Minimal cardiac transit times--a sensitive parameter reflecting changes in cardiac volume-to-flow ratios.

Minimal cardiac transit times (MTTs) are differences between times of appearance of the indicator at consecutive segments of the cardiopulmonary circulation. The MTTs are shown to be directly proportional to the quotient of volume to flow. The relationship of the cardiac MTTs to ventricular ejection fraction was derived. Utilizing this technique the ejection fractions of the left and right ventricles in 72 normal individuals were calculated. Theoretical aspects of measuring cardiac MTTs were related to experience of clinical application and confirmed its usefulness.