Carotid blood flow in man determined by video dilution technique: 1. Theory, procedure, and normal values

The blood flows in the common, internal, and external carotid arteries were determined as a percentage of the cardiac output by video dilution technique in 20 normal subjects during routine angiography. Nine women and 11 men, ages 19-63 years, displayed a mean flow in the common carotid of 8.5% (SD±0.9%; n=40); internal carotid, 5.3% (SD±1.0%; n=24); and external carotid, 3.2% (SD±0.4%; n=24). Relative flow is calculated by a modification of the Stewart-Hamilton principle. The technique is fast, simple, highly accurate, and avoids the errors connected with previous videodensitometric mean transit time techniques. The method can be used in routine angiography without prolonging the catheterization procedure or adding to the patient's risk or cost.