Renal hemodynamics during selective renal angiography

Effect of IV Injection of Radiographic Contrast Media on Human Renal Blood Flow

OBJECTIVE

The purpose of our study was to assess the effect of an i.v. injection of iodinated radiographic contrast medium on human renal blood flow using cine phase-contrast MRI.

SUBJECTS AND METHODS

We examined 12 healthy adult volunteers. Blood flow in one renal artery was measured using cine phase-contrast imaging (1.5-T MR system). Each volunteer received 120 mL of isotonic sodium chloride on study day 1 and 120 mL of a low-osmolar, nonionic, iodinated contrast medium (iomeprol, 400 mg I/mL) on study day 2. Repetitive measurements were performed before (up to five measurements in 5 minutes) and after (up to 13 measurements in 30 minutes) the injection was started.

RESULTS

Mean basal renal artery blood flow was 664 mL/min. In response to the injection of the test substances, we found a significantly larger decrease in average renal blood flow for contrast medium than for sodium chloride (31.9 mL/min vs 18.3 mL/min, p = 0.0481). Furthermore, in analyzing the measurements at early time points, we found a significant decrease (11.4% +/- 4.7% [SD]; Bonferroni-corrected, p < 0.05) in renal blood flow 2 minutes after the injection of the contrast medium was started. Sodium chloride did not produce a significant effect at any time.

CONCLUSION

Cine phase-contrast MRI can measure a decrease in renal blood flow in humans in response to an i.v. injection of iodinated radiographic contrast medium. Therefore, cine phase-contrast MRI can be a helpful and noninvasive tool for further investigations of contrast media-induced changes in human renal blood flow and their possible impact on the development of contrast-induced nephropathy.

Assessment of radiocontrast media induced renal vasoconstriction by color coded duplex sonography

INTRODUCTION

Changes in renal hemodynamics are suspected to be one of the major pathogenetic correlates in radiocontrast media-induced nephrotoxicity. We investigated whether color-coded duplex sonography is an appropriate method to document changes in intrarenal vascular resistance, after intravenous injection of the low-osmolar contrast material lopamidol.

METHODS

Intrarenal arterial doppler wave forms were analyzed every minute after intravenous injection of 100 mL lopamidol in 10 patients during a voiding cystourogram-procedure. The Resistive Index (RI) of each flow curve, reflecting intrarenal flow resistance, was calculated and compared to the mean of four RI measurements taken before contrast media application.

RESULTS

One minute after injection of Iopamidol the RI remained unchanged compared to the baseline standard of 0.70. In measurements obtained 2, 3, 4, and 5 minutes after lopamidol injection a statistically significant rise was seen: (minute 2: 0.74, p < 0.001/minute 3: 0.75, p = 0.001/minute 4: 0.72, p =0.018/minute 5: 0.74, p = 0.031). During the further course, the resistive indices decreased progressively and showed no significant difference in comparison with the baseline standard value.

CONCLUSION

Color coded duplex sonography is a simple method to detect changes in renal flow resistance after application of radiocontrast media. Based on our results, we believe that the analysis of intrarenal arterial doppler flow profiles constitutes an ideal method to investigate pathophysiologic mechanisms of radiocontrast media-induced nephrotoxicity, as well as pharmacological concepts in nephroprotectivity.

Adenosine antagonist theophylline prevents the reduction of glomerular filtration rate after contrast media application

Radiographic contrast media (CM) can induce renal failure and this may serve as an experimental model of acute renal failure (ARF). One vasoactive factor likely to be involved in ARF is adenosine. In a double-blind, placebo-controlled study we investigated the effect of theophylline (TP), an adenosine receptor antagonist, regarding changes in renal hemodynamics induced by CM. Thirty-nine patients who received 100 ml of a non-ionic low osmolar CM (iopromide) were studied for changes in GFR and RPF by continuous inulin and PAH clearance before and until four hours after CM application. Forty-five minutes before the application of CM, patients were randomized and received either theophylline (5 mg/kg body wt) or the vehicle and placebo (saline) intravenously in a blinded manner. We additionally measured the creatinine clearance on the day before and two days after CM application. Sodium excretion, N-acetyl-beta-glucosaminidase (NAG) excretion, plasma renin activity (PRA) and aldosterone levels were also measured before and after CM application. Theophylline levels were within the therapeutic range in patients of the theophylline group during and four hours after CM application (59.0 +/- 10.6 mumol/liter and 40.1 +/- 10.9 mumol/liter). GFR, measured by inulin clearance significantly declined under CM application in patients without TP application (N = 19; 88 +/- 40 to 75 +/- 32 ml/min/1.72 m2; P < 0.01). In the group of patients receiving theophylline (N = 18) the GFR remained constant (75 +/- 26 vs. 78 +/- 33 ml/min/1.72 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Radiocontrast-induced nephropathy in humans: role of renal vasoconstriction

Radiocontrast-induced nephropathy (RCIN) is a common cause of acute renal failure in hospitalized patients. Renal vasoconstriction figures prominently in the proposed pathogenesis of RCIN based on animal experiments. Prior human studies examining renal hemodynamic changes after contrast medium (CM) injection are inconclusive. No previous study of animals or humans has established a relationship between CM-associated renal hemodynamic changes and the subsequent development of RCIN. In the present study, we examined the renal hemodynamic effects of CM in patients at high risk of RCIN. In addition, we related those effects to the subsequent development of RCIN. Using renal vein thermodilution catheters, we measured renal blood flow (RBF) in 12 patients with chronic renal failure [serum creatinine (SCr) greater than or equal to 159 mumol/liter] during ionic CM injection for cardiac catheterization. We made measurements at the start of the procedure (t = 0), before the ventriculogram (t = 5), after the ventriculogram (t = 15), and after the coronary angiogram (t = 65). We measured SCr at t = 0 and again 24 and 48 hours later. Mean RBF for the group tended to increase after the ventriculogram, and increased significantly by t = 65 (P less than 0.005 vs. t = 0). When examined by individual patient, RBF fell below baseline in three patients (30%) at t = 15, but rose above baseline again by t = 65. Only one patient (8.3%) had a fall in RBF below baseline at t = 65. RCIN (defined as an increase in SCr greater than or equal to 25% above baseline) developed in six patients (50%) within 48 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal handling of iodamide and diatrizoate. Evidence of active tubular secretion of iodamide

Active tubular secretion of iodamide, a water-soluble contrast medium, was demonstrated by comparing the clearances of iodamide, iothalamate and inulin. Passive tubular back diffusion was not found. The fraction excreted by tubular secretion was significantly reduced at "clinical" plasma concentrations. The glomerular filtration rate was slightly depressed at these concentrations of iodamide and diatrizoate.

Renal bloodflow and function in the rabbit after surgical trauma. I. An experimental study

The aim of the present study was to examine the influence of surgical trauma on renal blood flow (RBF) and renal funciotn. The renal vessels were catheterized in lightly anaesthetized rabbits and the dye-dilution technique was used to measure renal blood flow and cardiac output. The renal fraction of the cardiac output (RBF % CO), the total peripherauation of the glomerular and tubular function was made by measuring the extraction of EDTA and of Hippuran. A decrease in the cardiac output was accompanied by a diminution of renal blood flow. Renal blood flow was reduced, regardless of whether surgery or puncture of the kidney was performed, probably due to vasoconstriction in the kidney caused by an increase in sympathetic tonus or in the concentration of plasma catecholamines. Manipulation of the renal artery seemed to stimulate further vasoconstriction in the ipsilateral kidney by a direct effect. The glomerular and tubular function decreased initially, independently of surgical trauma, and it is therefore assumed that the initial renal vasoconstriction includes the afferent arterioles. Renal function was not greatly influenced by handling of the renal artery.