Effects of the arteriovenous fistula on pulmonary artery pressure and cardiac output in patients with chronic renal failure.

INTRODUCTION: Access to the vascular system is necessary in patients with chronic renal failure planned to undergo dialysis. One of the complications of end-stage renal disease patients is pulmonary hypertension (PHT). Temporary arteriovenous access closure and successful kidney transplantation causes a significant fall in cardiac output and pulmonary artery pressure (PAP), indicating the possibility that excessive pulmonary blood flow is involved in the pathogenesis of the disease. We attempted to study the relationship of PHT with arteriovenous fistula (AVF) creation, as well as to assess the relationship between AVF flow and fistula characteristics.

METHODS: Fifty patients were included in the study. Echocardiography was used to evaluate systolic PAP, cardiac output (CO), and ejection fraction (EF) before creating the AVF. After a follow-up interval of at least 6 months, a second echocardiographic assessment and a Doppler sonographic assessment of their fistula flow were carried out. Complete data were available for 34 patients.

RESULTS: Study data were collected from 34 patients, 28 males and 6 females with a mean age of 52 yrs ranging from 15-78 yrs. The data showed a statistically significant positive correlation between fistula flow and PAP2 and PAP changes (p <0.05). Mean fistula flow was 1322 ml/min in patients without PHT and 2750 ml/min in patients with PHT. This difference (1428 ml/min) was statistically significant (p=0.03). We found a significant negative correlation between PAP1 and EF1 and PAP2 and EF2 (p <0.05). In addition, the mean EF2 in patients without PHT was 57% in contrast to 46% in patients with PHT. Mean fistula flow in radial fistulae (mean=422 ml/min, range: 370-474 ml/min) was significantly less than brachial fistulae (mean=1463 ml, range: 270-3300 ml/min) (p=0.03). Mean systolic PAP2 of 14.8 mmHg in transplanted patients was 5.9 mmHg less than those who were not transplanted (20.7 mmHg). Diabetes was the most common cause of renal failure and diabetics had a significant reduction in their EF (15.5%) compared with non-diabetic patients (1% reduction) (p=0.016).

CONCLUSION: Fistula flow, PAP and EF of all patients should be checked at least 6 months after fistula creation. Patients with higher fistula flow rates and patients with diabetes mellitus need to be more closely observed. In addition, elderly patients with significant cardiac and other comorbidities may be more prone to develop symptoms after AVF creation.