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The effects of arteriovenous shunts on cardiac function in renal dialysis patients--an echocardiographic evaluation
Insights
Echocardiography revealed that arteriovenous (AV) fistula flow significantly impacts cardiac function in dialysis patients. Occluding the AV fistula improved cardiac index and heart rate, suggesting echocardiography can identify patients benefiting from smaller fistulae.
Area of Science:
- Cardiology
- Nephrology
- Medical Imaging
Background:
- Arteriovenous (AV) fistulae are crucial for hemodialysis access.
- High AV fistula flow can negatively affect cardiac function.
- Echocardiography offers a non-invasive method to assess cardiac hemodynamics.
Purpose of the Study:
- To estimate AV fistula flow rate using echocardiography.
- To evaluate the effect of AV fistula occlusion on cardiac function in dialysis patients.
- To identify echocardiographic predictors for improved cardiac performance after fistula occlusion.
Main Methods:
- Echocardiographic assessment of 7 dialysis patients before and after 10-minute AV fistula occlusion.
- Measurement of cardiac index, heart rate, mean velocity of fiber shortening (Vcf), and ejection fraction.
- Estimation of AV fistula flow rate.
Main Results:
- Cardiac index significantly decreased after AV fistula occlusion (4.31 to 3.89 l/min/m2), primarily due to a reduced heart rate.
- Estimated AV fistula flow rate was 0.71 +/- 0.17 l/m.
- Patients with poor left ventricular function and septal hypertrophy showed improved cardiac performance upon fistula occlusion.
Conclusions:
- Echocardiography can accurately estimate AV fistula flow and its impact on cardiac function.
- AV fistula occlusion can normalize elevated cardiac index in dialysis patients.
- Echocardiography may help select patients who benefit from smaller AV fistulae for optimal renal and cardiac management.
Abstract:
To estimate the flow rate in arteriovenous dialysis fistulae and its effect on cardiac function we investigated 7 dialysis patients (1 woman, 6 men, mean age 33 +/- 3 years) echocardiographically before and after 10 minutes occlusion of the arteriovenous shunt. Cardiac index was signigicantly raised (4.31 +/- 0.23 l/min/m2) and fell significantly into the normal range to 3.89 +/- 0.11 l/min/m2 after occlusion of the AV fistula. This reduction was mainly due to a fall in heart rate from 82 +/- 4 beats/min to 76 +/- 5 beats/min. The estimated AV fistula flow rate (0.71 +/- 0.17 l/m) has been similarly reported in invasive hemodynamic studies. Parameters of cardiac contractility were in the lower range of normal with an average of 1.16 +/- 0.10 circ/sec for the mean velocity of fiber shortening (Vcf) and 65 +/- 4% for the ejection fraction. These decreased minimally after fistula occlusion. The single echocardiographic measurements of Vcf and ejection fraction showed good correlation (r=0.97) and revealed evidence that only these patients with poor left ventricular function and septal hypertrophy showed improved cardiac performance after occlusion of the arteriovenous fistula. Thus echocardiography may offer the opportunity to select those patients who need small AV-fistulae for optimal renal and cardiac treatment.