Alterations in preload and ejection phase indices of left ventricular performance,.

Area of Science:

• Cardiology
• Physiology
• Echocardiography

Background:

• Ejection phase indices (mean velocity of circumferential fiber shortening [V-cf], ejection fraction [EF], mean normalized systolic ejection rate [MSER]) are used to assess left ventricular (LV) inotropic state.
• While sensitive to afterload, their response to preload alterations is less understood.

Purpose of the Study:

• To investigate the effect of acute preload reduction on LV ejection phase indices in normal subjects.

Main Methods:

• Ten healthy subjects underwent head-up tilt (75 degrees) from a supine position.
• Echocardiography and carotid pulse recordings were used to measure LV diameter, ejection time, V-cf, MSER, LV end-diastolic volume (LVEDV), stroke volume (SV), and EF.
• Systemic blood pressure (BP) and heart rate (HR) were also monitored.

Main Results:

• Head-up tilt significantly reduced LVEDV, SV, and ejection time.
• No significant changes were observed in BP or HR.
• V-cf, EF, and MSER remained largely unchanged despite the preload reduction.

Conclusions:

• Acute alterations in preload do not significantly affect V-cf, MSER, and EF in normal individuals.
• Compensatory sympathetic responses, though not evident in HR, might influence these findings.