Inflammatory responses in SARS-CoV-2 associated Multisystem Inflammatory Syndrome and Kawasaki Disease in children: An observational study.

Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe inflammatory disease in children related to SARS-CoV-2 with multisystem involvement including marked cardiac dysfunction and clinical symptoms that can resemble Kawasaki Disease (KD). We hypothesized that MIS-C and KD might have commonalities as well as unique inflammatory responses and studied these responses in both diseases. In total, fourteen children with MIS-C (n=8) and KD (n=6) were included in the period of March-June 2020. Clinical and routine blood parameters, cardiac follow-up, SARS-CoV-2-specific antibodies and CD4+ T-cell responses, and cytokine-profiles were determined in both groups. In contrast to KD patients, all MIS-C patients had positive Spike protein-specific CD3+CD4+ T-cell responses. MIS-C and KD patients displayed marked hyper-inflammation with high expression of serum cytokines, including the drug-targetable interleukin (IL)-6 and IFN-γ associated chemokines CXCL9, 10 and 11, which decreased at follow-up. No statistical differences were observed between groups. Clinical outcomes were all favourable without cardiac sequelae at 6 months follow-up. In conclusion, MIS-C and KD-patients both displayed cytokine-associated hyper-inflammation with several high levels of drug-targetable cytokines.

Improvement of physical activity levels in children and adolescents after surgery for congenital heart disease: preferences and use of physical therapy.

PURPOSE: After surgery for congenital heart disease in children and adolescents, an active lifestyle is important to achieve and maintain good physical fitness. This study aimed to describe physical activity, as well as the use of patients' and parents' preferences for rehabilitative care after surgery for congenital heart disease. METHODS: This cross-sectional study included patients aged 4-16 years old, who had undergone surgery for congenital heart disease 2 years prior to the study onset. Patients and/or parents were invited to complete questionnaires on physical activity, and on their preferences for, and -use of, rehabilitative care after surgery. RESULTS: Forty-five of the 92 eligible patients and/or parents completed the questionnaires. The median age of the children was 12.2 years (IQR 7.8-16.1). Two children (4%) met the recommendations for taking part in moderate physical activity and 13 (29%) having done so for vigorous physical activity. Postoperatively 15 children (33%) had had physical therapy in primary care. More than 50% of the patients/parents would have preferred to have had more information on physical activity and to have taken part in an individual exercise program delivered during their primary care. CONCLUSION: The majority of eligible patients do not meet public health recommendations for engaging in physical activity and do not use physical therapy after surgery for congenital heart disease. The majority of patients and parents preferred more information as well as individual physical therapy treatments.Implications for rehabilitationsTwo years after surgery for congenital heart disease children and adolescents are less active compared to typically developing peers.Patients with a congenital heart disease and their parents need more information and support regarding stimulation of physical activity and physical fitness after heart surgery.In the postoperative process, a well-structured and supportive (individual) rehabilitation program should be introduced to improve physical activity and physical fitness.

Midline crossing pulmonary vein: right upper lobe dual venous drainage, with partial anomalous venous return of the right lung into a persistent left superior vena cava.

INTRODUCTION: We present a case of dual drainage of the right upper lobe of the lung into the left atrium and via partial anomalous venous pulmonary return (PAPVR) into a persistent left superior vena cava (SVC). DISCUSSION: It is only in the minority of PAPVR cases where the anomalous pulmonary veins cross the midline. We provide a review of current literature on this topic and an explanatory embryological model. Knowledge of embryonic development and possible anatomic variations, including the concept of dual venous drainage of the lung, leads to better interpretation of imaging, with more accurate description of the morphology at hand. High-resolution multidetector computed tomography (MDCT) helps to delineate the exact vascular anatomy. This will enhance a better understanding of and anticipation on the patient's disease status, with more accurate planning of intervention, and possibly less complications.

Coronary artery assessment in Kawasaki disease with dual-source CT angiography to uncover vascular pathology.

BACKGROUND: Kawasaki disease (KD) is a vasculitis with formation of coronary artery aneurysms (CAAs) that can lead to myocardial ischemia. Echocardiography is the primary imaging modality for the coronary arteries despite limited visualization. Coronary angiography (CAG) is the gold standard yet invasive with high-radiation exposure. To date however, state-of-the-art CT scanners enable high-quality low-dose coronary computed tomographic angiography (cCTA) imaging. The aim of our study in KD is to report (i) the diagnostic yield of cCTA compared to echocardiography, and (ii) the radiation dose. METHODS AND RESULTS: We collected data of KD patients who underwent cCTA. cCTA findings were compared with echocardiography results. In 70 KD patients (median age 15.1 years [0.5-59.5 years]; 78% male; 38% giant CAA), the cCTA identified 61 CAAs, of which 34 (56%, with a Z score > 3, in 22 patients) were not detected by echocardiography. In addition, the left circumflex (aneurysmatic in 6 patients) was always visible upon cCTA and not detected upon echocardiography. Calcifications, plaques, and/or thrombi were visualized by cCTA in 25 coronary arteries (15 patients). Calcifications were seen as early as 2.7 years after onset of disease. In 5 patients, the cCTA findings resulted in an immediate change of treatment. The median effective dose (ED) in millisievert differed significantly (p < 0.01) between third-generation dual-source and other CT scanners (1.5 [0.3-9.4] (n = 56) vs 3.8 [1.7-20.0] (n = 14)). CONCLUSIONS: The diagnostic yield of third-generation dual-source cCTA combined with reduced radiation exposure makes cCTA a favorable diagnostic modality to complete the diagnosis and long-term treatment indications for KD. KEY POINTS: • cCTA is a favorable diagnostic modality to complete the diagnosis and long-term treatment indications for Kawasaki disease. • Kawasaki disease patients with proven coronary artery involvement on echocardiography require additional imaging.

Longitudinal Myocardial Deformation Does Not Predict Single Ventricle Ejection Fraction Assessed by Cardiac Magnetic Resonance Imaging in Children with a Total Cavopulmonary Connection.

Survival of children with single ventricle heart defects after the total cavopulmonary connection (TCPC) has improved, but impaired cardiac function remains a major cause of morbidity and mortality. Cardiac magnetic resonance imaging (cMRI) is the gold standard in assessing single ventricle volume and function, but high costs and limited availability hamper its routine use. A cheaper and more available alternative is echocardiography. Myocardial function can be studied in more detail using speckle tracking echocardiography (STE). The purpose of the study was to describe the association between myocardial deformation assessed by speckle tracking echocardiography (STE) and single ventricle function assessed by cMRI and to evaluate differences in myocardial deformation in children with single left and single right ventricular morphology. Cross-sectional, multicenter study in 77 children after TCPC was conducted. STE segmental and global longitudinal peak strain and systolic strain rate (SR) of the dominant ventricle were measured. Impaired SV function by cMRI was defined as ejection fraction (EF) < 45%. Mean age was 11.8 (range 9.7-14.3) years. Pearson R for cMRI EF versus global longitudinal strain and SR was - 0.25 (p = 0.06) and - 0.03 (p = 0.82), respectively. Global single ventricle longitudinal strain and SR was similar in patients after TCPC with single left and single right ventricular morphology (- 19.0 ± 3.1% vs 19.2 ± 3.2%, p = 0.94). STE myocardial deformation parameters do not correlate with single ventricle ejection fraction assessed by cMRI.

Dissecting Kawasaki disease: a state-of-the-art review.

Kawasaki disease (KD) is a pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. The diagnosis is based on the presence of persistent fever and clinical features including exanthema, lymphadenopathy, conjunctival injection, and changes to the mucosae and extremities. Although the etiology remains unknown, the current consensus is that it is likely caused by an (infectious) trigger initiating an abnormal immune response in genetically predisposed children. Treatment consists of high dose intravenous immunoglobulin (IVIG) and is directed at preventing the development of CAA. Unfortunately, 10-20% of all patients fail to respond to IVIG and these children need additional anti-inflammatory treatment. Coronary artery lesions are diagnosed by echocardiography in the acute and subacute phases. Both absolute arterial diameters and z-scores, adjusted for height and weight, are used as criteria for CAA. Close monitoring of CAA is important as ischemic symptoms or myocardial infarction due to thrombosis or stenosis can occur. These complications are most likely to arise in the largest, so-called giant CAA. Apart from the presence of CAA, it is unclear whether KD causes an increased cardiovascular risk due to the vasculitis itself. CONCLUSION: Many aspects of KD remain unknown, although there is growing knowledge on the etiology, treatment, and development and classification of CAA. Since children with previous KD are entering adulthood, long-term follow-up is increasingly important. What is known: • Kawasaki disease (KD) is a pediatric vasculitis with coronary artery damage as its main complication. • Although KD approaches its 50th birthday since its first description, many aspects of the disease remain poorly understood. What is new: • In recent years, multiple genetic candidate pathways involved in KD have been identified, with recently promising information about the ITPKC pathway. • As increasing numbers of KD patients are reaching adulthood, increasing information is available about the long-term consequences of coronary artery damage and broader cardiovascular risk.

Regression and Complications of z-score-Based Giant Aneurysms in a Dutch Cohort of Kawasaki Disease Patients.

Kawasaki disease (KD) is a pediatric vasculitis. Its main complication is the development of coronary artery aneurysms (CAA), with giant CAA at the end of the spectrum. We evaluated regression and event-free rates in a non-Asian cohort of patients with giant CAA using the current z-scores adjusted for body surface area instead of absolute diameters. KD patients with giant CAA (z-score ≥10) visiting our outpatient clinic between January 1999 and September 2015 were included. Patient characteristics and clinical details were extracted from medical records. Regression was defined as all coronary arteries having a z-score of ≤3. A major adverse event was defined as cardiac death, myocardial infarction, cardiogenic shock, or any coronary intervention. Regression-free and event-free rates were calculated using the Kaplan-Meier method. We included 52 patients with giant CAA of which 45 had been monitored since the acute phase. The 1-, 2-, and 5-year regression-free rates were 0.86, 0.78, and 0.65, respectively. The 5-year, 10-year, and 15-year event-free rates were 0.79, 0.75, and 0.65, respectively. Four children, whose CAA would not have been classified as 'giant' based on absolute diameters instead of z-scores, had experienced an event during follow-up. CONCLUSION: We found a high percentage of children in whom the lumen of giant CAA completely normalized. Four children not classified as 'giant' based on absolute diameters with z-scores of ≥10 experienced a cardiac event. Hence, the use of z-scores seems to be justified.

KinCor, a national registry for paediatric patients with congenital and other types of heart disease in the Netherlands: aims, design and interim results.

OBJECTIVE: Studies in children with heart disease have been hampered by a lack of easily identifiable patient groups. Currently, there are few prospective population-based registries covering the entire spectrum of heart disease in children. KinCor is a Dutch national registry for children with heart diseases. This paper presents the aims, design and interim results of the KinCor project. METHODS: All children presenting at a Dutch university medical centre with a diagnosis of heart disease from 2012 onwards were eligible for registration in the KinCor database. Data entry is through a web-based portal. Entry codes have been synchronised with the European Paediatric Cardiac Coding system, allowing coupling with similar databases for adults, such as CONCOR. RESULTS: Between June 2012 and July 2015, 8421 patients were registered (76 % of those eligible). Median age of the patients was 9.8 years, 44.7 % were female; 6782 patients had morphological congenital heart disease. The most prevalent morphological congenital heart defects were ventricular septal defects (18 %), Tetralogy of Fallot (10 %) and transposition of great arteries (9 %). For 42 % of the patients additional diagnoses were registered. Sixty percent of patients had undergone at least one intervention (catheter intervention or surgery). CONCLUSION: The KinCor database has developed into a large registry of data of children with all types of heart disease and continues to grow. This database will provide the opportunity for epidemiological research projects on congenital and other types of heart disease in children. Entry codes are shared with the CONCOR database, which may provide a unique dataset.

Cardiovascular imaging in children and adults following Kawasaki disease.

Kawasaki disease (KD) is a paediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. Two guidelines exist regarding the follow-up of patients after KD, by the American Heart Association and the Japanese Circulation Society. After the acute phase, CAA-negative patients are checked for cardiovascular risk assessment or with ECG and echocardiography until 5 years after the disease. In CAA-positive patients, monitoring includes myocardial perfusion imaging, conventional angiography and CT-angiography. However, the invasive nature and high radiation exposure do not reflect technical advances in cardiovascular imaging. Newer techniques, such as cardiac MRI, are mentioned but not directly implemented in the follow-up. Cardiac MRI can be performed to identify CAA, but also evaluate functional abnormalities, ischemia and previous myocardial infarction including adenosine stress-testing. Low-dose CT angiography can be implemented at a young age when MRI without anaesthesia is not feasible. CT calcium scoring with a very low radiation dose can be useful in risk stratification years after the disease. By incorporating newer imaging techniques, detection of CAA will be improved while reducing radiation burden and potential complications of invasive imaging modalities. Based on the current knowledge, a possible pathway to follow-up patients after KD is introduced. Key Points • Kawasaki disease is a paediatric vasculitis with coronary aneurysms as major complication. • Current guidelines include invasive, high-radiation modalities not reflecting new technical advances. • Cardiac MRI can provide information on coronary anatomy as well as cardiac function. • (Low-dose) CT-angiography and CT calcium score can also provide important information. • Current guidelines for follow-up of patients with KD need to be revised.

Ventricular function and cardiac reserve in contemporary Fontan patients.

BACKGROUND/OBJECTIVE: Total cavopulmonary connection (TCPC) has been the preferred treatment for patients with univentricular hearts. Current TCPC-techniques are the intra-atrial lateral tunnel (ILT) and the extracardiac conduit (ECC). We aimed to determine ventricular function during rest and stress, and to compare results for both techniques and for left (LV) versus right ventricular (RV) dominance. METHODS: 99 patients, aged 12.5 ± 4.0 years underwent echocardiography and magnetic resonance imaging (MRI), and 69 patients underwent stress MRI. RESULTS: Echocardiography showed impaired systolic and diastolic function. MRI parameters were comparable between ILT and ECC at rest. During dobutamine there was a decrease in end-diastolic volume (EDVi) (91 ± 21 vs. 80 ± 20 ml/m(2) p<0.001). Ejection fraction (EF) and cardiac index (CI) during dobutamine were lower for ILT patients (59 ± 11 (ILT) vs. 64 ± 7% (ECC), p=0.027 and 4.2 ± 1.0 (ILT) vs. 4.9 ± 1.0L/min/m(2) (ECC), p=0.006), whereas other parameters were comparable. TEI-index was higher in ILT-patients (0.72 ± 0.27 (ILT) vs. 0.56 ± 0.22 (ECC), p=0.002). Diastolic function was frequently impaired in patients with a dominant RV (67% (RV) vs. 39% (LV), p=0.011). Patients with dominant LV's had smaller end-systolic volume (ESVi) (40 ± 13 (LV) vs. 47 ± 16 (RV) ml/m(2), p=0.030) and higher EF (55 ± 8 (LV) vs. 49 ± 9 ml/m(2) (RV), p=0.001) and contractility (2.3 ± 0.8 (LV) vs. 1.9 ± 0.7 mmHg/ml/m(2) (RV), p=0.050) during rest and higher EF during dobutamine (63 ± 8 (LV) vs. 58 ± 10 ml/m(2) (RV), p=0.043). CONCLUSION: Ventricular function is relatively well preserved in modern-day Fontan patients. With dobutamine stress there is a decrease in EDVi. ECC patients have higher CI and EF during stress. Patients with a dominant RV have lower systolic, including impaired contractility, and diastolic function.

The effect of exercise training on cardiac remodelling in children and young adults with corrected tetralogy of Fallot or Fontan circulation: a randomized controlled trial.

BACKGROUND: Exercise can improve physical fitness in children and adults with congenital heart disease. We hypothesized that exercise training would not lead to adverse cardiac remodelling in this population. METHODS AND RESULTS: This multi-centre randomized controlled trial included children and young adults (10 to 25 years) with either corrected tetralogy of Fallot or Fontan circulation. The exercise-group was enrolled in a 12 week standardized aerobic dynamic exercise training program. The control-group continued their life-style and received care as usual. Both groups underwent cardiopulmonary exercise testing, cardiac magnetic resonance imaging (MRI), echocardiography and neurohormonal assessment, within 2 weeks before and 2 weeks after the intervention period. Fifty-six patients were randomized to the exercise-group and 37 to the control-group. We assessed changes between the pre- and the post-intervention period for the exercise group compared to the changes in the control-group. Peak load increased significantly in the exercise-group compared to the control-group (exercise-group 6.9 ± 11.8 W; control-group 0.8 ± 13.9 W; p=0.047). There were no adverse events linked to the study. Ventricular systolic parameters, cardiac dimensions and neurohormonal markers during follow-up did not change in patients allocated to the exercise-group and control-group. Although there were some isolated minor changes in inflow parameters, there was no consistent pattern of changes, indicating a lack of true change in the diastolic function. CONCLUSION: We demonstrated that no clinically relevant adverse cardiac remodelling occurred after 12 weeks of exercise training in patients with either corrected tetralogy of Fallot or Fontan circulation. CLINICAL TRIAL REGISTRATION: www.trialregister.nl, identification NTR2731.

Two cases of aorto-right atrial tunnel: clinical presentation, imaging and percutaneous closure.

Communication between the aortic sinus and a cardiac chamber is a rare anomaly that can be diagnosed in children and young adults. We describe two cases with a tunnel between the aortic sinus and right atrium, discuss diagnostic modalities, and review the literature on this anomaly.

Polymorphisms in chemokine receptor genes and susceptibility to Kawasaki disease.

Kawasaki disease (KD) is an acute vasculitis occurring in young children. Its aetiology is unknown, but an infectious agent is assumed. Increased levels of proinflammatory cytokines and chemokines have been reported in KD. Genetic variation in these genes and the receptors for these genes could influence the regulation of cytokines and chemokines. In a case-control study of 170 Dutch Caucasian KD patients and 300 healthy Dutch Caucasian controls, common genetic variants in chemokine receptor genes CCR3, CCR2, CCR5, CX3CR1, CXCR1 and CXCR2 were analysed. Of the eight studied single nucleotide polymorphisms (SNPs) in the CCR3-CCR2-CCR5 gene cluster, four showed a significant association with susceptibility to KD. Moreover the CCR5-Delta32 was observed with an allele frequency of 10.7% in the control population compared to 6.5% in the KD patients (P = 0.04). Two haplotypes of the CCR3-CCR2-CCR5 gene-cluster appear to be at risk haplotypes for KD and one a protective haplotype. No association was observed with the studied SNPs in CX3CR1, CXCR1 and CXCR2. In conclusion, in a Dutch cohort of KD patients an association of KD occurrence with common genetic variants in the chemokine receptor gene-cluster CCR3-CCR2-CCR5 was observed.

The involvement of Fc gamma receptor gene polymorphisms in Kawasaki disease.

Kawasaki disease is an acute febrile syndrome in infancy, characterized by vasculitis of medium-sized arteries. Without treatment the disease can lead to coronary artery lesions (CAL) in approximately 25% of the children. Therapy consists of intravenous immunoglobulins (IVIG), leading to a decrease of complications to 5-16%. Little is known about the working mechanisms of IVIG. In this study we evaluated the involvement of Fcgamma receptors (FcgammaRs) in Kawasaki disease by the determination of the frequency of known single nucleotide polymorphisms (SNPs) in the genes coding for the FcgammaRs and compared this with frequencies in a cohort of healthy controls. There was no difference in the distribution of the functionally relevant genotypes for FcgammaRIIa-131H/R, FcgammaRIIb-232I/T, FcgammaRIIIa-158 V/F and FcgammaRIIIb-NA1/NA2 between the patient group and the healthy controls. Furthermore, there were no polymorphisms linked to the disease severity as indicated by the absence or development of CAL during the disease. Altered transcription or expression of FcgammaR on specific cell types of the immune system may still play a role in susceptibility and treatment success, but at a level different from the functional SNPs in FcgammaR genes tested in this study.

Vascular endothelial growth factor gene haplotypes in Kawasaki disease.

OBJECTIVE: To investigate whether common genetic variants in the vascular endothelial growth factor (VEGF) gene are associated with Kawasaki disease (KD) and the subsequent development of coronary artery lesions. METHODS: Common genetic variants in the VEGF gene were analyzed in an association study in a Dutch cohort of 170 KD patients and 300 healthy Dutch Caucasian controls. Genotyping was done with 5'-nuclease TaqMan assays and 3'-hybridization-triggered fluorescence minor groove binder Eclipse assays. RESULTS: An association with susceptibility to KD was observed with 2 of the 6 single-nucleotide polymorphisms analyzed in VEGF: -2594 A>C (rs699947) and the 236 bp 3' of STP C>T (rs3025039). Also for an 18-bp deletion in the promoter of VEGF a significant difference in the genotype and allele frequencies was observed between the KD patients and the controls. The haplotype CGCC (based on rs699947, rs2010963, rs25648, and rs3025039) was significantly associated with the development of KD (hap score 3.8; P = 0.0002). VEGF plasma levels were significantly higher in patients with the early phase of KD than in the healthy controls, and there was a trend toward higher VEGF plasma levels in KD patients with the -2594 CC and 236 bp 3' of STP CC genotypes. CONCLUSION: Our results suggest that polymorphisms of the VEGF gene may play a role in the pathogenesis of KD.

Sustained activation of neutrophils in the course of Kawasaki disease: an association with matrix metalloproteinases.

Kawasaki disease (KD) is an acute febrile syndrome of childhood, characterized by vasculitis of the medium-sized arteries. White blood cell counts and the inflammatory parameter C-reactive protein (CRP) are known to be elevated in the acute phase of the disease. In this study we investigated the course of inflammatory cell type-specific parameters in KD over a longer period of time. Plasma levels of human neutrophil elastase (HNE), matrix metalloproteinases-2 and -9 (MMP2, MMP9), and neutrophil gelatinase-associated lipocalin (NGAL), macrophage neopterin and CRP were measured. Plasma samples were collected in the acute, subacute and early convalescent stage, and three months after the onset of disease. Median CRP and neopterin normalized within two weeks. In contrast, six weeks and three months after onset of disease, levels of HNE were still elevated, with median values of 163 ng/ml and 156 ng/ml, respectively (control children median < 50 ng/ml; for all time-points P < 0.0001). Values of NGAL correlated with the levels of HNE (r = 0.39, P = 0.013). These results demonstrate a longer state of neutrophil activation in KD than was previously assumed. The potential relationship between this prolonged neutrophil activation, coronary artery lesion formation and their persistence, as well as the risk of premature atherosclerosis warrants further evaluation.

Initiation and maintenance of continuous breathing at birth.

Changes in arterial PCO2 (PaCO2) and body temperature normally occurring at the moment of birth may play a role in the initiation and maintenance of continuous breathing. To clarify these mechanisms, five chronically instrumented fetal lambs were connected to an extracorporeal membrane oxygenation (ECMO) system. ECMO was initiated in utero at a flow rate sufficient to support the fetus totally, the umbilical cord was occluded, and the fetuses were delivered into a warm isotonic saline bath. Breathing activity was present periodically before connection to the ECMO system and on ECMO during fetal normocapnia and normoxia. Near delivery there were no breathing movements, because all ewes were in labor. After delivering the fetuses into the warm saline bath, breathing movements remained episodic, being absent during high voltage electrocortical activity, whereas fetal PaCO2 remained constant. However, after 36-192 min, breathing activity became present continuously in all animals, at a time when fetal central temperature decreased. Once initiated, continuous breathing could be stopped by reducing the PaCO2. We conclude that maintenance of fetal PaCO2 and a slow decrease in central temperature after cord occlusion delays the establishment of continuous breathing, and that the level of PaCO2 is important in the maintenance of breathing activity during early postnatal life.

The effect of hypercapnia and hypercapnia associated with central cooling on breathing in unanesthetized fetal lambs.

In utero breathing activity is present periodically, but it must become continuous at birth. We investigated the effect of hypercapnia and of hypercapnia combined with central cooling on fetal breathing in seven chronically instrumented fetal lambs of 131-134-d gestation, using an extracorporeal membrane oxygenation (ECMO) system to control fetal blood gases and fetal temperature. During fetal hypercapnia (from a partial pressure of arterial CO2 (Paco2) 6.18 +/- 0.11 kPa to Paco2 7.39 +/- 0.15 kPa) frequency, amplitude, and incidence of fetal breathing movements during low voltage electrocortical activity (LV ECoG) increased significantly compared with isocapnic control on ECMO, but breathing remained absent during high voltage electrocortical activity (HV ECoG). During hypercapnia accompanied by central cooling (Paco2 7.90 +/- 0.13 kPa, temperature decreased by 2.1 degrees C) there were similar changes in fetal breathing movements during LV ECoG, but in four out of seven fetuses fetal breathing movements continued throughout HV ECoG. Hypercapnia accompanied by central cooling can thus override the inhibitory effects of HV ECoG on fetal breathing movements. This may be due to changes in sensitivity to CO2 produced by an increase in afferent input to the CNS.

Effect of maternal hypoxemia on behavior in unanesthetized normoxic or mildly hyperoxic fetal lambs.

To determine whether hypoxemia inhibits fetal activity by substances from the mother or placenta, six fetal lambs were chronically instrumented at 128-132 days gestation for extra-corporeal membrane oxygenation (ECMO). Severe maternal hypoxemia (arterial PO2 decreased to 6.00 +/- 0.60 kPa) was produced while fetal arterial PO2 was maintained normoxic or mildly hyperoxic using ECMO. The incidences of fetal breathing movements were 34.8 +/- 3.1% (SE) during baseline before ECMO, 36.8 +/- 3.4% during baseline with ECMO, and 21.4 +/- 3.5% (P < 0.05 compared with baseline with ECMO) during maternal hypoxemia. The durations of periods of breathing were 9.8 +/- 1.2 min before ECMO, 9.3 +/- 1.1 min with ECMO, and 10.5 +/- 1.7 min (P = NS) during maternal hypoxemia. In 7 of 14 maternal hypoxemia experiments, breathing activity stopped too late (7-23 min) to be attributed to maternal hypoxemia. Fetal electrocorticographic activity (P = NS), nuchal electromyographic activity (P = NS), and eye movements were normal before ECMO, with ECMO, and during maternal hypoxemia. Fetal blood pressure and heart rate did not change. We conclude that the inhibition of fetal activity during maternal hypoxemia does not seem to be mediated by release of factors from the maternal side of the placenta or the ewe.