Aortic dissection in a young male with persistent ductus arteriosus and a novel variant in MYLK

Pathogenic variants in several genes involved in the function or regulation of smooth muscle cells (SMC) are known to predispose to congenital heart disease and thoracic aortic aneurysm and dissection (TAAD). Variants in MYLK are primarily known to predispose to TAAD, but a growing body of evidence points toward MYLK also playing an essential role in the regulation of SMC contraction outside the aorta. In this case report, we present a patient with co-occurrence of persistent ductus arteriosus (PDA) and thoracic aortic dissection. Genetic analyses revealed a novel splice acceptor variant (c.3986-1G > A) in MYLK, which segregated with disease in the family. RNA-analyses on fibroblasts showed that the variant induced skipping of exon 24, which resulted in an in-frame deletion of 101 amino acids. These findings suggest that MYLK-associated disease could include a broader phenotypic spectrum than isolated TAAD, including PDA and obstructive pulmonary disease. Genetic analyses could be considered in families with TAAD and PDA or obstructive pulmonary disease.

Vav2 promotes ductus arteriosus anatomic closure via the remodeling of smooth muscle cells by Rac1 activation

The ductus arteriosus (DA), bridging the aorta and pulmonary artery, immediately starts closing after birth. Remodeling of DA leads to anatomic obstruction to prevent repatency. Several histological changes, especially extracellular matrices (ECMs) deposition and smooth muscle cells (SMCs) migration bring to anatomic closure. The genetic etiology and mechanism of DA closure remain elusive. We have previously reported a novel copy number variant containing Vav2 in patent ductus arteriosus (PDA) patients, but its specific role in DA closure remains unknown. The present study revealed that the expression of Vav2 was reduced in human patent DA, and it was less enrichment in the adjacent aorta. Matrigel experiments demonstrated that Vav2 could promote SMC migration from PDA patient explants. Smooth muscle cells with Vav2 overexpression also presented an increased capacity in migration and downregulated contractile-related proteins. Meanwhile, SMCs with Vav2 overexpression exhibited higher expression of collagen III and lessened protein abundance of lysyl oxidase, and both changes are beneficial to DA remodeling. Overexpression of Vav2 resulted in increased activity of Rac1, Cdc42, and RhoA in SMCs. Further investigation noteworthily found that the above alterations caused by Vav2 overexpression were particularly reversed by Rac1 inhibitor. A heterozygous, rare Vav2 variant was identified in PDA patients. Compared with the wild type, this variant attenuated Vav2 protein expression and weakened the activation of downstream Rac1, further impairing its functions in SMCs. In conclusion, Vav2 functions as an activator for Rac1 in SMCs to promote SMCs migration, dedifferentiation, and ECMs production. Deleterious variant potentially induces Vav2 loss of function, further providing possible molecular mechanisms about Vav2 in PDA pathogenesis. These findings enriched the current genetic etiology of PDA, which may provide a novel target for prenatal diagnosis and treatment. KEY MESSAGES: Although we have proposed the potential association between Vav2 and PDA incidence through whole exome sequencing, the molecular mechanisms underlying Vav2 in PDA have never been reported. This work, for the first time, demonstrated that Vav2 was exclusively expressed in closed DAs. Moreover, we found that Vav2 participated in the process of anatomic closure by mediating SMCs migration, dedifferentiation, and ECMs deposition through Rac1 activation. Our findings first identified a deleterious Vav2 c.701C>T variant that affected its function in SMCs by impairing Rac1 activation, which may lead to PDA defect. Vav2 may become an early diagnosis and an effective intervention target for PDA clinical therapy.

Anatomy of the Ductus Arteriosus in Fetal Autopsies: Correlations With Placental Pathology and Cause of Death

BACKGROUND

Differences in the shape of the ductus arteriosus (DA), an important vascular shunt between the pulmonary artery and aorta, may reflect fetoplacental blood flow. Our aim was to examine tapering of the DA in a fetal autopsy population and correlate it with placental pathology and cause of death (COD).

METHODS

This autopsy case control study of stillborn fetuses selected cases (tapered DA) and consecutive age-matched controls (no DA tapering) between January 2017 and January 2022. We abstracted demographic and clinical data from pathology reports. Autopsy data included COD and histologic evidence of fetal hypoxia. Placental pathology included umbilical cord abnormalities, acute and chronic inflammation, fetal vascular malperfusion (FVM), and maternal vascular malperfusion (MVM).

RESULTS

We identified 50 cases and 50 controls. Gestational age ranged from 18 to 38 weeks. Maternal and fetal demographic characteristics did not differ significantly between cases and controls. COD related to an umbilical cord accident/FVM was significantly more prevalent in cases vs controls (46% vs 26%, P = .037), and FVM in the placenta, regardless of COD, trended higher in cases than controls.

CONCLUSION

Tapering of the DA is present in stillborn fetuses and associated with COD related to fetal vascular blood flow obstruction.

Improvement in fetal pulmonary hypertension and maturity after reversal of ductal constriction: prospective cohort study

OBJECTIVES

To test the hypotheses that estimated mean pulmonary arterial pressure (MPAP) decreases and pulmonary vascular maturation, assessed by the ratio of pulmonary arterial flow acceleration time to ejection time (AT/ET ratio), increases after reversal of fetal ductus arteriosus constriction by reducing maternal intake of the causal agent (prostaglandin inhibitors, such as polyphenol-rich foods or non-steroidal anti-inflammatory drugs), and that these effects are independent of gestational age, which are inferences not yet demonstrated in the clinical setting.

METHODS

This was a prospective cohort study comparing Doppler echocardiographic ductal flow dynamics, MPAP and pulmonary arterial flow AT/ET ratio in third-trimester fetuses (≥ 28 weeks' gestation) with ductus arteriosus constriction, at the time of diagnosis and after 2 weeks of reduced maternal intake of prostaglandin inhibitors either by suspending the use of pharmacological agents with potential for prostaglandin inhibition or by restricting the consumption of polyphenol-rich foods. MPAP was estimated using the Dabestani equation (MPAP = 90 - (0.62 × AT)), and pulmonary vascular maturity was assessed using the AT/ET ratio, according to reported validation studies. Student's t-test was used for comparison of variables at diagnosis with those after reversal of ductal constriction. Change in MPAP and pulmonary AT/ET ratio between the two assessments was compared with the expected change in the same gestational period in normal fetuses based on reference curves of MPAP and pulmonary AT/ET ratio constructed in normal fetuses from healthy pregnant women at 19-37 weeks' gestation, encompassing the same gestational age range as the study group (28-37 weeks).

RESULTS

Seventy pregnancies with fetal ductus arteriosus constriction were included in the study. After 2 weeks of reduced maternal intake of prostaglandin inhibitors, normalization of mean systolic (change from 1.86 ± 0.34 m/s at diagnosis to 1.38 ± 0.41 m/s; P < 0.001) and diastolic (change from 0.41 ± 0.11 m/s to 0.21 ± 0.065 m/s; P < 0.001) ductal velocities and of mean pulsatility index (change from 1.99 ± 0.20 to 2.55 ± 0.42; P < 0.001) was demonstrated. MPAP decreased between the assessments (change from 66.7 ± 6.90 mmHg at diagnosis to 54.5 ± 6.70 mmHg after 2 weeks; P < 0.001) and mean pulmonary AT/ET ratio increased (change from 0.20 ± 0.06 to 0.33 ± 0.07; P < 0.001). Change in MPAP between diagnosis and after 2 weeks of reduced maternal intake of prostaglandin inhibitors was -12.2 ± 0.30 mmHg, which was 5.3-times higher than that in 305 normal fetuses over 2 weeks during the same gestational period (-2.3 ± 0.19 mmHg) (P < 0.001), and change in pulmonary AT/ET ratio between the two assessments was 0.13 ± 0.08, which was 8.7-times higher than that in normal fetuses in the same gestational period (0.015 ± 0.08) (P < 0.001).

CONCLUSIONS

Resolution of fetal ductal constriction is followed by a fall in MPAP and by an increase in pulmonary vascular maturity, to a significantly greater degree than is observed in normal fetuses in the same gestational-age period. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal paracetamol intake and fetal ductus arteriosus constriction or closure: a case series analysis

Recent case reports describe an association between maternal paracetamol intake and fetal ductus arteriosus constriction or closure. To put these cases into perspective and explore causality, a structured literature search was conducted. The World Health Organization Uppsala Monitoring Centre (WHO-UMC) causality tool was applied to the cases retrieved. The search resulted in 12 papers with 25 case descriptions, of which one case was classified as unlikely, nine as possible, 11 as probable and four as certain. Consequently, we concluded that a causal relationship between maternal paracetamol intake and fetal ductus arteriosus constriction or closure is likely. These findings suggest that pharmacovigilance studies on paracetamol safety during pregnancy are warranted to quantify the event and put the current findings into clinical perspective. Although analgesia during pregnancy and during the peripartum period is of obvious relevance, alternative analgesics such as opioids or other nonsteroidal anti-inflammatory drugs also have side effects.

Molecular Mechanisms for Regulating Postnatal Ductus Arteriosus Closure

The ductus arteriosus (DA) connects the main pulmonary artery and the aorta in fetal circulation and closes spontaneously within days after birth in normal infants. Abnormal patent DA (PDA) causes morbidities and mortality, especially in preterm infants. Closure of the DA is a complex interactive process involving two events: functional and anatomic closure. Functional closure by smooth muscle contraction was achieved through the regulatory factors of vaso-reactivity. These factors include oxygen sensing system, glutamate, osmolality, prostaglandin E₂, nitric oxide, and carbon monoxide. Anatomic closure by vascular remodeling involved several vascular components including endothelium, extracellular matrix, smooth muscle cells, and intraluminal blood cells. Despite advances in understanding of PDA pathogenesis, the molecular mechanism for regulation of DA closure is complex and not fully understood. In this article we review recent evidence regarding the molecular mechanisms of DA closure.

Tissue-type plasminogen activator contributes to remodeling of the rat ductus arteriosus

AIMS

The ductus arteriosus (DA) closes after birth to adapt to the robust changes in hemodynamics, which require intimal thickening (IT) to occur. The smooth muscle cells of the DA have been reported to play important roles in IT formation. However, the roles of the endothelial cells (ECs) have not been fully investigated. We herein focused on tissue-type plasminogen activator (t-PA), which is a DA EC dominant gene, and investigated its contribution to IT formation in the DA.

METHODS AND RESULTS

ECs from the DA and aorta were isolated from fetal rats using fluorescence-activated cell sorting. RT-PCR showed that the t-PA mRNA expression level was 2.7-fold higher in DA ECs than in aortic ECs from full-term rat fetuses (gestational day 21). A strong immunoreaction for t-PA was detected in pre-term and full-term rat DA ECs. t-PA-mediated plasminogen-plasmin conversion activates gelatinase matrix metalloproteinases (MMPs). Gelatin zymography revealed that plasminogen supplementation significantly promoted activation of the elastolytic enzyme MMP-2 in rat DA ECs. In situ zymography demonstrated that marked gelatinase activity was observed at the site of disruption in the internal elastic laminae (IEL) in full-term rat DA. In a three-dimensional vascular model, EC-mediated plasminogen-plasmin conversion augmented the IEL disruption. In vivo administration of plasminogen to pre-term rat fetuses (gestational day 19), in which IT is poorly formed, promoted IEL disruption accompanied by gelatinase activation and enhanced IT formation in the DA. Additionally, experiments using five human DA tissues demonstrated that the t-PA expression level was 3.7-fold higher in the IT area than in the tunica media. t-PA protein expression and gelatinase activity were also detected in the IT area of the human DAs.

CONCLUSION

t-PA expressed in ECs may help to form IT of the DA via activation of MMP-2 and disruption of IEL.

Pathology and molecular mechanisms of coarctation of the aorta and its association with the ductus arteriosus

Coarctation of the aorta (CoA) is defined as a congenital stenosis of the thoracic aorta and is one of the most common congenital cardiovascular diseases. Despite successful surgical treatment for CoA, arterial abnormalities, including refractory hypertension, aortic aneurysm, and proatherogenic phenotypic changes, frequently affect patients' quality of life. Emerging evidence from morphological and molecular biological investigations suggest that the area of CoA is characterized by phenotypic modulation of smooth muscle cells, intimal thickening, and impaired elastic fiber formation. These changes extend to the pre-and post-stenotic aorta and impair arterial elasticity. The aim of this review is to present current findings on the pathology and molecular mechanisms of vascular remodeling due to CoA. In particular, we will discuss the association between CoA and the ductus arteriosus since the most common site for the stenosis is in the proximity of the ductus arteriosus.

Hemodynamic consequences of a restrictive ductus arteriosus and foramen ovale in fetal transposition of the great arteries

D-transposition of the great arteries (D-TGA) is the most commonly diagnosed cyanotic congenital heart disease presenting in the neonatal period. The survival after an arterial switch operation, with freedom from adverse cardiovascular events, has been reported to be as high as 93% at 25 years. However, despite excellent surgical outcomes, there continues to be significant preoperative morbidity and potential mortality due to compromise in the delivery room from foramen ovale closure requiring urgent balloon atrial septostomy for stabilization in the first minutes of life. The prenatal diagnosis of D-TGA using fetal echocardiography has aided in the perinatal management and delivery planning of these infants, lowering preoperative morbidity and mortality and preventing delivery room compromise. Fetuses with D-TGA have more highly oxygenated blood supplying the pulmonary arteries and ductus arteriosus which likely results in ductal constriction and increased pulmonary blood flow. This may be the cause of foramen ovale restriction or closure in-utero, which then increases the risk for postnatal compromise at delivery. Theories regarding the cause of the abnormal pulmonary vasculature that may be seen in D-TGA, including aorto-pulmonary collateral formation, have been proposed but to our knowledge, observation of the ultrasound findings throughout mid and late gestation describing the progression of the abnormal fetal physiology have not been previously described. We present a case of D-TGA in which serial assessment using fetal echocardiography enabled observation of the in-utero progression of disease, predicting postnatal compromise and facilitating the planning of life-saving specialized delivery room care and intervention.

Elevated NCX1 and NCKX4 expression in the patent postnatal ductus arteriosus of ductal-dependent congenital heart disease patients

Patency of the ductus arteriosus (DA) after birth is essential in ductal-dependent congenital heart disease. The Na(+)/Ca(2+) exchanger (NCX) has been demonstrated to play a key role in regulating vascular tone. The potassium-dependent Na(+)/Ca(2+) exchanger (NCKX) is a related family of NCX depending on the K(+) gradients which triggers DA constriction. The present study investigated the comparative expression of NCX and NCKX between a constricted DA and patent DA in human ductal-dependant congenital heart disease. Human DAs, which were patent (n = 10, age = 20.2 ± 4.3 days) or constricted (n = 10, age = 18.3 ± 3.9 days), were excised during surgery from neonates with ductal-dependent congenital heart disease. Western blotting analysis, real-time quantitative polymerase chain reaction analysis and immunofluorescence studies were performed to detect the protein and mRNA levels of NCX1, NCKX3, and NCKX4. The expressions of NCX1 and NCKX4 were significantly higher in the patent DA group at both the protein and mRNA levels, and expression was localized to the smooth muscle layer. These findings indicate that NCX1 and NCKX4 are up-regulated in human postnatal patent DAs and may represent potential therapeutic targets for maintaining DA patency in ductal-dependent congenital heart disease.

Cardiovascular magnetic resonance of cardiac function and myocardial mass in preterm infants: a preliminary study of the impact of patent ductus arteriosus

BACKGROUND

Many pathologies seen in the preterm population are associated with abnormal blood supply, yet robust evaluation of preterm cardiac function is scarce and consequently normative ranges in this population are limited. The aim of this study was to quantify and validate left ventricular dimension and function in preterm infants using cardiovascular magnetic resonance (CMR). An initial investigation of the impact of the common congenital defect patent ductus arteriosus (PDA) was then carried out.

METHODS

Steady State Free Procession short axis stacks were acquired. Normative ranges of left ventricular end diastolic volume (EDV), stroke volume (SV), left ventricular output (LVO), ejection fraction (EF), left ventricular (LV) mass, wall thickness and fractional thickening were determined in "healthy" (control) neonates. Left ventricular parameters were then investigated in PDA infants. Unpaired student t-tests compared the 2 groups. Multiple linear regression analysis assessed impact of shunt volume in PDA infants, p-value ≤ 0.05 being significant.

RESULTS

29 control infants median (range) corrected gestational age at scan 34+6(31+1-39+3) weeks were scanned. EDV, SV, LVO, LV mass normalized by weight and EF were shown to decrease with increasing corrected gestational age (cGA) in controls. In 16 PDA infants (cGA 30+3(27+3-36+1) weeks) left ventricular dimension and output were significantly increased, yet there was no significant difference in ejection fraction and fractional thickening between the two groups. A significant association between shunt volume and increased left ventricular mass correcting for postnatal age and corrected gestational age existed.

CONCLUSION

CMR assessment of left ventricular function has been validated in neonates, providing more robust normative ranges of left ventricular dimension and function in this population. Initial investigation of PDA infants would suggest that function is relatively maintained.

Prenatal exposure to hyperoxia modifies the thromboxane prostanoid receptor-mediated response to H2O2 in the ductus arteriosus of the chicken embryo

O2 tension plays a critical role in the control of prenatal patency and postnatal closure of the ductus arteriosus (DA). We hypothesized that exposure of chicken embryos to hyperoxia alters the morphology and function of DA. Hyperoxia was induced by incubating fertilized eggs at 60% O2 from day 15 to 19 of the 21-d incubation period. DA reactivity (assessed by wire myography), morphometry and mRNA expression of antioxidant enzymes were studied on day 19. Hyperoxic incubation neither affected embryonic growth nor induced signs of DA constriction or changed the mRNA expression of superoxide dismutase and catalase. The contractions induced by O2 (21%), KCl, 4-aminopyridine, phenylephrine, and endothelin-1 and the relaxations induced by acetylcholine (ACh), sodium nitroprusside, isoproterenol, and hydroxyfasudil were similar in DA from embryos incubated under normoxic or hyperoxic conditions. In contrast, hyperoxic incubation impaired the thromboxane prostanoid (TP) receptor-mediated contractions evoked by U46619, 15-E2t-Isoprostane and high concentrations (≥3 μM) of ACh. Exogenous hydrogen peroxide (H2O2) evoked endothelium-dependent contraction in the normoxic DA and endothelium-dependent relaxation in the hyperoxic group. The presence of the TP receptor antagonist SQ 29548 unmasked a relaxant response to H2O2 in the normoxic DA and the cyclooxygenase (COX) inhibitor indomethacin blocked H2O2-induced contraction (in the normoxic group) and relaxation (in the hyperoxic group). Altogether our functional data suggest that, in the chicken DA, exogenous H2O2 induces the release of endothelium-derived COX metabolite(s) with contractile and relaxant properties. Under normal conditions H2O2-induced contraction prevails and relaxation is unmasked after pharmacological or functional (i.e.hyperoxia) TP receptor impairment.

Indicators of surgical treatment of patent ductus arteriosus in preterm neonates in the first week of life

OBJECTIVE

To identify clinical and echocardiographic indicators of the necessity for early surgical closure of patent ductus arteriosus in preterm neonates.

METHODS

The prospective study was conducted at the Neonatal Unit of Hospital Municipal Odilon Behrens between 2006 and 2010. The study population comprised 115 preterm neonates diagnosed with patent ductus arteriosus in the first week after birth, of whom 55 (group S) were submitted to clinical and or surgical closure and 60 (group NS) received non-surgical treatment. The parameters analyzed were birth weight, diameter of the ductus arteriosus (DAD), left atrial-to-aortic root diameter ratio (LA:Ao), the quotient of DAD² and birth weight (mm²/kg), and ductal shunting.

RESULTS

The study population comprised 58 males and 57 females. The average birth weight of group S (924 ± 224.3 g) was significantly (P=0.049) lower than that of group NS (1012.3 ± 242.8 g). The probability of the preterm neonates being submitted to surgical closure was 62.1% (P=0.006) when the DAD2/birth weight index was > 5 mm²/kg, 72.2% (P=0.001) when the LA:Ao ratio was > 1.5, and 61.2% when ductal shunting was high (P=0.025).

CONCLUSION

The parameters DAD²/birth weight index > 5 mm²/kg, LA:Ao ratio > 1.5 and high ductal shunting were statistically significant indicators (P<0.05) of the need for surgical closure of patent ductus arteriosus in low birth weight preterm neonates. Moreover, when an LA:Ao ratio > 1.5 was associated with the occurrence of shock, the probability of surgical closure increased to 78.4%.

[An index internal diameter ductus arteriosus/body surface area as a need for closure of duct in the preterm newborn]

OBJECTIVE

To determine a rate of internal diameter (ID), the narrowest of ductus arteriosus (DA)/body surface area (BSA) in preterm newborns (PTNB) for need for closure of DA either medically or surgically.

MATERIAL AND METHODS

Prospective (cohort), held in a Neonatology Service in February 2010 to January 2011. Inclusion criteria were PTNB from 28 to 36 weeks of gestation from 0 to 28 days after birth, which confirmed diagnosis of patent ductus arteriosus (PDA) by echocardiogram, taking the narrowest ID, who did not present heart complex congenital or other major malformations in other systems without pulmonary arterial hypertension, that had not received drug treatment with prostaglandin inhibitors to close the DA. The exclusion criteria for complications of mechanical ventilation (air leaks, atelectasis, etc.) before measurements. BSA was determined based on their weight and height. There were two comparison groups during its evolution, those who finally merited either closure medical or surgical closure or was indicated but the poor conditions of the patient by the same PDA mainly, the procedure was not carried out (Group A) and Group B, those that are not operated or not medically closed DA not being hemodynamically significant [corrected]. Statistical analysis was performed using descriptive statistics and inferential. Significance levels were set at p < 0.05.

RESULTS

The study population consisted of 32 patients who were divided into two groups: group A of 13 patients and group B with 19 patients. The study population characteristics between the two groups showed significant difference only in the Apgar Score for the Group B. In multivariate analysis found statistically significant as need for closure of DA only a index ID DA/ BSA when it was > 14.

CONCLUSIONS

It is important to take into account a number of known ways to assess whether the DA is hemodynamically significant and therefore should be closed medically or surgically and according to this study, a parameter to requiring its closure is an index ID DA/BSA with a value > 14.

Idiopathic constriction of the fetal ductus arteriosus: three cases and review of the literature

Premature constriction or closure of the ductus arteriosus can occur during fetal life. It is a rare phenomenon and has been described secondary to medication or structural lesions or as idiopathic constriction. Premature closure of the ductus arteriosus can lead to progressive right heart dysfunction with tricuspid regurgitation, congestive heart failure, fetal hydrops, and intrauterine death. This series describes diagnosis of fetal ductus arteriosus constriction of unknown etiology in 3 cases, prenatal management, and outcomes. Constriction of the ductus arteriosus can be diagnosed prenatally with careful interrogation of the ductal arch using pulsed Doppler sonography and complete fetal echocardiography. Close monitoring is mandatory to rule out development of right heart failure and to determine the intervention time.

[Developmental toxicity of naproxen]

Naproxen is a nonsteroidal antiinflammatory drug (NSAID) with an antiinflammatory, analgesic, antipyretic and tocolytic activity. Due to high therapeutical potency and good adult toxicological profile it is available as over-the-counter (OTC) drug. Experimental studies indicated that naproxen inhibited ovulation and readily passed the placental barrier. However, its developmental toxicity is not fully defined. Similar to other NSAIDs, naproxen causes constriction of the ductus arteriosus and fetal anuria or oliguria that could let to pulmonary arterial hypertension and oligohydramnion, respectively. It may also induce lip and/or palate clefts and cardiac malformations, especially the ventricular septal defect.

In vivo dilatation of the postnatal ductus arteriosus by atrial natriuretic peptide in the rat

BACKGROUND

Alpha-human atrial natriuretic peptide (hANP) reportedly increases in premature infants with patent ductus arteriosus (PDA).

OBJECTIVES

To clarify a possible hANP effect to reopen the postnatal ductus, we studied in vivo reopening of the postnatal DA by a recombinant hANP, carperitide, in rats.

METHODS

Near-term rat pups were incubated at 33 degrees C following caesarean section. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing. The DA constricted quickly after birth, and the inner diameter was 0.80 and 0.08 mm at 0 min (fetal state) and 60 min after birth. hANP concentration in the pup blood and the ductus-dilating effect of hANP were studied by subcutaneous injection of hANP at 60 min after birth, and by measurement 7, 15, 30 and 60 min later.

RESULTS

The peak hANP concentration was 790 pg/ml at 7 min with 1 mg/kg, which is similar to the level seen in preterm infants with symptomatic PDA. hANP dilated the postnatal ductus dose dependently and maximally at 7 min after injection. hANP dilated the postnatal constricted ductus completely to 0.79 mm in diameter with a large dose (10 mg/kg) and to 0.55 mm with 1 mg/kg.

CONCLUSIONS

hANP reopens the constricted postnatal DA dose dependently in rats. The increased hANP, accompanying premature PDA, may delay closure of the DA.

Isolated left pulmonary artery: Interventional stenting of a persistent fifth aortic arch

A few cases of isolated pulmonary artery have been successfully palliated by stenting the arterial duct using coronary stents. However, progressive luminal narrowing within the stent due to neointimal proliferation and peal formation is a considerable problem. We report the successful interventional palliation in a 7-week-old infant with isolated left pulmonary artery using sirolimus-eluting stents. In this unusual case, the isolated pulmonary artery was supplied by a duct-like remnant of a persistent fifth aortic arch, whereby the distal part of this vessel showed severe constriction. Implantation of two sirolimus-eluting coronary stents re-established good perfusion of the left pulmonary artery. Seven months after the procedure, echocardiography revealed that perfusion of the stented vessel and the left pulmonary artery was still very good. Stents eluting antimitotic agents also help to preserve the patency of small vessels in infants, and may be useful for ductal stenting.

[Diverticulum of the ductus arteriosus. Cause of traumatic aortic ruptures?]

INTRODUCTION

According to angiographic studies 9-26% of all adult aortae show a ductus arteriosus diverticulum (DAD), i.e. an indention of the aortic wall at the insertion of the obliterated ductus arteriosus. This region is predisposed for traumatic aortic rupture. Up to now fixation at the transition from aorta transversa to fixed aorta descendens is regarded as cause. It is unclear whether ductus diverticulum favours traumatic aortic rupture.

MATERIAL AND METHODS

A total of 143 thoracic aortas (female symbol:37; male symbol:106, 17-91 years) were scanned histomorphologically for DAD. Calcification was quantified by CT multislice volume scan.

RESULTS

A DAD was detected in 44% of macroscopically non-calcified and slightly calcified aortic specimens. Histologically, autochthonal elastic and collagenous fibres of the media were disrupted. CT in macroscopically non-calcified aortas proved isolated calcification in 78%.

DISCUSSION

The incidence of 44% DAD-higher than in angiographic studies-can be explained by the method (histopathology), allowing diagnosis of diverticula down to microm. These morphological alterations are to be seen, at least in part, as a causative factor for the predilection to traumatic aortic ruptures.

Persistent ductus arteriosus in the Brown-Norway inbred rat strain

Persistent ductus arteriosus (PDA) is a common cardiovascular anomaly in children caused by the pathologic persistence of the left sixth pharyngeal arch artery. The inbred Brown-Norway (BN) rat presents with increased vascular fragility due to an aortic elastin deficit resulting from decreased elastin synthesis. The strikingly high prevalence of PDA in BN rats in a pilot study led us to investigate this vascular anomaly in 12 adolescent BN rats. In all BN rats, a PDA was observed macroscopically, whereas a ligamentum arteriosum was found in adult controls. The macroscopic appearance of the PDA was tubular (n = 2), stenotic (n = 8), or diverticular (n = 2). The PDA had the structure of a muscular artery with intimal thickening. In the normal closing ductus of the neonatal controls, the media consisted of layers of smooth muscle cells (SMCs) intermingled with layers of elastin. The intima was thin and poor in elastin. By contrast, the media of PDA in BN rats elastin lamellae were absent and the intima contained many elastic fibers. The abnormal distribution of elastin in the PDA of BN rats suggests that impaired elastin metabolism is related to the persistence of the ductus and implicates a genetically determined factor that may link the PDA with aortic fragility.

Premature closure of the ductus arteriosus: variable response among monozygotic twins after in utero exposure to indomethacin

Exposure of the fetus to indomethacin by administration of the drug to the mother may cause many side effects, including premature closure of the ductus arteriosus. Hypoxia is a predisposing factor for premature ductal closure and often occurs after maternal indomethacin therapy. We present two sets of monozygotic twins with twin-to-twin transfusion, where in utero ductal closure occurred in the donor twin while the recipient twin appeared unaffected. This selective closure of the ductus arteriosus suggests that the affected twin was predisposed to hypoxia and thus was more susceptible to ductal closure in response to indomethacin exposure.

CD44-v6 expression in smooth muscle cells in the postnatal remodeling process of ductus arteriosus

Closure of the ductus arteriosus (DA) is due to functional constriction followed by wall remodeling, with neointimal formation caused by proliferation and migration of smooth muscle cells (SMCs) from the media to subendothelium. CD44 is a surface cell proteoglycan family. Its isoform, CD44-v6, is only minimally expressed in SMCs in the media of normal arteries, but is highly expressed in SMCs in the intima and media of injured arteries (e.g., atherosclerosis). Twenty-two autopsy DA specimens, 11 from full-term babies (age range 2 days to 5 months) and 11 from premature babies (age range 3 days to 5 months), with varying degrees of ductal wall remodeling, were evaluated by immunohistochemistry using antiactin, antifibronectin-extradomain A, anti-leukocyte common antigen, anti-CD44, and anti-CD44-v6. In DA with wall remodeling, synthetic antifibronectin-extradomain A-positive SMCs were evident at the neointimal mounds, and the SMCs were highly positive for the CD44-v6 isoform, irrespective of gestational age at birth. Conversely, SMCs of either closed DAs or persistently patent DAs were CD44-v6 negative. In conclusion, the present data provide evidence that closure of DA involves synthetic SMCs highly positive for CD44-v6, and patent or closed DAs are populated by CD44-v6-negative SMCs.

Postnatal constriction, ATP depletion, and cell death in the mature and immature ductus arteriosus

After birth, constriction of the full-term ductus arteriosus induces oxygen, glucose and ATP depletion, cell death, and anatomic remodeling of the ductus wall. The immature ductus frequently fails to develop the same degree of constriction or anatomic remodeling after birth. In addition, the immature ductus loses its ability to respond to vasoconstrictive agents, like oxygen or indomethacin, with increasing postnatal age. We examined the effects of premature delivery and postnatal constriction on the immature baboon ductus arteriosus. By 6 days after birth, surrogate markers of hypoxia (HIF1alpha/VEGF mRNA) and cell death [dUTP nick-end labeling (TUNEL)-staining] increased, while glucose and ATP concentrations (bioluminescence imaging) decreased in the immature ductus. TUNEL-staining was significantly related to the degree of glucose and ATP depletion. Glucose and ATP depletion were directly related to the degree of ductus constriction; while TUNEL-staining was logarithmically related to the degree of ductus constriction. Extensive cell death (>15% TUNEL-positive cells) occurred only when there was no Doppler flow through the ductus lumen. In contrast, HIF1alpha/VEGF expression and ATP concentrations were significantly altered even when the immature ductus remained open after birth. Decreased ATP concentrations produced decreased oxygen-induced contractile responses in the immature ductus. We hypothesize that ATP depletion in the persistently patent immature newborn ductus is insufficient to induce cell death and remodeling but sufficient to decrease its ability to constrict after birth. This may explain its decreasing contractile response to oxygen, indomethacin, and other contractile agents with increasing postnatal age.

Severity of the ductal shunt: a comparison of different markers

BACKGROUND

When the ductus arteriosus (DA) is patent, the ductal shunt is proportional to the ratio of left ventricular output (LVO) to systemic blood flow. Systemic blood flow can be estimated by measuring flow in the superior vena cava (SVC).

OBJECTIVE

To re-evaluate the accuracy of standard echocardiographic markers of patent ductus arteriosus (PDA) using LVO/SVC flow ratio.

METHODS

Prospective study. Preterm infants of 24-30 weeks gestational age and postnatal age less than 48 hours. The following echocardiographic criteria were measured: left atrial to aortic root ratio (LA/Ao); DA diameter by B mode and colour Doppler; mean and end diastolic flow velocity of the left pulmonary artery (LPA); LVO; SVC flow.

RESULTS

Twenty three preterm infants were enrolled (median gestational age 28 weeks (range 24-30), median birth weight 840 g (500-1440)). The DA was closed in eight (mean (SD) LVO/SVC 2.4 (0.3)) and open in 15 (mean (SD) LVO/SVC 4.5 (0.6)). An LA/Ao ratio > or =1.4, a DA diameter > or =1.4 mm/kg, and a mean and end diastolic flow velocity of LPA respectively > or =0.42 and > or =0.20 m/s identified an LVO/SVC > or =4 with a sensitivity and a specificity above 90%.

CONCLUSION

This study indicates that LA/Ao ratio, DA diameter, and mean and end diastolic flow velocity of the LPA are accurate markers of PDA. These standard echocardiographic variables are easy to measure and need less skill and resources than direct measurements of ductal shunt.

In vivo dilation of fetal and neonatal ductus arteriosus by inhibition of phosphodiesterase-5 in rats

A recent in vitro study showed that sildenafil, a type 5 phosphodiesterase inhibitor, dilated the constricted ductus arteriosus of neonatal rabbits. We studied the in vivo ductus-dilating effects of sildenafil in fetal and neonatal rats. Ductus diameters were measured with whole-body freezing and cutting on a freezing microtome. Indomethacin (10 mg/kg) constricted the fetal ductus severely at 4 and 8 h after orogastric administration to the dams. Sildenafil, administered orogastrically and simultaneously with indomethacin, dilated the near-term fetal [21 fetal days (FD)] ductus constricted by indomethacin completely with 1 mg/kg at 8 h after administration. The preterm fetal ductus was more sensitive to sildenafil at 19FD. The ductus constricted rapidly after birth, and the ductal diameter was only 10% of the fetal diameter at 1 h after birth. The ductus-dilating effect of sildenafil was studied by i.p. injection at 1 h after birth, and the ductus diameter was studied 30 and 60 min later. Sildenafil dilated the neonatal constricted ductus moderately with a massive dose (100 mg/kg) and only minimally with 1 mg/kg. In conclusion, sildenafil, a type 5 phosphodiesterase inhibitor, dilated the constricted fetal ductus completely at 8 h with 1 mg/kg in the near-term fetus and completely with a smaller dose (0.1 mg/kg) in the preterm fetus. However, sildenafil dilated the neonatal constricted ductus only moderately with large doses and minimally with 1 mg/kg. Probably, sildenafil is useful clinically for treating idiopathic and secondary fetal ductal constriction and not useful for dilation of the neonatal constricted ductus.

Challenges encountered during closure of patent ductus arteriosus

Transcatheter closure of patent ductus arteriosus (PDA) was one of the first interventions established in invasive cardiology and is now more than 30 years old. The challenges for successful closure with the first devices in children consisted of handling the rather large introducer sheaths and stiff application systems. Today, interventional closure can be performed with different types of plugs, occluders, and coils. Thus, beyond infancy, transcatheter closure can be successfully performed in almost all cases. Challenging from the technical standpoint can be the closure of window-type ducts, in which excessive protrusion of the device into the descending aorta should be avoided, as well as the closure of tubular ducts, in which secure anchoring of one or more devices in the vessel can be very difficult. For the combination of a coarctation and an open duct, different strategies can be considered. In selected cases, use of a covered stent can be helpful. From the physiological standpoint, open ducts in patients with pulmonary hypertension with or without concomitant congenital heart diseases can be challenging because testing of vasoreactivity with temporarily blocked duct and the option of subsequent treatment with vasodilators may be necessary prior to making the decision whether the patient may benefit from definitive duct occlusion or not. Large ducts in infants less than 8 kg can be difficult to treat due to a relative mismatch of introducers, plugs, or occluders to the small anatomic dimensions. The implantation of multiple coils can be associated with a higher risk of device embolization. Unfortunately, for the large group of preterm infants with very low body weights and large ducts of tubular shape there is currently no standardized interventional therapy available.

Pulmonary vascular effects of sildenafil on the development of chronic pulmonary hypertension in the ovine fetus

We investigated the pulmonary vascular effects of prophylactic use of sildenafil, a specific phosphodiesterase-5 inhibitor, in late-gestation fetal lambs with chronic pulmonary hypertension. Fetal lambs were operated on at 129 +/- 1 days gestation (term = 147 days). Ductus arteriosus (DA) was compressed for 8 days to cause chronic pulmonary hypertension. Fetuses were treated with sildenafil (24 mg/day) or saline. Pulmonary vascular responses to increase in shear stress and in fetal PaO2 were studied at, respectively, day 4 and 6. Percent wall thickness of small pulmonary arteries (%WT) and the right ventricle-to-left ventricle plus septum ratio (RVH) were measured after completion of the study. In the control group, DA compression increased PA pressure (48 +/- 5 to 72 +/- 8 mmHg, P < 0.01) and pulmonary vascular resistance (PVR) (0.62 +/- 0.08 to 1.15 +/- 0.11 mmHg x ml(-1) x min(-1), P < 0.05). Similar increase in PAP was observed in the sildenafil group, but PVR did not change significantly (0.54 +/- 0.06 to 0.64 +/- 0.09 mmHg x ml(-1) x min(-1)). Acute DA compression, after brief decompression, elevated PVR 25% in controls and decreased PVR 35% in the sildenafil group. Increased fetal PaO2 did not change PVR in controls but decreased PVR 60% in the sildenafil group. %WT and RVH were not different between groups. Prophylactic sildenafil treatment prevents the rise in pulmonary vascular tone and altered vasoreactivity caused by DA compression in fetal lambs. These results support the hypothesis that elevated PDE5 activity is involved in the consequences of chronic pulmonary hypertension in the perinatal lung.

Sensitivity and Specificity of Prenatal Features of Physiological Shunts to Predict Neonatal Clinical Status in Transposition of the Great Arteries

BACKGROUND

Although prenatal diagnosis of transposition of the great arteries (TGA) reduces neonatal mortality, the preoperative course can be complicated in infants with a restrictive foramen ovale (FO) or a ductus arteriosus (DA) constriction. We sought to determine the specificity and sensitivity of prenatal features of physiological shunts in predicting postnatal clinical status in prenatally diagnosed TGA in babies delivered in a tertiary care center providing all facilities for neonatal urgent care.

METHODS AND RESULTS

The outcomes of 130 fetuses with TGA were reviewed over a period of 5.5 years. Restriction of the FO and/or constriction of the DA could be analyzed in 119/130 fetuses at 36+/-2.7 weeks of gestation. Twenty-four out of 119 had at least 1 abnormal shunt (23 FO, 5 DA, and 4 both). Thirteen of 130 neonates had profound hypoxemia (PaO2<25 mm Hg) and metabolic acidosis (pH <7.15) in the first 30 minutes and required immediate balloon atrioseptostomy. Two who had abnormal FO and DA died despite aggressive resuscitation. The specificity and sensitivity of the fetal echo in predicting neonatal emergency were 84% and 54%, respectively. The specificity and sensitivity of a combination of restrictive FO and DA constriction were 100% and 31%, respectively.

CONCLUSIONS

Restriction of the FO and/or of the DA has a high specificity to predict the need for emergency neonatal care in fetuses with TGA, but the sensitivity is too low to detect all high-risk fetuses. Exceptional procedures should be considered for fetuses that have a combination of restrictive FO and DA constriction.

Increased cardiac workload by closure of the ductus arteriosus leads to hypertrophy and apoptosis rather than to hyperplasia in the late fetal period

It is generally thought that adult mammalian cardiomyocytes compensate for an increased workload by hypertrophy, whereas fetal myocardium grows by cellular proliferation. We analyzed the response of late-fetal rat hearts upon an increased workload imposed by premature constriction of the ductus arteriosus with indomethacin. Initially the fetal heart responds by proliferative growth, as both wet weight and labeling index (bromodeoxyuridine incorporation) of the ventricles increased, whereas neither a change in the fibroblast fraction, ploidy and nucleation in the ventricles is observed. However, this hyperplastic growth is abrogated by a subsequent burst in apoptosis and followed by a hypertrophic response as based on a decrease in DNA and increase in both RNA and protein concentration. This hypertrophic growth was accompanied by a 1.4-fold increase in the volume of the cardiomyocytes. Changes in the molecular phenotype characteristic of pressure-overload hypertrophic growth accompany the process. Thus, the levels of expression of beta-myosin heavy chain and atrial natriuretic factor mRNA increased, of sarcoplasmic/endoplasmic reticulum ATPase (SERCA2) mRNA decreased, and of alpha-myosin heavy chain, phospholamban, and calsequestrin mRNA did not change. In situ hybridization showed that the pattern of mRNA expression changed first in the right ventricular wall and subsequently in the left ventricular free wall as well. It is concluded that pressure-overload imposed on the late-fetal heart induces limited proliferative growth complemented by extensive hypertrophic growth.

Idiopathic constriction of the fetal ductus arteriosus

Constriction of the ductus arteriosus in the fetus is well studied, but mostly secondary to maternal exposure to indomethacin or other non-steroidal anti-inflammatory medications, or structural cardiac lesions. We present a case of a fetus presenting with right ventricular hypertrophy secondary to an S-shaped ductus arteriosus with distal constriction diagnosed by pulsed Doppler imaging. A review of the recent English literature of similar cases is presented.

Persistent pulmonary hypertension in a premature newborn after 16 hours of antenatal indomethacin exposure

Premature constriction of the fetal ductus arteriosus has been described with long-term indomethacin therapy, but not in fetuses who have been exposed to the drug for less than 72 hours. The sensitivity of the ductus to extended indomethacin tocolysis increases with advancing gestational age. For this reason, it is recommended that indomethacin not be used beyond 31 weeks of gestation. In the present case the gestational age of the patient was 27 weeks and the period of indomethacin exposure was only 16 hours. Our observations of pulmonary hypertension in this case suggest that administration of indomethacin even hours before delivery can significantly affect the ductus arteriosus and the pulmonary vasculature.

Patent ductus arteriosus (PDA) in adults evaluated in echocardiography and multi-slice computed tomography (MSCT)

The authors presented three cases of patent ductus arteriosus (PDA) diagnosed in adulthood as an solated defect in patients without clinical signs using echocardiography and MSCT. The paper discusses extensively the techniques of both examinations, the use of various reconstructive algorithms in MSCT and possible visualization of the arterial duct as well as concomitant changes in the vessels and heart. SCT, although not used in PDA diagnosis to date, was found to be a valuable non-invasive diagnostic method of detecting this defect in patients in whom echocardiography failed or in examinations conducted due to non-cardiological clinical indications.

Influence of ductal size on the results of transcatheter closure of patent ductus arteriosus with coils

To assess the influence of ductal size on the results of transcatheter closure of patent ductus arteriosus (PDA) with coils, 154 consecutive patients were studied prospectively. Ductal size was defined as the narrowest diameter of ductus measured on aortography. All patients were divided into 5 groups according to ductal size: < 1 mm, 1-1.9 mm, 2-2.9 mm, 3-3.9 mm, and > or = 4 mm. The occlusion of PDA with coils was performed through a transarterial approach. The results were evaluated by angiography at 10 minutes and by color Doppler echocardiography at 1 day, 2 days, 1 week, 1 month, 3 months, 6 months, and 12 months after the procedure. The immediate occlusion rates for ductal sizes < 1 mm, 1-1.9 mm, 2-2.9 mm, 3-3.9 mm, and > or = 4 mm were 89.7%. 75.4%, 51.4%, 30.8%, and 40%, respectively; whereas the occlusion rates at 12-months follow-up were 100%, 98.5%, 97.3%, 69.2%, and 80%, respectively. There were no significant differences in occlusion rate at 12-months follow-up among the groups with ductal sizes < 3 mm or among the groups with ductal sizes > or = 3 mm. The occlusion rate for ductal size < 3 mm at each follow-up time was significantly higher than that for ductal size > or = 3 mm (10 minutes: 71.8% vs 34.8%. P = 0.001; 12-months: 98.5% vs 73.9%, P < 0.001). The occlusion rate of residual shuntings at 12-months follow-up for ductal size < 3 mm was also significantly higher than that for ductal size > or = 3 mm (94.6% vs 60%, P = 0.007). The results of the present study demonstrate that ductal size < 3 mm had a higher occlusion rate than that for a size > or = 3 mm. PDA with a size > or = 3 mm may need other treatment strategies or other devices to achieve better results.

Cyclooxygenase-1-selective inhibition prolongs gestation in mice without adverse effects on the ductus arteriosus

Preterm delivery is the leading cause of neonatal mortality and contributes significantly to infant morbidity. Classical cyclooxygenase (COX) inhibitors, such as indomethacin, which inhibit both COX-1 and COX-2, are effective for delaying premature labor, but their use is limited by serious complications to the fetus and neonate, including adverse effects on the ductus arteriosus (DA). Using isoform-selective inhibitors, we characterized the roles of the COX isoforms in the initiation of labor and the regulation of fetal and neonatal DA closure in mice. Chronic inhibition of COX-2 during pregnancy (gestation days 15-18) significantly increased neonatal mortality by preventing closure of the DA after birth, whereas acute COX-2 inhibition near the end of term (gestation day 18) constricted the fetal DA. In contrast, the inhibition of COX-1 during pregnancy lacked these prenatal and postnatal adverse effects on the DA and effectively delayed the initiation of full-term labor and LPS-induced preterm labor. These findings suggest that premature fetal DA closure or neonatal patent DA observed following indomethacin tocolysis in women may result from the inhibition of COX-2. Therefore, COX-1-selective inhibitors may provide effective treatment to delay preterm labor with fewer adverse effects on fetal or neonatal health than nonselective or COX-2-selective inhibitors.

Fetal aortic isthmus growth and morphology in late gestation

OBJECTIVE

To establish normal values for fetal aortic isthmus diameter in late gestation and to identify any changes in aortic isthmus dimensions and morphology in pathological conditions.

METHODS

In this prospective study, the fetal aortic isthmus was evaluated in 110 low-risk pregnant women at between 30 and 40 weeks of gestation and 42 pregnant women who were at high risk for congenital heart defects. From coronal echocardiographic images of the connection between the aorta and ductus arteriosus, the internal diameter of the aorta was measured at the middle of the isthmus, at the point of the isthmus just proximal to the entry of the ductus arteriosus and at the descending aorta below the entry of the ductus arteriosus.

RESULTS

Correlation coefficients for the diameter of each aortic segment when related to gestational age varied from r = 0.60 to r = 0.80 (P < 0.001 for each), and growth curves were derived from the third and 97th percentiles about each linear regression analysis. The mean and the third percentile for the ratio of the isthmus just proximal to the entry of the ductus arteriosus to the middle of the isthmus were 1 and 0.81. In one fetus of the high-risk patients, a contraductal shelf and the accompanying area of tubular isthmic hypoplasia were suspected and a diagnosis of coarctation of the aorta was subsequently confirmed after birth. In two fetuses with growth restriction and one fetus with intestinal atresia, the isthmus diameters were below the third percentile but the ratios of the isthmus end to the middle of the aortic isthmus were all normal and no cardiac anomalies were detected after birth.

CONCLUSIONS

We could establish normal values for aortic isthmus diameters in late gestation from a coronal view and identify even minimal changes in aortic isthmus dimensions and morphology in pathological conditions.

Ibuprofen pharmacokinetics in preterm infants with patent ductus arteriosus

OBJECTIVE

Our objective was to study the pharmacokinetics of ibuprofen in premature infants with patent ductus arteriosus on day 3 and day 5 after birth.

METHODS

Ibuprofen was administered on days 3, 4, and 5 by a 15-minute intravenous infusion of 10, 5, and 5 mg/kg, respectively, with the aim of closing the ductus arteriosus. Blood samples were drawn at time zero and at 0.5, 1, 2, 4, 12, and 24 hours after the first and third doses. Ibuprofen plasma concentrations were assayed by HPLC.

RESULTS

A total of 27 premature infants were included (gestational age, 28.6 +/- 1.9 weeks; birth weight, 1250 +/- 460 g; values are mean +/- standard deviation). Ibuprofen pharmacokinetics followed a 2-compartment open model. Between the first and third doses (day 3 and day 5) there was a significant decrease of the volume of distribution of the central compartment (Vd(c)) (0.244 versus 0.171 L/kg; P =.03) and area under the plasma concentration-time curve (524 versus 447 mg. h/L; P =.01). The decrease in Vd(c) was most pronounced in patients with a closing ductus. Total body clearance and plasma half-life did not change significantly. No significant differences were observed in ibuprofen peak plasma concentrations after the first and third doses in relation to ductal status after treatment.

CONCLUSION

Ibuprofen pharmacokinetics showed a large interindividual variation in premature infants during treatment for patent ductus arteriosus, and significant changes may occur between day 3 and day 5 after birth in those infants with a closing ductus. These findings may have implications for the treatment schedule with ibuprofen in patients with patent ductus arteriosus.

Interventional treatment for fetus and newborn infant with congenital heart disease

BACKGROUND

Catheter intervention has become popular not only in adult patients but in younger patients with congenital heart disease. The early neonatal catheter interventional treatment has also been attempted in conjunction with the development of prenatal diagnosis of the congenital heart disease.

METHOD

Recent articles concerning several severe structural cardiac diseases in newborns, such as critical aortic stenosis, complete transposition of the great arteries, premature constriction of the ductus arteriosus, and pulmonary stenosis or atresia with intact ventricular septum are introduced with consideration.

RESULTS

This study investigated our own experiences of early neonatal balloon valvuloplasty in a patient with critical aortic stenosis carried out immediately after the delivery following prenatal diagnosis. A case with prenatal diagnosis of premature constriction of ductus arteriosus which could prevent persistent pulmonary hypertension of the newborn by early delivery at 39 weeks and 1 day of gestation were reported.

CONCLUSION

Several cardiac interventional treatments performed in the present time during the perinatal period and some prospects in the near future are described in the discussion.

Aneurysmal dilatation of the ductus arteriosus in a neonate

Fetal ultrasound provides the capacity for early detection of a variety of congenital heart diseases. We report a case of aneurysmal dilatation of a patent ductus arteriosus detected in utero and subsequently confirmed by transthoracic echocardiography in the neonatal period. Prompt recognition of the ductus aneurysm with resultant surgical ligation may have averted potentially serious complications from this condition.

Persistent pulmonary hypertension after maternal naproxen ingestion in a term newborn: a case report

Constricting effect of indomethacin on the ductus arteriosus of the fetus is well known. The fetal effects of other nonsteroid anti-inflammatory drugs (NSAIDs) like naproxen are not well reported. We report here a case of a 3,790-g term neonate who developed persistent pulmonary hypertension after birth with a closed ductus arteriosus. The mother admitted to taking naproxen sodium immediately prior to the birth of the infant. The course of illness was progressively better on conservative management. Like indomethacin, other NSAIDs can also cause premature closure of fetal ductus arteriosus, pulmonary hypertension, and life-threatening problems to the neonate. Patient education regarding over-the-counter pain medication during pregnancy should be emphasized.

Failure of ductus arteriosus closure and remodeling in neonatal mice deficient in cyclooxygenase-1 and cyclooxygenase-2

The transition to pulmonary respiration following birth requires rapid alterations in the structure of the mammalian cardiovascular system. One dramatic change that occurs is the closure and remodeling of the ductus arteriosus (DA), an arterial connection in the fetus that directs blood flow away from the pulmonary circulation. A role for prostaglandins in regulating the closure of this vessel has been supported by pharmacological and genetic studies. The production of prostaglandins is dependent on two cyclooxygenases (COX-1 and COX-2), which are encoded by separate genes. We report here that the absence of either or both COX isoforms in mice does not result in premature closure of the DA in utero. However, 35% of COX-2(-/-) mice die with a patent DA within 48 h of birth. In contrast, the absence of only the COX-1 isoform does not affect closure of the DA. The mortality (35%) and patent DA incidence due to absence of COX-2 is, however, significantly increased (79%) when one copy of the gene encoding COX-1 is also inactivated. Furthermore, 100% of the mice deficient in both isoforms die with a patent DA within 12 h of birth, indicating that in COX-2-deficient mice, the contribution of COX-1 to DA closure is gene dosage-dependent. Together, these data establish roles for COX-1, and especially for COX-2, in the transition of the cardiopulmonary circulation at birth.

Restenosis after balloon angioplasty of coarctation: relationship with ductus arteriosus

BACKGROUND

Recently, balloon angioplasty (BA) has been used for the treatment of coarctation of the aorta (CoA) and the effectiveness of this treatment has been reported. However, the restenosis rate following BA in native CoA in the infant is high and the cause may be related to tissue properties at the origin of the ductus arteriosus (DA). However, the mechanisms responsible for restenosis remain uncertain.

METHODS/RESULTS

The present study was designed to examine transformation of the smooth muscle cell (SMC) phenotypes using immunohistologic studies and to investigate the cause of restenosis of CoA following BA. A CoA model was surgically created in 15 newborn pigs (10-14-days-old; 2.4-4.1 kg). Balloon angioplasty was performed 1 month after the initial operation. One or 3 months after BA, animals were killed and immunohistologic studies on smooth muscle cell (SMC) antibodies against SM1, SM2 and SMemb of the myosin heavy chain (MHC) isoform were performed in the aorta at the CoA and DA. In the neointima, only SMemb was positive. In the SMC layer of the DA, only SM2 was positive. One month after BA, the external layer of the tunica media was strongly positive for SM2 only in the area around the origin of the DA.

CONCLUSIONS

The first cause of restenosis is obstructive neointimal formation caused by the proliferation of undifferentiated SMC into the subendothelial tissue. This proliferation seems to be triggered by BA. The distribution of SM2 1 month after balloon angioplasty showed a similar pattern of proliferation of SMC in the external layer around the DA. This may represent a second mechanism of restenosis.

[Aneurysm of the ductus arteriosus Botalli]

A congenital aneurysm of the ductus arteriosus Botalli was detected by chest X-ray as an intrathoracic mass in a 7-day-old infant. Following confirmation of the diagnosis by echocardiography and MRI the aneurysm was successfully resected via left lateral thoracotomy without cardiopulmonary bypass. The postoperative course was uneventful. Six years after operation the patient is asymptomatic and growing normally. An intrathoracic mass may be considered in the differential diagnosis especially in infants and children. Aneurysms of ductus arteriosus potentially are associated with serious complications. Timely diagnosis and early surgical intervention are decisive for prevention of serious complication and death.

Isolated ductus arteriosus aneurysm in the fetus and infant: a multi-institutional experience

OBJECTIVES

The purpose of this study was to describe the clinical characteristics and outcome and to elucidate the pathogenesis of ductus arteriosus aneurysm (DAA).

BACKGROUND

Ductus arteriosus aneurysm is a rare lesion that can be associated with severe complications including thromboembolism, rupture and death.

METHOD

We reviewed the clinical records, diagnostic imaging studies and available histology of 24 cases of DAA, diagnosed postnatally (PD) in 15 and antenatally (AD) in 9 encountered in five institutions.

RESULTS

Of PD cases, 13 presented at <2 months, and all AD cases were detected incidentally after 33 weeks of gestation during a late trimester fetal ultrasound study. Of the 24, only 4 had DAA-related symptoms and 6 had associated syndromes: Marfan, Smith-Lemli-Opitz, trisomies 21 and 13 and one possible Ehlers-Danlos. Three had complications related to the DAA: thrombus extension into the pulmonary artery, spontaneous rupture, and asymptomatic cerebral infarction. Six underwent uncomplicated DAA resection for ductal patency, DAA size or extension of thrombus. In the four examined, there was histologic evidence of reduced intimal cushions in two and abnormal elastin expression in two. Five of the 24 died, with only one death due to DAA. Of 19 survivors, all but one remain clinically asymptomatic at a median follow-up of 35 months; however, two have developed other cardiac lesions that suggest Marfan syndrome. A review of 200 consecutive third trimester fetal ultrasounds suggests an incidence of DAA of 1.5%.

CONCLUSIONS

Ductus arteriosus aneurysm likely develops in the third trimester perhaps due to abnormal intimal cushion formation or elastin expression. Although it can be associated with syndromes and severe complications, many affected infants have a benign course. Given the potential for development of other cardiac lesions associated with connective tissue disease, follow-up is warranted.