Circulation and Blood Pressure in the Great Vessels and Heart of the Turtle (Chelydra serpentina)

¹ From the Department of Physiology, University of Illinois, Urbana, Illinois, and the Section of Physiology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota

Circulation through the heart of the turtle (Chelydra serpentina) was studied by means of simultaneous recordings of oxygen saturation, blood-saturation dye curves and pressure measurements in the cardiac chambers and arteries leaving the heart. The saturation levels of the blood leaving the heart via the right and left aortas are the same while pulmonary artery blood is distinctly more venous. Resection of the septal mechanism resulted in oxygen saturations of similar value in all vessels leaving the heart. The dye curves showed that less than 10% of the blood of the turtle may pass from right to left but a much larger volume of blood passes from left to right. The findings in the turtle heart resemble those found in human patients with congenital ventricular septal defects. Blood pressure patterns in the carotid, subclavian arteries and the two aortas are very similar. Systolic pressures in the aortas and pulmonary artery are the same, but diastolic pressure in the pulmonary artery is distinctly lower than in the aortas.