Haemodynamics at rest and under effort in chronic arteriovenous fistulae (AVFs)

Latero-lateral femoro-femoral arteriovenous fistulae (AVFs) were surgically created in mongrel dogs. After 7-9 months during which the dogs were trained on a treadmill, devices suitable for recording arterial pressure and aortic and coronary flow were chronically implanted. Haemodynamic parameters of the dogs were controlled either at rest or after effort, keeping AVFs open or manually closed. The results, when statistically processed, showed that haemodynamic changes induced by occlusion of AVFs at rest and under effort are similar from a qualitative point of view, but considerably more marked after muscular exercise. Under effort the shunt index calculated rose to a higher extent than cardiac output. The decrease in heart rate after AVFs occlusion was significantly correlated with flow in the fistulae. However, the Nicoladoni-Branham phenomenon ought to be used for indirect evaluation of the shunt flow.