Carlo Basile and colleagues from hospitals in Manduria, Italy, were among the first to recognize the relationship between vascular access flow of arteriovenous fistulas (AVFs) and cardiac output (CO). In 2008 they conducted a study to glean better insight into this rarely explored aspect of HD pathophysiology.
Their study included 96 hemodialysis patients with AVFs who were evaluated for the existence of cardiac failure according to the four-stage functional classification of the American College of Cardiology/American Heart Association task force.
The four classifications were:
- Patients at high risk for heart failure but without structural heart disease or symptoms of heart failure.
- Patients who have developed structural heart disease that is strongly associated with the development of heart failure.
- Patients who have current or prior symptoms of heart failure.
- Patients with refractory heart failure requiring specialized interventions.
Flow Access and CO were measured by the ultrasound dilution technique in 65 patients with lower arm AVFs and 31 patients had upper arm AVFs.
The clinicians found that:
- The difference in the mean flow (Qa) between the two groups was statistically significant (lower arm AVF group: 0.948 ± 0.428 L/min, upper arm AVF group: 1.58 ± 0.553 L/min)
- CO and CPR (Cardio-Pulmonary Recirculation defined as Qa/CO) were significantly higher in the upper arm AVF group than in the lower arm AVF group
- Seven of the 10 patients who were classified as having stage C cardiac failure as well as high-output cardiac failure had upper arm AVFs
- The 10 patients with stage C (and high-output) cardiac failure were significantly older than other patients
- 0.95 and 2.2 L/min were identified as access flow thresholds where the CO trend significantly changed in the analysis of the regression equation.
- Access flow values ≥ 2.0 L/min predicted the occurrence of high-output cardiac failure most accurately.
- CPR values ≥ 20% was the second best predictor after flow.
Basile and colleagues concluded that access flow in AVFs and CO are related and upper arm AVFs are associated with an increased risk of high-output cardiac failure.