Correlations between endocardial voltage mapping, diagnosis and genetic in patients with arrhythmogenic right ventricular cardiomyopathy

Background

The relations between voltage mapping and diagnosis or genetic background of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been investigated so far.

Objective

To investigate if diagnosis or genetic background were linked to voltage mapping in ARVC.

Method

97 patients with proved or suspected ARVC undergoing 3D endocardial mapping and genetic testing have been retrospectively included. Presence, localisation and extension of low voltage areas were correlated to ARVC diagnosis and presence of a culprit mutation.

Results

68 patients (70%) fulfilled ARVC diagnosis according to the Task Force criteria and 43 (44%) had ARVC-causal mutations. 78 (80%) presented with some bipolar or unipolar endocardial scar. 60/ 78 patients with endocardial scar (77%) fulfilled the criteria for a definitive ARVC diagnosis versus 8/19 patients without scar (42%) (p=0.003).

In the 68 patients with a definitive diagnosis of ARVC, the presence of endocardial scar was similar whether an ARVC-causal mutation was present or not (35/40 vs 25/28, p=ns). While there was slightly more infero-lateral scars in patients carrying a pathogenic genetic variant (34/40 vs 18/28, p=0.04), there was no difference for right ventricular outflow tract (24/40 vs 17/28) and apical scars (12/40 vs 11/28) or for multiple scars (26/35 vs 14/25 patients with scars). Scar extension was greater in patients with pathogenic variants (bipolar 12±10 vs 6±10%, p=0.02, and unipolar 22±13 vs 12±15%, p=0.01).

Conclusion

3D endocardial mapping could have an important role for refining ARVC diagnosis. Trends for larger and more infero-lateral scars were observed in mutated patients, without difference according to the mutated genes.

Funding Acknowledgement

Type of funding sources: None.

Endocardial ablation of ventricular tachycardia ablation in arrhythmogenic right ventricular cardiomyopathy aiming epicardial late potential abolition

Funding Acknowledgements

Type of funding sources: None.

Background

Catheter ablation is frequently needed to treat ventricular tachycardia (VT) in ARVC patients. Ablation aiming non-inducibility (NI) and late potential (LP) abolition has been shown to be effective1. Simultaneous endo-epicardial mapping demonstrate epicardial involvement in most VT2. However epicardial fat and vicinity of coronary artery may prevent effective epicardial ablation.

Aims

(a) evaluate endocardial-only ablation guided by epicardial late-potential recording (EA-ELP) to achieve LP abolition (LPA) and NI; (b) measure ablation-index(AI) values allowing epicardial LP suppression by endocardial ablation, as a surrogate for transmurality.

Methods

From 2019 to 2021 the authors (XW, EG) evaluated EA-ELP in ARVC patients patient referred for ablation. Our ablation protocol was previously described3. Endo and epicardial voltage mapping of the right ventricle (RV) were performed in sinus rhythm using 0.5-1.5 mV threshlods for endocardial scar and 0.5-1 mV for the epicardial. All LP were manually tagged. Programmed ventricular stimulation (PVS) was performed till S4 from the RV apex and other sites, all inducible tolerated VT were mapped. Endocardial ablation was performed with an irrigated tip catheter positioned in front of epi-LP recorded by a multi-electrode catheter aiming to eliminate or delay epi-LP as a surrogate for transmurality. For each lesion fulfilling the «transmurality criteria», the AI values were recorded. Remap was performed to validate LPA and NI was tested. Patient follow-up (FU) rely on telemonitoring in ICD-carriers and holter/exercise test for the others.

Results

11 patients were enrolled (9M/2F, mean age 45 years), 9 for VT recurrence (3 redo) and 2 for de novo VT. The median ICD therapy before ablation was 5/patient (mean 1.7). The clinical VT originated from the RV outflow tract (RVOT) in 5 patients, peritricuspid (PT) in 2, RV free wall (RFW) in 4. Substrate were more extended in the epicardium compared to the endocardium: epi-LP and scar surfaces were 42.5 cm2/118 cm2 versus 24.5 cm2/25.5 cm2 for the endocardium. In one patient, additional epicardial lesion was necessary to achieve LPA. The mean ablation duration was 3377 s. Remap showed LPA in all patients and PVS was negative in all (not tested in one due to hemodynamic instability). One patient presented retrosternal hematoma after ablation with spontaneous favorable outcome. Endocardial AI values allowing epi-LP abolition were 595 for the inferior wall, 625 in the RVOT, 604 for PT and 639 for RFW. During a mean FU of 12 months (median 16.5 mths), only one patient had VT recurrence.

Conclusion

Based on this case-series, EA-ELP appeared as a safe and effective method to treat VT in ARVC. EA-ELP ablation allowed VT suppression in 91 % of patients after an mean FU of 12 mths. The RV endocardial AI needed to suppress epi-LP ranged was between 595-639 and could be used as surrogate for transmurality in ARVC.

A new brain mitochondrial sodium-sensitive potassium channel: effect of sodium ions on respiratory chain activity

We have determined the electropharmacological properties of a new potassium channel from brain mitochondrial membrane using a planar lipid bilayer method. Our results show the presence of a channel with a conductance of 150 pS at potentials between 0 and -60 mV in 200 mM cis/50 mM trans KCl solutions. The channel was voltage independent, with an open probability value of approximately 0.6 at different voltages. ATP did not affect current amplitude or open probability at positive and negative voltages. Notably, adding iberiotoxin, charybdotoxin, lidocaine or margatoxin had no effect on the channel behavior. Similarly, no changes were observed by decreasing the cis pH to 6. Interestingly, the channel was inhibited by adding sodium in a dose-dependent manner. Our results also indicated a significant increase in mitochondrial complex IV activity and membrane potential and a decrease in complex I activity and mitochondrial ROS production in the presence of sodium ions. We propose that inhibition of mitochondrial potassium transport by sodium ions on potassium channel opening could be important for cell protection and ATP synthesis.

When prevention is dangerous: perceptions of isoniazid preventive therapy in KwaZulu-Natal, South Africa

Setting

In 2011, the South African government began to offer isoniazid preventive therapy (IPT) through the public health system to presumptively treat latent tuberculous infection (LTBI) among people living with human immunodeficiency virus.

Objective

To describe IPT perceptions and experiences in three Zulu communities in KwaZulu-Natal Province, South Africa.

Design

Using a combination of community-based research and ethnographic methods, we undertook 17 individual and group interviews between October 2014 and May 2015. Interviews transcripts were analysed using qualitative content analysis and validated with grass-roots community advisors.

Results

Participants reported multiple ways in which IPT was perceived as dangerous: when costs related to pill collection or consumption were unsustainable, or when daily pill consumption resulted in stigma or was seen to introduce excess dirt or toxins, 'ukungcola', in the body. Theories on dirt are evoked to describe how IPT was perceived as 'matter out of place' when given to people who believed themselves to be healthy, suggesting that under the current TB aetiological model in Zulu culture, 'prevention as tablet' may not fit.

Conclusion

Implementing IPT without understanding the realities of community stakeholders can unintentionally undermine TB control efforts by worsening the situation for people who already encounter numerous daily problems.

Impact of pre-pregnancy diabetes mellitus on congenital anomalies, Canada, 2002-2012

OBJECTIVE

To examine the impact of pre-pregnancy diabetes mellitus (DM) on the population birth prevalence of congenital anomalies in Canada.

METHODS

We carried out a population-based study of all women who delivered in Canadian hospitals (except those in the province of Quebec) between April 2002 and March 2013 and their live-born infants with a birth weight of 500 grams or more and/or a gestational age of 22 weeks or more. Pre-pregnancy type 1 or type 2 DM was identified using ICD-10 diagnostic codes. The association between DM and all congenital anomalies as well as specific congenital anomaly categories was estimated using adjusted odds ratios; the impact was calculated as a population attributable risk percent (PAR%).

RESULTS

There were 118,892 infants with a congenital anomaly among 2,839,680 live births (41.9 per 1000). While the prevalence of any congenital anomaly declined from 50.7 per 1000 live births in 2002/03 to 41.5 per 1000 in 2012/13, the corresponding PAR% for a congenital anomaly related to pre-pregnancy DM rose from 0.6% (95% confidence interval [CI]: 0.4-0.8) to 1.2% (95% CI: 0.9-1.4). Specifically, the PAR% for congenital cardiovascular defects increased from 2.3% (95% CI: 1.7-2.9) to 4.2% (95% CI: 3.5-4.9) and for gastrointestinal defects from 0.8% (95% CI: 0.2-1.9) to 1.4% (95% CI: 0.7-2.6) over the study period.

CONCLUSION

Although there has been a relative decline in the prevalence of congenital anomalies in Canada, the proportion of congenital anomalies due to maternal pre-pregnancy DM has increased. Enhancement of preconception care initiatives for women with DM is recommended.

Evidence for a KATP Channel in Rough Endoplasmic Reticulum (rerKATP Channel) of Rat Hepatocytes

We report in a previous study the presence of a large conductance K⁺ channel in the membrane of rough endoplasmic reticulum (RER) from rat hepatocytes incorporated into lipid bilayers. Channel activity in this case was found to decrease in presence of ATP 100 µM on the cytoplasmic side and was totally inhibited at ATP concentrations greater than 0.25 mM. Although such features would be compatible with the presence of a K_ATP channel in the RER, recent data obtained from a brain mitochondrial inner membrane preparation have provided evidence for a Maxi-K channel which could also be blocked by ATP within the mM concentration range. A series of channel incorporation experiments was thus undertaken to determine if the ATP-sensitive channel originally observed in the RER corresponds to K_ATP channel. Our results indicate that the gating and permeation properties of this channel are unaffected by the addition of 800 nM charybdotoxin and 1 µM iberiotoxin, but appeared sensitive to 10 mM TEA and 2.5 mM ATP. Furthermore, adding 100 µM glibenclamide at positive potentials and 400 µM tolbutamide at negative or positive voltages caused a strong inhibition of channel activity. Finally Western blot analyses provided evidence for Kir6.2, SUR1 and/or SUR2B, and SUR2A expression in our RER fractions. It was concluded on the basis of these observations that the channel previously characterized in RER membranes corresponds to K_ATP, suggesting that opening of this channel may enhance Ca²⁺ releases, alter the dynamics of the Ca²⁺ transient and prevent accumulation of Ca²⁺ in the ER during Ca²⁺ overload.

Coagulase-negative staphylococcus sepsis in preterm infants and long-term neurodevelopmental outcome

OBJECTIVE

The objective of this study was to examine the impact of Coagulase-negative staphylococcus (CoNS) sepsis in preterm infants on the neurodevelopmental outcomes at 30 to 42 months corrected age (CA).

STUDY DESIGN

This is a retrospective cohort study. All preterm infants born at <29 weeks gestational age between 1995 and 2008 and had a neurodevelopmetnal assessment at 30 to 42 months CA were eligible. The neurodevelopmetnal outcomes of infants exposed to CoNS sepsis were compared with infants unexposed to any type of neonatal sepsis.

RESULT

A total of 105 eligible infants who were exposed to CoNS sepsis were compared with 227 infants with no neonatal sepsis. In univariate analysis, infants with CoNS sepsis were more likely to have total major disability (odds ratio (OR)=1.9; 95% CI: 1.07 to 3.38) and cognitive delay (OR=2.53; 1.26 to 5.14).There was no significant difference in the incidence of cerebral palsy, blindness and deafness between the two groups. After correcting for potential confounders, CoNS sepsis was associated with increased risk of cognitive delay (adjusted odds ratio (aOR)= 2.23; 95% CI 1.01 to 4.9), but not with the total major disability (aOR=1.14; 95% CI: 0.55 to 2.34).

CONCLUSION

Our study suggests that CoNS sepsis in preterm infants might be associated with increased risk for cognitive delay at 36 months CA.

Histological chorioamnionitis and bronchopulmonary dysplasia: a retrospective cohort study

OBJECTIVE

To examine the association between histological chorioamnionitis (HC) with or without fetal inflammatory response (FIR) and bronchopulmonary dysplasia (BPD) in preterm infants.

STUDY DESIGN

We conducted a retrospective cohort study of infants born at <29 weeks gestation admitted to the neonatal intensive care unit from 2000 to 2006, who had placental histology. We compared the incidence of BPD among three groups: No HC group, HC without FIR group and HC with FIR group. The multivariable model based on generalized estimating equation was fitted to estimate the adjusted risk ratios (aRR) and 95% confidence intervals (CIs) for BPD and combined outcome of BPD or death.

RESULT

Of 529 infants, 84 (16%) had HC without FIR, 186 (35%) had HC with FIR and 259 (49%) had no HC. Compared with the no HC group, HC with and without FIR group infants were of lower gestational age and singleton births. Multivariable modeling based on generalized estimating equation revealed that HC with FIR is associated with decreased risk of both BPD (aRR 0.88, 95% CI 0.81 to 0.95) and the combined outcome of BPD or death (aRR 0.91, 95% CI 0.86 to 0.97). HC without FIR showed a trend toward reduction in BPD (aRR 0.93, 95% CI 0.86 to 1.00).

CONCLUSIONS

HC with FIR is associated with decreased risk of both BPD and the combined outcome of BPD or death in preterm infants.

Histological chorioamnionitis and neurodevelopmental outcome in preterm infants

OBJECTIVE

The objective of this study is to examine the neurodevelopmental outcome at 30 to 42 months corrected age of preterm infants with histological chorioamnionitis (HCA).

STUDY DESIGN

The study design is a retrospective cohort study with a prospective follow-up. All surviving infants with birth gestational age <29 weeks, born between 2000 and 2006, who had a neurodevelopmental assessment at 30 to 42 months corrected age were included. We compared the neurodevelopmental outcomes of infants with or without HCA.

RESULT

Of the 384 infants, 197 (51%) were born to mothers with evidence of HCA. Infants with HCA were of lower gestational age (26 weeks vs 26.6 weeks) and more likely to have intraventricular hemorrhage (27.9% vs 14.4%), periventricular leukomalacia (2.5% vs 0%) and retinopathy of prematurity ≥ stage 3 (31.4% vs 22.4%). On univariate analysis, infants with HCA were more likely to have cerebral palsy (12.6% vs 6.4%, P=0.04). There was no significant difference in the incidence of cognitive delay, deafness, blindness, or total major disabilities between the two groups. After adjusting for perinatal variables, HCA was associated with increased risk of cerebral palsy (odds ratio (OR): 2.45; 95% confidence interval (CI) 1.11 to 5.40), but not for total major disabilities (OR: 1.22; 95% CI: 0.64 to 2.34). There was a trend towards increased risk of cerebral palsy with HCA with funisitis.

CONCLUSION

HCA is associated with increased risk of cerebral palsy at 30 to 42 months corrected age in preterm infants.

The risk of unexplained antepartum stillbirth in second pregnancies following caesarean section in the first pregnancy

OBJECTIVE

To determine if a previous caesarean section increases the risk of unexplained antepartum stillbirth in second pregnancies.

STUDY DESIGN

Retrospective cohort study.

SETTING

Large Canadian perinatal database.

POPULATION

158 502 second births.

METHODS

Data were obtained from a large perinatal database, which supplied data on demographics, pregnancy complications, maternal medical conditions, previous caesarean section and pregnancy outcomes.

MAIN OUTCOME MEASURES

Total and unexplained stillbirth.

RESULTS

The antepartum stillbirth rate was 3.0/1000 in the previous caesarean section group compared with 2.7/1000 in the previous vaginal delivery group (P= 0.46). Multivariate logistic regression modelling, including terms for maternal age (polynomial), weight >91 kg, smoking during pregnancy, pre-pregnancy hypertension and diabetes, did not document an association between previous caesarean section and unexplained antepartum stillbirth (OR 1.27, 95% CI 0.92-1.77).

CONCLUSION

Caesarean section in the first birth does not increase the risk of unexplained antepartum stillbirth in second pregnancies.

ATP regulation of a large conductance voltage-gated cation channel in rough endoplasmic reticulum of rat hepatocytes

ATP-sensitive K+ channels play an important role in regulating membrane potential during metabolic stress. In this work we report the effect of ATP and ADP-Mg on a K+ channel present in the membrane of rough endoplasmic reticulum (RER) from rat hepatocytes incorporated into lipid bilayers. Channel activity was found to decrease in presence of ATP 100 microM on the cytoplasmic side and was totally inhibited at ATP concentrations greater than 0.25mM. The effect appeared voltage dependent, suggesting that the ATP binding site was becoming available upon channel opening. Channel activity was suppressed by the nonhydrolyzable ATP analog (ATPgammaS), ruling out a phosphorylation-based mechanism. Notably addition of 2.5mM ADP-Mg to the cytosolic side increased the channel open probability at negative potentials. We conclude that the large conductance voltage-gated cation channel in RER of rat hepatocytes is an ATP and ADP sensitive channel likely to be involved in cellular processes such as Ca(2+) signaling or control of membrane potential across the endoplasmic reticulum membrane.

Maternal haemolysis, elevated liver enzymes and low platelets syndrome: perinatal and neurodevelopmental neonatal outcomes for infants weighing less than 1250 g

OBJECTIVES

To study mortality and short-term morbidity of infants born to women with HELLP (haemolysis, elevated liver enzymes, and low platelets) syndrome and to compare the long-term neurodevelopmental morbidity of a subgroup with birth weight (BWT) less than 1250 g (study group) with weight matched controls.

METHODS

Retrospective chart review and prospective neurodevelopmental follow-up through a Perinatal Follow-up clinic. Analysis of perinatal and neonatal data for women diagnosed with HELLP from 1993 to 1996. Neurodevelopmental outcome for the study group was compared to a group of weight matched controls.

RESULTS

A total of 109 infants (mean gestational age 32.6 weeks, mean BWT 1766 g) were born to 104 women with HELLP syndrome. There was a significant decrease in mortality (P = 0.002) and morbidity (P < 0.05) with increasing gestational age and birthweight. No significant differences in neonatal mortality and morbidity were present between the infants weighing less than 1250 g study and weight matched control group. However, at 3 years, the study group had fewer children with cerebral palsy (P = 0.024) and mental disability (P trend = 0.07). Mean cognitive index was 99 versus 91 in the controls (P = 0.101).

CONCLUSION

Improved health outcomes occur with increased gestational age. Infants with BWT less than 1250 g born to women with HELLP syndrome were not at risk of increased neurodevelopmental disability compared to controls.

The risk of stillbirth in pregnancies before and after the onset of diabetes

AIMS

There is significant controversy as to whether or not stillbirth is increased in pregnancies prior to the onset of diabetes. An observed increase may be indicative of risks associated with untreated gestational diabetes. It is generally accepted that the risk of stillbirth in pregnancies that occur after the onset of diabetes has been diminished by modern obstetric care. However, the degree of residual risk is not well quantified. This study sought to examine the rates of stillbirth before and after the onset of diabetes compared with the general population.

METHODS

Retrospective cohort and nested case-control study. The study population was drawn from the UK-based General Practice Research Database, comprising some 300 practices, with data collection from the late 1980s until September 1999. From the base population, 913 diabetic women who had had a pregnancy were identified and 10,000 subjects without diabetes were randomly chosen as controls. Stillbirth was defined as death in utero after 20 weeks or with birth weight >500 g.

RESULTS

The stillbirth rates were higher in prediabetic pregnancies (19.7/1000), and in those occurring after the diagnosis of diabetes (33.7/1000), compared with the non-diabetic population (5.5/1000). Stillbirths were matched to four live births by maternal age and year of birth. Prediabetic pregnancy and pregnancy after the onset of diabetes were strongly associated with stillbirth: odds ratio (OR)=4.68 (1.67, 13.08) and OR=4.39 (2.22, 8.64), respectively.

CONCLUSIONS

The risk of stillbirth was increased in both prediabetic and post-diabetic pregnancy.

Beyond biology: the social context of prenatal behaviour and birth outcomes

OBJECTIVES

In this study we examine the factors that are associated with adverse birth outcomes using a representative national sample. In our analysis we take into account factors which are related to the mother's behaviour during pregnancy and also consider the socio-economic circumstances of the family.

METHODS

A series of logistic regression models are used to determine the increased risks of low birth weight, preterm, and small for gestational age births associated with maternal smoking, alcohol consumption and high blood pressure in relation to socio-economic factors, such as family dysfunction, social support, income adequacy, age, and education.

RESULTS

All socio-economic factors showed gradients of maternal smoking during pregnancy while only mother's education and socio-economic status demonstrated gradients of alcohol use and high blood pressure. Maternal smoking, high blood pressure, higher levels of family dysfunction, and lower levels of mother's education were found to significantly increase the risk of an adverse birth outcome.

CONCLUSIONS

Interventions designed to mitigate the hazards of adverse birth outcomes should be designed to reflect the gradients of risky prenatal maternal behaviours associated with age, education, income, and family dysfunction.

Secular trends in congenital anomaly-related fetal and infant mortality in Canada, 1985-1996

Prenatal diagnosis of major congenital anomalies and subsequent termination of affected pregnancies has been widely available as part of routine obstetric care in recent years. In this study, vital statistical data on stillbirths, live births, and infant deaths were used to examine secular trends in gestational age-specific and category-specific fetal and infant mortality due to congenital anomalies in Canada (excluding Ontario and Newfoundland) from 1985-1996. Comparisons of the rates between 1985-1987 and 1994-1996 were made using relative risks and 95% confidence intervals (CI). The overall fetal mortality rate due to congenital anomalies increased significantly, from 68.0 per 100,000 total births in 1985-1987 to 78.6 per 100,000 total births in 1994-1996, while the overall infant mortality rate due to congenital anomalies decreased significantly over the same period, from 2.47 to 1.79 per 1,000 live births. The fetal death rate due to congenital anomalies at 20-21 weeks of gestation increased approximately five-fold (relative risk [RR] = 4.83, 95% CI = 3.28-7.11) from 4.5 to 21.5 per 100,000 fetuses at risk, while the rate at 37-41 weeks decreased by 30% (RR = 0.70, 95% CI = 0.50-0.97). Fetal death rates among pregnancies at 20-25 weeks of gestation increased in all categories of congenital anomaly except anencephaly and respiratory system anomalies. Congenital anomaly-related fetal and infant deaths have increased at early gestation but declined at later gestation in Canada. These changes suggest an increase in prenatal diagnosis and selective termination of pregnancies with congenital anomalies in recent years.

Prediabetes and perinatal mortality

OBJECTIVE

The association between gestational diabetes mellitus (GDM) and perinatal outcome is largely based on case series and retrospective studies that found an increased risk of perinatal mortality and stillbirth as the onset of diabetes approached. Our objective was to assess the relationship between latency to diabetes and perinatal outcome of prediabetic pregnancies in a contemporary population of women with adult-onset diabetes.

RESEARCH DESIGN AND METHODS

A population of 403 diabetic women from two recruitment sites completed a pretested questionnaire.

RESULTS

Details of 1,181 pregnancy outcomes were obtained. This comprised 1,024 live births, 22 stillbirths, and 8 early neonatal deaths. Crude analysis suggested a relationship between time to diabetes (latency) < or =20 years and both perinatal death and stillbirth: odds ratio (95% CI), 2.41 (1.17-4.95) and 2.15 (0.93-4.98). Generalized additive modeling revealed a nonlinear relationship between the variables time to diabetes, and maternal age and perinatal outcome. Final logistic regression analysis was then performed for the outcomes perinatal death and stillbirth, with maternal age as a second-degree polynomial, year of birth as a continuous variable, and time to diabetes dichotomized < or =20 years to diagnosis and >20 years. This final analysis documented a significant association between time to diabetes < or =20 years and both perinatal death (4.06 [1.79-9.36]) and stillbirth (3.35 [1.25-9.05]).

CONCLUSIONS

There appeared to be an increased risk of perinatal death and stillbirth in pregnancies occurring in the last 20 years before the diagnosis of diabetes.

Two-year survey of Alberta laboratories processing of antenatal group B streptococcal (GBS) screening specimens: implications for GBS screening programs

We evaluated specimen types received and methods used by laboratories to process screening GBS specimens from pregnant women. Surveys during 1995 and 1997 of all laboratories in the province of Alberta, Canada that culture GBS from screening genital specimens were completed. Between surveys, there was dissemination of information about appropriate culture techniques. Survey completion rates were 100% in both years (38/38 in 1995 and 20/20 in 1997). During 1995 as compared to 1997, laboratories were less likely to a) have a specific written protocol for identification of genital GBS screening specimens (1995: 78.2% versus 1997: 100%, p = 0.08) b) be receiving combined vaginal-anorectal swabs (1995: 18% of all swabs received versus 1997: 60.4%, p < 0.001), and c) be using selective GBS culture media (1995: 45.5% versus 1997: 86.7%, p = 0.01). Regions using screening based approaches for GBS prevention need to ensure that their laboratories are using adequate techniques for GBS detection.

Outcome at 1-year adjusted age of 957 infants weighing more than 1250 grams with respiratory distress syndrome randomized to receive synthetic surfactant or air placebo. American and Canadian Exosurf Neonatal Study Groups

This study determined outcomes at 12-months adjusted age of 957 infants weighing more than 1250 gm at birth who were subjects in a randomized, double-blind, controlled trial of synthetic surfactant or air placebo administered in a rescue trial at 23 hospitals in the United States and 13 hospitals in Canada. Follow-up results were available for 475 of 563 surviving infants who received air placebo (84%) and 482 of 571 infants who received synthetic surfactant (84%). Developmental outcome was equivalent in the two groups. Morbidity was less in the synthetic surfactant group as assessed by the need for medication for chronic lung disease (52 of 475 (11%) for the air placebo group vs 32 of 482 (7%) for the synthetic surfactant group) or respiratory support (10 of 475 (2%) for the air placebo group vs 1 of 482 (< 1%) for the synthetic surfactant group) at 1-year adjusted age. Bayley Scales of Infant Development (mental development Index: 102 for both the air placebo and synthetic surfactant groups; psychomotor development index: 95 for the air placebo group vs 94 for the synthetic surfactant group) and impairment rates (94 of 475 (20%) for the air placebo group vs 86 of 482 (18%) for the synthetic surfactant group) were similar in the two groups. Infants weighing more than 1250 gm who have respiratory distress syndrome have previously been shown to have improved survival rates and lower neonatal morbidity after treatment with synthetic surfactant. These follow-up data confirm that developmental outcome as determined at 12-months adjusted age is at least as good in those receiving synthetic surfactant.

Double-blind 1-year follow-up of 1540 infants with respiratory distress syndrome randomized to rescue treatment with two doses of synthetic surfactant or air in four clinical trials. American and Canadian Exosurf Neonatal Study Groups

Synthetic surfactant has been shown to reduce neonatal and 1-year mortality and neonatal morbidity in infants with respiratory distress syndrome. However, less is known about the effects of synthetic surfactant on developmental outcome and long-term morbidity. Four multicenter, randomized, placebo-controlled trials of synthetic surfactant administered as rescue therapy were conducted in the United States and Canada, with a total enrollment of 2224 patients. Double-blind developmental evaluations of survivors were conducted at 1 year of age (adjusted for prematurity) in all four trials. Of the 1802 patients enrolled in the placebo-controlled rescue trials who survived to 1 year, 1540 (85%) completed the 1-year follow-up evaluation. Height, weight, and head circumference measurements were not different in the treatment and control groups. Mean and median Bayley Scores of Infant Development for both the Mental Development Index and the Psychomotor Development Index were also equivalent. The incidence of impairments was not different in the two groups (mild to moderate impairment, 12% (92 of 745) for the air placebo group vs 11% (86 of 771) for the synthetic surfactant group; severe impairment, 15% (114 of 745) for the air placebo group vs 13% (102 of 771) for the synthetic surfactant group). No differences in rates of retinopathy of prematurity or hearing impairment were found in the treatment groups. The need for surgery after day 28 of life (relative risk, 0.779; 95% confidence interval, 0.665, 0.927) and the need for respiratory support at 1 year (relative risk, 0.525; 95% confidence intervals, 0.303, 0.911) were both reduced in the synthetic surfactant group. These results indicate that developmental outcome at 1 year of age is at least as good among infants with respiratory distress syndrome who received rescue therapy with synthetic surfactant as it is in infants who received air placebo; the results also indicate that the incidence of long-term morbidity is reduced.

Spinal cord injury at birth: diagnostic and prognostic data in twenty-two patients

OBJECTIVES

To establish criteria, evident soon after birth, that predict long-term outcome of neonates with spinal cord injury (SCI) at birth.

DESIGN

Retrospective case-series.

SETTING

Five Canadian regional neonatal tertiary care centers.

PATIENTS

Consecutive samples of patients referred to five centers for a total of 22 subjects, in whom SCI was diagnosed during life. Sites of lesions were above the fourth cervical vertebrae (n = 14), at the fourth cervical to the fourth thoracic vertebrae (n = 6), and at the thoracolumbar region (n = 2).

MEASUREMENTS AND MAIN RESULTS

All 14 patients with upper cervical SCI had cephalic presentations, whereas all 6 patients with cervicothoracic SCI had breech presentations (p < 0.0001). The site and extent of lesion were best diagnosed by clinico-imaging correlations. Ultrasonography appeared to be the most useful imaging study. In patients with upper cervical SCI who had no coexistent central nervous system abnormality associated with early death, long-term outcome in survivors (dependency on mechanical ventilation and on aids for upper limb activity and for ambulation) was best predicted by age when breathing was first observed and by rate of recovery of limb motor function in the first 3 months. The presence of breathing movements on day 1 (n = 2) was associated with mild disability. The absence of breathing movements on day 1 and little or no recovery of motor function in the first 3 months was associated with permanent total dependency on mechanical ventilation and severe quadriplegia (n = 5). Apnea on day 1 and intermediate recovery rates in the first 3 months was associated with variable long-term prognoses (n = 3).

A randomized controlled trial of early amniotomy

OBJECTIVE-To determine if a policy of early amniotomy resulted in a reduction in mean labour duration when compared to a policy of conservation of the membranes. DESIGN-A single-centre randomized controlled trial. SETTING-A tertiary care teaching hospital in Alberta, Canada. SUBJECTS-Ninety-seven term nulliparae in spontaneous labour, baby in cephalic presentation. INTERVENTION-Early amniotomy versus intent to keep membranes intact. MAIN OUTCOME MEASURES-Interval from randomization to delivery, rate of abnormalities of fetal heart rate tracings, cord artery blood pH, Apgar scores. RESULTS-The mean interval from randomization to delivery was 390.9 (SE 29.1) min in the amniotomy group and 442.9 (SE 34.1) min in the control group (P = 0.251). There were no differences between groups in the occurrence of fetal heart rate tracing abnormalities, nor was there a difference in the proportion of babies with abnormal Apgar scores, or abnormal cord pH (less than 7.20). CONCLUSION-The results of the study fail to support the long held belief that early amniotomy is an effective method for reducing labour duration.

External ATP triggers a biphasic activation process of a calcium-dependent K+ channel in cultured bovine aortic endothelial cells

We have used the patch-clamp method in order to investigate the single-channel events underlying the effect of external ATP on the potassium permeability of bovine aortic endothelial cells (BAE). The results obtained from cell-attached and inside-out experiments led first to conclude that BAE cells possess an inward rectifying potassium channel activated by internal calcium at micromolar concentrations. The channel conductance for inward currents was estimated at 40 pS in symmetrical 200 mM KCl and the open-channel probability was found to be voltage insensitive within the membrane voltage range -50 to -100 mV. Based on results obtained in the cell-attached configuration, it could next be established that external ATP and ADP at micromolar concentrations could trigger, via the stimulation of P2 purinergic receptors, a time variable activation process of the observed calcium-dependent potassium channel. This activation process was found to occur in a biphasic manner with an initial phase independent of the presence of calcium in the cell bathing medium. The second phase which could be blocked by calcium channel blockers such as Co2+ or La3+ required, however, the presence of external calcium and could be abolished by depolarizing the cells using high K+ external solutions. Another important aspect related to this phenomenon was the observation that removing ATP from the external medium during the second phase led to a complete abolition of the associated calcium-dependent potassium channel activation process. It is suggested from these results that the action of ATP on the potassium permeability of BAE cells is related to a second messenger mediated release of calcium from internal calcium stores coupled to an ATP-dependent calcium influx abolished at depolarizing voltages.

Pulmonary hypoplasia testing in clinical obstetrics

An ultrasound-based diagnostic test for predicting pulmonary hypoplasia antenatally by measurements of fetal chest circumference was applied prospectively to 45 patients at risk for developing this disorder. The outcome for the newborn infant and the autopsy findings were correlated with the antenatal prediction. The results of this test demonstrated a sensitivity and a specificity of 88% and 96%, respectively. The application of this test to clinical practice is recommended.