Moraceae species had mean annual diameter increments of between 0.4 and 3 mm/yr. Growth rates increased two to six times in the 1 st and 2nd yr following (selective) logging, but began to decline somewhat in the 3 rd and 4th yr. Growth rate variation among trees in a population was considerable, with most trees showing little or no growth, and a few, high growth rates. Saplings of Artocarpus species increased in diameter at the same mean rate as adult trees. Annual mortality rates were low in primary forest, typically

(1) Liana (climber or woody vine) abundance and climbing habitats were studied in primary dipterocarp forest in Lambir National Park, Sarawak. (2) Sample plots of 01 ha were established on the upper slopes of a broad ridge at altitudes of about 100-140 m and in an adjacent valley at an altitude of approximately 50 m. Five plots were selected at random in each area. The diameters of all lianas > 1 cm dbh and trees > 10 cm dbh were measured and the proportion of trees infested with lianas was recorded. In a 0 04 ha area in each plot we identified all lianas > 1 cm dbh, recorded on which trees the lianas were growing, and noted how the lianas attached to their host trees. Vines 2 cm ha-' in the valley and on the hilltop, respectively. Upright (self-supporting) liana seedlings were also approximately twice as abundant in the valley. (4) A total of seventy-nine woody liana species representing twenty-four familes were recorded, with thirty-nine species in the ridge plots and fifty-three species in the valley plots. Only fourteen species were common to both areas. (5) Approximately half of the trees > 20 cm dbh were liana-infested in both the valley and hilltop plots. Trees supporting more than one liana were more numerous in the valley. The average canopy liana connected the crowns of 1 4 trees > 20 cm dbh in both areas. (6) The influences of soil fertility and frequency of forest disturbance on the abundance of lianas are discussed with reference to data from other tropical forests.