Patent ductus arteriosus in the newborn

Therapeutic management of patent ductus arteriosus

Management of patent ductus arteriosus (PDA) in premature neonates has always been a challenge to the neonatologist and continues to be a controversial topic. Indications for treatment are not clear. Approximately 40% of ductus arteriosus close spontaneously even in extremely-low-birth-weight neonates. Prophylactic or early pre-symptomatic treatment may unnecessarily expose these babies, in whom the ductus might close spontaneously, to pharmacologic agents and their adverse effects. On the other hand, with advancing postnatal age, delaying treatment could potentially decrease successful medical closure thereby increasing the rate of surgical ligation and the complications associated with surgery. We tried to develop some clinical guidelines for management of PDA in premature neonates based on evidence, or lack thereof, and experience.

Catheter closure of the arterial duct in preterm infants

BACKGROUND

When medical treatment of a symptomatic arterial duct in a preterm infant fails, management is surgical.

PATIENTS AND METHODS

10 preterm neonates referred to a tertiary cardiac centre for treatment of a symptomatic patent arterial duct who underwent cardiac catheterisation with the intention of device closure.

RESULTS

Successful catheter device closure of the arterial duct in nine preterm infants is described.

CONCLUSION

In selected cases, catheter device closure may offer an alternative to thoracotomy and surgical ligation.

Outcome following patent ductus arteriosus ligation in premature infants: a retrospective cohort analysis

Background

The patent ductus arteriosus (PDA) is an important problem in premature infants. Surgical PDA ligation is usually only be considered when medical treatment has either failed or was contraindicated. The aims of our study were to determine the mortality and morbidity following patent ductus arteriosus ligation in premature infants, and whether prostaglandin synthetase inhibitor (PSI) use prior to ligation affects outcome.

Methods

A retrospective case note review study to determine the outcome of premature infants undergoing patent ductus arteriosus ligation in one tertiary neonatal intensive care unit and two paediatric cardiothoracic centres.

Results

We had follow-up data on 87 infants. Cumulative mortality rates at 7 days, 30 days and at hospital discharge were 2%, 8% and 20% respectively. The incidence of chronic lung disease, intraventricular haemorrhage, necrotising enterocolitis and retinopathy of prematurity were 77%, 39%, 26% and 28% respectively. There was no difference in mortality, incidence of chronic lung disease or duration of oxygen dependence between those who had and those who had not received a PSI prior to surgical ligation. In those who had received 2 or more courses of PSI prior to surgical ligation, there was a trend to increase in the duration of oxygen therapy and chronic lung disease, but no difference in mortality.

Conclusion

This study shows that patent ductus arteriosus ligation is a relatively safe procedure (30 day survival 92%) but there is substantial late mortality and a high incidence of morbidity in the survivors. 2 or more courses of PSI prior to surgical ligation trends to increased oxygen dependence and chronic lung disease. This high risk population requires careful follow-up. A definitive prospective cohort study is lacking.

Treatment of patent ductus arteriosus

Patent ductus arteriosus (PDA) continues to be one of the most common problems found in premature infants. The incidence is inversely related to gestation, but may be reduced by use of antenatal steroids, lower volume fluid regimen and judicious use of phototherapy. However, there continues to be controversy as to the appropriate indications for treatment, varying from prophylaxis on the basis of gestation to treatment only when a PDA is demonstrably significant. The situation is further complicated by differing diagnostic criteria for ductal patency or significance. Prophylactic treatment is likely to result in up to 64% of babies being treated unnecessarily. Early treatment of significant or symptomatic PDA depends upon accurate diagnosis. PDA closure can then be achieved using medical means, with surgery reserved for patients in whom this fails or in whom there are contra-indications. However, the optimum timing for intervention remains unknown.

Tolerance to early human milk feeding is not compromised by indomethacin in preterm infants with persistent ductus arteriosus

AIM

Early human milk feeding is beneficial for gut and brain development. Persistent ductus arteriosus (PDA) and indomethacin may compromise enteral function in preterm infants. For many years enteral milk feedings have continued in preterm infants receiving indomethacin for PDA. The aim of this study was to investigate whether this strategy is efficient in terms of risks and tolerance to early enteral feeding.

METHODS

This retrospective study included 64 inborn infants of <29 wk gestational age (GA), 32 infants who received indomethacin for symptomatic PDA (case infants) and 32 matched controls. Case infants had a mean (SD) GA of 26.3 wk (1.3) and body weight 839 g (203) versus controls GA 26.4 wk (1.2) and body weight 896 g (213) (p = 0.82 and 0.27, respectively). Case infants had higher respiratory morbidity; 90.6% versus 50% of controls needed mechanical ventilation (p = 0.000).

RESULTS

Case infants received human milk from a median (range) age of 4.0 h (1.5-27.5), and controls from 5.3 h (2.0-38.0) (p = 0.092). The first dose of indomethacin was given at a mean age of 1.7 d (1.0). There were no differences between the two groups in feeding volumes or gastric residuals on days 1 to 7. Mean (SD) feeding volume on day 7 was 64 ml/kg (31) in case infants and 76 ml/kg (30) in controls (p = 0.23). Four infants developed necrotizing enterocolitis: two case infants and two controls (p = 1.00).

CONCLUSION

Early enteral feeding with human milk, starting within the first hours of life, seems to be as well tolerated in preterm infants treated with indomethacin for PDA as in their matched controls.

Treatment and outcome of serious structural congenital heart disease

Serious structural congenital heart disease usually presents to the neonatal paediatrician, although increasingly these conditions are being diagnosed before birth. It is, therefore, important that those dealing with these fetuses and infants have some knowledge of their natural and modified history. The vast majority of lesions can either be corrected or given symptomatic palliation and this review discusses treatment options and provides up-to-date outcome information to enable fetal and neonatal staff to anticipate and to complement information given to families by paediatric cardiologists.

The role of nitric oxide in dilating the fetal ductus arteriosus in rats

Prostaglandin E is a major dilator of the fetal ductus arteriosus (DA), but the role of nitric oxide in fetal ductal dilation has not been established. We studied the effects of a potent nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME), on the fetal DA in rats. L-NAME was injected into the dorsum of pregnant rats, and fetal DA was studied 4 h later with a rapid whole body freezing method. The inner diameters of the DA and the main pulmonary artery were measured on a freezing microtome. The inner diameter ratio of DA to main pulmonary artery (DA/PA) was 1.02+/-0.03 (mean +/- SEM; number of fetuses [n], 21) in normal near-term fetuses. The effect of prostaglandin synthesis inhibition was studied after orogastric administration of indomethacin to pregnant rats. In near-term rats on the 21st day of gestation (term, 21.5 d), a large dose of L-NAME (100 mg/kg) caused only mild ductal constriction, with DA/PA reduced to 0.83+/-0.05 (n = 20). Indomethacin (1 mg/kg) caused moderate ductal constriction, and DA/PA was decreased to 0.65+/-0.05 (n = 21). Combined administration of L-NAME (10 mg/kg) and indomethacin (1 mg/kg) caused severe ductal constriction, with DA/PA of 0.26+/-0.03 (n = 16). In preterm rats on the 19th day of gestation, a moderate dose of L-NAME (10 mg/kg) caused severe ductal constriction, with a DA/PA of 0.32+/-0.05 (n = 24). Indomethacin (1 mg/kg) alone caused only mild ductal constriction, with DA/PA 0.86+/-0.02 (n = 16). In conclusion, prostaglandin has a major role and nitric oxide has a minor role in dilating the DA in the near-term fetal rat. In contrast, nitric oxide has a major role and prostaglandin has a minor role in dilating the DA in preterm fetal rats.

Closure of persistently patent arterial duct and its impact on cerebral circulatory haemodynamics in children

PURPOSE

Closure of a patent arterial duct (PDA) is suggested as a risk factor associated with intraventricular haemorrhage and/or cerebral ischemia in neonates. This study evaluate the effects of transcatheter closure of a patent arterial duct in children on cerebral blood flow velocity.

METHODS

Twelve children, aged from one to eight years were enrolled. Anaesthesia induction consisted of thiopentone, fentanyl and diazepam. Tracheal intubation was facilitated with vecuronium. Anaesthesia was maintained with N2O 70% in O2 and a PaCO2 between 35 to 40 mmHg. No cerebral vasoactive agents were used. Mean arterial pressure (MAP), central venous pressure (CVP), heart rate were continuously recorded. Systolic (Vs) and diastolic (Vd) cerebral blood flow velocity (CBFV) were recorded. Cerebral perfusion pressure (CPP) was calculated. The mean CBFV, the systolic-mean ratio and the cerebral blood volume were estimated from the area under the velocity-time curve (AUC) before PDA closure, immediately after and for 10 min following occlusion.

RESULTS

The mean (+/- SD) age and weight were 30 +/- 22 mo and 13 +/- 5 kg, respectively. Continuous recording during duct closure showed an abrupt increase in Vd (P < 0.05) whereas Vs remained constant. The AUC increased after closure and persisted for 10 min (P < 0.05).

CONCLUSION

This study confirms that closure of a PDA leads to acute changes in intracerebral diastolic flow and volume. This observation gives weight to mechanisms involved in IVH in smaller infants after arterial surgical duct closure. The anaesthetic technique used for arterial duct closure in these procedure could influence these observations.

Clinical profile and management of PDA in neonates

Patent ductus arteriosus (PDA) is recognised more often with increasing survival of preterm babies. The pharmacological closure of ductus by indomethacin has changed the management of PDA. Twenty neonates admitted over a period of 21 months to Neonatal Intensive Care Unit (NICU) of M.S. Ramaiah Medical College hospital, Bangalore, who were diagnosed to have PDA, were analyzed. The objectives of this retrospective analysis were to study the clinical profile, the efficacy of oral indomethacin and the outcome of PDA. 2-D and Doppler echocardiaography were used to confirm the clinically suspected PDA. These neonates were treated with 3 doses of oral indomethacin (0.2-0.25 mg/kg/dose 12 hourly) along with fluid restriction and oxygen. Echocardiography was repeated to demonstrate the closure of PDA. The incidence of PDA was 2.3% of total NICU admissions. Seventy percent of this cohort were < 32 weeks of gestation, 55% had birth weight of < 1500 gms. Seventy percent (14) neonates had onset of PDA after 48 hrs of life. 81.25% of neonates responded to indomethacin and overall survival rate in treated group was 67%. Drug related complications were noted in 2 newborns. This study illustrates the utility of echocardiography in diagnosing and monitoring PDA in preterm and low birth weight babies with high index of suspicion of this common congenital heart disease. Pharmacological intervention with indomethacin is rewarding with acceptable results.

Experimental evaluation of a new self-expanding patent ductus arteriosus occluder in a canine model

PURPOSE

A new self-expanding patent ductus arteriosus (PDA) occluder was designed.

MATERIALS AND METHODS

Percutaneous closure of surgically created aortopulmonary shunts was attempted in 19 dogs. The occlusion device consisted of a nitinol wire frame tightly woven into a cylinder with a flat retention disc. A polyester-filled frame was used in the last six procedures. A 6-F introducing sheath was advanced across the aortopulmonary conduit into the descending thoracic aorta. The prosthesis (attached on a stiff delivery cable) was advanced through the introducing sheath. The retention disc was first released in the descending thoracic aorta, then the cylindrical device frame was expanded within the conduit by withdrawing the sheath.

RESULTS

Subtotal misplacement into the descending aorta occurred in one procedure (overall technical success rate, 95%), and one animal died before the 1-week follow-up. Complete angiographic shunt closure was achieved in seven of 18 (39%) animals at 30 minutes, 12 of 17 (71%) animals at 1 week, 14 of 17 (82%) animals at 1 month, and 11 of 12 (92%) animals at 3 months. Significantly higher 30-minute closure rates occurred with polyester-filled occluders compared with nonfilled occluders (five of five [100%] vs one of 13 [15%]; P = .002). Persistent shunt at 3 months occurred in only one nonfilled device (6%). In the remaining 16 animals, both orifices of the shunt were covered by a smooth glistening neoendothelium at postmortem examination.

CONCLUSION

This device combines the advantages of small delivery system, easy placement, self-centering, and repositionability. Immediate shunt closure can be reliably accomplished with the polyester-filled prosthesis.