[Determination of the right ventricular ejection fraction from the exponential decrease in the thermodilution curve--a comparison with biplanar cineventriculography].

Abstract

Using the exponential downslope of the thermodilution curve right ventricular ejection fraction and volumes can be calculated. To evaluate the accuracy of this method for clinical application thermodilution measurements were compared to the results of biplane cineventriculography in 40 patients. Mean right ventricular ejection fraction was 52 +/- 9% determined by thermodilution (Th), and 53 +/- 8% determined by angiography (A). Mean enddiastolic volume was 189 +/- 74 ml (Th) and 162 +/- 42 ml (A) and mean endsystolic volume 92 +/- 42 ml (Th) and 75 +/- 20 ml (A). Ejection fraction of thermodilution measurements correlated with the results of angiography (r = 0.59; SEE = 7%; % SEE = 13 rel. %; p less than 0.001). The correlation for endsystolic volume was: r = 0.50; SEE = 36 ml; % SEE = 48%; p less than 0.001, and for enddiastolic volume: r = 0.36; SEE = 70 ml; % SEE = 43%; p less than 0.05. The differences in ejection fraction calculated by the two different methods were especially high (up to 25%) in patients (n = 10) with low (less than 110 ml) or high (greater than or equal to 200 ml) enddiastolic volume. For the other 30 patients the correlation for right ventricular ejection fraction was: r = 0.82; SEE = 5%; % SEE = 9 rel. %; p less than 0.001. Thus, the thermodilution method allows an approximative assessment of right ventricular ejection fraction only in patients with a normal right ventricle. Since right ventricular ejection fraction cannot be determined with sufficient accuracy in patients with right ventricular dilatation, the clinical application of this method is limited.