[show abstract][hide abstract] ABSTRACT: Oxidative stress caused by contrast medium is thought to be one of the main mechanisms of contrast-induced acute kidney injury. A prospective study was conducted to evaluate the relationship between oxidative stress caused by contrast agent administration and long-term renal function.
Thirty-six consecutive patients who underwent coronary angiography were enrolled. Urinary F2-isoprostane, a marker of oxidative stress, was measured at baseline and 24h after angiography, and serum creatinine was measured at baseline, 24h and 1 year after the procedure. The change in estimated glomerular filtration rate (eGFR) at 1 year after angiography correlated significantly with the change in eGFR at 24h after angiography (r=0.729, P<0.001). We also found a significant correlation between the increase in urinary F2-isoprostane at 24h and the decrease in eGFR at 1 year (r=0.439, P=0.022). In multivariate analysis, the decrease in eGFR at 1 year after coronary angiography correlated with the increase in F2-isoprostane at 24h after angiography as well as the decrease in eGFR at 24h after angiography (P=0.039 and P<0.001, respectively).
Contrast-induced nephrotoxicity might be transient; however, an early decrease in eGFR and increase in oxidative stress are associated with chronic renal insufficiency. Careful long-term follow-up and adequate medical intervention are necessary for these patients.
[show abstract][hide abstract] ABSTRACT: In patients with chronic heart failure, an inadequate increase in muscle blood flow resulting from impaired vasodilation plays a key role in their exercise intolerance. However, no non-invasive methods to assess muscle vasodilation during dynamic exercise were available. We investigated whether the changes in tissue hemoglobin and myoglobin content (total-Hb + Mb) determined by non-invasive measurement using near-infrared spectroscopy (NIRS) reflect vessel conductance of working muscle during exercise.
Sixteen patients (10 patients with normal cardiac systolic function, 6 with cardiac dysfunction) performed incremental bicycle exercise testing. Total-Hb + Mb from the right vastus lateralis muscle was monitored using NIRS. Leg blood flow (LBF) in the right femoral vein was measured using a thermodilution technique every 30-60 s. Leg vessel conductance was calculated as LBF/mean arterial pressure at each time of the measurement. In all cases except 1, the levels of total-Hb + Mb showed significant correlation with the leg vessel conductance (r=0.792 to 0.980). Intra-subject reproducibility of the NIRS measurement was also confirmed in 6 patients.
Total-Hb + Mb from NIRS reflected muscle vasodilation during sub-maximal dynamic exercise in patients with and without cardiac dysfunction, indicating that NIRS provides a valuable method to assess the working muscle vasodilation.