The chronic kidney disease
patients are referred to vascular surgeons for creating an arterio-venous
fistula for hemodialysis with different types of hidden cardio-vascular
problems. We have noted that those patients with sub clinical congestive heart
failure are at greater risk of worsening of the cardiac condition after
creation of the arterio-venous fistula for hemodialysis. In general, it was
observed that patients with CHF and ESRD have poor prognosis. Optimizing the
hemodynamics is crucial in both these conditions. Adding the AVF as a third
factor in these patients can also make the optimization of hemodynamics more
difficult. When an AVF is created, it reduces peripheral resistance, increases
the preload and the stroke volume and cardiac output are increased. In 7 to 10
days the cardiac output is increased by 15% to 20%, left ventricular end diastolic
pressure is increased by 5% to 10%. The Atrial naturietic and brain naturietic
factors (ANP, BNP) are elevated. The
higher flows throughs the AVF was not seem to be linked to the incidence of
high output failure. The fistula flows will be twice higher in the upper limb
than those at the wrist. The upper arm AVF flows (Qa) will be
between 1.13 to 1.72 Lit/min. The fistula flow can be higher than 2 lit/min (Qa)
in 15% of the patients. Generally, the ratio between cardiac output and fistula
flow (Qa) is 22% in the upper limbs. The risk of high output heart
failure is high when CO/Qa is more than 40%. It was observed that
17% of the patients developed de novo congestive heart failure in the HEMO
study. Median time to develop high output heart failure will be 51 days and it
is noted in 40% of the upper limb Brachio-cephalic and 8% of the Radio-cephalic
arteriovenous fistula.
Dr. Pinjala R K
14 April 2017
