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KMID : 0811720020060000163
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Korean Journal of Physiology & Pharmacology
2002 Volume.6 No. 0 p.163 ~ p.0
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Assessment of Left Ventricular Ejection Fraction by Impedance Cardiography
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Choi Jang-Kyu
Kim Kyoung-Ryong
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Abstract
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Left ventricular ejection fraction (EF) is an important indicator of cardiac performance. The purpose of this study was to derive a useful tool of evaluating EF, regardless of change in cardiac preload, using impedance cardiography (IMP).
IMP and multi-gated equilibrium radionuclide ventriculography (MUGA) were simultaneously applied to eight healthy male students in sitting and supine positions. Seven cardiac variables (i.e. thoracic base impedance Z0, maximum value of the first time derivatives of thoracic impedance change dZ/dtmax, maximum value of the second time derivatives of thoracic impedance change d2Z/dt2max, heart rate period HRP, pre-ejection period PEP, ventricular ejection time VET and systolic time interval STI) were obtained from IMP and ECG. The relationships between cardiac variables combined variously and EFMUGA measured from ventricular scintigrams was evaluated by linear regression analysis. The limits of agreement between EF estimated using linear regressions and EFMUGA were determined by bias plot.
The linear regressions, which was included (dZ/dtmax)/(d2Z/dt2max), (d2Z/dt2max)/ (dZ/dtmax), (d2Z/dt2max)/HRP and (dZ/dtmax*VET)/(Z0*PEP) as dependent variable, were significant in both body postures (p＜0.002). However, the (dZ/dtmax*VET)/(Z0*PEP)- included regression line was different between the two body postures (p＜0.01). Since the regression lines including the others were similar in the two body postures, the combined linear regression equations were obtained as below:
EFA (%)=-71.5 * (dZ/dtmax)/(d2Z/dt2max)+323.9 (r=0.790, p＜0.001)
EFB (%)=+9.42 * (d2Z/dt2max)/(dZ/dtmax)-195.4 (r=0.792, p＜0.001)
EFC (%)=+12.82 * (d2Z/dt2max)/HRP-20.5 (r=0.639, p＜0.001)
The mean difference between EF estimated using these equations and EFMUGA were all 0.0% in these equations, and the standard deviation of the difference was 4.2-5.2%. These data indicate that the new equations may provide reliable EF value in healthy subjects, regardless of change in cardiac preload.
Source: Korean Journal of Physiology & Pharmacology.2002 Oct;6(Suppl II):S111-S111
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KEYWORD
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left ventricular ejection fraction, impedance cardiography
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