Impedance cardiograms reliably estimate beat-by-beat changes of left ventricular stroke volume in humans

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Accurate measurement of left ventricular stroke volume is crucial for cardiovascular assessment.
• Left ventriculography is an invasive but accurate method for determining stroke volume.
• Non-invasive methods for stroke volume estimation are highly desirable.

Purpose of the Study:

• To compare stroke volumes calculated from tetrapolar impedance cardiography (ICG) with those from simultaneous left ventriculography (LVG).
• To assess the reliability of ICG for estimating beat-by-beat left ventricular stroke volumes in humans.

Main Methods:

• Linear regression analysis was employed to compare stroke volumes.
• Data were collected from 14 patients undergoing diagnostic left heart catheterization.
• Three to five consecutive stroke volumes were calculated from each ventriculogram and compared with ICG data.

Main Results:

• Left ventricular stroke volumes estimated by ICG and LVG showed close correlation (average patient r=0.91, pooled data r=0.79, p<0.001).
• Changes in left ventricular stroke volume measured by both methods also correlated well (pooled data r=0.89, p<0.001).
• ICG provided reliable estimates of beat-by-beat stroke volume changes and reasonable estimates of absolute levels.

Conclusions:

• Tetrapolar impedance cardiography offers a reliable non-invasive method for assessing beat-by-beat left ventricular stroke volume variations.
• ICG can provide reasonable estimates of absolute stroke volume levels, complementing invasive methods.
• These findings support the use of ICG in clinical settings for monitoring cardiac function.