Carotid-Jugular Fistula Model to Study Systemic Effects and Fistula-Related Microcirculatory Changes

Background: Arteriovenous fistulae impair the distal circulation, but their effects at the microcirculatory level are not well understood. This study presents the carotid-jugular fistula (CJF) as a model to evaluate fistula-related microcirculatory and systemic changes. Materials and Methods: Female Wistar rats were anesthetized and divided into a fistula group (FG, n = 10) and a sham group (SG, n = 6). End-to-end anastomosis was performed between the right carotid artery and the jugular vein in the FG. The hemodynamic status was followed for 6 weeks. On the sixth postoperative week, liver and kidney microcirculation was measured using laser Doppler; then microcirculatory changes were assessed after occlusion of the carotid artery. At the end of the experiment, histological samples were taken and the weights of the organs were measured. Results: The heart rate and systolic blood pressure decreased significantly due to the CJF. Laser Doppler showed a reduction in liver blood flow units (BFU) in the FG in comparison with the SG (p = 0.01), and they increased (p < 0.01) after occlusion of the fistula. Kidney BFU showed slight changes only. The comparative morphological study revealed significant increases in heart weight (p < 0.001) and left ventricular hypertrophy (p = 0.008) in the FG. Conclusion: Beside hemodynamic and morphologic changes, a CJF causes a deterioration in the microcirculation of the liver rather than of the kidney, but occlusion of the CJF immediately reverses these changes.