[Systolic time intervals. 1st communication: normal values from children without heart diseases]

Area of Science:

• Cardiology
• Pediatric Cardiology
• Noninvasive Cardiac Diagnostics

Background:

• Systolic time intervals (STI) are key noninvasive cardiologic parameters.
• STI include total electromechanical systole (QS2), left ventricular ejection time (LVET), and preejection period (PEP).
• PEP determination via QS2-LVET offers improved accuracy over traditional methods.

Purpose of the Study:

• To establish standard values for systolic time intervals in children aged 3-15 years.
• To statistically evaluate the relationships between STI and age, heart rate, and sex.
• To provide reference ranges for accurate individual case assessment.

Main Methods:

• Polygraphic tracings were recorded from 96 children (3-15 years).
• Systolic time intervals (QS2, LVET, PEP, PEP/LVET) were calculated.
• Statistical analysis, including regression equations, was performed to determine standard values and correlations.

Main Results:

• QS2 and LVET demonstrated linear increases with age and linear decreases with heart rate.
• PEP showed a significant inverse correlation with heart rate; PEP/LVET correlation was not significant.
• Girls exhibited longer PEP and higher PEP/LVET ratios compared to boys.

Conclusions:

• Established normal ranges for STI in children aged 3-15 years.
• Age and heart rate significantly influence QS2 and LVET.
• Sex-based differences in PEP and PEP/LVET necessitate sex-specific reference values for clinical interpretation.