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Left ventricular contractility in extremely premature infants in the first day and response to inotropes
David A Osborn1, Nick Evans, Martin Kluckow
1RPA Newborn Care, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia. david.osborn@email.cs.nsw.gov.au
Insights
Infants born prematurely with low systemic blood flow (SBF) exhibit impaired myocardial contractility. Inotropes like dopamine and dobutamine did not improve contractility in these vulnerable infants.
Area of Science:
- Neonatal physiology
- Cardiovascular research
- Pharmacology
Background:
- Premature infants (<30 wk gestation) are susceptible to low systemic blood flow (SBF).
- Assessing myocardial contractility is crucial for managing these neonates.
Purpose of the Study:
- To evaluate myocardial contractility in preterm infants with low SBF.
- To compare the effects of dobutamine versus dopamine on contractility.
Main Methods:
- Superior vena cava (SVC) flow measured SBF at 3, 10, and 24 hours in 106 infants.
- Myocardial contractility assessed via left ventricular (LV) mean velocity of circumferential fiber shortening (mVcfs) and wall stress.
- 37 infants received randomized inotrope therapy (dobutamine or dopamine).
Main Results:
- Low SBF infants showed worse contractility at 3 hours, but not 10 hours.
- At 24 hours, low-flow infants had reduced mVcfs for given LV stress.
- Neither inotrope improved contractility; dopamine increased LV stress at 20 mcg/kg/min, while dobutamine decreased it.
Conclusions:
- Preterm infants developing low SBF have impaired myocardial contractility early on.
- Dobutamine and dopamine did not enhance contractility in this cohort.
- Further research is needed to identify effective treatments for low SBF in neonates.
Abstract:
The aim was to assess myocardial contractility in infants born <30 wk gestation developing low systemic blood flow (SBF) in the first day, and the effect of dobutamine versus dopamine. Superior vena cava (SVC) flow was used as a measure of SBF at 3, 10, and 24 h (n = 106). Infants with low SVC flow randomized to dopamine or dobutamine. Myocardial contractility was determined by the relationship between left ventricular (LV) mean velocity of circumferential fiber shortening (mVcfs) and wall stress. Infants who developed low SVC flow had significantly worse myocardial contractility at 3 h, but not 10 h. At 24 h, low-flow infants had lower than expected mVcfs for any given LV stress. In 37 infants randomized to inotrope, there was no significant difference in contractility at 10 microg/kg/min. At 20 microg/kg/min (n = 21), dopamine increased whereas dobutamine decreased LV stress. Infants on dobutamine had significantly lower than expected mVcfs for any given LV stress compared with infants on dopamine. Contractility was not improved by either inotrope at either dose. In conclusion, infants developing low SVC flow in the first day have worse myocardial contractility at 3 h. Neither inotrope increased contractility, but dopamine increased LV stress at 20 microg/kg/min.
