The determination of cardiac output by the dilution method without arterial sampling. II. Validation of precordial recording.

The selection of an external site for a radioisotope determination of cardiac output is discussed with respect to satisfying the analytical conditions of the Stewart-Hamilton dilution equation. Examples of both single-chamber and multichamber recording are illustrated, along with a discussion of the difficulties of curve calibration and extrapola. tion from multiple sites. The development of a method independent of critical placement or patient variability is described.