Arteriovenous access fistulae diminish cardiac reserve, anaerobic threshold and work capacity: A case for fistula closure in stable renal transplant recipients

A patent arteriovenous fistula (AVF) in stable renal transplant recipients may be viewed as 'insurance' against late graft failure and a return to haemodialysis. A patent AVF may, however, exert signifib cant chronic demands on cardiac output (CO) which may in turn adversely affect the prognosis of patients already at risk of cardiac disease. Doppler echocardiography and anaerobic threshold (AT) assessment were used to measure the CO and the work capacity of nine stable renal transplant recipients >15 months post transplantation who had patent AVF. Cardiac output fell from 6.9 +/- 1.48 L/min with the AVF open to 6.0 +/- 0.97 L/min with the AVF closed (P < 0.002). The AT rose from 14.1 +/- 5.67 with the AVF open to 16.5 +/- 6.72 with the AVF closed (P < 0.002). The work capacity to reach the AT improved from 68.7 +/- 30.8 watts with the AVF open to 84.6 +/- 38.0 watts with the AVF closed (P < 0.004). This study suggests that a significant and chronic increase in left ventricular work-load accompanies a patent AVF resulting in a markedly reduced exercise efficiency. A patent AVF is ideal where graft survival is doubtful but, where long-term graft function is expected, the adverse effects of AVF patency, a chronic elevation in CO and reduced exercise capacity make a strong case for considering AVF closure. The prognostic advantage for left ventricular function may outweigh AVF preservation in stable renal transplant recipients.