Measurement of cardiac output without right heart catheterization: reliability, advantages, and limitations of a left-sided indicator dilution technique

This study was done to determine the accuracy and reliability of cardiac output measurements by the injection of indocyanine green into the left ventricle, with simultaneous sampling from a systemic artery. In 40 patients (18 men, 22 women, aged 34 to 74 years), cardiac output was measured in close temporal proximity by (a) standard indicator dilution (right atrium-to-pulmonary artery thermodilution in 11, pulmonary artery-to-systemic artery indocyanine green in 29) and (b) left ventricle-to-systemic artery indocyanine green. There was excellent agreement between the two techniques (r = 0.98, SEE = 0.12 liters/minute). In 28 of the patients, cardiac output also was measured by ascending aorta-to-systemic artery indocyanine green. In these individuals, this technique yielded results that were disparate from those obtained by standard indicator dilution (difference between standard indicator dilution and left ventricle-to-systemic artery indocyanine green = 0.18 +/- 0.13 [mean +/- SD] liters/minute; difference between standard indicator dilution and ascending aorta-to-systemic artery indocyanine green = 0.72 +/- 0.55 liters/minute; p less than 0.001), and in 22 of the 28, the ascending aorta-to-systemic artery indocyanine green cardiac outputs were greater than those obtained by standard indicator dilution. Thus, cardiac output can be measured accurately by injecting indocyanine green into the left ventricle, with simultaneous sampling from a systemic artery, but it cannot be quantified reliably by introducing indicator into the ascending aorta. The left ventricle-to-systemic artery indocyanine green technique can be used in patients undergoing only left heart catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)