Patency of Arteriovenous Anastomosis in the Kidneys of Dogs

Abstract

The patency of arteriovenous anastomosis (AVA) in the renal microcircula tion has been a controversial topic. To study the possibility of AVA as part of the renal microcirculation a cathe ter was placed under radiological control in a renal artery in each of eight anesthetized dogs. Albumin microspheres 15-52 micra in diameter labeled with 3-5 mCi of Tc99m were injected into the renal artery through this catheter. Counts over the lungs, kidneys and bladder were obtained with detectors. The spatial distribution of the radioactivity in the dogs were also studied by scintigraphy and there was imaging of the kidneys which corroborates the find ings obtained with detectors, there was no visualization of the lungs. In some studies the bladder was visualized because of the presence of free Tc99m. The lack of radioactivity in the lungs indicates that there are not patent AVA in canine kidneys because the radioactive microspheres injected in the renal artery became lodged in the arterioles, for being larger than the capillaries they could not cross to the renal veins.