Glucose-insulin infusion improves cardiac function during fetal tachycardia.
OBJECTIVE
The aim of this work was to study the effects of substrate deficiency and supplementation on cardiac function during fetal tachycardia.


BACKGROUND
Although sustained fetal tachycardia may lead to cardiac failure and intrauterine death, neonatal tachycardia is generally better tolerated. Fetal myocardial energy production relies almost solely on glucose as substrate. We hypothesized that increased substrate availability by glucose-insulin (GI) infusion would improve fetal myocardial responses to tachycardia.


METHODS
We used three porcine models: 1) an isolated fetal heart model; 2) an in vivo fetal model; and 3) an in vivo closed-chest neonatal model. Each animal was randomized to control or GI treatment during tachycardia. In model 1, the controls were perfused with conventional Krebs-Henseleit solution containing a glucose concentration of 5.5 mmol/l; the GI hearts received double glucose concentration and added insulin. In models 2 and 3, the GI animals received insulin in a 20% glucose solution. All hearts were exposed to 90 min of pacing at 250 to 330 beats/min.


RESULTS
The isolated fetal hearts in the GI group showed no decline in dP/dt(max) during pacing, while the controls declined. In the in vivo fetal hearts, dP/dt(max) remained unchanged in the GI group and decreased significantly in the control group. Myocardial glycogen content was higher in the GI group than in controls. Functional indexes remained unchanged among both neonatal groups despite a higher glycogen content in the GI group.


CONCLUSIONS
Glucose-insulin infusion during fetal tachycardia has a beneficial effect on myocardial metabolism and cardiac function. These observations may have direct clinical relevance to the management of fetal arrhythmia.
Schmidt
Michael Rahbek
MR
Department of Cardiology, Research Unit, Aarhus University Hospital (Skejby), Skejby Sygehus, Brendstrupgaardsvej 100, DK-8200 Aarhus N, Denmark. rahbek@dadlnet.dk
Kristiansen
Steen Buus
SB
White
Paul
P
Smerup
Morten
M
Bøtker
Hans Erik
HE
Vogel
Michael
M
Hjortdal
Vibeke
V
Sørensen
Keld
K
Redington
Andrew
A
D000818:Animals; D000831:Animals, Newborn; D004338:Drug Combinations; D005260:Female; D005315:Fetal Diseases / Q000188:drug therapy* / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage*; D006003:Glycogen / Q000378:metabolism; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage*; D023421:Models, Animal; D010477:Perfusion / Q000379:methods; D011247:Pregnancy; D013552:Swine; D013610:Tachycardia / Q000188:drug therapy* / Q000378:metabolism; D016276:Ventricular Function / Q000187:drug effects* / Q000502:physiology
D004338:Drug Combinations; D007328:Insulin; D006003:Glycogen; D005947:Glucose