Immune-Mediated Fetal Complete Atrioventricular Block: Can Dexamethasone Therapy Revert the Process?

BACKGROUND: Fetal complete atrioventricular block (CAVB) is usually autoimmune mediated. The risk of developing CAVB is 2% to 3% in anti-Ro/SS-A seropositive pregnancies and it increases 10 times after previous CAVB in siblings. Despite being a rare complication, CAVB carries a 20% mortality rate and substantial morbidity, as about 65% of newborns will eventually need life-long pacing. Once found, fetal CAVB is almost always irreversible, despite aggressive immunotherapy. This poor outcome prompted some research groups to address this situation. All groups followed anti-Ro/SS-A seropositive pregnancies on a weekly basis during the second trimester of pregnancy and tried to detect first degree atrioventricular block (AVB) using accurate echocardiographic tools, assuming they may characterize the initiation of the immune damage to the A-V conduction system, at which point the process might still be reversible. Some of the groups treated fetuses with first degree AVB with maternal oral fluorinated steroids. We summarized the results of all groups, including our group. We describe a case of a fetus that developed CAVB 6 days after normal sinus rhythm (NSR), who under aggressive dexamethasone therapy gradually reverted to NSR. This fetus had a previous sibling with CAVB. We assumed the immune damage to the conduction system in this small group of fetuses with a previous CAVB sibling may have occurred more quickly than usual. We therefore recommend a twice-weekly follow-up with these fetuses.

Conotruncal malformations and absent thymus due to a deleterious NKX2-6 mutation.

BACKGROUND: Truncus arteriosus (TA) accounts for ~1% of congenital heart defects. The aetiology of isolated TA is largely unknown but when occurring as part of a syndrome, it is mostly associated with chromosome 22q11 deletion. Vice versa, the most common congenital heart defects associated with chromosome 22q11 deletion are conotruncal malformations. In this study we investigated the cause of multiple conotruncal malformations accompanied by athymia in a consanguineous family. METHODS AND RESULTS: Whole exome analysis revealed a homozygous deleterious mutation in the NKX2-6 gene. CONCLUSIONS: NKX2-6 encodes a homeobox-containing protein which is expressed in mouse embryo at E8.0-E9.5 at the caudal pharyngeal arches and the outflow tract. A single missense mutation was previously implicated in the aetiology of familial isolated TA; however, null mice are entirely normal. The clear phenotype associated with a homozygous deleterious mutation in the present report, falls well within the spectrum of the cardiac defects seen in DiGeorge syndrome, is in agreement with NKX2-6 downstream location in the TBX1 signalling pathway and confirms NKX2-6 role in human cardiogenesis.

Prevalence of persistent superior vena cava and association with congenital heart anomalies.

A contralateral persistent superior vena cava (PSVC) can occur in a normal child or in association with congenital heart defects (CHDs). Its prevalence has been demonstrated in relatively small cohorts. We aim to assess the frequency of a PSVC in a large cohort of children with and without CHDs. To estimate its significance, we have searched for a PSVC in all children referred for echocardiography in our institution during a 16.5-year period. A group of 17,219 children comprised 8,140 children with a structural heart anomaly and 9,079 children with a structurally normal heart. Association between a PSVC and specific classes of CHD were looked for. A total of 288 children (1.7%) had a PSVC; 0.56% (51 of 9,079) in the normal heart group and 2.9% (237 of 8,140) in the congenital heart anomalies group. Odds ratio for having heart anomaly in the presence of PSVC was 5.2 (95% confidence interval 3.7 to 7.0). A PSVC was above all associated with atrioventricular septal defects, conotruncal malformations, and left-sided defects. The odds ratio of having PSVC in the aforementioned malformations compared with the normal heart group was 23.8, 13.6, and 11.0, respectively. In conclusion, although present in normal subjects, PSVC was more often associated with congenital heart and other anomalies, especially with atrioventricular septal defects, conotruncal malformations, and left-sided defects.

Intracardiac echogenic foci have no hemodynamic significance in the fetus.

Intracardiac echogenic foci (ECFs), probably representing microcalcifications of the papillary muscles, are a common finding in fetal ultrasonic screening examinations. Their significance is unclear, and their value as markers for chromosomal anomalies is debatable. It also is unknown whether ECFs predict abnormal cardiac performance. This prospective study analyzed and compared the systolic and diastolic properties of the heart in 28 fetuses with ECFs and 70 fetuses without ECFs using both conventional and novel myocardial deformation methods. The findings suggest that left-sided ECFs do not predict depressed left- or right-side systolic or diastolic properties in the fetus. A longitudinal study that would follow ECF fetuses into their childhood is warranted to confirm the findings of this study.

Analysis of segmental and global function of the fetal heart using novel automatic functional imaging.

BACKGROUND: Functional assessment of the fetal heart has always been a challenge. Automatic functional imaging (AFI), a novel non-Doppler methodology based on 2-dimensional acoustic markers tracking, measures myocardial deformation regardless of angle of interrogation. Thus, we studied the validity of AFI in segmental and global assessment of myocardial function in the fetus. METHODS: AFI-based myocardial deformation parameters including segmental tissue velocity, strain, and strain rate as well as biventricular global strain and strain rate were measured from raw scan-line data obtained from 28 normal fetuses (20-38, median 28 weeks of gestation). Interobserver and intraobserver variability was analyzed. AFI data were compared with analogous Doppler-derived tissue velocity imaging parameters measured in the same 28 fetuses. RESULTS: AFI was feasible in 94% of the fetuses studied with high reproducibility. AFI-based tissue velocity (3.9 +/- 1 cm/s) was comparable with tissue velocity imaging-based velocity (4 +/- 1.6 cm/s) in the right ventricle and in the left ventricle (AFI velocity 3.3 +/- 0.6 vs tissue velocity imaging 3.1 +/- 0.9 cm/s). Strain rate obtained by these two methods was also similar. Biventricular global strain and strain rate measured 16 +/- 4% and 1.6 +/- .5 seconds(-1), respectively. Tissue velocity increased whereas segmental strain rate decreased throughout gestation. Strain remained unchanged. Global strain rate significantly decreased with gestational age (r = -0.7). CONCLUSION: AFI, a novel non-Doppler methodology, allows fast and accurate quantification of segmental and global myocardial function in the fetus. AFI-based tissue velocity increases with gestational age whereas segmental and the new parameter global strain rate decrease throughout gestation.

Assessment of fetal myocardial performance using myocardial deformation analysis.

Conventional techniques for the assessment of cardiac function on the basis of M-mode or 2-dimensional modalities are technically difficult, load dependent, and provide information on global ventricular function only. Newer techniques, which analyze myocardial performance, such as tissue velocity, strain, and especially the less load dependent strain rate, may provide more appropriate information. Myocardial systolic and diastolic motion and performance were calculated using tissue velocity, strain, and strain rate imaging on a large cohort of normal fetuses. The assessment of myocardial performance was feasible in all 98 normal fetuses. Normal systolic and diastolic values for tissue velocity, strain, and strain rate were established. All data were highly reproducible. Tissue velocity was age dependent, whereas strain and strain rate were stable throughout gestation. All parameters were heart rate independent. In conclusion, fetal myocardial velocity, strain, and strain rate measurements are easy to obtain and reproducible, and therefore, may serve as reference data. Increases in tissue velocity throughout gestation probably reflect the growth of the fetal heart, whereas intrinsic myocardial properties as measured by strain rate do not change. In comparison with recently published myocardial performance values in children, these strain rate data suggest that fetal myocontractile properties that are already established during the second half of pregnancy remain constant throughout gestation and after birth.

Comparison of N-terminal pro-B-type natriuretic peptide levels in critically ill children with sepsis versus acute left ventricular dysfunction.

OBJECTIVE: N-terminal pro-B-type natriuretic peptide has been shown to be a marker for cardiac dysfunction. The peptide level is also elevated in patients with sepsis. The purpose of this study was to assess whether N-terminal pro-B-type natriuretic peptide levels can differentiate pediatric patients with sepsis from patients with acute left ventricular dysfunction. PATIENTS AND METHODS: Pediatric patients admitted to an ICU with sepsis or acute left ventricular dysfunction were evaluated clinically, and the grade of systemic inflammatory-response syndrome was determined. Echocardiography was performed, and their levels of N-terminal pro-B-type natriuretic peptide were measured. The N-terminal pro-B-type natriuretic peptide level was also measured in patients with simple febrile illness. RESULTS: There were 10 patients with sepsis and 10 with acute left ventricular dysfunction. The age of the patients was similar, and systemic inflammatory-response syndrome grading was not different (sepsis: 2.8 +/- 0.4; acute left ventricular dysfunction: 2.6 +/- 0.7). N-terminal pro-B-type natriuretic peptide levels were elevated in patients with sepsis (median: 6064 pg/mL; range: 495-60,417 pg/mL) but were significantly higher in patients with acute left ventricular dysfunction (median: 65,630 pg/mL; range: 15,125-288,000). The area under the receiver operating characteristics curve for the diagnosis of acute left ventricular dysfunction was 0.9. N-terminal pro-B-type natriuretic peptide levels of patients with sepsis and impaired systolic function were not different from those of patients with sepsis and normal systolic function. The N-terminal pro-B-type natriuretic peptide levels of 20 patients with simple febrile illness were significantly lower. CONCLUSIONS: N-terminal pro-B-type natriuretic peptide levels are elevated in pediatric patients with sepsis but are higher in some, but not all, patients with acute left ventricular dysfunction. The overlap between N-terminal pro-B-type natriuretic peptide levels in sepsis and acute left ventricular dysfunction precludes the use of the peptide's level as a sole means to differentiate between these conditions. Excessive elevation in N-terminal pro-B-type natriuretic peptide levels, however, suggests cardiac etiology for acute hemodynamic deterioration in infants and children.