Identification of Six Pathogenic Genes for Tibetan Familial Ventricular Septal Defect by Whole Exome Sequencing

INTRODUCTION

Ventricular septal defect (VSD) is the most common congenital heart malformation in children. This study aimed to investigate potential pathogenic genes associated with Tibetan familial VSD.

METHODS

Whole genomic DNA was extracted from eight Tibetan children with VSD and their healthy parents (a total of 16 individuals). Whole-exome sequencing was performed using the Illumina HiSeq platform. After filtration, detection, and annotation, single nucleotide variations and insertion-deletion markers were examined. Comparative evaluations using the Sorting Intolerant from Tolerant, PolyPhen V2, Mutation Taster, and Combined Annotation Dependent Depletion databases were conducted to predict harmful mutant genes associated with the etiology of Tibetan familial VSD.

RESULTS

A total of six missense mutations in genetic disease-causing genes associated with the development of Tibetan familial VSD were identified: activin A receptor type II-like 1 (c.652 C > T: p.R218 W), ATPase cation transporting 13A2 (c.1363 C > T: p.R455 W), endoplasmic reticulum aminopeptidase 1 (c.481 G > A: p.G161 R), MRI1 (c.629 G > A: p.R210Q), tumor necrosis factor receptor-associated protein 1 (c.224 G > A: p.R75H), and FBN2 (c.2260 G > A: p.G754S). The Human Gene Mutation Database confirmed activin A receptor type II-like 1, MRI1, and tumor necrosis factor receptor-associated protein 1 as pathogenic mutations, while FBN2 was classified as a probable pathogenic mutation.

CONCLUSIONS

This novel study directly screens genetic variations associated with Tibetan familial VSD using whole-exome sequencing, providing new insights into the pathogenesis of VSD.

SOX7 deficiency causes ventricular septal defects through its effects on endocardial-to-mesenchymal transition and the expression of Wnt4 and Bmp2

SOX7 is a transcription factor-encoding gene located in a region on chromosome 8p23.1 that is recurrently deleted in individuals with ventricular septal defects (VSDs). We have previously shown that Sox7-/- embryos die of heart failure around E11.5. Here, we demonstrate that these embryos have hypocellular endocardial cushions with severely reduced numbers of mesenchymal cells. Ablation of Sox7 in the endocardium also resulted in hypocellular endocardial cushions, and we observed VSDs in rare E15.5 Sox7flox/-;Tie2-Cre and Sox7flox/flox;Tie2-Cre embryos that survived to E15.5. In atrioventricular explant studies, we showed that SOX7 deficiency leads to a severe reduction in endocardial-to-mesenchymal transition (EndMT). RNA-seq studies performed on E9.5 Sox7-/- heart tubes revealed severely reduced Wnt4 transcript levels. Wnt4 is expressed in the endocardium and promotes EndMT by acting in a paracrine manner to increase the expression of Bmp2 in the myocardium. Both WNT4 and BMP2 have been previously implicated in the development of VSDs in individuals with 46,XX sex reversal with dysgenesis of kidney, adrenals and lungs (SERKAL) syndrome and in individuals with short stature, facial dysmorphism and skeletal anomalies with or without cardiac anomalies 1 (SSFSC1) syndrome, respectively. We now show that Sox7 and Wnt4 interact genetically in the development of VSDs through their additive effects on endocardial cushion development with Sox7+/-;Wnt4+/- double heterozygous embryos having hypocellular endocardial cushions and perimembranous and muscular VSDs not seen in their Sox7+/- and Wnt4+/- littermates. These results provide additional evidence that SOX7, WNT4 and BMP2 function in the same pathway during mammalian septal development and that their deficiency can contribute to the development of VSDs in humans.

Effectiveness of the critical congenital heart disease screening program for early diagnosis of cardiac abnormalities in newborn infants

Objectives:

To evaluate the effectiveness of critical congenital heart disease (CCHD) screening program for early diagnosis of cardiac anomalies in newborn infants.

Methods:

This is a hospital-based prospective cross-sectional study conducted in the Pediatric and Neonatology Department, King Fahad Hospital at Albaha, Saudi Arabia, between February 2016 and February 2017.

Results:

We screened 2961 (95.4%) of 3103 patients in a nursery unit; 142 (4.6%) patients were not screened. The test was positive in 114 (3.9%) patients and negative in 2847 (96.1%). There were 94 (3.2%) false positives and 20 (0.7%) true positives. Critical cardiac defects were diagnosed in 7 (0.2%) patients of all screened infants, and severe pulmonary hypertension was diagnosed in 13 (0.4%) patients. True negative results were found in 2841(96%) patients, and no cardiac defect was diagnosed, whereas false negative results were seen in 6 (0.2%) patients diagnosed with ventricular septal defect. The sensitivity was 77%, and the specificity was very high at 97%, with a positive predictive value of 18%, and a negative predictive value of 99.8% (95% confidence interval 13.78-19.18, p=0.0001).

Conclusion:

Pulse oximetry was found to be easy, safe, sensitive, and highly specific for diagnosis of CCHD.

Near-Infrared Spectroscopy Monitoring of Brain Oxygen in Infant Cardiac Surgery

The use of near-infrared spectroscopy for monitoring cerebral oxygenation during different types of cardiopulmonary bypass was evaluated in 24 patients aged 5 to 13 months. They underwent open-heart surgery under cardiopulmonary bypass with moderate hypothermia, deep hypothermia with low flow, or deep hypothermia with circulatory arrest. Near-infrared spectroscopy data were compared with electroencephalography and biochemical indicators (neuron-specific enolase, lactate). Near-infrared spectroscopy data showed no correlation with biochemical indicators in patients undergoing cardiopulmonary bypass with moderate hypothermia or deep hypothermia with low flow. In the deep hypothermia with circulatory arrest group, the oxygenated hemoglobin signal declined to a nadir during circulatory arrest. The period from reaching the nadir until reperfusion and the minimum values of oxygenated hemoglobin correlated closely with increases in neuron-specific enolase and lactate. All patients with an oxygenated hemoglobin-signal nadir time < 35 min were free from behavioral evidence of brain injury. The oxygenated hemoglobin-signal nadir time may be useful in predicting the safe duration of circulatory arrest.

Decreased Yes-Associated Protein-1 (YAP1) Expression in Pediatric Hearts with Ventricular Septal Defects

Background

Ventricular septal defects (VSDs) are the most common and simplest type of congenital heart diseases (CHDs). Animal studies have suggested that the downregulation of Yes-associated protein 1 (YAP1) during embryonic development causes VSD-associated CHDs. However, how YAP1 contributes to isolated VSD (iVSD) is unclear.

Methods and Results

Twenty right atrial specimens were obtained from iVSD patients during routine congenital cardiac surgery and we assessed YAP1 expression in these specimens. For controls, six right atrial specimens were obtained from normal hearts of children without heart disease, three of whom died from cerebral palsy, and three who underwent heart transplants. YAP1 mRNA and protein levels and nuclear localization were significantly reduced in iVSD specimens compared to normal heart specimens. Concomitantly, mRNA levels of YAP1 downstream targets CTGF and AXL were also significantly decreased in iVSD specimens. Although Ki67-positive cardiomyocytes in iVSD specimens were comparable to normal heart specimens, Ki67-positive non-cardiomyocytes were significantly decreased.

Conclusions

YAP1 expression was markedly decreased in hearts of iVSD children. Given the important role of YAP1 during heart development, downregulation of YAP1 expression may contribute to iVSD and affect the proliferation of non-cardiomyocytes.

ASK1 mediates the teratogenicity of diabetes in the developing heart by inducing ER stress and inhibiting critical factors essential for cardiac development

Maternal diabetes in mice induces heart defects similar to those observed in human diabetic pregnancies. Diabetes enhances apoptosis and suppresses cell proliferation in the developing heart, yet the underlying mechanism remains elusive. Apoptosis signal-regulating kinase 1 (ASK1) activates the proapoptotic c-Jun NH2-terminal kinase 1/2 (JNK1/2) leading to apoptosis, suggesting a possible role of ASK1 in diabetes-induced heart defects. We aimed to investigate whether ASK1 is activated in the heart and whether deleting the Ask1 gene blocks diabetes-induced adverse events and heart defect formation. The ASK1-JNK1/2 pathway was activated by diabetes. Deleting Ask1 gene significantly reduced the rate of heart defects, including ventricular septal defects (VSDs) and persistent truncus arteriosus (PTA). Additionally, Ask1 deletion diminished diabetes-induced JNK1/2 phosphorylation and its downstream transcription factors and endoplasmic reticulum (ER) stress markers. Consistent with this, caspase activation and apoptosis were blunted. Ask1 deletion blocked the increase in cell cycle inhibitors (p21 and p27) and the decrease in cyclin D1 and D3 and reversed diabetes-repressed cell proliferation. Ask1 deletion also restored the expression of BMP4, NKX2.5, and GATA5, Smad1/5/8 phosphorylation, whose mutations or deletion result in reduced cell proliferation, VSD, and PTA formation. We conclude that ASK1 may mediate the teratogenicity of diabetes through activating the JNK1/2-ER stress pathway and inhibiting cell cycle progression, thereby impeding the cardiogenesis pathways essential for ventricular septation and outflow tract development.

Down-regulation of EBAF in the heart with ventricular septal defects and its regulation by histone acetyltransferase p300 and transcription factors smad2 and cited2

As a NODAL pathway inhibitor, EBAF plays a critical role during mammalian cardiac development. As recent tests that have been conducted on gene-targeted mice indicate, its expression is frequently altered where cardiac defects are present. We aimed to explore the EBAF expression pattern and molecular mechanism of EBAF gene for VSD genesis. In this report, we show that the average expression of EBAF in the disease tissues of VSD patients was lower than the expression in normal fetuses without VSD. Further study showed that the expression pattern of EBAF was potentially involved in cardiomyocyte apoptosis by Annexin-V and RT-PCR assays. We also found that abnormal activation of NODAL-PITX2C pathway was associated with down-regulation of EBAF. By luciferase reporter assays, we find that EBAF expression is mediated by transcriptional factors smad2 and cited2. In addition, ChIP assays showed that histone acetyltransferase p300 is involved in the activation of EBAF through inducing hyperacetylation of histone H4 at the EBAF promoter. Co-immunoprecipitation also indicates that the expression of EBAF is regulated by a transcriptional complex including p300, smad2, and cited2. This study revealed a novel regulator mechanism of EBAF, which may be a potential molecular target for halting the onset of VSDs. They also indicate that smad2, cited2, and p300 may play important roles in modulating the confirmation of ventricular septal defects.

A hypomorphic lsd1 allele results in heart development defects in mice

Lysine-specific demethylase 1 (Lsd1/Aof2/Kdm1a), the first enzyme with specific lysine demethylase activity to be described, demethylates histone and non-histone proteins and is essential for mouse embryogenesis. Lsd1 interacts with numerous proteins through several different domains, most notably the tower domain, an extended helical structure that protrudes from the core of the protein. While there is evidence that Lsd1-interacting proteins regulate the activity and specificity of Lsd1, the significance and roles of such interactions in developmental processes remain largely unknown. Here we describe a hypomorphic Lsd1 allele that contains two point mutations in the tower domain, resulting in a protein with reduced interaction with known binding partners and decreased enzymatic activity. Mice homozygous for this allele die perinatally due to heart defects, with the majority of animals suffering from ventricular septal defects. Molecular analyses revealed hyperphosphorylation of E-cadherin in the hearts of mutant animals. These results identify a previously unknown role for Lsd1 in heart development, perhaps partly through the control of E-cadherin phosphorylation.

Versican/PG-M is essential for ventricular septal formation subsequent to cardiac atrioventricular cushion development

Versican (Vcan)/proteoglycan (PG)-M is a large chondroitin sulfate proteoglycan which forms a proteoglycan/hyaluronan (HA) aggregate in the extracellular matrix (ECM). We tried to generate the Vcan knockout mice by a conventional method, which resulted in mutant mice Vcan(Δ3/Δ3) whose Vcan lacks the A subdomain of the G1 domain. The Vcan knockout embryos died during the early development stage due to heart defects, but some Vcan(Δ3/Δ3) embryos survived through to the neonatal period. The hearts in Vcan(Δ3/Δ3) newborn mice showed normal cardiac looping, but had ventricular septal defects. Their atrioventricular canal (AVC) cushion was much smaller than those of wild-type (WT) embryos, and the extracellular space for cardiac jelly was narrow. The Vcan deposition in the Vcan(Δ3/Δ3) AVC cushion had decreased, whereas the HA deposition was maintained and condensed. In the tip of ventricular septa, both Vcan and HA had decreased. The cell proliferation based on the number of Ki67-positive cells had remarkably increased in both the AVC cushion and ventricular septa, compared with that of WT embryos. Vcan(Δ3/Δ3) seemed to have endocardial and mesenchymal mixed characteristics. When the ex vivo explant culture of these regions was performed on the collagen gel, hardly any migration to make sufficient space for the ECM construction was apparent. Our results suggest that the proteoglycan aggregates are necessary in both the AVC cushion and ventricular septa to fuse interventricular septa, and the Vcan A subdomain plays an essential role for the interventricular septal formation by constituting the proteoglycan aggregates.

Molecular signatures of cardiac defects in Down syndrome lymphoblastoid cell lines suggest altered ciliome and Hedgehog pathways

Forty percent of people with Down syndrome exhibit heart defects, most often an atrioventricular septal defect (AVSD) and less frequently a ventricular septal defect (VSD) or atrial septal defect (ASD). Lymphoblastoid cell lines (LCLs) were established from lymphocytes of individuals with trisomy 21, the chromosomal abnormality causing Down syndrome. Gene expression profiles generated from DNA microarrays of LCLs from individuals without heart defects (CHD⁻; n = 22) were compared with those of LCLs from patients with cardiac malformations (CHD⁺; n = 21). After quantile normalization, principal component analysis revealed that AVSD carriers could be distinguished from a combined group of ASD or VSD (ASD+VSD) carriers. From 9,758 expressed genes, we identified 889 and 1,016 genes differentially expressed between CHD⁻ and AVSD and CHD⁻ and ASD+VSD, respectively, with only 119 genes in common. A specific chromosomal enrichment was found in each group of affected genes. Among the differentially expressed genes, more than 65% are expressed in human or mouse fetal heart tissues (GEO dataset). Additional LCLs from new groups of AVSD and ASD+VSD patients were analyzed by quantitative PCR; observed expression ratios were similar to microarray results. Analysis of GO categories revealed enrichment of genes from pathways regulating clathrin-mediated endocytosis in patients with AVSD and of genes involved in semaphorin-plexin-driven cardiogenesis and the formation of cytoplasmic microtubules in patients with ASD-VSD. A pathway-oriented search revealed enrichment in the ciliome for both groups and a specific enrichment in Hedgehog and Jak-stat pathways among ASD+VSD patients. These genes or related pathways are therefore potentially involved in normal cardiogenesis as well as in cardiac malformations observed in individuals with trisomy 21.

Immunohistochemical detection of uPA, PAI-1, and alpha-SMA in aneurysms of patients with perimembranous ventricular septal defect

BACKGROUND AND AIM OF THE STUDY

A perimembranous ventricular septal defect (PMVSD) may be partially or completely occluded by aneurysms that originate from the tricuspid valve leaflets, though the exact mechanisms of closure remain unknown. It is hypothesized that valvar interstitial cells (VICs) mediate extracellular matrix (ECM) remodeling in aneurysms via the secretion of a serine proteinase and its inhibitor.

METHODS

The functional characteristics of VICs in 15 aneurysms and in four normal tricuspid valve leaflets obtained at autopsy were evaluated by detecting the expression of urokinase plasminogen activator (uPA), plasminogen activator inhibitor-1 (PAI-1), and alpha-smooth muscle actin (alpha-SMA) in the specimens, using immunohistochemical methods.

RESULTS

uPA and alpha-SMA were recognized predominantly in VICs located mainly in regions adjacent to the endothelium and smooth muscle cells of blood vessels. PAI-1 was identified in VICs found mainly in granulation tissues, and in endothelial cells. Two types of granulation tissue (myxoid and fibrous tissue) were associated with aneurysms. Nine aneurysms expressed a high uPA activity and a low PAI-1 activity (uPA/PAI-1 ratio 1.78), while six aneurysms expressed a low uPA activity and a high PAI-1 activity (uPA/PAI-1 ratio 0.14).

CONCLUSION

The expression of uPA, PAI-1 and alpha-SMA in VICs suggests that interactions among these molecules contribute to ECM remodeling during aneurysm formation and development. This provides a potential mechanism for defect closure in patients with PMVSD.

Investigation of somatic NKX2-5 mutations in congenital heart disease

BACKGROUND

Reports of somatic mutations found in hearts with cardiac septal defects have suggested that these mutations are aetiologic in pathologic cardiac development. However, the hearts in these reports had been fixed in formalin for over 22 years. Because of the profound implication of this finding, we attempted to replicate it using fresh frozen tissue obtained in the current era from 28 patients with septal defects who underwent cardiac surgery and who were enrolled in our congenital heart disease tissue bank.

METHODS

Our cohort included patients with atrial septal defects (ASD, n = 13), ventricular septal defects (VSD, n = 5), and atrioventricular canal defects (AVCD, n = 10). Cardiac tissue samples were collected both from diseased tissue located immediately adjacent to the defect and from anatomically normal tissue located at a site remote from the defect (right atrial appendage). Tissue samples were immediately frozen in liquid nitrogen and stored at -80 degrees C. Genomic DNA was isolated and amplified using the same methodology described in the previously published reports. 42 pathologic cardiac tissue samples were sequenced.

RESULTS

One non-synonymous germline sequence variant was identified in one patient. Two synonymous germline sequence variants were identified in two separate patients. A common single nucleotide polymorphism (SNP) was identified in 16 patients. Based on the incidence of somatic mutations described in the previously published reports, our study was adequately powered to replicate the previous studies. No evidence of somatic mutations was found in this study.

CONCLUSION

Somatic mutations in NKX2-5 do not represent an important aetiologic pathway in pathologic cardiac development in patients with cardiac septal defects.

Laparoscopic Gastrostomy in Children with Congenital Heart Disease

AIM

The aim of this study was to study the type and frequency of complications and change in weight after a laparoscopic gastrostomy procedure in 31 children with congenital heart disease, comparing patient groups of children with univentricular and biventricular circulation, and with completed and uncompleted cardiac surgery.

METHODS

The method used was that of a retrospective study of all 31 children with congenital heart disease who underwent a laparoscopic gastrostomy at our center from 1995 to 2004.

MAIN OUTCOME MEASURES

Postoperative complications and body weight changes during follow-up were the main outcome measures used in this study.

RESULTS

Minor stoma-related problems were common in both groups. Two severe complications requiring an operative intervention occurred in the univentricular circulation group. Weight was normal at birth, low at the time of the gastrostomy procedure, and did not catch up completely during the follow-up period of a mean of 20 months. There were no significant differences regarding mean weight gain between the groups.

CONCLUSIONS

The complication rate after the laparoscopic gastrostomy procedure was higher in our patient group, compared to previously studied children with various diseases. Comparisons regarding mean weight gain between the groups showed no significant differences. The mean weight gain was low, suggesting that the energy expenditure in this patient group of children with severe congenital heart disease may be even higher than previously assumed.

Down regulation of IGF-I and IGF-IR gene expression in right atria tissue of ventricular septal defect infants with right atria hypoxemia

BACKGROUND

Our previous studies showed serum insulin-like growth factor-I (IGF-I) concentrations significantly decreased in infants with congenital ventricular septal defect (VSD) and that they were associated with increased concentrations of growth hormone. In order to confirm the relationship between IGF-I axis and VSD, we further compared the IGF-I and insulin-like growth factor-I receptor(IGF-IR) gene expressions in the cardiac tissue of VSD infants.

METHODS

Right atrium biopsies of 27 infants were studied. Five infants not having VSD were classified as controls (Group I). Twenty VSD patients were then divided into 2 groups according to their shunting magnitude index (level of pulmonary vascular resistance compared with systemic vascular resistance, Qp/Qs). VSD patients with minor shunts (Qp/Qs<1.7) were classified as Group II; VSD patients with larger shunts (Qp/Qs> or =2) as Group III. Besides, seven tetralogy of fallot (TOF) with shunt (Qp/Qs>4) infants were classified as the Group IV. A non-radioactive DIG-RNA probe detection system, western blotting and immunohistochemistry were used to detect the gene expression levels and protein products of IGF-I and IGF-IR in the right atrium samples of VSD infants.

RESULTS

The relative protein levels of IGF-I were 0.96+/-0.05, 0.43+/-0.03, 0.15+/-0.04, 0.12+/-0.03 and IGF-IR were 0.80+/-0.08, 0.57+/-0.03, 0.38+/-0.02, 0.24+/-0.04 in the right atrium of 4 group patients. The relative mRNA levels of IGF-I were 0.95+/-0.01, 0.41+/-0.03, 0.29+/-0.05, 0.15+/-0.01 and IGF-IR were 0.85+/-0.05, 0.56+/-0.03, 0.17+/-0.01, 0.18+/-0.01, respectively. There was a significantly greater but more gradual decrease in protein levels and in mRNA levels of IGF-I and IGF-IR in Group II (p<0.05), Group III and IV (p<0.01) than in Group I. The results of immunohistochemistry also demonstrated a similar decrease in VSD patients. In addition, the decrease of mRNA and protein levels in IGF-I/IGF-IR of VSD patients show related to the saturation of oxygen in the right atrium and the ratio of systolic right ventricular pressure to left ventricular pressure.

CONCLUSION

We further confirmed the down regulation of IGF-I/IGF-IR in cardiac tissue of VSD infants and the decrease to be associated with shunt magnitude and the severity of hypoxemia in the cardiac chamber of VSD.

Vasoconstrictor administration during cardiopulmonary bypass affects acid-base balance in infants and children

BACKGROUND

In experimental reports, blood flow redistribution occurred during cardiopulmonary bypass (CPB) and perfusion pressure was restored by vasoconstrictor administration without improving splanchnic perfusion. The influence of vasoconstrictor administration during CPB was clinically examined.

MATERIALS AND METHODS

Twenty-two consecutive pediatric CPB cases of ventricular septal defect without blood transfusion were divided into two groups, depending upon whether a vasoconstrictor was administered during CPB or not (n = 7 vs. 15). Bypass flow and systemic perfusion pressure during CPB were maintained at 2.5 L/m(2)/min and not lower than 30 mm Hg by vasoconstrictor administration, respectively.

RESULTS

Although preoperative state and CPB conditions were comparable between the two groups, more sodium bicarbonate was administered (P < 0.05); duration from the operation to extubation was longer (P < 0.05); and bowel movement occurred later in the vasoconstrictor-administered group than in the control group.

CONCLUSIONS

Vasoconstrictor administration during CPB may deteriorate the acid-base balance and the postoperative state in infants and children.

Basal metabolic state of hearts of patients with congenital heart disease: the effects of cyanosis, age, and pathology

BACKGROUND

Experimental models have established numerous myocardial metabolic changes with chronic hypoxia and maturation. We conducted this study to specifically look at the effects of cyanosis, age, and pathology upon the basal metabolic state of the immature human heart.

METHODS

One hundred and eighty-one pediatric patients (37 cyanotic, 144 acyanotic) undergoing open heart surgery were recruited. A myocardial biopsy was collected before ischemia and analyzed for adenine nucleotides, purines, and lactate. The effect of cyanosis was estimated by an analysis of age-matched pairs of children with either ventricular septal defects or tetralogy of Fallot, and by multiple regression modeling. The effects of age and pathology were estimated in acyanotic children also by multiple regression modeling (adjustments were made for baseline differences).

RESULTS

The only effect of cyanosis was for lactate where the paired t test, and unadjusted and adjusted regression analyses were all consistent (ranging from 1.33 to 1.48 times higher in cyanotic than acyanotic children). The concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) declined with age, whereas the ATP/ADP ratio increased; these associations remained significant even in the adjusted regression analysis. None of the effects of acyanotic pathology were highly significant (p < 0.01), implying that few important metabolic differences were attributable to pathology.

CONCLUSIONS

Cyanosis and age are important factors that determine the basal metabolic state of the pediatric heart. Cyanotic patients have higher myocardial lactate concentrations, whereas young age is associated with lower ATP/ADP ratios and higher adenine nucleotide levels.

[Expression and variation of angiotensin II type 1 receptor on vascular smooth muscle cells of systemic and pulmonary circulations in experimental ventricular septal defect in pigs]

OBJECTIVE

To investigate the expression of angiotensin II type 1 receptor (AT1R) on the vascular smooth muscle cells (VSMC) of both systemic and pulmonary circulations and their variation caused by intracardiac left to right shunting using an animal model of the ventricular septal defect (VSD).

METHODS

Nineteen young pigs were divided into 3 groups: operation (experimental VSD), sham-operation, and normal control. One month after operation, the pigs were catheterized and then put to death. Smooth muscle cells were taken from aorta, pulmonary artery, pulmonary arteriole, mesenteric arteriole and VSMC were isolated. Radioligand binding assay for AT1R was done to measure the Bmax and KD.

RESULTS

There were no significant differences in Bmax and KD of AT1R between the sham-operation group and the control. Bmax of the aorta (112.11+/-35.77) fmol/10(6), main pulmonary artery (52.37+/-31.09) fmol/10(6) and mesenteric arteriole (106.98+/-100.48) fmol/10(6) in the operation group were remarkably elevated in comparison with the control (P<0.05). In the operation group, Bmax of the aorta VSMC was higher than that of main pulmonary artery VSMC (P<0.05), and Bmax of the mesenteric arteriole VSMC was higher than that of the small pulmonary arteriole VSMC (P<0.05).

CONCLUSION

The findings in AT1R expression in experimental VSD were supportive to the previously proposed hypothesis that ATR expression might be stronger in systemic VSMC than in pulmonary VSMC in young animal, especially in the presence of intracardiac left to right shunt, which may provide a sound rationale for the pharmacological management of VSD infants with angiotensin converting enzyme inhibitor or AT1R antagonist.

Right ventricular collagen and fibronectin levels in patients with pulmonary atresia and ventricular septal defect

Pulmonary atresia (PA) with ventricular septal defect (VSD) is an extreme form of tetralogy of Fallot with characteristic right ventricular hypertrophy. To reduce the right ventricular overload, these children have to undergo staged corrective surgery to restore physiological pulmonary perfusion. We studied the degree of fibrosis by analysing the myocardial expression pattern (at mRNA and protein level) of the extracellular matrix proteins, collagen and fibronectin in biopsies taken at corrective surgery from 14 patients affected by PA,VSD. Expression analysis by RT-PCR showed significantly higher levels for collagen III (p = 0.03), whereas collagen Ialpha (p = 0.31) and fibronectin (p = 0.47) mRNA levels remained unaltered in PA, VSD patients as compared to age matched controls. Video image analysis of immunohistochemical staining showed unchanged interstitial levels for total collagen (p = 0.17) as well as for fibronectin (p = 0.13) in the patients with PA, VSD. However, peri-vascular staining for collagen (p < 0.01) and fibronectin (p = 0.02) represented as the peri-vascular stained area corrected for the vessel lumen area showed significantly decreased levels in the PA, VSD group as compared to controls. Our results indicate that the patients with PA, VSD have inadequate extracellular matrix support for their coronary blood vessels and perhaps due to an altered biosynthesis of collagen and fibronectin network.

[The changes of angiotensin II receptor expression in cardiomyocytes of ventricles in pigs with experimental ventricular septal defect]

OBJECTIVE

To investigate the changes of angiotensin II receptors expression in cardiomyocytes of both ventricles in pigs with experimental ventricular septal defect (VSD).

METHODS

Nineteen young pigs were divided into 3 groups: the pigs that received operation to produce experimental VSD, the pigs that underwent sham-operation, and the pigs as normal control. One month after the operation, the pigs were catheterized and then put to death; the cardiomyocytes were taken from their ventricles and were isolated. Radioligand binding assay was done to measure the Bmax and KD of angiotensin II receptor per 10(6) cells.

RESULTS

For both Bmax and KD of angiotensin II receptors, there were no significant differences between the sham-operation group and the control. The Bmax of left ventricle AT1R (188.42 +/- 133.97 fmol/10(6)) and Bmax of right ventricle AT1R (272.14 +/- 232.74 fmol/10(6)) and AT2R (40.42 +/- 34.76 fmol/10(6)) in the operation group were significantly elevated in comparison with the control (Bmax of left ventricle AT1R 29.20 +/- 19.50 fmol/L, and Bmax of right ventricle AT1R 76.72 +/- 51.21 fmol/L and AT2R 9.63 +/- 1.27 fmol/L) respectively, P < 0.05.

CONCLUSION

Intracardiac left-to-right shunt related volume overload leads to the elevation of AT1R expression in cardiomyocytes, which serves as an important mechanism of ventriclular hypertrophy and remodling in congenital heart disease. The increased expression of AT2R in right ventricle is a possible explanation of the phenomenon that moderately sized VSDs usually show left other than right ventriclular hypertrophy, taking into account that AT2R has been suggested to mediate antitrophic reaction.

Pathology-related troponin I release and clinical outcome after pediatric open heart surgery

BACKGROUND

Perioperative myocardial injury is determined by the ischemic duration, pathology, and preoperative myocardial status. Our aim was to evaluate pathology-related differences in troponin I (TnI) release, a sensitive and specific marker of myocardial injury, and its relation to clinical outcome after pediatric open heart surgery.

METHODS

Troponin I was measured serially postoperatively in 133 children undergoing repair of atrial (ASD, n = 41) and ventricular septal defects (VSD, n = 46), and tetralogy of Fallot (TOF, n = 46). The length of the right ventricular outflow tract (RVOT) incision in the latter was classified as either minimum(n = 33) or extended(n = 13).

RESULTS

Postoperative TnI levels were lesion specific and did not correlate with clinical outcome for ASDs. Peak TnI correlated with inotropic duration for VSD (r = 0.69, p < 0.0001) and TOF (r = 0.51, p = 0.0004). Significant correlations were also observed for the durations of ventilation (r = 0.64 and 0.36, respectively) and ICU stay (r = 0.60 and 0.55). Younger age (<1 year old) in children with VSDs and an extended incision into the RVOT in TOF were associated with greater TnI release and worse clinical outcome.

CONCLUSIONS

Postoperative TnI release is pathology related and reflects myocardial damage from both ischemia-reperfusion injury and direct myocardial trauma.

Intramyocardial synthesis of pro- and anti-inflammatory cytokines in infants with congenital cardiac defects

OBJECTIVES

We sought to test the hypothesis that cytokines would be expressed in the myocardium of infants with congenital cardiac defects and to identify the signaling pathways involved.

BACKGROUND

Mechanical stress upregulates pro-inflammatory cytokines in the myocardium.

METHODS

Fifteen infants with tetralogy of Fallot (TOF) (n = 7) or with ventricular septal defects (VSDs) (n = 8) were investigated. Concentrations of pro- and anti-inflammatory cytokines and of the inducible nitric oxide synthase (iNOS) were measured by enzyme-linked immunosorbent assay and/or Western blotting in the right ventricular myocardium taken during cardiac surgery. Activation of the nuclear factor-kappa-B (NF-kappa-B) and p38 mitogen-activated protein kinase (MAPK) pathways was assessed by electrophoretic mobility shift assay with supershift and/or Western blotting, respectively.

RESULTS

The pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1-beta, and IL-6 and the anti-inflammatory cytokine IL-10 were detected in the myocardium of all patients. Concentrations of the pro-inflammatory cytokines and also of phosphorylated p38 MAPK were higher in patients with TOF than in those with VSD and correlated with the degree of pressure overload of the right ventricle. Levels of phosphorylated I-kappa-B-alpha, iNOS, and IL-10 were similar in patients with TOF and in those with VSD.

CONCLUSIONS

Our results show intramyocardial synthesis of pro-inflammatory cytokines in infants with congenital cardiac defects. This is associated with activation of both the NF-kappa-B and p38 MAPK pathways. The latter could be particularly important for the transduction of mechanical signals in the infant's myocardium. Synthesis of IL-10 indicates an intramyocardial anti-inflammatory potential in this age group.

Role of adrenomedullin in congenital heart disease associated with pulmonary hypertension

The changes of adrenomedullin (ADM), endothelin-1 (ET-1) and nitric oxide (NO) levels before and after operation in congenital heart disease (CHD) associated with pulmonary hypertension (PH) were observed in order to investigate their role in CHD with PH and their clinical significance. The CHD patients were divided into 3 groups according to pulmonary artery systolic pressure (PASP): Non-PH group: PASP < or = 30 mmHg (n = 11); mild-PH group: PASP 31-49 mmHg (n = 10); moderate or severe-PH group: PASP > or = 50 mmHg (n = 12). The control group consisted of 15 health children. Plasma ADM, ET-1 and NO levels were determined by radioimmunoassay and colorimetry methods. The correlation between ADM and ET-1, NO, PASP was analyzed. The changes in plasma ADM, ET-1 and plasma NO on the 7th day after operation among the groups were compared. The results showed that plasma ADM levels in non-PH group were significantly higher than that in control group (P < 0.05), but there was no significant difference in ET-1 and NO levels between the two groups (P > 0.05). ADM and ET-1 levels in mild-PH group were significantly elevated as compared with those in non-PH group (both P < 0.05), but NO levels were decreased (P < 0.05). ADM and ET-1 levels in moderate or severe-PH groups were increased as compared with those in mild-PH group (both P < 0.01), but NO level significantly declined (P < 0.05). On the 7th day after operation, plasma ADM and ET-1 levels in PH group were significantly decreased (P < 0.05, P < 0.01) as compared with those before operation, but there was no significant difference in NO levels (P > 0.05). But NO levels in non-PH group were significantly increased (P < 0.05). Plasma ADM levels in CHD were positively correlated with PASP and ET-1 (r = 0.77, P < 0.01; r = 0.82, P < 0.01), negatively correlated with NO (r = -0.56, P < 0.05). It was concluded that during the progression of PH in the cases of CHD, plasma ADM, ET-1 and NO might play an important role in the development of PH. The increased ADM may represent a compensatory mechanism. It can interact with NO and ET-1 to regulate pulmonary circulation in the pathophysiology of PH with CHD. ADM may be involved in the defence mechanism against further increase of pulmonary arterial pressure. ADM could be used as a reliable indicator of the severity of CHD associated PH.

Changes in myocardial metabolism and ultrastructure of myocardial microvessels during pharmacological and cold cardioplegia under hypothermic conditions without perfusion

A combination of pharmacological and cold cardioplegia in with hypothermia without perfusion in open-heart surgery guarantee the reversible character of shifts in energy and free radical balance in the myocardium. However, this procedure can impair coronary micricirculation due to structural and functional changes in microvessel endothelium. Our results demonstrate that new cytoprotective approaches are extremely needed for cardiac protection during surgery.

Heat shock protein 72 expression in the right ventricle of patients undergoing congenital cardiac surgery

While heat shock protein (HSP) 72 is known as a stress protein, there have been no reports of HSP 72 expression in patients who have undergone surgery for congenital heart disease. Fourteen patients (7 males and 7 females) who had undergone surgery for congenital heart disease were studied. The ages of the patients ranged from 2 months to 43 years old (mean 6.5 +/- 10.8 years old; median 3.0 years old). The diagnoses were Tetralogy of Fallot in seven, pulmonary atresia with ventricular septal defect (VSD) in three, complex anomalies in three, and VSD in one patient. Histological study and HSP analysis using Western blots and immunostaining with anti-HSP 72 monoclonal antibody were performed for right ventricular muscle samples resected during the surgery. The histological findings showed hypertrophic changes of ventricular cardiomyocytes in all samples studied. Western blots detected HSP 72 expression of various degrees in all specimens. Immunostaining using monoclonal antibody against HSP 72 showed that the protein was present in the nuclei and cytoplasm of cardiomyocytes. In conclusion, although it is difficult to determine the cause of the "stress" that triggers HSP 72 expression in cardiomyocytes, low O2 saturation and pressure overload might act as a "stress", and the only common factor that induced HSP 72 in every sample was hypertrophy.

Thiamine deficiency in children with congenital heart disease before and after corrective surgery

BACKGROUND

Malnutrition is common in children with congenital heart disease, while thiamine deficiency (TD) is common in malnutrition, in critically ill children, and in adults with congestive heart failure treated with loop diuretics. Our goal was to determine whether children with congenital heart disease had TD and whether treatment with loop diuretics is related to TD in these patients.

METHODS

Twelve children with ventricular septal defect (VSD) treated with furosemide, and 10 children with tetralogy of Fallot (TOF) referred for corrective surgery were consecutively enrolled into a prospective study. Data were collected 24 hours before surgery and 5 days after surgery for nutrition evaluation, medications used, anthropometric measurements, and laboratory markers of malnutrition. Thiamine and pyridoxine deficiencies were evaluated using activated enzyme assays.

RESULTS

Seven children (32% of patients) did not meet the recommended daily allowance (RDA) for calories and 18% of patients did not meet the RDA for thiamine intake. Anthropometric measurements were low in both groups, more so in those with VSD, although the difference did not reach statistical significance. Overall, 18% (1/12 with VSD and 3/10 with TOF) of children with congenital heart disease had thiamine deficiency before surgery. Three of the four children with TD had adequate intake of thiamine. Six children (27%) had TD 5 days postsurgery (3 children with VSD and 3 children with TOF).

CONCLUSIONS

TD is common in children with congenital heart disease (CHD) referred for corrective surgery both before and after surgery. Our results suggest that neither diuretic treatment nor malnutrition can fully explain the development of TD in these children.

[Mechanism of selenium defending against free radical damages during myocardial ischemia/reperfusion in human]

OBJECTIVE

To investigate the modulate mechanism of selenium (Se) on glutathione peroxidase expression in the myocardium by defending against free radical superoxidizing during myocardial ischemia/reperfusion (I/R) period.

METHODS

46 patients with ASD or VSD were separated into control (23 patients) and Se (23 patients) groups. Patients in the Se group received 400 micrograms Se supplementation each day for 7 days before heart surgery. Biochemical techniques, atomic absorption, RT-PCR, cDNA sequence testing were taken to evaluate and compare the changes in myocadial MDA level, GPX activity, GPX mRNA expression, GPX cDNA nucleotide sequence, and Se, Ca and Mg concentrations during I/R.

RESULTS

In Se group, Se supplementation by oral administration neither changed plasma Se content nor blood cells. At 30 minute of myocardial reperfusion, in Se group, Se content in the myocardium did significantly increase but decreased in RBCs, and the elementary rate of GPX activity was lower than that in control. Se group had higher myocardial GPX mRNA expression with a normal nucleotida sequence pre- and post-reperfusion.

CONCLUSION

Se supplement, which promotes the myocardial Se content and mainly improves GPX mRNA expression during I/R, can defend against free radical superoxidizing damages to the myocardium.

Effect of ultrafiltration during cardiopulmonary bypass for pediatric cardiac surgery

The effect of ultrafiltration during cardiopulmonary bypass (CPB) was evaluated for correcting ventricular septal defects with associated pulmonary hypertension in patients less than 18 months old. Interleukin (IL)-6 and IL-8 concentrations in the blood, ultrafiltrate, and urine were measured. The blood IL-6 concentration increased to 128.4+/-20.2 pg/ml by the end of surgery, which is lower than the concentration seen in adult patients (273.1+/-48.2 pg/ml, p < 0.02). The blood IL-8 concentration was not significantly different than that of adults. The total amounts of excreted IL-6 in the ultrafiltrate and urine during CPB were 11.5+/-0.32 pg/kg and 0.32+/-0.07 pg/kg, respectively (p < 0.05). The total amounts of excreted IL-8 in the ultrafiltrate and urine were 4.64+/-0.69 pg/kg and 1.92+/-0.56 pg/kg, respectively (p < 0.05). No differences were seen in these values for excretion between children and adults. We conclude that ultrafiltration during CPB in pediatric patients is more effective in removing proinflammatory cytokines than in adults and more effective than renal filtration alone.

Total but not resting energy expenditure is increased in infants with ventricular septal defects

OBJECTIVE

The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants.

METHODS

Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance.

RESULTS

No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group.

CONCLUSIONS

REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation.

[The effects of cardiopulmonary bypass on pulmonary surfactant activity]

OBJECTIVE

To study the effects of cardiopulmonary by pass(CPB) on pulmonary surfactant (PS) activity.

METHOD

In 12 children with patent ductus arteriosus(PDA) and 19 patients with ventricular septal defect (VSD), saturated phosphatidylcholine (SatPC), total phospholipids (TPL), total protein (TP) and surfactant protein-A(SP-A) in sequential airway aspirates before and after operation were determined. Tetroxide osmium digestion and neutral alumina column chromatography were used for SatPC, and a modified immunoblot method with a rabbit anti-human SP-A polyclonal antibody for SP-A measurment.

RESULTS

In 19 VSD patients with CPB, SatPC/TPL was significantly decreased from 48% to 34% (t = 2.737, P < 0.05), SatPC/TP decreased from 64 to 33 mg/g (t = 3.011, P < 0.01), and SP-A from 23 to 11mg/g (t = 2.987, P < 0.01). In 12 patients without CPB, SatPC/TPL, SatPC/TP, SP-A/TP levels were not changed.

CONCLUSIONS

CPB significantly reduces pulmonary surfactant activity.

Skeletal muscle energy substrates, metabolic products and enzyme activity in infants with symptomatic ventricular septal defect

Muscle biopsy studies were performed on 26 infants with symptomatic ventricular septal defect (VSD) (mean age 4.7 months) and 10 healthy infants (mean age 7.8 months). Analyses were made of muscle energy substrates, metabolic products, muscle enzyme activity, fibre types and fibre sizes. Relatively few differences were noted between the groups. The most important difference was a reduced ATP level in the VSD group. Glucose 6-phosphate concentrations were also lower in the VSD group. These differences could indicate a low metabolic activity in skeletal muscle in infants with heart failure. Most muscle enzyme activity was comparable with the exception of lactate dehydrogenase (LD), which was lower in the VSD group. Within the VSD group, no differences were revealed in muscle substrate concentrations for muscle enzyme activity in terms of the degree of heart failure. We conclude that low energy levels are probably explained by undernourishment and/or reduced blood flow to skeletal muscle and that the lack of other discrepancies in muscle metabolism indicates a desirable relatively normal motor activity in these infants with symptomatic VSD.

Serum protein of 135-kDa molecular weight--a molecular signal for cardiac hypertrophy

A serum protein, similar to the 135-kDa protein which appears during experimentally induced cardiac hypertrophy in rats, was identified in human serum by Western blot analysis using anti-rat 135-kDa protein antibody. The rat protein antibody gave a very strong positive signal when reacted with sera obtained from cardiac patients, suggesting an induced level of this protein in patients' sera when compared to normal sera from healthy individuals. Multiple injections of polyclonal anti-rat 135-kDa protein antibody to aorta-constricted animals completely inhibited the development of cardiac hypertrophy, suggesting that this protein could be hypertrophy specific. This was further substantiated by the decrease in the expression of a molecular marker such as the beta myosin heavy chain gene in aorta-constricted but antibody-injected animals. Further, the presence of high levels of this protein in first- and third-day neonatal animals is also suggestive of the hypertrophy-specific nature of this protein as the heart is subjected to high pressure overload immediately after birth.

Pharmacokinetics of lidocaine in children with congenital heart disease

The purpose of this study was to determine the pharmacokinetics of lidocaine in children with congenital heart disease (CHD). Fifteen children with left to right intracardiac shunting of blood (acyanotic group) and 15 children with right to left intracardiac shunting of blood (cyanotic group) were studied and compared with 15 children without CHD (control group). Lidocaine (1.5 mg.kg-1) was injected into a peripheral vein over 30 sec and serial samples of arterial blood were obtained up to 120 min after completion of the infusion. Total and free lidocaine were analyzed by enzyme immunoassay. The serum concentration of alpha 1-acid glycoprotein (alpha 1-AGP) at induction of anaesthesia was measured in the three groups by radial immunodiffusion. The percent free lidocaine (100 x [free lidocaine]/[total lidocaine]) was greater at 30 sec post-infusion in all three groups (35-37%) than it was at any other time but was not significantly different among the three groups (P less than 0.05). There was no significant difference in either the percent free or the total lidocaine concentration at any sample time or in any of the pharmacokinetic variables among the three groups. The serum concentration of alpha 1-AGP did not differ significantly among the three groups of patients. We conclude that the presence of intracardiac shunts does not alter the pharmacokinetic behaviour of intravenous lidocaine (1.5 mg.kg-1) in children. The percent free lidocaine is greatest immediately post-injection and this may mitigate against rapid bolus administration of intravenous lidocaine in children.

[Differences in the activity of enzymes associated with energy metabolism in the heart atria and ventricles in children]

Tissue specimens from the right atrium and ventricle of the same heart were obtained during surgery in 45 children operated on account of congenital heart disease (tetralogy of Fallot and ventricular septal defect). Significant differences were found in the enzyme activities between the atrial and ventricular musculature. The activities of enzymes associated with aerobic metabolism (citrate synthase, malate dehydrogenase, with lactate metabolism) lactate dehydrogenase (and the fatty acid oxidation) hydroxyacyl-SoA-dehydrogenase) were significantly higher in the ventricular musculature. Hexokinase, the enzyme responsible for glucose phosphorylation was on the other hand, significantly higher in the atria. From this ensues that the right ventricle can utilize and oxidize to a full extent all main nutrients (fatty acids, glucose and lactate), while the right atrium utilizes above all glucose. These atrio-ventricular differences do not depend on the type of the congenital heart disease and it may be assumed that they exist also in healthy subjects.

[Vasoactive hormone metabolism in the lungs of patients with congenital heart defects]

The role of pulmonary metabolism of adrenaline, noradrenaline (NA), serotonin and histamine in the pathogenesis of hemodynamic disorders was examined in relation to the magnitude of intracardiac discharge (ID) in 30 patients with septal defects. Irrespective of the magnitude of arteriovenous ID, pulmonary tissue deactivation of NA is shown to be disrupted. Where ID averages 7.7 +/- 2.1 1/min, venous blood NA level is 59.8% higher (p less than 0.05) than that of patients with average ID of 3.1 +/- 0.7 1/min. A positive correlation (r = 0.51) is demonstrated between venous NA levels and ID in the latter group. The data obtained suggest that high ID values are associated with disturbed pulmonary metabolism and increased arterial levels of serotonin and NA, a significant contribution to the development of functional and morphologic vascular disorders of systemic and pulmonary circulation.

Effects of alterations of oxygen transport on the neonate

In the foregoing discussion we have attempted to provide an overview of much of the information available on the effects of changes in systemic oxygen transport on the neonatal and young subject. Using data synthesized from both human and animal studies, we have described the normal developmental changes and the findings of studies in which oxygen transport has been acutely altered by experimental means. This was intended to highlight the potentially delicate balance that can occur between oxygen supply and utilization during the critical period of rapid growth after birth. Finally, using the left-to-right shunt as an example, we have tried to show how a common pathologic condition can impair oxygen transport at multiple sites, and how normal development can make matters worse. It is anticipated that from an understanding of both normal and abnormal physiology, we will be able to develop rational approaches to the management of infants in whom the oxygen transport system has been stressed beyond its reserve.

Physical exercise effect on certain acid-base equilibrium parameters in children with small ventricular septal defects

Forty-seven children aged from 7 to 16 years were studied: 28 children had small ventricular septum defects and 19 healthy children served as controls. The following acid-base equilibrium parameters were determined in all children: pH, BE, pCO2, metabolic pH and respiratory pH in the arterialized capillary blood taken from the fingertip using an Astrup microapparatus. The determinations were made during three types of physical exercise: normal everyday locomotion and graded exercise raising the heart rate to about 170-180/min and about 190/min. The intensity of the exercise in the step test was calculated from the formula of Nikodemowicz. It was found that metabolic acidosis during these three exercise workloads developed significantly more easily in the children with septum defect than in healthy controls. The same differences were observed in the children with septum defect during the most intense exercise in relation to the exercise of lower intensity.

[Acid-base state and the electrolyte balance of young infants in the immediate postoperative period after radical correction of an interventricular septal defect under artificial circulation]

Acid-base equilibrium and electrolyte balance were studied in 80 infants in the immediate postoperative period after surgery for ventricular septal defect under conditions of extracorporeal circulation. Decompensated metabolic alkalosis was the most characteristic disorder of acid-base equillibrium in patients with an uncomplicated postoperative period, whereas decompensated respiratory alkalosis and metabolic acidosis were characteristic of patients with compensated and decompensated forms of cardiac insufficiency. Plasma hypokaliemia and hypochloremia attended by intracellular retention of sodium were typical disorders of the electrolyte balance in all forms of changes in the acid-base equilibrium.

[Changes of the volume of body fluids in cardiac insufficiency of patients with congenital heart defects]

Results consequent upon investigations into variations of the water metabolism, central and intracardiac hemodynamics and myocardial contractility in 42 patients with congenital heart defects are reported. It is established that an increase in the content of total water in the body and of the intracellular liquid may be considered to be a significant sign pointing to circulatory insufficiency, even in the absence of any clinical manifestations of this condition.