The In Vivo Determination of Left Ventricular Volume: Comparison of the Fiberoptic‐Indicator Dilution and the Angiocardiographic Methods

End-diastolic volumes, stroke volumes, and ejection fractions determined in quick succession by the fiberoptic indicator-dilution technique and the angiocardiographic method were compared in 63 patients with various disorders, aged 6 weeks to 58 years. The calibration methods are discussed in detail.Good agreement was found (r=0.965) although end-diastolic volume by the fiberoptic-indicator method (FO) (mean, 106.3 ml/m2) consistently exceeded enddiastolic volume by the angiocardiographic method (A) (92.5 ml/m2). Variations in injection techniques, the absolute size of the volume (range, 31.0 to 478.5 ml/m2), and heart rate (from 55 to 179 beats/min) did not influence this correspondence significantly.Stroke volumes, ejection fractions, and end-systolic volumes were compared in 41 patients with nonregurgitant lesions. The correlation coefficients are 0.808, 0.824, and 0.950, respectively.These results show better agreement than was previously suggested by workers utilizing other indicator-dilution systems. Reasons for this finding, such as the fact that studies were carried out in quick succession in the same patients, the advantage of indocyanine green over other indicators, the characteristics of the fiberoptic sampling system, the adequacy of mixing in the human left ventricle, and the errors inherent in the angiocardiographic method are discussed. Since agreement existed over a wide range of volumes, a set of regression equations was calculated that permitted the interchange of stroke volume, ejection fraction, and end-systolic and end-diastolic volumes in situations where one technique is favored over the other. Thus, for end-diastolic volume by angiocardiography, EDVA=0.785 EDVFO + 10.6 (in ml/m2).