Population-based review of tetralogy of Fallot with absent pulmonary valve: is prenatal diagnosis really associated with a poor prognosis?

OBJECTIVES

Tetralogy of Fallot with absent pulmonary valve syndrome (TETAPV) is reported in obstetric literature to have an extremely poor prognosis. We sought to determine the clinical outcome associated with TETAPV and whether prenatal diagnosis confers a poor prognosis.

METHODS

All cases of TETAPV diagnosed in British Columbia between 1980 and 2009 were reviewed and grouped according to time of diagnosis, either prenatal or postnatal. The groups were compared with respect to mortality, respiratory problems, number of interventions and functional capacity at last follow-up.

RESULTS

Eight and 11 patients were included in the prenatally and postnatally diagnosed groups, with overall long-term survival of 71% and 82%, respectively. There was no significant difference in mortality, frequency of preoperative intubation, number of interventions or functional capacity between groups.

CONCLUSION

From a population-based retrospective analysis of TETAPV cases identified over three decades it is concluded that the prognosis for TETAPV is better than that previously reported in the obstetric literature. This information should be used to guide prenatal counseling.

Endothelial dysfunction and compromised eNOS/Akt signaling in the thoracic aorta during the progression of Marfan syndrome

BACKGROUND AND PURPOSE

Aortic complications account for the major mortality in Marfan syndrome (MFS), a connective tissue disorder caused by mutations in FBN1 encoding fibrillin-1. We hypothesized that MFS impaired endothelial function and nitric oxide (NO) production in the aorta.

EXPERIMENTAL APPROACH

Mice (at 3, 6, 9 and 12 months of age) heterozygous for the Fbn1 allele encoding a cysteine substitution (Fbn1 (C1039G/+), Marfan mice, n=75), the most common class of mutation in MFS, were compared with age-matched control littermates (n=75). Thoracic and abdominal aortas from the two groups were studied.

KEY RESULTS

Isometric force measurements revealed that relaxation to ACh (but not to sodium nitroprusside) was diminished in the phenylephrine-precontracted Marfan thoracic aorta at 6 months of age (pEC(50)=6.12+/-0.22; maximal response, E(max)=52.7+/-6.8%; control: pEC(50)=7.34+/-0.19; E(max)=84.8+/-2.2%). At one year, both inhibition of NO production with N(omega)-nitro-L-arginine methyl ester, or denudation of endothelium increased the phenylephrine-stimulated contraction in the control thoracic aorta by 35%, but had no effect in the Marfan aorta, indicating a loss of basal NO production in the Marfan vessel. From 6 months, a reduced phosphorylation of endothelial NOS (eNOS)(Ser1177) and Akt(Thr308) detected by Western blotting was observed in the Marfan thoracic aorta, which was accompanied by decreased levels of cGMP. Expressions of Akt and eNOS in the abdominal aorta were not different between the two groups.

CONCLUSIONS AND IMPLICATIONS

MFS impairs endothelial function and signaling of NO production in the thoracic aorta, suggesting the importance of NO in the age-related progression of thoracic aortic manifestations.

Diagnosis of fetal ductus arteriosus aneurysm: importance of the three-vessel view

OBJECTIVE

To present four cases of ductus arteriosus aneurysm (DAA) detected by fetal echocardiography and highlight the value of the three-vessel view in the diagnosis of DAA.

METHODS

In addition to the standard fetal echocardiographic views, we examined the three-vessel view in four cases of DAA. The three-vessel view was achieved by sliding the transducer cranially from the four-chamber plane toward the fetal upper mediastinum to demonstrate cross-sections of the main pulmonary artery, the ascending aorta and superior vena cava arranged in a straight line from the left anterior to the right posterior aspect of the mediastinum. DAA was diagnosed when there was a tortuous ductus arteriosus with a dilation that protruded leftward of the aortic arch.

CASE SERIES

In the first case, an insulin-dependent diabetic woman underwent fetal ultrasound examination at 36 weeks' gestation showing right-to-left cardiac disproportion and bidirectional flow in the aorta and main pulmonary artery (PA). The three-vessel view showed a dilated ductus arteriosus (DA) which was stenosed at its distal end. In the second case, a woman had fetal ultrasound scans at 38 and 39 weeks' gestation for suspected intrauterine growth restriction and oligohydramnios. The scans identified an abnormal aortic arch and the three-vessel view showed an elongated vascular structure at the distal end of the PA, which was the DAA. In the third case, a woman with a high-risk obstetric history had multiple scans showing an abnormal PA to aorta relationship, with an apparent 'kink' in the PA. The three-vessel view clarified that this was the DAA. In the fourth case, a woman was scanned because of a 3-kg weight gain in 1 week. The fetal ultrasound scan showed moderate polyhydramnios with normal fetal growth and normal intracardiac anatomy and flow, and the three-vessel view demonstrated a large DA. In each of these cases, the DAA appeared to have occurred in isolation with non-specific clinical findings.

CONCLUSION

We advocate the use of the three-vessel view, in conjunction with the standard echocardiography views currently employed, to assist in the diagnosis of DAA.

Myocardial contractility in premature neonates with and without patent ductus arteriosus

Controversy exists as to whether a hemodynamically significant left-to-right shunt due to a patent ductus arteriosus (PDA) affects ventricular contractility. Load-dependent indices such as ejection fraction and shortening fraction have traditionally been used to assess contractility, but the relationship between the rate-corrected velocity of fiber shortening (MVCFc) and wall stress may be more suitable, as it is a preload-independent, afterload-adjusted method of assessing ventricular contractility. Age-related differences have been established for these variables in normal adults and children and it has been recommended for use in the premature neonate. The study was performed to assess left ventricular contractility in premature neonates with a significant left-to-right shunt due to a PDA. Using echocardiography, we measured the relationship of MVCFc to stress at peak systole (SPS) in two groups of premature infants. Group 1 consisted of 15 controls (680-1495 g, 25-32 weeks' gestation), and Group 2 of 15 neonates with hemodynamically significant PDA (840-1635 g, 26-33 weeks' gestation). In both groups, MVCFc was linearly and inversely related to SPS ( p < 0.001). The regression equations were as follows: Group 1, MVCFc = -0.0153SPS + 1.70 ( R(2) = 0.68); and Group 2, MVCF = - 0.019SPS + 1.89 ( R(2) = 0.76). There was no significant difference in the relationship between the two groups, but their slopes were significantly steeper and had a higher Y-intercept than the relationship we previously reported for older children. This preliminary study establishes the normal MVCFc/SPS relationship in the premature neonate (25-33 weeks' gestation) and suggests that premature infants function at a higher resting contractile state than older children. A hemodynamically significant PDA has no effect on contractility. These data will be useful in assessing left ventricular contractility in premature neonates with other types of ventricular loading and noncardiac stress.