Studies on separating the impedance change components of blood vessels and ventricles in thorax from mixed impedance signals on chest surface

Abstract

The mathematical model and the measurement method for the separation in the present paper are feasible.

Analyzing the formation of normal and abnormal O waves in thoracic impedance graph using the impedance change components for aorta, blood vessels in lung and ventricles

“…The experiment results of 80 cases show that the main waveforms of the vascular components (AO, PL, and PR) in the systolic phase are upward, while those of the ventricle components (LV and RV) are downward, and they are in opposite phase [18]. This corresponds with the cardiovascular active process that the volume of ventricles diminishes, while the volume of the blood vessels expands in the systolic phase.…”

“…In these graphs, the O waves of the vascular components (AO, PL, and PR) are positive or negative, and the amplitude is smaller. While the O waves of the ventricle components (LV and RV) are positive, the amplitude is bigger [18].…”

“…The transducer for sensing the phonocardiogram (PCG) is placed at the position of cardiac apex on chest surface. The measurement instrument used in this study was developed by the research group [18]. The body height, body weight, chest circumference, chest breadth between left and right sides of thorax, blood pressure, as well as the name, sex and age are entered into the computer prior to the measurement.…”

“…The thoracic mixed impedance changes and basic impedances are measured with 6 leads consisting of 15 electrodes [18]. The electrode positions are shown in Figure 3.…”

“…This method lacks the uniqueness in evaluating the cardiac function of the left ventricle (LV). For this reason, we have separated the impedance change components for the AO, blood vessel in left lung (PL), blood vessel in right lung (PR), LV and right ventricle (RV) from the mixed impedance changes measured on the chest surface [17,18]. There is also an O wave in differential graphs of these impedance change components, as shown in Figure 2.…”