The Cardiovascular Effects of Arteriovenous Fistulas: A Cause for Concern?
Jennifer MacRae and her colleagues from the University of Calgary, Calgary, Alberta, Canada, reviewed the hemodynamic and cardiovascular consequences of arteriovenous fistulas. Their findings were published in a 2006 paper in Seminars in Dialysis.
MacRae identified three periods when the presence of an AV fistula influences a patient's hemodynamics.
1. Immediate Effects of Creation of an AV Fistula
- Increase in cardiac output (10-20%)
- Increase in sympathetic nervous system activity (increasing contractility)
- Increase in stroke volume and heart rate
- Decrease in peripheral resistance
2. Hemodynamic Changes Within 1 Week of Creation of an AV Fistula
- Increase in circulating blood volume
- Increase in neuro-hormones
- Decrease in plasma renin and aldosterone levels
- Decrease in Systemic vascular resistance and systolic/diastolic blood pressure
3. Consequences of Long-Term AV Fistulas
- Left Ventricular hypertrophy
- High-Output cardiac failure
- Exacerbation of coronary ischemia
- Central vein stenosis
From their analysis, MacRae and her team concluded that:
- A thorough cardiac assessment should be performed in patients with coronary artery disease before placing an AV fistula.
- Regular careful evaluations are necessary in patients with cardiac disease and AV fistulas.
- Patients with a large AV fistula and high flow should be monitored closely.
- Patients with high flow fistulas (flow greater than 2 L/min) and increasing LVEDV are recommended to have a flow reduction procedure on their AVF.
- Patients with preexisting severe ischemic heart disease (class III unstable angina) should avoid an AV fistula placement if the underlying ischemia cannot be treated.