Opening an arteriovenous fistula in rats resulted in a progressive increase in cardiac index up to 307% at 5 weeks, with initial decreases in systemic flow and MAP that normalized by 5 weeks.
Creation of an arteriovenous fistula in rats induces a progressive high-output state characterized by massive increases in cardiac index and atrial natriuretic peptide, with initial drops in systemic flow and blood pressure that normalize by 5 weeks.
Time course of multiple hemodynamic changes in rats after opening an AV fistula was assessed. The fistula was made in male Sprague-Dawley rats by anastomosing the aorta and vena cava below the renal arteries. At 1 h (1H), 1 day (1D), 1 wk (1W) and 5 wk (5W) in sham controls or after opening an AV fistula, we measured cardiac output (CO) and tissue flows by using radioactive microspheres. The flow of microspheres to the lungs was used as a measure of shunt flow. In the fistula animals this lung flow (fistula flow) was 50-77% of the CO compared with 1-3% in the control animals. Cardiac index in the fistula animals increased by 40, 107, 129, and 307% compared with the respective control animals in the consecutive time groups. Systemic flow, tissue flows, and mean arterial blood pressure (MAP) in the fistula animals in the 1H and 1W groups were significantly decreased below control values, but each of these variables returned to control levels after 5W. Hematocrit (Hct) significantly decreased, whereas right atrial pressure (RAP) gradually increased over the experimental period. These two observations suggest retention of fluid. Plasma renin activity increased in the 1H animals but returned to control in the 1D animals. Atrial natriuretic peptide (ANP) gradually increased throughout the 5 wk from 86 +/- 22 (1H) to 709 +/- 217 pg/ml (5W). The increase in ANP correlated with the increase in RAP. Calculated total peripheral resistance in fistula animals was significantly decreased throughout the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
Huang et al. (Sun,) conducted a other in Arteriovenous fistula. Opening an arteriovenous fistula vs. Sham controls was evaluated on Time course of multiple hemodynamic changes (cardiac output, tissue flows, etc.). Opening an arteriovenous fistula in rats resulted in a progressive increase in cardiac index up to 307% at 5 weeks, with initial decreases in systemic flow and MAP that normalized by 5 weeks.