Mixing of dye and blood in the canine aorta

Abstract

Paired simultaneous arterial sampling curves from both femoral or iliac arteries of 10 dogs were obtained following injections of indicator in the superior vena cava (SVC), right atrium (RA), left ventricle (LV), aortic root (AR), and descending thoracic aorta(DA). Calculated paired cardiac outputs following injection into the SVC or RA showed an average difference of 5.8% (SE 0.97). Injections into the LV were not significantly different in this regard, having an average difference of 6.3% (P < 0.85). Injections into the AR and DA showed progressive increases in the differences of the paired curves, averaging 9.9% and 23.1%, respectively. The degree of aortic mixing of blood and dye appears to be related to the distance available for such mixing. Whie this cannot be interpreted as evidence for the existence of laminar flow in arteries, the degree of any existing turbulence is inadequate for complete mixing.