[Measurement by isotope study of the cardiac output in the elderly].

Cardiac output and haemodynamic volumetric values (stroke volume, stroke index, left ventricular end-diastolic volume, blood volume, mean corpuscular volume and packed red cell volume) were measured in a population of 69 very old subjects (80 to 102 years) whose heart was regarded as normal on the basis of criteria determined, by radiocardiography and radionuclide ventriculography. These harmless and non-invasive techniques provided reference values in subjects of a seldom explored age group. Altogether, these values were lower than those of younger adults, and they decreased with age. Their reliability is due to the fact that they were obtained by true measurement and not by extrapolation of results observed in adults.