Cardiac remodeling after reduction of high-flow arteriovenous fistulas in end-stage renal disease.

In patients with end-stage renal disease, excessive blood flow through an arteriovenous fistula (AVF) may lead to volume overload-induced cardiac remodeling and heart failure. It is unclear which patients with hyperfunctional AVF may benefit from AVF reduction or ligation. The indication for the procedure is often based on AVF flow. Because cardiac remodeling is driven by increased venous return, which is equivalent to cardiac output, we hypothesized that an elevated cardiac index (CI) might better identify subjects with reverse remodeling after AVF reduction. Thirty patients (age 52±12 years, 73% male) with AVF flow ⩾1.5 l min(-1) underwent comprehensive echocardiographic evaluations before and after AVF reduction. At baseline, 16 patients had a normal CI (2.5-3.8 l min(-1) m(-2)) and 14 had a high CI (4.0-6.0 l min(-1) m(-2)). A left ventricular end-diastolic diameter decrease after operation was predicted by elevated baseline CI (P<0.01), but not elevated AVF flow (P=0.07). There was a significant decrease in CI, left ventricular mass, left atrial and right ventricular diameter and pulmonary systolic pressure in the high CI group but not in the normal CI group. After AVF reduction, systemic vascular resistance decreased in the normal CI group, whereas it did not change in the high CI group. In conclusion, reduction of high-flow AVF leads to reverse cardiac remodeling but only in patients with elevated CI. The variability of the response of systemic vascular resistance to AVF flow may explain this observation. Increased CI but not increased AVF flow may better determine candidates for AVF reduction.

Prevention of contrast-induced nephropathy in diabetic patients with impaired renal function: a randomized, double blind trial of sodium bicarbonate versus sodium chloride-based hydration.

AIMS: Diabetes mellitus and decreased renal function are important risk factors for contrast-induced nephropathy (CIN) in which oxidative stress damage may play a role. Alkalinization with sodium bicarbonate (NaHCO3) has been proposed as a means of reducing free-radical mediated renal injury; however, the effectiveness of NaHCO3 treatment to prevent CIN in high-risk patients remains uncertain. METHODS: We performed a prospective, randomized, double blind, sodium chloride (NaCl) hydration-controlled study of NaHCO3 in 120 diabetic patients with impaired renal function (serum creatinine ≥100 µmol/L) undergoing an elective procedure with use of low-osmolar contrast media. The primary endpoint was the incidence of CIN defined as creatinine increase of ≥25% and/or ≥44 µmol/L within 2 days after contrast. Secondary end-points were maximal changes in serum creatinine and estimated glomerular filtration rate. Urine F2-isoprostane levels were also assessed as measure of oxidative stress. RESULTS: There were no significant group differences in baseline characteristics except for the marginally lower age of the NaHCO3 treated patients (63 ± 11 vs. 67 ± 10 years; p=0.05). CIN occurred in 7 (11.5%) and 5 (8.5%) patients of the NaHCO3 and NaCl groups, respectively (p=0.76; incidence rate ratio 1.35; 95% CI 0.37-5.41). No significant differences were seen in secondary outcome measures and changes in the parameter of oxidative stress. CONCLUSIONS: In diabetic patients with renal function impairment sodium bicarbonate does not confer protection against contrast-induced nephropathy greater than sodium chloride-based hydration. Its specific role in mitigating oxidative stress damage in CIN is also not supported by our data.