[Effect of dopamine on left-ventricular systolic time interval in children after open-heart surgery]

Area of Science:

• Pediatric Cardiology
• Pharmacology
• Cardiovascular Physiology

Background:

• Children undergoing open heart surgery often experience hemodynamic instability.
• Dopamine is a commonly used inotrope to manage cardiac function post-surgery.
• Assessing the precise effects of dopamine on pediatric cardiac function is crucial.

Purpose of the Study:

• To evaluate the impact of low-dose (3 µg/kg/min) and high-dose (6 µg/kg/min) dopamine on systolic time intervals (STI) in children after open heart surgery.
• To assess changes in basic hemodynamic parameters, including heart rate and blood pressure, in response to dopamine infusion.
• To determine if STI is a sensitive indicator of dopamine's inotropic effect in this patient population.

Main Methods:

• A study involving 16 children who underwent open heart surgery.
• Administration of dopamine at two doses: 3 µg/kg/min and 6 µg/kg/min.
• Monitoring of systolic time intervals (STI), heart rate, systolic blood pressure, diastolic blood pressure, and mean blood pressure.

Main Results:

• Heart rate remained unchanged during both dopamine infusion rates.
• Significant increases in systolic, diastolic, and mean blood pressure were observed at the higher dopamine dose (6 µg/kg/min).
• Dopamine administration at both 3 and 6 µg/kg/min significantly decreased the ratio of pre-ejection period (PEP) to left-ventricular ejection time (LVET). The pre-ejection period index also decreased at the higher dose.

Conclusions:

• Dopamine effectively modulates systolic time intervals in children following open heart surgery.
• The higher dose of dopamine (6 µg/kg/min) led to significant increases in blood pressure.
• Systolic time intervals provide a sensitive, noninvasive measure of dopamine's inotropic action in pediatric cardiac surgery patients.