Determination of Left Ventricular Ejection Fraction and Volume by Thermodilution. An Appraisal of a New Equation to Calculate Ejection Fraction from Thermodilution Curve

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We investigated a method of determining left ventricular ejection fraction (EF) and volume by thermodilution. Theoretically, EF is to be calculated from the equation below : [numerical formula] where _VT_0=blood temperature in the left ventricle (LV) immediately after injection of cold heat (CH) in to LV, _aT_0=left atrial blood temperature after injection of CH into LV, _vT_n=blood temperature in the ascending aorta on the n th beat after injection. Stroke volume (SV), which is calculated by integrating thermodilution curve, gives LV end-diastolic volume (EDV) when divided by EF. We tested this hypothesis in 36 experiments employing 15 dogs. Cardiac output (CO), EF, and EDV obtained by thermodilution were compared with those obtained by electromagnetic flowmeter and pressure-volume curve of excised hearts. The correlation coefficients (r) between values obtained by the above two methods were as follows: r=0.91 (p<0.001) for CO, r=0.55 (p<0.002) for EF, r=0.85 (p<0.001) for EDV. We conclude that (1) LVEF and EDV as well as CO can be reasonably accurately determined by thermodilution, and (2) this principle could be applied to indicators other than CH.
北里大学の論文
1987-04-30