Anatomical and hemodynamic evaluations of the heart and pulmonary arterial pressure in healthy children residing at high altitude in China

A Computational Model of Ventricular Dimensions and Hemodynamics in Growing Infants

Previous computer models have successfully predicted cardiac growth and remodeling in adults with pathologies. However, applying these models to infants is complicated by the fact that they also undergo normal, somatic cardiac growth and remodeling. Therefore, we designed a computational model to predict ventricular dimensions and hemodynamics in healthy, growing infants by modifying an adult canine left ventricular growth model. The heart chambers were modeled as time-varying elastances coupled to a circuit model of the circulation. Circulation parameters were allometrically scaled and adjusted for maturation to simulate birth through 3 yrs of age. Ventricular growth was driven by perturbations in myocyte strain. The model successfully matched clinical measurements of pressures, ventricular and atrial volumes, and ventricular thicknesses within two standard deviations of multiple infant studies. To test the model, we input 10th and 90th percentile infant weights. Predicted volumes and thicknesses decreased and increased within normal ranges and pressures were unchanged. When we simulated coarctation of the aorta, systemic blood pressure, left ventricular thickness, and left ventricular volume all increased, following trends in clinical data. Our model enables a greater understanding of somatic and pathological growth in infants with congenital heart defects. Its flexibility and computational efficiency when compared to models employing more complex geometries allow for rapid analysis of pathological mechanisms affecting cardiac growth and hemodynamics.

Cognitive Function Mainly Shaped by Socioeconomic Status Rather Than Chronic Hypoxia in Adolescents at High Altitude

Yu, Linyang, Jinqing Feng, Chen Zhou, Xiaohan Zhu, Xiaobin Lou, Jian Yang, Haiying Qi, and Jia Li. Cognitive function mainly shaped by socioeconomic status rather than chronic hypoxia in adolescents at high altitude. High Alt Med Biol. 23:000-000, 2022. Background: The study evaluated cognitive function in relation to the changes in brain tissue oxygenation in three groups of high school students from different socioeconomic regions including Tibetans in Jiuzhi and Lhasa (both at 3,600 m), and Han in Beijing (44 m). Methods: Jiuzhi, Lhasa, and Beijing Group included 21 Tibetans, 24 Tibetans, and 23 Han, respectively. Wechsler Intelligence Scale was used for cognitive evaluation. Functional near infrared spectroscopy was used to measure the changes of oxygenated hemoglobin (oxy-Hb) during the cognitive assessment. Gross domestic product (GDP) was used to indicate the socioeconomic status. Results: All the cognitive scores were significantly lower in the two high altitude groups compared with the Beijing Group (p < 0.001). The scores in Jiuzhi Group were significantly lower compared with the Lhasa Group (p < 0.001). The changes in oxy-Hb in channels 6 and 15 in both high-altitude groups were significantly greater compared with the Beijing Group (p < 0.05), without significant difference between the two high-altitude groups. GDP was significantly correlated with all the scores (p < 0.001), but not altitude. Conclusions: Cognitive impairment occurs in adolescents at high altitude, being severer in Jiuzhi Group compared with the Lhasa Group. The lower performance in both high-altitude groups require greater brain activity over-compensated by cerebral oxygen delivery as indicated by the changes in oxy-Hb. The cognitive scores were significantly correlated with GDP rather than altitude. Cognitive function in adolescents at high altitude is not limited by chronic hypoxia, but mainly shaped by socioeconomic determinants.

Newborn screening for congenital heart disease using echocardiography and follow-up at high altitude in China

BACKGROUND

Pulse oximetry screening for critical congenital heart disease (CHD) is inapplicable to high altitude due to the variedly decreased arterial saturations and rare complex CHD. We examined the incidence and spectrum of CHD in newborns using echocardiography at high altitude and followed up their outcomes.

METHODS

A total of 1337 babies were studied. Echocardiography was performed in 1002 asymptomatic newborns (3-5 days). In the same period, retrospectively studied 394 newborns (≤2 days) admitted to the NICU where echocardiograph was performed in 335. In both groups, follow-up was made at 1-3, 6 and 12-18 months.

RESULTS

The incidence of CHD in asymptomatic newborns was 27.8%, consisting secundum atrial septal defect (ASD) [175 (62.7%)], patent ductus arteriosus (PDA) [61 (21.9%)], ventricular septal defect (VSD) [8 (2.9%)] and multiple defects [35 (12.6%)]. And 19.4% in NICU patients with similar spectrum, except for 2 with complex CHD who died before discharge. By 12-18 months of follow-up, 30% of CHD remained open. Thirteen patients developed mild to severe pulmonary arterial hypertension (PAH), and 2 of them died of heart failure.

CONCLUSIONS

The incidence of CHD in newborns at high altitude is about 20 times higher than that at low altitude, consisting mostly of simple forms with left to right shunt, with rare complex CHD. By 12-18 months, the incidence of CHD is still about 10 times higher than that at low altitude. About 8% patients developed PAH or death. Follow-up must be reinforced in order to provide early intervention and prevent from PAH or death.