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Changes in left ventricular volume and systolic function before and after the closure of ductus arteriosus in
Y Takahashi1, K Harada, A Ishida
1Department of Pediatrics, Akita University School of Medicine, Japan.
Insights
The patent ductus arteriosus significantly increases left ventricular (LV) cardiac output in newborns by leveraging the Frank-Starling mechanism. This enhanced cardiac performance relies on volume load, not increased contractility or heart rate.
Area of Science:
- Neonatal Cardiology
- Pediatric Cardiovascular Physiology
Background:
- The patent ductus arteriosus (PDA) is common in preterm and term infants.
- PDA can lead to significant hemodynamic alterations, including increased preload and afterload.
- Understanding the impact of PDA on left ventricular (LV) function is crucial for management.
Purpose of the Study:
- To investigate the changes in LV volume and systolic function before and after ductal closure in term infants.
- To determine the mechanisms contributing to altered LV performance during PDA patency.
Main Methods:
- Echocardiographic assessment of LV volume and systolic function in 18 term infants.
- Measurements performed within 6 hours of birth and on day 5.
- Biplane Simpson's rule for LV volume calculation.
- Doppler echocardiography to confirm PDA with left-to-right shunt.
Main Results:
- LV end-diastolic volume, stroke volume, and cardiac output were >1.3-fold higher before ductal closure.
- Ejection fraction showed a similar increase, while contractility and heart rate remained unchanged.
- LV performance operated at a higher level on the Frank-Starling curve when the ductus was open.
Conclusions:
- LV cardiac output is significantly higher with a patent ductus arteriosus.
- Enhanced cardiac performance is primarily attributed to the Frank-Starling response to volume load, not increased contractility or heart rate.
Abstract:
Using echocardiographic techniques, the change in left ventricular (LV) volume and its effect on systolic function were studied before and after the closure of ductus arteriosus in 18 full-term infants. Examinations were performed twice in each infant, within 6 h after birth and on day 5, and the patency of the ductus with left-to-right shunt was confirmed at the first examination by Doppler echocardiography. A biplane Simpson's rule method was used for volume measurements. The LV end-diastolic volume, stroke volume, and cardiac output were more than 1.3-fold before the ductal closure, and the ejection fraction showed the similar change. However, the mean normalized systolic ejection rate, an index of contractility, and heart rate showed no significant difference. The Frank-Starling curve was obtained from the relationship between the LV end-diastolic and stroke volumes, and the LV performance was operated at a higher level on that curve when the ductus was open. Our data indicated that LV cardiac output was significantly higher during the patency of the ductus arteriosus and that this high cardiac performance might depend more on the Frank-Starling response to the volume load through the ductus arteriosus than on the increase of LV contractility and heart rate.