An Official Journal of the American Heart Association Application of a Constant Indicator Dilution Method to the Measurement of Local Venous Flow

• Many investigations of the cardiovascular system require estimations of regional or single vessel blood flow. Although direct methods ' have been devised for this purpose, most have a limited application in man because they involve exposure of the appropriate blood vessel. When multiple and frequent flow estimations over a long period are desired in experimental animals, repeated exposures of the same vessel or region may present difficulties. Hence, a technique that would eliminate this procedure would be of value. Although indicator dilution methods have been used to estimate regional or single vessel blood flow in man and experimental animals, certain problems in their application have emerged. Andres et al. measured human brachial artery flow, Peterson et al. left ventricular output, and Grace et al. thoracic aortic flow by injecting Evans blue dye at a constant rate into the artery and recording a dilution curve from an accompanying vein or