Severe Antenatal Hypertrophic Cardiomyopathy Secondary to ACAD9-Related Mitochondrial Complex I Deficiency

Introduction

Antenatal presentation of hypertrophic cardiomyopathy (HCM) is rare. We describe familial recurrence of antenatal HCM associated with intrauterine growth restriction and the diagnostic process undertaken.

Methods

Two pregnancies with antenatal HCM were followed up. Biological assessment including metabolic analyses, genetic analyses, and respiratory chain study was performed. We describe the clinical course of these two pregnancies, antenatal manifestations as well as specific histopathological findings, and review the literature.

Results

The assessment revealed a deficiency in complex I of the respiratory chain and two likely pathogenic variations in the ACAD9 gene.

Discussion and Conclusion

Antenatal HCM is rare and a diagnosis is not always made. In pregnancies presenting with cardiomyopathy and intrauterine growth restriction, ACAD9 deficiency should be considered as one of the potential underlying diagnoses, and ACAD9 molecular testing should be included among other prenatal investigations.

Overlapping and Distinct Features of Cardiac Pathology in Inherited Human and Murine Ether Lipid Deficiency

Inherited deficiency in ether lipids, a subgroup of glycerophospholipids with unique biochemical and biophysical properties, evokes severe symptoms in humans resulting in a multi-organ syndrome. Mouse models with defects in ether lipid biosynthesis have widely been used to understand the pathophysiology of human disease and to study the roles of ether lipids in various cell types and tissues. However, little is known about the function of these lipids in cardiac tissue. Previous studies included case reports of cardiac defects in ether-lipid-deficient patients, but a systematic analysis of the impact of ether lipid deficiency on the mammalian heart is still missing. Here, we utilize a mouse model of complete ether lipid deficiency (Gnpat KO) to accomplish this task. Similar to a subgroup of human patients with rhizomelic chondrodysplasia punctata (RCDP), a fraction of Gnpat KO fetuses present with defects in ventricular septation, presumably evoked by a developmental delay. We did not detect any signs of cardiomyopathy but identified increased left ventricular end-systolic and end-diastolic pressure in middle-aged ether-lipid-deficient mice. By comprehensive electrocardiographic characterization, we consistently found reduced ventricular conduction velocity, as indicated by a prolonged QRS complex, as well as increased QRS and QT dispersion in the Gnpat KO group. Furthermore, a shift of the Wenckebach point to longer cycle lengths indicated depressed atrioventricular nodal function. To complement our findings in mice, we analyzed medical records and performed electrocardiography in ether-lipid-deficient human patients, which, in contrast to the murine phenotype, indicated a trend towards shortened QT intervals. Taken together, our findings demonstrate that the cardiac phenotype upon ether lipid deficiency is highly heterogeneous, and although the manifestations in the mouse model only partially match the abnormalities in human patients, the results add to our understanding of the physiological role of ether lipids and emphasize their importance for proper cardiac development and function.

Incremental Detection of Severe Congenital Heart Disease by Fetal Echocardiography Following a Normal Second Trimester Ultrasound Scan in Québec, Canada

Background:

The benefit of fetal echocardiograms (FE) to detect severe congenital heart diseases (SCHD) in the setting of a normal second-trimester ultrasound is unclear. We aimed to assess whether the increase in SCHD detection rates when FE are performed for risk factors in the setting of a normal ultrasound was clinically significant to justify the resources needed.

Methods:

This is a multicenter, population-based, retrospective cohort study, including all singleton pregnancies and offspring in Quebec (Canada) between 2007 and 2015. Administrative health care data were linked with FE clinical data to gather information on prenatal diagnosis of CHD, indications for FE, outcomes of pregnancy and offspring, postnatal diagnosis of CHD, cardiac interventions, and causes of death. The difference between the sensitivity to detect SCHD with and without FE for risk factors was calculated using generalized estimating equations with a noninferiority margin of 5 percentage points.

Results:

A total of 688 247 singleton pregnancies were included, of which 30 263 had at least one FE. There were 1564 SCHD, including 1071 that were detected prenatally (68.5%). There were 12 210 FE performed for risk factors in the setting of a normal second-trimester ultrasound, which led to the detection of 49 additional cases of SCHD over 8 years. FE referrals for risk factors increased sensitivity by 3.1 percentage points (95% CI, 2.3–4.0; P<0.0001 for noninferiority).

Conclusions:

In the setting of a normal second-trimester ultrasound, adding a FE for risk factors offered low incremental value to the detection rate of SCHD in singleton pregnancies. The current ratio of clinical gains versus the FE resources needed to screen for SCHD in singleton pregnancies with isolated risk factors does not seem favorable. Further studies should evaluate whether these resources could be better allocated to increase SCHD sensitivity at the ultrasound level, and to help decrease heterogeneity between regions, institutions and operators.

Alternative to body surface area as a solution to correct systematic bias in pediatric echocardiography Z scores

BACKGROUND

Z scores are the method of choice to report dimensions in pediatric echocardiography. Z scores based on body surface area (BSA) have been shown to cause systematic biases in overweight and obese children. Using aortic valve (AoV) diameters as a paradigm, the aims of this study were to assess the magnitude of Z score underestimation in children with increased body mass index Z score (BMI-Z) and to determine if a predicting model with height and weight as independent predictors would minimize this bias.

METHODS

In this multicenter, retrospective, cross-sectional study, 15,006 normal echocardiograms in healthy children 1-18 years old were analyzed. Residual associations with body size were assessed for previously published Z score. BSA-based and alternative prediction models based on height and weight were developed and validated in separate training and validation samples.

RESULTS

Existing BSA-based Z scores incompletely adjusted for weight, BSA and BMI-Z and led to an underestimation of >0.8 Z score units in subjects with higher BMI-Z, compared to lean subjects. BSA-based models led to overestimation of predicted AoV diameters with increasing weight or BMI-Z. Models using height and weight as independent predictors improved adjustment with body size, including in children with higher BMI-Z.

CONCLUSIONS

BSA-based models result in underestimation of Z scores in patients with high BMI-Z. Prediction models using height and weight as independent predictors minimize residual associations with body size and generate well-fitted predicted values that could apply to all children, including those with low or high BMI-Z.

Rationale and Design of the FREQUENCY Study: The Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology

OBJECTIVE

Prenatal detection of congenital heart diseases (CHD) decreases morbidity and cost. To improve detections rates, most physicians refer pregnant women with high-risk pregnancies to fetal cardiologists even when there is no suspicion of CHD at the second trimester screening. This paper presents the rationale and detailed method of the Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology (FREQUENCY) study. The overall objective is to assess the impact of second trimester ultrasound screening (U/S) and referral pattern in fetal cardiology on detection rates, health care costs, and resource utilization, as well as perinatal morbidity and mortality.

METHODS

This multicentre retrospective population-based cohort study will link fetal echocardiography data from all centres performing fetal echocardiography in Québec with administrative health care data. This data linking will allow the determination of a true denominator (all women in Québec who underwent second trimester U/S) with complete follow-up of up to 2 years for offspring. This protocol meets Canadian Task Force Classification II-2.

RESULTS

The study investigators have collected and cleaned fetal echocardiography data for 24 259 eligible pregnancies referred to fetal cardiology. These data will be matched to approximately 860 000 pregnancies between 2007 and 2015.

CONCLUSION

The results of the FREQUENCY study will shed light on the impact of the current prenatal CHD screening strategy in Canada.

Prenatal diagnosis of right ventricular outflow tract obstruction with intact ventricular septum, and detection of ventriculocoronary connections

OBJECTIVES

To determine the accuracy of prenatal diagnosis of pulmonary atresia and intact ventricular septum (PAIVS), and pulmonary stenosis, including prenatal detection of ventriculocoronary connections, to evaluate heart size during the prenatal period, and to evaluate the outcome.

DESIGN AND PATIENTS

Medical records of 20 cases with prenatally diagnosed PAIVS and pulmonary stenosis were reviewed retrospectively. Prenatal and postnatal echocardiography were also reviewed and dimensions of the ventricles and vessels were measured retrespectively.

RESULTS

Of 20 prenatal diagnoses (15 PAIVS and five pulmonary stenosis), 16 were confirmed as correct. One critical pulmonary stenosis case had been diagnosed as PAIVS prenatally; three had no confirmation. Eight pregnancies were terminated, three had no active treatment, and nine were treated; all survived. Of 13 assessed with ventriculocoronary connections prenatally, seven were diagnosed correctly (four with, three without ventriculocoronary connections), but one was falsely positive; five had no confirmation. The more prominent hypoplasia of the main pulmonary artery and the tricuspid valve annulus, and the sigmoid shape of the ductus arteriosus, seemed to be associated with the presence of ventriculocoronary connections.

CONCLUSIONS

Current prenatal echocardiography can accurately diagnose right ventricular outflow tract obstruction and ventriculocoronary connections. Prenatal detection of this constellation of abnormalities aids in family counselling and decisions on postnatal management.

Evolution of fetal ventricular aneurysms and diverticula of the heart: an echocardiographic study

Due to the rarity of congenital ventricular diverticula and aneurysms, their natural history remains unclear. An excellent prognosis has been suggested for those cases diagnosed during fetal life: From October 1992 to January 1996 seven fetuses were diagnosed with ventricular diverticula or aneurysms. Gestational age ranged from 18 to 36 weeks. The indications for fetal echocardiogram were cardiomegaly, abnormal four-chamber view, a large pericardial effusion, and hydrothorax. Echocardiography revealed a moderate sized apical left ventricular aneurysm (2), a small subvalvular right ventricular diverticulum (1), small apical right ventricular diverticulum (2), a large submitral left ventricular aneurysm (1), and a large diverticulum arising from the lateral free wall of the left ventricle (1). Decreased left ventricular function was detected in three fetuses with left ventricular aneurysms. Two fetuses with large lesions, developed hydrops and died in utero. Postnatal echocardiograms confirmed prenatal findings in all survivors. All infants remained asymptomatic, with age on follow-up from 8 to 24 months. An accurate diagnosis of ventricular diverticula and aneurysms is feasible prenatally. Outcome depends on the size and progression of the lesion. The presence of a large pericardial effusion in three cases with a diverticula was noted.

Isolated ductal closure in utero diagnosed by fetal echocardiography

In utero isolated ductal closure is uncommon and can lead to fetal hydrops and death if not recognized. Five fetuses were diagnosed prenatally by echocardiography. The reasons for referral were hydrops (2), cardiomegaly (1), polyhydramnios and choroid plexus cyst (1), and polyhydramnios and teratoma of the neck (1). Gestational age was median 32, range 18-41 weeks. Two mothers received indomethacin for polyhydramnios, with the echocardiogram performed 5 and 3 days after the last dose. Three had a negative history of drug ingestion. Fetal echocardiograms showed absent flow in the ductus arteriosus, dilated right ventricle with decreased function, and mild or moderate tricuspid and pulmonary insufficiency in all. The left ventricle was hypercontractile, with significantly increased left ventricular stroke output when compared to the right. Four fetuses were delivered by cesarean section and had an uneventful course. One fetus died shortly after birth due to airway obstruction from a large teratoma. Autopsy showed ductal constriction. Postnatal echocardiograms showed absent ductal flow and dilated right ventricle. On follow-up, survivors remained asymptomatic with cardiac size returning to normal. Premature closure of the ductus arteriosus should be considered in hydrops of unknown etiology, right ventricular dysfunction, and following indomethacin therapy. Urgent delivery results in an excellent prognosis.

Heart rate and cardiac output after atropine in anaesthetised infants and children

PURPOSE

Heart rate is considered to be a major determinant of cardiac output in infants and small children but the relationships between age, heart rate and cardiac output in humans have never been clearly established. This study was designed to determine the change in cardiac output following atropine iv to anaesthetised infants and small children.

METHODS

Following Institutional Ethics Committee approval and written-informed consent, 20 ASA I or II unpremedicated patients aged from 1 to 36 mo were studied. Anaesthesia was induced with 5 mg.kg-1 thiopentone, 2 micrograms.kg-1 fentanyl and maintained with halothane 0.5% in nitrous oxide 66% in oxygen. Vecuronium 0.1 mg.kg-1 was used to provide muscular relaxation. Cardiac output was measured by non-invasive transthoracic blind continuous-wave Doppler echocardiography before and after the administration of 0.02 mg.kg-1 atropine iv.

RESULTS

Atropine increased both heart rate and cardiac index by 31.1 +/- 12.8% and 29.4 +/- 17.3% respectively (P < 0.05). The cardiac index before atropine was 5.1 +/- 1.2 L.min-1.m-2 and the increase after atropine varied widely from 1.4 to 52.1%. Although atropine did not alter the overall stroke index the recorded changes ranged from -20.8 to +18.0%. There was no association between age and either cardiac index or % change in cardiac index after atropine. However, there was a positive but weak correlation between percentage change in heart rate and cardiac output (r2 = 0.46).

CONCLUSION

Atropine causes a variable increase in cardiac output in infants and children aged between 1 and 36 mo. The change in cardiac output, considering the limits of the transthoracic echocardiography methodology, suggests that this is related to the increase in heart rate but is not dependent of age.