Does the use of fiberoptic catheters accurately measure cardiac output and regurgitant volumes compared to conventional methods during cardiac catheterization?
Fiberoptic catheters provide accurate measurements of cardiac output and regurgitant volumes with minimal blood withdrawal during cardiac catheterization.
The fiberoptic instrument and catheters described in the preceding study were employed in the measurement of indocyanine-green concentrations in the circulatory system by a simple change of filters. Cardiac output was calculated from the recorded curves in 19 instances. In 13 of these, the results were compared with cardiac output determinations simultaneously obtained by a conventional method. There was good agreement for each of the values obtained (range 2.37 to 7.32L./min., r = 0.985). The only blood withdrawn in each patient was the 8 ml. needed for calibration. Distinct step-function was seen in the descending as well as the ascending portions of the curves. In three instances left ventricular injections were done and end-diastolic and end-systolic volumes calculated. The results are similar to those reported for thermodilution methods. From the rapidly changing concentration of dye within one cardiac cycle in the presence of aortic regurgitation, a formula was derived by which the amount of regurgitation could be calculated. This method was tested in a model where regurgitation varied up to twice the forward stroke volume by means of a ther-modilution method. Good agreement between measured and calculated degrees of regurgitation (r = 0.928) in 26 observations is shown. The application of the formula to a patient with proven aortic regurgitation is demonstrated.
Hugenholtz et al. (Mon,) studied this question.