Asbjørn Langslet

Ultrasonographic study of ductus venosus in healthy neonates

AIM To assess ultrasonographically the flow pattern and the time of postnatal closure of ductus venosus related to the other fetal shunts. METHODS Fifty healthy, term neonates were studied from day 1 up to day 18 using a VingMed CFM 800A ultrasound scanner. RESULTS Ductus arteriosus was closed in 94% of the infants before day 3. Ductus venosus, however, was closed in only 12% at the same time, in 76% before day 7, and in all infants before day 18. A closed ductus venosus or ductus arteriosus did not show signs of reopening. Pulsed and colour Doppler flow could be detected across the foramen ovale in all infants during the sequential investigation. At day 1, when the pulmonary vascular resistance was still high, a reversed Doppler flow velocity signal was seen in ductus venosus in 10 infants (20%) and a bidirectional flow in ductus arteriosus in 26 (52%). Closure of the ductus venosus was not significantly correlated with closure of the ductus arteriosus nor related to sex nor weight loss. CONCLUSIONS The time of closure of the ductus venosus evaluated by ultrasonography is much later than that of the ductus arteriosus. The flow pattern in ductus venosus reflects the portocaval pressure gradient and the pressure on the right side of the heart and in the pulmonary arteries. Both the flow pattern in the ductus venosus as well as that in the ductus arteriosus may be an indication of compromised neonatal haemodynamics.

Postnatal closure of ductus venosus in preterm infants ≤32 weeks: An ultrasonographic study

Aim: To assess ultrasonographically the flow pattern and the time of postnatal closure of ductus venosus in preterm infants ≤32 weeks. Methods: Thirty-three preterm infants ≤32 weeks were studied within the first 1 to 5 days of life and followed every second day with ultrasound until no flow was detected either through the ductus venosus or the ductus arteriosus. Results: The ductus venosus was closed in only 9% by day 3, in 40% by day 8 and 88% by day 18. All were closed by day 37. This is significantly later than in healthy term neonates. Closure of the ductus venosus was not significantly correlated with closure of ductus arteriosus. Conclusion: The ductus venosus shows a delayed closure in preterm infants, with no significant correlation to the closure of the ductus arteriosus or the condition of the infant. We speculate that immaturity of the ductus venosus and possibly increased levels of dilating prostaglandins leads to a delayed obliteration of the vessel. An open ductus venosus represents a portocaval shunt and may have metabolical and pharmacological consequences.

Ductus venosus blood velocity in persistent pulmonary hypertension of the newborn

AIMS To investigate the ductus venosus flow velocity (DVFV) in infants with persistent pulmonary hypertension of the newborn (PPHN); to evaluate the DVFV pattern as a possible diagnostic supplement in neonates with PPHN and other conditions with increased right atrial pressure. METHODS DVFV was studied in 16 neonates with PPHN on days 1–4 of postnatal life using Doppler echocardiography. DVFV was compared with that in mechanically ventilated neonates with increased intrathoracic pressure, but without signs of PPHN (n=11); with neonates with congenital heart defects resulting in right atrial pressure (n=6); and with preterm neonates without PPHN (n=46); and healthy term neonates (n=50). RESULTS Infants with PPHN and congenital heart defects with increased right atrial pressure were regularly associated with an increased pulsatile pattern and a reversed flow velocity in ductus venosus during atrial contraction. A few short instances of reversed velocity were also noted in normal neonates before the circulation had settled during the first day after birth. CONCLUSIONS A reversed velocity in the ductus venosus during atrial contraction at this time signifies that central venous pressure exceeds portal pressure. This negative velocity deflection is easily recognised during Doppler examination and can be recommended for diagnosing increased right atrial pressure and PPHN.

Endogenous norepinephrine stimulates both α1- and β-adrenoceptors in myocardium from children with congenital heart defects

Atrial tissue removed from the cannulation site prior to cardioplegia ( n = 15), and ventricular tissue therapeutically excised from the outflow tract of the right ventricle, (RVOT) 1 ( n = 2) were examined with respect to adrenoceptor mediated inotropic effect in children with congenital heart defects (CHD). We used sequential reversal by adrenoceptor antagonists of the tyramine enhanced response to endogenous norepinephrine to quantify the role of the β- and the α 1 -adrenoceptors, respectively, in the intropic response. Atrial myocardium had an α 1 -adrenoceptor mediated component of 14% (median) (range 0-44%) and a β-adrenoceptor mediated component of 86% (median) (range 56-100%). The patients with the highest α 1 -adrenoceptor mediated inotropic components, had right ventricular pressure loads in the systemic range. In one specimen from RVOT, the ventricular α 1 -adrenoceptor component was estimated to be 22% of the total inotropic response, compared to 26% in the corresponding right atrium. In a ventricular specimen from another patient, we could not demonstrate any α 1 -adrenoceptor mediated inotropic component in contrast to 13% in the right atrium. This patient, however, had infusion of the α-adrenoceptor antagonist phentolamine after the excision of atrial tissue, but before the excision of muscular tissue from RVOT. In myocardium of children with CHD we found evidence that endogenous norepinephrine stimulated α 1 -adrenoceptors in addition to β-adrenoceptors. The relative contributions from the two adrenoceptors to the inotropic response varied considerably, and may be related to the pressure load of the right ventricle. These observations may be relevant with respect both to pathophysiology and to choice of drug therapy.

Functional characterization of an ex vivo preparation of atrial myocardium from children with congenital heart defects: sensitivity to tyramine and adrenoceptor antagonists.

Summary Small pieces of atrial tissue removed from the cannulation site before cardioplegia were used to develop a method for studying adrenergic regulation of the myocardial contractile force in children operated on for congenital heart defects (CHD). We measured the development of the isometric force of contraction dT/dtmax (Tmax). Reduction in basal contractility induced by the β-adrenoceptor antagonist timolol indicated that the myocardium was about half-maximally stimulated by endogenous norepinephrine (NE), probably released from nerve endings by the electrical stimulation. The inotropic effect of endogenous NE could be further increased by tyramine (EC50 5 μM). A maximal concentration of tyramine increased T‘max by a median of 62.5% above the basal level. Sequential blockade of the β- and α1-adrenoceptors after tyramine stimulation by timolol and prazosin, respectively, indicated that a near-maximal response to combined adrenoceptor stimulation by endogenous NE was mediated by both β-adrenoceptors (median 77%) and α1-adrenoceptors (median 23%). The basal level of endogenous NE may conceal inotropic effects by exogenous α-agonists added to this type of preparation. This preparation is suitable for studying adrenergic regulation by reversing the effects of endogenous NE.

61 COST-BENEFIT ANALYSIS OF NEONATAL CARE

Costs of neonatal care in the County of Vestfold 1980-84 (level II neonatal unit, 15% admitted from an unselected population averaging 2087 deliveries a year) were US

Ductus Venosus Blood Velocity in Persistent Pulmonary Hypertension of the Newborn

0.8 million a year (1984 exchange) (including costs of level III intensive care and transportation), 1.6% of the countys total costs for hospital services. Costs per treated patient were on average US

Postnatal Closure of Ductus Venosus in Preterm Infants Less than 32 Weeks of Gestational Age. An ultrasonographic study of the relationship between closure of ductus venosus and ductus arteriosus 111

2443. Salaries accounted for 82.2%, running expences 13.5%, and equipment 2%. Epidemiological data on neonatal mortality and handicaps showed a net gain of 25 infants with intact survival 1980-84 compared to 1970-79. Costs of treatment for these 25 patients (calculated as the 5 most expensive patients each year 1980-84 with intact survival) were on average US

Normal Flow Pattern and Closure of Ductus Venosus. 86

28409, rehospitalization costs during the year after birth included (6.7% of the expenditures). Total lifetime income and taxes were calculated to 21.2 and 3.1 times treatment costs. Progress in neonatal care 1970-84 in our county has caused considerable medical gains, with a strongly positive economic benefit.

26 ADDRENERGIC |[alpha]|-RECEPTORS IN THE HEART: DO THEY MATTER?

AIMS To investigate the ductus venosus flow velocity (DVFV) in infants with persistent pulmonary hypertension of the newborn (PPHN); to evaluate the DVFV pattern as a possible diagnostic supplement in neonates with PPHN and other conditions with increased right atrial pressure. METHODS DVFV was studied in 16 neonates with PPHN on days 1-4 of postnatal life using Doppler echocardiography. DVFV was compared with that in mechanically ventilated neonates with increased intrathoracic pressure, but without signs of PPHN (n=11); with neonates with congenital heart defects resulting in right atrial pressure (n=6); and with preterm neonates without PPHN (n=46); and healthy term neonates (n=50). RESULTS Infants with PPHN and congenital heart defects with increased right atrial pressure were regularly associated with an increased pulsatile pattern and a reversed flow velocity in ductus venosus during atrial contraction. A few short instances of reversed velocity were also noted in normal neonates before the circulation had settled during the first day after birth. CONCLUSIONS A reversed velocity in the ductus venosus during atrial contraction at this time signifies that central venous pressure exceeds portal pressure. This negative velocity deflection is easily recognised during Doppler examination and can be recommended for diagnosing increased right atrial pressure and PPHN.