| [ Summary ] |
Arteriovenous fistulas for hemodialysis blood access, increase the preload and caridac output while decreasing the afterload. The decrese in afterload instantaneously increases cardiac output, which in turn increases venous return. In a new steady state, increased venous return is counterbalanced by increased cardiac output. Within the cardiac output reserve, the fistulas never cause heart failure symptoms. However, it should be emphasized that AV fistulas in fact insidiously reduce the cardiac reserve. Hypervolemia, usually present in hemodialyzed patients, further reduces cardiac reserves, which predisposes the patient to progressive heart failure, when conditions such as severe hypertension, infection, ischemia, cardiomyopathy, arrythmia and valvular diseases are complicated. On creating AV fistulas, the oriface for anastomosis must properly be designed to avoid excessive flow. |