Abstract
Circulatory changes occur during perinatal life that increase cardiac output and left ventricular contractile reserve. To examine postnatal changes in left ventricular systolic function and ventricular-vascular coupling, piglets underwent cardiac catheterization at 1, 2, 4, and 6 wk of age. We measured end-systolic elastance (Ees), preload-recruitable stroke work, dP/dtmax, the dP/dtmax end-diastolic volume relation, cardiac index, heart rate, arterial elastance (Ea), and the ratio Ea/Ees at rest, during isoproterenol infusions (0.05-1.0 μg/kg/min), and after propranolol (1 mg/kg i.v.). Resting heart rate and cardiac index decreased between 1 and 6 wk. In 1 wk olds, resting Ees was at maximum and was unchanged during isoproterenol infusion; isoproterenol increased other contractility indices. Two, 4, and 6 wk olds demonstrated reserve using all contractility indices. Contractile efficiency was not different between ages. In 1 wk olds, Ea decreased during isoproterenol infusion; isoproterenol did not change Ea at 6 wk .Ea/Ees was higher at rest at 6 wk than at 1 wk, and fell significantly on isoproterenol; isoproterenol did not change Ea/Ees at 1 wk. Withβ-adrenergic stimulation, 1 wk olds increased cardiac index by increasing heart rate and decreasing afterload, 6 wk olds increased cardiac index by increasing heart rate and contractility; no change in contractile efficiency was found in either group. In summary, contractile reserve is limited at 1 wk when measured by Ees, but other indices demonstrated reserve. Indexed Ea falls in response to β-adrenergic stimulation in all ages but 6 wk. Ventricular-vascular coupling is optimized at 1 wk even under baseline conditions.
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Abbreviations
- E es :
-
end-systolic elastance
- E a :
-
arterial elastance
- ESP/SVI:
-
arterial elastance indexed to body weight
- PRSW:
-
preload-recruitable stroke work
- dP/dt max :
-
maximum first derivative of left ventricular pressure
- V c :
-
parallel conductance
- MVo2:
-
myocardial oxygen consumption
- PVA:
-
pressure-volume area
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Acknowledgements
The authors thank Amy Crews for her tireless efforts in the laboratory, and John Hayes for his advice on the statistical analysis of the data.
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Supported in part by the Bremer Foundation.
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Cassidy, S., Chan, D. & Allen, H. Left Ventricular Systolic Function, Arterial Elastance, and Ventricular-Vascular Coupling: A Developmental Study in Piglets. Pediatr Res 42, 273–281 (1997). https://doi.org/10.1203/00006450-199709000-00005
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DOI: https://doi.org/10.1203/00006450-199709000-00005
