Evaluation of left ventricular function by impedance cardiography: a review

Area of Science:

• Cardiovascular Physiology
• Medical Instrumentation
• Diagnostic Techniques

Background:

• The impedance waveform offers potential for assessing ventricular function.
• Systolic time intervals derived from impedance measurements are the most validated method currently.
• Existing research primarily focuses on left ventricular (LV) function, with limited understanding of right ventricular (RV) influence.

Purpose of the Study:

• To evaluate the predictive capability of impedance waveform analysis for ventricular function.
• To validate the relationship between Pre-Ejection Period/Ventricular Ejection Time (PEP/VET) and Ejection Fraction (EF).
• To investigate the potential contribution of right ventricular function to impedance tracings.

Main Methods:

• Analysis of impedance waveform characteristics.
• Measurement of systolic time intervals, specifically PEP/VET.
• Comparison of impedance-derived indices with established measures of ventricular function (e.g., EF).

Main Results:

• Systolic time intervals show the best validation among impedance-derived methods for predicting ventricular function.
• Further validation is required across diverse patient populations (ICU and non-ICU) to establish a stable PEP/VET and EF relationship.
• The contribution of right ventricular function to the impedance waveform requires additional investigation.

Conclusions:

• Impedance waveform analysis, particularly systolic time intervals, holds potential for non-invasively assessing ventricular function.
• More extensive clinical validation is necessary to establish the reliability and widespread application of these impedance-derived indices.
• Future research should incorporate techniques like first-pass radionuclear imaging to specifically assess RV function and its impact on impedance measurements.