Dynamic changes in the direction of blood flow through the ductus arteriosus at birth.
Major cardiovascular changes occur at birth, including increased pulmonary blood flow (PBF) and closure of the ductus arteriosus (DA), which acts as a low resistance shunt between the fetal pulmonary and systemic circulations. Although the pressure gradient between these circulations reverses after birth, little is known about DA blood flow changes and whether reverse DA flow contributes to PBF after birth. Our aim was to describe the changes in PBF and DA flow before, during and after the onset of pulmonary ventilation at birth. Flow probes were implanted on the left pulmonary artery (LPA) and DA in preterm fetal sheep (n = 8) approximately 3 days before they were delivered and ventilated. Blood flow was measured in the LPA and DA, before and after umbilical cord occlusion (UCO) and for 2 h after ventilation onset. Following UCO, DA flow decreased from 534 +/- 57 ml min(1) to 237 +/- 29 ml min(1) which reflected a similar reduction in right ventricular output. Within 5 min of ventilation onset, PBF increased from 11 +/- 6 ml min(1) to 230 +/- 13 ml min(1) whereas DA flow decreased to 172 +/- 54 ml min(1); negative values indicate reverse DA flow (left-to-right shunting). Reverse flow through the DA contributed up to 50% of total PBF at 30 min and a decrease in this contribution accounted for 71 +/- 13% of the time-related decrease in PBF after birth. DA blood flow is very dynamic after birth and depends upon the pressure gradient between the pulmonary and systemic circulations. Following ventilation, reverse DA flow provided a significant contribution to total PBF after birth.
Crossley
Kelly J
KJ
Department of Physiology, PO Box 13F, Monash University, Vic. 3800, Australia.
Allison
Beth J
BJ
Polglase
Graeme R
GR
Morley
Colin J
CJ
Davis
Peter G
PG
Hooper
Stuart B
SB
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D004373:Ductus Arteriosus / Q000502:physiology*; D005260:Female; D008955:Models, Cardiovascular; D036801:Parturition / Q000502:physiology; D011247:Pregnancy; D011651:Pulmonary Artery / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012121:Respiration, Artificial; D012756:Sheep
Eur J Obstet Gynecol Reprod Biol. 1999 Jun;84(2):127-32
10428335
Pediatr Res. 2004 Dec;56(6):932-8
15470203
Am J Physiol Lung Cell Mol Physiol. 2003 Sep;285(3):L501-13
12902315
Pediatr Res. 1990 Apr;27(4 Pt 1):372-8
2342829
J Appl Physiol (1985). 1990 Nov;69(5):1630-6
2272954
Exp Physiol. 1998 Nov;83(6):833-42
9782192
Annu Rev Physiol. 2004;66:77-101
14977397
Pediatr Res. 2004 Aug;56(2):198-204
15181198
Am J Physiol Regul Integr Comp Physiol. 2001 Jul;281(1):R291-301
11404305
Annu Rev Physiol. 1979;41:383-95
35091
J Pediatr. 2000 Jul;137(1):68-72
10891824
Pediatr Res. 1993 Jun;33(6):639-44
8378125
J Clin Invest. 1990 Oct;86(4):1270-7
2212011
J Perinatol. 2006 May;26 Suppl 1:S14-8; discussion S22-3
16625216
Clin Exp Pharmacol Physiol. 1995 Apr;22(4):235-47
7671435
Semin Perinatol. 1993 Apr;17(2):106-21
8327901
J Appl Physiol (1985). 1999 Nov;87(5):1637-43
10562602
Exp Lung Res. 1996 May-Jun;22(3):283-98
8792122
Circ Res. 1985 Dec;57(6):811-21
3905044
Pediatr Res. 2007 Jul;62(1):37-42
17515834
Biol Neonate. 2006;89(4):330-5
16770073
J Appl Physiol (1985). 2005 Oct;99(4):1453-61
15890759
J Appl Physiol (1985). 2009 Apr;106(4):1347-55
19213936
J Appl Physiol (1985). 1994 Nov;77(5):2260-8
7868443
J Appl Physiol (1985). 2008 Aug;105(2):603-10
18535129