Orthostatic effects on echocardiographic measures of ventricular function

Area of Science:

• Cardiology
• Physiology
• Medical Imaging

Background:

• Orthostatic changes in Doppler echocardiographic measures of ventricular function are not well-defined.
• Understanding these changes offers insights into ventricular responses to altered loading conditions.

Purpose of the Study:

• To define orthostatic-induced alterations in Doppler echocardiographic measures of ventricular function.
• To investigate the impact of reduced ventricular size on these measures.

Main Methods:

• Standard assessment of mitral inflow velocity and tissue Doppler imaging (TDI) of left ventricular longitudinal myocardial velocities.
• Measurements were taken in the supine position and after assuming a sitting position in 14 young males.
• Hemodynamic parameters including heart rate, stroke volume, cardiac output, and systemic vascular resistance were monitored.

Main Results:

• Sitting induced significant decreases in stroke volume (-28%) and cardiac output (-18%), with increased heart rate (+14%) and systemic vascular resistance (+27%).
• Mitral E peak velocity, TDI-E', and TDI-S all decreased significantly.
• Adjusting for reduced left ventricular end-diastolic volume lessened the fall in TDI-E' but not TDI-S.

Conclusions:

• Decreases in TDI measures upon assuming an upright position primarily reflect reduced left ventricular size.
• The orthostatic fall in TDI-E' is influenced by smaller ventricular size and potentially reduced ventricular relaxation.
• E/E' values do not accurately reflect preload alterations during orthostatic challenges.