Nephrotoxic effects in high-risk patients undergoing angiography

Neutrophil Gelatinase-Associated Lipocalin as an Early Marker of Contrast-Induced Nephropathy After Coronary Angiography

We investigated whether serum neutrophil gelatinase-associated lipocalin (NGAL) was an early predictive biomarker of contrast-induced nephropathy (CIN) in patients with chronic kidney disease (n = 100) undergoing coronary catheterization. Serum creatinine (SCr) levels were measured at baseline, 24 hours, and 48 hours post procedure. Serum NGAL was measured preprocedure, 4 hours, and 24 hours post procedure. The frequency of CIN was 11%. In patients with CIN, SCr achieved significance only at 48 hours ( P = .006), whereas serum NGAL increased ≥25% from baseline at 24 hours in 7 of 11 patients with CIN ( P = .04) but did not change in the other 4. However, serum NGAL also rose ≥25% in 12 of 89 non-CIN patients. This subgroup could have had “incipient CIN.” Serum NGAL delta value at baseline, 24 hours was superior to SCr for early diagnosis of CIN. In conclusion, serum NGAL is an early predictive biomarker for CIN.

Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

The authors present an overview of the current evidence and management recommendations for evaluation and treatment of adults with acute ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators responsible for the care of acute ischemic stroke patients within the first 48 hours from stroke onset. These guidelines supersede the prior 2007 guidelines and 2009 updates.

METHODS

Members of the writing committee were appointed by the American Stroke Association Stroke Council's Scientific Statement Oversight Committee, representing various areas of medical expertise. Strict adherence to the American Heart Association conflict of interest policy was maintained throughout the consensus process. Panel members were assigned topics relevant to their areas of expertise, reviewed the stroke literature with emphasis on publications since the prior guidelines, and drafted recommendations in accordance with the American Heart Association Stroke Council's Level of Evidence grading algorithm.

RESULTS

The goal of these guidelines is to limit the morbidity and mortality associated with stroke. The guidelines support the overarching concept of stroke systems of care and detail aspects of stroke care from patient recognition; emergency medical services activation, transport, and triage; through the initial hours in the emergency department and stroke unit. The guideline discusses early stroke evaluation and general medical care, as well as ischemic stroke, specific interventions such as reperfusion strategies, and general physiological optimization for cerebral resuscitation.

CONCLUSIONS

Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke remains urgently needed.

Effect of low-osmolar contrast medium iopromide and iso-osmolar iodixanol on DNA fragmentation in renal tubular cell culture

BACKGROUND

Intravascular administration of iodinated contrast media continues to be a common cause of hospital-acquired acute kidney injury. Accumulating evidence suggests that radiocontrast agent-induced nephrotoxicity is associated with increased oxidative stress, which leads to renal tissue damage with DNA fragmentation. We therefore tested whether an iso-osmolar contrast medium (iodixanol) causes less oxidative DNA damage to renal tubular cells than a low-osmolar contrast medium (iopromide).

METHODS

HK-2 cells (human proximal renal tubular cell line) were incubated at different time points (10 min-2 h) with increasing concentrations (20-120 mg/ml iodine) of iodixanol or of iopromide. Oxidative DNA damage to renal tubular cells was measured by alkaline comet assay (single-cell gel electrophoresis).

RESULTS

Both iso- and low-osmolar contrast agents induced time- and concentration-dependent DNA fragmentation. DNA fragmentation was maximal at 2 h with 120 mg/ml iodine for iopromide (32 ± 27 tail moments) and iodixanol (46 ± 41 tail moments); both were significantly different from the control value with 3.15 ± 1.6 tail moments (Student's t test; p < 0.001). After 1 and 2 h and for all concentrations, iodixanol produced significantly higher DNA fragmentation than iopromide (ANOVA for 1 h p = 0.039 and 2 h p = 0.025, respectively).

CONCLUSION

We were able to demonstrate for the first time that an iso-osmolar contrast medium induced even greater oxidative stress and DNA damage than a low-osmolar agent in HK-2 cells. This could provide an explanation for the nephrotoxicity that also is observed with iodixanol in clinical practice.

New strategy of α- and γ-tocopherol to prevent contrast-induced acute kidney injury in chronic kidney disease patients undergoing elective coronary procedures

BACKGROUND

Contrast-induced acute kidney injury (CI- AKI) increases the likelihood of patient morbidity and mortality following coronary procedures. Volume supplement with saline is the standard treatment to prevent CI-AKI. Additional antioxidant prophylaxis has often yielded conflicting results. The present study was conducted to examine the role of novel application vitamin E (tocopherol) in preventing CI-AKI.

METHODS

This prospective, double-blind, randomized and placebo-controlled trial was carried out in 305 patients with chronic kidney disease (CKD) undergoing coronary procedures. All patients were randomly assigned to prophylaxis administration with 0.9% saline infusions plus daily oral medication comprised of either (i) placebo (n = 101), (ii) α-tocopherol (n = 102) or (iii) γ-tocopherol (n = 102) starting 5 days before and ending 2 days after coronary procedures. The CI-AKI risk score of each patient was calculated. All coronary procedures were performed using a low-osmolar, non-ionic contrast agent.

RESULTS

CI-AKI developed in 14.9% in the placebo group, 4.9% in the α-tocopherol group (P = 0.02 versus the placebo group) and 5.9% in the γ-tocopherol group (P = 0.04 versus the placebo group). In patients with diabetes, hypertension, anaemia, aged over 55 years, male gender or with contrast agent dosages >120 mL, α-tocopherol showed a larger effect than γ-tocopherol when compared with the placebo group (P < 0.05).

CONCLUSIONS

Prophylaxis administration with oral α- or γ-tocopherol in combination with 0.9% saline is effective in protecting against CI-AKI in CKD patients undergoing elective coronary procedures.

Increased urinary excretion of albumin, hemopexin, transferrin and VDBP correlates with chronic sensitization to gentamicin nephrotoxicity in rats

Drug nephrotoxicity is a serious health and economic problem worldwide. Rats can be acutely sensitized to acute kidney injury (AKI) by subnephrotoxic treatments with potentially nephrotoxic drugs. Acquired sensitization to AKI poses a silent risk impossible to diagnose pre-emptively with the technology available at the clinical level. Herein, we hypothesized whether a chronic, subnephrotoxic insult to the kidneys might result in chronically acquired sensitization to AKI, and whether chronic sensitization might be detected through specific urinary markers. To this end, rats were treated with a subtoxic dosage of the experimental nephrotoxin uranyl nitrate (UN) in the drinking water for 21 weeks, or plain water (as control), and then with low-dose gentamicin for 7 days. Renal function and renal tissue damage were evaluated through the experiment. The mild renal damage caused by gentamicin was markedly magnified in rats having received UN chronically, which was evident both at the functional and histological level. Four proteins, namely albumin, hemopexin, transferrin and vitamin D binding protein were increased in the urine in temporal association with the appearance of chronic predisposition. Although further studies are necessary, our results suggest that these proteins might be potentially used as markers of hidden, chronic predisposition to gentamicin nephrotoxicity, in order to appropriately and pre-emptively stratify and handle individuals according to their specific risk in the long term, and to conveniently optimize their life conditions or additional clinical procedures or treatments that might trigger the disease. This might reduce AKI incidence and severity and the associated costs.

Effects of carperitide on contrast-induced acute kidney injury with a minimum volume of contrast in chronic kidney disease patients

BACKGROUND/AIMS

Although contrast-induced acute kidney injury (CIAKI) is a major complication associated with angiography, the prophylaxis is not well established. Use of a low dose of carperitide for preventing CIAKI remains controversial. We examined the protective effect of carperitide on CIAKI after coronary angiography with a small contrast volume in chronic kidney disease (CKD) patients with coronary artery disease.

METHODS

We randomly assigned 112 consecutive patients to a carperitide or a control group. The contrast volume was kept under 150 ml. The primary endpoint was the incidence of CIAKI defined by a serum creatinine of ≥25% or a serum creatinine of ≥0.5 mg/dl from baseline within 48 h. The secondary endpoint was a change in renal function at 1 week after the procedure.

RESULTS

The baseline characteristics and contrast volumes (carperitide group: 67.4 ± 38.2 ml vs. control group: 64.8 ± 20.5 ml, p = 0.661) were comparable in the two groups. The incidence of CIAKI was similar in the two groups (carperitide group: 8.5% vs. control group: 5.7%, p = 0.564). A multivariate analysis revealed that a hypotension ≥20 mm Hg was a significant predictor of developing CIAKI in the carperitide group (p = 0.015). The incidence of CIAKI in the carperitide group without hypotension was rare, but not significantly different (carperitide group: 2.4% vs. control group: 5.7%, p = 0.432).

CONCLUSIONS

This study indicated that the use of a small contrast volume suppressed the incidence of CIAKI and that carperitide had no prophylactic effect against CIAKI. Our results also revealed the impact of hypotension on the development of CIAKI in the carperitide group.

Cardiological Society of India practice guidelines for angiography in patients with renal dysfunction

PREAMBLE: The potential risk of contrast-induced acute kidney injury (CI-AKI) has made utilization of coronary angiography in the work-up for the diagnosis of coronary artery disease in CKD quite low.(1) This is in contrast to increasing prevalence and severity of CAD as the serum creatinine rises.(2) In fact most CKD patients will succumb to CAD and not to ESRD.(3) Thus the judicious use of CAG/PCI in this setting is of prime importance but underused. The CSI began to develop guidelines for Indian context as most guidelines are those developed by ACC/AHA or ESC. The aim was to assist the physicians in selecting the best management strategy for an individual patient under his care based on an expert committee who would review the current data and write the guidelines with relevance to the Indian context. The guidelines were developed initially in June 2010 as an initiative of Delhi CSI. Three interventional cardiologist (SB, AS, KKS), one nephrologist (SCT) and two clinical cardiologists (ST, RG) along with Dr. Roxana Mehran (New York) and Dr. Peter McCullough (Missouri), U.S.A.; were involved in a three-way teleconference to discuss/debate the data. This was presented by SB, and over the next two hours each data subset was debated/agreed/deleted and this resulted in the "Guidelines for CAG in Renal Dysfunction Patients". These were then written and re- circulated to all for final comments. Further, these guidelines were updated and additional Task Force Members nominated by Central CSI were involved in the formation of the final CSI Guidelines. Both (Roxana Mehran and Peter McCullough) reviewed these updated Guidelines in October 2012 and after incorporating the views of all the Task Force members-the final format is as it is presented in this final document.

Cardiac surgery-associated acute kidney injury

Cardiac surgery-associated acute kidney injury (AKI) is a major health problem that is extremely common and has a significant effect on cardiac surgical outcomes. AKI occurs in nearly 30 % of patients undergoing cardiac surgery, with about 1-2 % of these ultimately requiring dialysis. The development of AKI predicts a significant increase in morbidity and mortality independent of other risk factors. The pathogenetic mechanisms associated with cardiac surgery-associated AKI include several biochemical pathways, of which the most important are hemodynamic, inflammatory and nephrotoxic factors. Risk factors for AKI have been identified in several models, and these facilitate physicians to prognosticate and develop a strategy for tackling patients predisposed to developing renal dysfunction. Effective therapy of the condition is still suboptimal, and hence the accent has always been on risk factor modification. Thus, strategies for reducing preoperative anemia, perioperative blood transfusions and surgical re-explorations may be effective in attenuating the incidence and severity of this complication.

Impact of a high loading dose of atorvastatin on contrast-induced acute kidney injury

BACKGROUND

The role of statins in the prevention of contrast-induced acute kidney injury (CIAKI) is controversial.

METHODS AND RESULTS

First, we investigated the in vivo effects of atorvastatin on CIAKI. Patients with chronic kidney disease enrolled in the Novel Approaches for Preventing or Limiting Events (NAPLES) II trial were randomly assigned to (1) the atorvastatin group (80 mg within 24 hours before contrast media [CM] exposure; n=202) or (2) the control group (n=208). All patients received a high dose of N-acetylcysteine and sodium bicarbonate solution. Second, we investigated the in vitro effects of atorvastatin pretreatment on CM-mediated modifications of intracellular pathways leading to apoptosis or survival in renal tubular cells. CIAKI (ie, an increase >10% of serum cystatin C concentration within 24 hours after CM exposure) occurred in 9 of 202 patients in the atorvastatin group (4.5%) and in 37 of 208 patients in the control group (17.8%) (P=0.005; odds ratio=0.22; 95% confidence interval, 0.07-0.69). CIAKI rate was lower in the atorvastatin group in both diabetics and nondiabetics and in patients with moderate chronic kidney disease (estimated glomerular filtration rate, 31-60 mL/min per 1.73 m(2)). In the in vitro model, pretreatment with atorvastatin (1) prevented CM-induced renal cell apoptosis by reducing stress kinases activation and (2) restored the survival signals (mediated by Akt and ERK pathways).

CONCLUSIONS

A single high loading dose of atorvastatin administered within 24 hours before CM exposure is effective in reducing the rate of CIAKI. This beneficial effect is observed only in patients at low to medium risk.

Selecting a prognostic renal surrogate for patients with hepatocellular carcinoma undergoing transarterial chemoembolization

BACKGROUND AND AIM

Renal insufficiency (RI) often coexists with hepatocellular carcinoma (HCC) and predicts a poor outcome in patients receiving transarterial chemoembolization (TACE). The modification of diet in renal disease (MDRD) and chronic kidney disease epidemiology collaboration (CKD-EPI) equations are used to provide estimated glomerular filtration rate (eGFR). This study aimed to determine a prognsotic renal surrogate for outcome prediction in HCC patients receiving TACE.

METHODS

A total of 684 patients with HCC undergoing TACE were retrospectively analyzed. The prognostic ability between the MDRD and CKD-EPI equation was compared by the Akaike information criterion (AIC).

RESULTS

Patients were categorized by eGFR into > 60, 30-60 and < 30 mL/min per 1.73 m(2) (equivalent to CKD stages 1-2, 3, and 4-5, respectively) groups. The eGFR generated by the MDRD equation had a better predictive accuracy by having a lower AIC score (3234.5) compared to the CKD-EPI equation (3236.7). The adjusted risk ratio for patients with eGFR 30-60 mL/min per 1.73 m(2) by the MDRD was 1.313 (P = 0.041) compared with patients with eGFR > 60 mL/min per 1.73 m(2) in the multivariate Cox model. The eGFR defined by the MDRD equation consistently had better prognostic ability when patients were stratified by the Child-Turcotte-Pugh score of 5 and > 5 and Cancer of the Liver Italian Program score 0 to 1 and > 1.

CONCLUSIONS

The eGFR according the MDRD equation may provide better prognostic accuracy than the CKD-EPI equation independent of liver functional reserve and tumor staging, and is a more feasible renal surrogate for outcome prediction in CKD stage 1-3 HCC patients receiving TACE.

Acute kidney injury

Acute kidney injury (formerly known as acute renal failure) is a syndrome characterised by the rapid loss of the kidney's excretory function and is typically diagnosed by the accumulation of end products of nitrogen metabolism (urea and creatinine) or decreased urine output, or both. It is the clinical manifestation of several disorders that affect the kidney acutely. Acute kidney injury is common in hospital patients and very common in critically ill patients. In these patients, it is most often secondary to extrarenal events. How such events cause acute kidney injury is controversial. No specific therapies have emerged that can attenuate acute kidney injury or expedite recovery; thus, treatment is supportive. New diagnostic techniques (eg, renal biomarkers) might help with early diagnosis. Patients are given renal replacement therapy if acute kidney injury is severe and biochemical or volume-related, or if uraemic-toxaemia-related complications are of concern. If patients survive their illness and do not have premorbid chronic kidney disease, they typically recover to dialysis independence. However, evidence suggests that patients who have had acute kidney injury are at increased risk of subsequent chronic kidney disease.

Prevention of contrast-induced nephropathy: A randomized controlled trial of sodium bicarbonate and N-acetylcysteine

BACKGROUND

Contrast-induced nephropathy (CIN) continues to be a common cause of acute renal failure in high-risk patients undergoing radiocontrast studies. However, there is still a lack of consensus regarding the most effective measures to prevent CIN.

METHODS

ONE HUNDRED EIGHTEEN PATIENTS WITH DIABETES MELLITUS AND/OR RENAL INSUFFICIENCY, SCHEDULED FOR CORONARY ANGIOGRAPHY OR INTERVENTION, WERE RANDOMLY ASSIGNED TO ONE OF FOUR TREATMENT GROUPS: intravenous (IV) 0.9% NaCl alone, IV 0.9% NaCl plus N-acetylcysteine (NAC), IV 0.9% sodium bicarbonate (NaHCO(3)) alone or IV 0.9% NaHCO(3) plus NAC. All patients received IV hydration as a preprocedure bolus and as maintenance. Iso-osmolar contrast was used in all patients. CIN was defined as an increase of greater than 25% in the serum creatinine concentration from baseline to 72 h.

RESULTS

The overall incidence of CIN was 6%. There was no statistically significant difference in the incidence of CIN among the groups. There was a CIN incidence of 7% in the NaCl only group, 5% in the NaCl/NAC group, 11% in the NaHCO(3) only group and 4% in the NaHCO(3)/NAC group (P=0.86). The maximum increase in serum creatinine was 14.14±12.38 μmol/L in the NaHCO(3) group, 10.60±29.14 μmol/L in the NaCl only group, 9.72±13.26 μmol/L in the NaCl/NAC group and 0.177±15.91 μmol/L for the NaHCO(3)/NAC group (P=0.0792).

CONCLUSION

CIN in high-risk patients may be effectively minimized solely through the use of an aggressive hydration protocol and an iso-osmolar contrast agent. The addition of NaHCO(3) and/or NAC did not have an effect on the incidence of CIN.

Impact of iso- and low-osmolar iodinated contrast agents on BOLD and diffusion MRI in swine kidneys

PURPOSE

To assess whether functional MR imaging using blood-oxygenation level-dependent (BOLD) imaging and diffusion-weighted imaging demonstrate changes in renal oxygenation and apparent diffusion coefficient (ADC) in a pig model.

MATERIALS AND METHODS

After administration of either 1-g iodine/kg body weight low-osmolar iopromide or iso-osmolar iodixanol, 8 mini pigs underwent a series of repeated BOLD measurements (TR/TE 106/5.9-48.7 ms, slice thickness 4 mm) and diffusion-weighted imaging measurements (TR/TE 3900/79 ms, slice thickness 4 mm) for 1 hour at 1.5 T. In this intraindividual cross over study, the second contrast agent injection with the other iodinated contrast agent was performed at least 24 hours after the initial contrast agent injection. BOLD-based R2* values as indirect measures of the renal oxygenation were determined for the cortex, the inner medulla, and the outer medulla. ADC values were measured for the cortex and the whole kidney.

RESULTS

For both contrast agents, a drop in R2* was found in the cortex, which normalized after 55 minutes. In the outer medulla and particularly in the inner medulla, a decreased initial drop of R2* was encountered with both contrast agents, with a slow increase toward the baseline R2*. In the inner medulla, elevated R2* values were found with the iso-osmolar contrast agent only. The ADC revealed an initial increase, which slowly decayed over the measurement period. This finding was more pronounced for the cortex compared with the whole-kidney analysis.

CONCLUSION

Functional MR imaging of the kidneys demonstrates increased R2* in the inner medulla only after the administration of the iodixanol potentially indicating hypoxia and thus a pathomechanism of contrast-induced nephropathy.

Objective evaluation of acute adverse events and image quality of gadolinium-based contrast agents (gadobutrol and gadobenate dimeglumine) by blinded evaluation. Pilot study

PURPOSE

The purpose was to objectively evaluate a recently FDA-approved gadolinium-based contrast agent (GBCA) in comparison to our standard GBCA for acute adverse events and image quality by blinded evaluation.

METHODS

Evaluation was made of a recently FDA-approved GBCA, gadobutrol (Gadavist; Bayer), in comparison to our standard GBCA, gadobenate dimeglumine (MultiHance; Bracco), in an IRB- and HIPAA-compliant study. Both the imaging technologist and patient were not aware of the brand of the GBCA used. A total of 59 magnetic resonance studies were evaluated (59 patients, 31 men, 28 women, age range of 5-85 years, mean age of 52 years). Twenty-nine studies were performed with gadobutrol (22 abdominal and 7 brain studies), and 30 studies were performed with gadobenate dimeglumine (22 abdominal and 8 brain studies). Assessment was made of acute adverse events focusing on objective observations of vomiting, hives, and moderate and severe reactions. Adequacy of enhancement was rated as poor, fair and good by one of two experienced radiologists who were blinded to the type of agent evaluated.

RESULTS

No patient experienced acute adverse events with either agent. The target minor adverse events of vomiting or hives, and moderate and severe reactions were not observed in any patient. Adequacy of enhancement was rated as good for both agents in all patients.

CONCLUSIONS

Objective, blinded evaluation is feasible and readily performable for the evaluation of GBCAs. This proof-of-concept study showed that both GBCAs evaluated exhibited consistent good image quality and no noteworthy adverse events.

Perioperative acute kidney injury

Acute kidney injury (AKI) is a serious complication in the perioperative period, and is consistently associated with increased rates of mortality and morbidity. Two major consensus definitions have been developed in the last decade that allow for easier comparison of trial evidence. Risk factors have been identified in both cardiac and general surgery and there is an evolving role for novel biomarkers. Despite this, there has been no real change in outcomes and the mainstay of treatment remains preventive with no clear evidence supporting any therapeutic intervention as yet. This review focuses on definition, risk factors, the emerging role of biomarkers and subsequent management of AKI in the perioperative period, taking into account new and emerging strategies.

CTO PCI Procedural Planning

Chronic total occlusion percutaneous coronary intervention (CTO PCI) procedural planning involves much thought and deliberation before one actually attempts to cross the CTO lesion in the cardiac catheterization laboratory. Careful preprocedural angiographic assessment is a key to successful CTO PCI. CTO PCI represents the most complex PCI one can perform, and thus operator and staff training as well as the concept of CTO days are all essential for a successful CTO PCI program.

Kidneys in chronic liver diseases

Acute kidney injury (AKI), defined as an abrupt increase in the serum creatinine level by at least 0.3 mg/dL, occurs in about 20% of patients hospitalized for decompensating liver cirrhosis. Patients with cirrhosis are susceptible to developing AKI because of the progressive vasodilatory state, reduced effective blood volume and stimulation of vasoconstrictor hormones. The most common causes of AKI in cirrhosis are pre-renal azotemia, hepatorenal syndrome and acute tubular necrosis. Differential diagnosis is based on analysis of circumstances of AKI development, natriuresis, urine osmolality, response to withdrawal of diuretics and volume repletion, and rarely on renal biopsy. Chronic glomerulonephritis and obstructive uropathy are rare causes of azotemia in cirrhotic patients. AKI is one of the last events in the natural history of chronic liver disease, therefore, such patients should have an expedited referral for liver transplantation. Hepatorenal syndrome (HRS) is initiated by progressive portal hypertension, and may be prematurely triggered by bacterial infections, nonbacterial systemic inflammatory reactions, excessive diuresis, gastrointestinal hemorrhage, diarrhea or nephrotoxic agents. Each type of renal disease has a specific treatment approach ranging from repletion of the vascular system to renal replacement therapy. The treatment of choice in type 1 hepatorenal syndrome is a combination of vasoconstrictor with albumin infusion, which is effective in about 50% of patients. The second-line treatment of HRS involves a transjugular intrahepatic portosystemic shunt, renal vasoprotection or systems of artificial liver support.

Within-hospital and 30-day outcomes in 107,994 patients undergoing invasive coronary angiography with different low-osmolar iodinated contrast media

Comparative clinical outcomes after exposure to alternate low osmolar contrast media (LOCM) during invasive coronary angiography (ICA) and/or percutaneous coronary intervention (PCI) have been incompletely examined. From a retrospective multicenter observational study, we identified 107,994 adults without previous hemodialysis undergoing ICA and/or PCI with iohexol, iopamidol, or ioversol. We created a propensity score for contrast media type using age, gender, coverage status, route of hospitalization, illness severity, physician specialty, co-morbidities, and procedure type. Propensity matching was performed in a 1:1 fashion for iohexol (n = 10,204) and iopamidol (n = 10,204) and in a 1:1 fashion for iohexol (n = 19,482) and ioversol (n = 19,482). Groups were examined for differences in in-hospital mortality or subsequent hemodialysis, length of stay, and 30-day readmission for contrast-induced nephropathy (CIN). Compared to patients exposed to iohexol, no differences were observed for patients exposed to iopamidol or ioversol for in-hospital hemodialysis (0.5% vs 0.4%, p = 0.45; 0.3% vs 0.5%, p = 0.05), in-hospital mortality (0.7% vs 0.6%, p = 0.60; 0.5% vs 0.6%, p = 0.42), or composite hemodialysis or mortality (1.1% vs 1.0%, p = 0.58; 0.8% vs 1.0%, p = 0.06); for hospital length of stay (2.9 ± 2.7 vs 2.9 ± 2.7 days, p = 0.05; 2.8 ± 2.6 vs 2.9 ± 3.1 days, p = 0.35); or for 30-day readmission for CIN (0.1% vs 0.1%, p = 0.82; 0.1% vs 0.1%, p = 0.52). In conclusion, for patients undergoing ICA and/or PCI exposed to alternate LOCM, in-hospital death, need for hemodialysis, or readmission for CIN are uncommon, with no apparent clinical advantage among LOCM agents.

Preventing radiocontrast-induced nephropathy in chronic kidney disease patients undergoing coronary angiography

Radiocontrast-induced nephropathy (RCIN) is an acute and severe complication after coronary angiography, particularly for patients with pre-existing chronic kidney disease (CKD). It has been associated with both short- and long-term adverse outcomes, including the need for renal replacement therapy, increased length of hospital stay, major cardiac adverse events, and mortality. RCIN is generally defined as an increase in serum creatinine concentration of 0.5 mg/dL or 25% above baseline within 48 h after contrast administration. There is no effective therapy once injury has occurred, therefore, prevention is the cornerstone for all patients at risk for acute kidney injury (AKI). There is a small but growing body of evidence that prevention of AKI is associated with a reduction in later adverse outcomes. The optimal strategy for preventing RCIN has not yet been established. This review discusses the principal risk factors for RCIN, evaluates and summarizes the evidence for RCIN prophylaxis, and proposes recommendations for preventing RCIN in CKD patients undergoing coronary angiography.

Cerebral computed tomography angiography using a low tube voltage (80 kVp) and a moderate concentration of iodine contrast material: a quantitative and qualitative comparison with conventional computed tomography angiography

OBJECTIVE

To investigate the feasibility of an 80-kVp protocol using a moderate concentration contrast material (MC-CM) for cerebral computed tomography angiography by comparison with a conventional 120-kVp protocol using a high concentration contrast material (HC-CM).

MATERIALS AND METHODS

Attenuation values and signal-to-noise ratios (SNRs) were determined in a head phantom for 2 tube voltages (80 and 120 kVp) and 2 different iodine concentration contrast materials (HC-CM and MC-CM). Among 90 consecutive patients, 45 patients were scanned with 120 kVp and 150 mAs(eff) after administration of 70 mL of HC-CM (370 mg iodine [mgI]/mL), whereas the other 45 patients were scanned with 80 kVp and 370 mAs(eff) after administration of 70 mL of MC-CM (300 mgI/mL). The Hounsfield units (HU) of the internal carotid artery T junction, SNR, contrast-to-noise ratio (CNR), subjective degree of arterial enhancement, image noise, sharpness of the cerebral arterial boundary, and overall diagnostic image quality were compared between the 2 groups.

RESULTS

The mean attenuation of the internal carotid artery T junction, SNR, and CNR was significantly higher in the 80 kVp with MC-CM group (379.2, 33.7, and 31.1 HU, respectively) than in the 120 kVp with HC-CM group (282.2, 31.1, and 27.2 HU, respectively). The 80-kVp protocol resulted in significantly higher score in arterial enhancement, sharpness of the cerebral arteries, and overall diagnostic image quality. The effective dose of 80 kVp (0.7 mSv) was 22.2% lower than that of 120 kVp (0.9 mSv).

CONCLUSIONS

The use of 80 kVp with MC-CM improved arterial enhancement, SNR, and CNR and provided superior quality images using a smaller amount of iodine and a lower radiation dose than the conventional protocol of 120 kVp with HC-CM.

Comparative investigation of i.v. iohexol and iopamidol: effect on renal function in low-risk outpatients undergoing CT

OBJECTIVE

The purpose of our study was to compare the effects of i.v. iohexol and iopamidol on renal function in outpatients undergoing CT.

SUBJECTS AND METHODS

We performed a prospective, double-blind, randomized clinical trial of 389 adults with low risk for contrast-induced nephropathy, comparing i.v. iohexol with iopamidol (300 mg I/mL). Serum creatinine (SCr) concentration was measured at baseline and 2 and 3 days after contrast administration. A noninferiority analysis was planned to compare the mean maximum SCr change from baseline between subject groups. Contrast-induced nephropathy rates (three definitions) for both contrast agents were compared as a secondary end point.

RESULTS

One hundred ninety and 199 subjects received iohexol and iopamidol, respectively. The mean change in SCr from baseline using the maximum day 2 or 3 measurement was 0.07 ± 0.12 mg/dL (95% CI, 0.05-0.09 mg/dL) for the iohexol group and 0.05 ± 0.12 mg/dL (95% CI, 0.03-0.07 mg/dL) for the iopamidol group. The difference between contrast agents with respect to the mean change in SCr from baseline was -0.02 ± 0.12 mg/dL (95% CI, -0.045 to 0.003 mg/dL; p = 0.08). Contrast-induced nephropathy rates were not statistically different using any definition.

CONCLUSION

Although our results were unable to show absolute noninferiority of iohexol compared with iopamidol because of a very small difference in increase in mean SCr from baseline (using a noninferiority margin of 0.04 mg/dL), this difference is likely of minimal or no clinical importance in outpatients undergoing CT with low risk for contrast-induced nephropathy.

Preventing the harm of a closer look: contrast-induced nephropathy in adults

Contrast media is administered to many patients in hospitals nationwide. Although the use of contrast and dyes is widespread and has a well accepted use among the medical profession, contrast-induced nephropathy can be a common and potentially harmful complication. Identifying patients at risk, attempting to minimize risk, and using preventative strategies should be priorities to decrease the harmful effects that are associated with the administration of contrast media. This article provides a general overview of contrast-induced nephropathy and a brief review of the risk factors and prophylactic treatment.

Chapter II: Diagnostic methods

Non-invasive vascular studies can provide crucial information on the presence, location, and severity of critical limb ischaemia (CLI), as well as the initial assessment or treatment planning. Ankle-brachial index with Doppler ultrasound, despite limitations in diabetic and end-stage renal failure patients, is the first-line evaluation of CLI. In this group of patients, toe-brachial index measurement may better establish the diagnosis. Other non-invasive measurements, such as segmental limb pressure, continuous-wave Doppler analysis and pulse volume recording, are of limited accuracy. Transcutaneous oxygen pressure (TcPO(2)) measurement may be of value when rest pain and ulcerations of the foot are present. Duplex ultrasound is the most important non-invasive tool in CLI patients combining haemodynamic evaluation with imaging modality. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are the next imaging studies in the algorithm for CLI. Both CTA and MRA have been proven effective in aiding the decision-making of clinicians and accurate planning of intervention. The data acquired with CTA and MRA can be manipulated in a multiplanar and 3D fashion and can offer exquisite detail. CTA results are generally equivalent to MRA, and both compare favourably with contrast angiography. The individual use of different imaging modalities depends on local availability, experience, and costs. Contrast angiography represents the gold standard, provides detailed information about arterial anatomy, and is recommended when revascularisation is needed.

Mechanisms for an effect of acetylcysteine on renal function after exposure to radio-graphic contrast material: study protocol

Background

Contrast-induced nephropathy is a common complication of contrast administration in patients with chronic kidney disease and diabetes. Its pathophysiology is not well understood; similarly the role of intravenous or oral acetylcysteine is unclear. Randomized controlled trials to date have been conducted without detailed knowledge of the effect of acetylcysteine on renal function. We are conducting a detailed mechanistic study of acetylcysteine on normal and impaired kidneys, both with and without contrast. This information would guide the choice of dose, route, and appropriate outcome measure for future clinical trials in patients with chronic kidney disease.

Methods/Design

We designed a 4-part study. We have set up randomised controlled cross-over studies to assess the effect of intravenous (50 mg/kg/hr for 2 hrs before contrast exposure, then 20 mg/kg/hr for 5 hrs) or oral acetylcysteine (1200 mg twice daily for 2 days, starting the day before contrast exposure) on renal function in normal and diseased kidneys, and normal kidneys exposed to contrast. We have also set up a parallel-group randomized controlled trial to assess the effect of intravenous or oral acetylcysteine on patients with chronic kidney disease stage III undergoing elective coronary angiography. The primary outcome is change in renal blood flow; secondary outcomes include change in glomerular filtration rate, tubular function, urinary proteins, and oxidative balance.

Discussion

Contrast-induced nephropathy represents a significant source of hospital morbidity and mortality. Over the last ten years, acetylcysteine has been administered prior to contrast to reduce the risk of contrast-induced nephropathy. Randomized controlled trials, however, have not reliably demonstrated renoprotection; a recent large randomized controlled trial assessing a dose of oral acetylcysteine selected without mechanistic insight did not reduce the incidence of contrast-induced nephropathy. Our study should reveal the mechanism of effect of acetylcysteine on renal function and identify an appropriate route for future dose response studies and in time randomized controlled trials.

Trial registration

Clinical Trials.gov: NCT00558142; EudraCT: 2006-003509-18.

Contrast-induced kidney injury: mechanisms, risk factors, and prevention

In general, iodinated contrast media (CM) are tolerated well, and CM use is steadily increasing. Acute kidney injury is the leading life-threatening side effect of CM. Here, we highlight endpoints used to assess CM-induced acute kidney injury (CIAKI), CM types, risk factors, and CIAKI prevention. Moreover, we put forward a unifying theory as to how CIAKI comes about; the kidney medulla's unique hyperosmolar environment concentrates CM in the tubules and vasculature. Highly concentrated CM in the tubules and vessels increases fluid viscosity. Thus, flow through medullary tubules and vessels decreases. Reducing the flow rate will increase the contact time of cytotoxic CM with the tubular epithelial cells and vascular endothelium, and thereby damage cells and generate oxygen radicals. As a result, medullary vasoconstriction takes place, causing hypoxia. Moreover, the glomerular filtration rate declines due to congestion of highly viscous tubular fluid. Effective prevention aims at reducing the medullary concentration of CM, thereby diminishing fluid viscosity. This is achieved by generous hydration using isotonic electrolyte solutions. Even forced diuresis may prove efficient if accompanied by adequate volume supplementation. Limiting the CM dose is the most effective measure to diminish fluid viscosity and to reduce cytotoxic effects.

Peripheral arterial disease: a literature review

INTRODUCTION

Peripheral arterial disease (PAD) is a common vascular condition that affects both quality of life and life expectancy with an increased risk of cardiovascular events.

SOURCES OF DATA

A literature search was carried out of Pub-Med, MEDLINE, the Cochrane Library and Google Scholar from the establishment of these databases up to February 2012. The search was performed by using the keywords 'peripheral arterial disease' and one of the following words: 'management', 'investigations', 'risk factors', 'epidemiology', 'revascularization', 'cryoplasty', 'atherectomy' and 'gene therapy'. Studies were limited to those published in English language.

AREAS OF AGREEMENT

Aggressive risk factors modification is needed to reduce cardiovascular-related mortality in PAD patients.

AREAS OF CONTROVERSY

Choice of endovascular or surgical intervention remains controversial in an ever-evolving field.

GROWING POINTS

There is a rapid expansion of endovascular technologies aiming to improve the effectiveness of this modality.

AREAS TIMELY FOR DEVELOPING RESEARCH

The advances in the fields of gene therapy and therapeutic angiogenesis mean these are potential future treatments. Tissue engineering is a developing area and aims to produce grafts with similar patency and infection profiles to those of autologous material. Further elucidation of the pathophysiology of atherosclerosis is required to provide new targets for pharmacotherapy.

Risks and complications of coronary angiography: a comprehensive review

Coronary angiography and heart catheterization are invaluable tests for the detection and quantification of coronary artery disease, identification of valvular and other structural abnormalities, and measurement of hemodynamic parameters. The risks and complications associated with these procedures relate to the patient’s concomitant conditions and to the skill and judgment of the operator. In this review, we examine in detail the major complications associated with invasive cardiac procedures and provide the reader with a comprehensive bibliography for advanced reading.

Comparison of serum creatinine and cystatin C for early diagnosis of contrast-induced nephropathy after coronary angiography and interventions

BACKGROUND

The diagnostic accuracy of serum creatinine and cystatin C (Cys) as early predictors of contrast-induced nephropathy (CIN) has been debated. We investigated the diagnostic sensitivities, diagnostic specificities, and variations from baseline for serum creatinine and Cys in CIN.

METHODS

We prospectively evaluated 166 patients at risk for CIN at baseline, and at 12, 24, and 48 h after exposure to contrast media. CIN occurred in 30 patients (18%). Changes (Δ) compared to baseline in serum creatinine and Cys were evaluated at the predefined time points. ROC curve analysis was performed for the Δ 12-h basal serum creatinine and Cys.

RESULTS

The Δ serum creatinine at 12 h from baseline was the earliest predictor of CIN [area under the ROC curve (AUC) = 0.80; P < 0.001]. The Δ serum creatinine 15% variation [0.15 mg/dL (13.2 μmol/L)] yielded 43% diagnostic sensitivity and 93% diagnostic specificity. The ΔCys at 12 h from baseline performed significantly worse than serum creatinine (AUC = 0.48; P = 0.74).

CONCLUSIONS

Variations from the serum creatinine baseline offer better diagnostic accuracy for predicting CIN at an earlier stage than similar variations in Cys. An additional diagnostic value of Cys over the determination of serum creatinine in the setting of CIN was not observed.

Estimation of glomerular filtration rate in calves using the contrast medium iodixanol

To develop a simple procedure for estimating glomerular filtration rate (GFR) in calves, a three-sample method using iodixanol was first compared to that using the standard agent inulin. Iodixanol and inulin were co-administered intravenously to calves at 40 mg I/kg and 40 mg/kg, respectively, and blood was collected 30, 60, 120, and 180 min later. Serum iodixanol and inulin concentrations were separately determined by high performance liquid chromatography and colorimetry. Serum urea nitrogen (UN) and creatinine concentrations were also measured. GFR estimated by iodixanol was consistent with that using inulin in clinically healthy calves. Based on GFR estimations in healthy calves and those renal-loaded with iodixanol, it was found that the serum creatinine concentrations became elevated when GFR decreased to 60% of the reference value. In contrast, serum UN concentrations fluctuated widely, presumably due to extra-renal factors. When GFR was estimated using the three-sample method and compared with the single-blood-sample method, 62/69 (90%) of samples tested were within the agreement plots. The results demonstrated that the single-blood-sample method using iodixanol may be useful in monitoring GFR in calves.

The Canadian Association of Radiologists Guidelines for the Prevention of Contrast-induced Nephropathy: A Critical Appraisal

Objective

The purpose of this study is to critically appraise the Canadian Association of Radiologists (CAR) guidelines on the prevention of contrast-induced nephropathy (CIN).

Methods

The Appraisal of Guidelines Research and Evaluation (AGREE) tool is a questionnaire that consists of 23 key items organized in 6 domains (scope and purpose, stakeholder involvement, rigor of development, clarity and presentation, applicability, editorial independence). Four radiologists read the guidelines and completed the questionnaire independently. To assess the quality of the evidence, the articles listed in the bibliography were reviewed, and the following data were collected and tabulated: the type of contrast, the administration route, and the level of evidence (Centre for Evidence Based Medicine, University of Oxford).

Results

The highest score was for scope and purpose (92%), whereas the lowest scores were for rigor of development (50%) and applicability (40%). The score for the remaining domains were the following: stakeholder involvement (59%), clarity and presentation (69%), and editorial independence (63%). Although the bibliography of the CAR guidelines list 46 articles, only 33 were deemed pertinent to support the recommendations related to risk stratification or risk reduction of CIN. Only 3 articles dealt specifically with intravenous injection of iodinated contrast. Four articles dealt with ionic contrast, and, in 17 references, the contrast type was not specified. The best evidence (level 1) was in support of risk-reduction recommendations, but, in 8 of the 9 articles cited, the route of administration studied was exclusively intra-arterial.

Conclusion

It would be appropriate to revisit the topic of CIN and formulate new guidelines. A formal systematic review of the literature should be undertaken and the data extraction should specifically address contrast type and route of administration, as well as the applicability of any recommendations.

Assessment of urinary N-acetyl-β-glucosaminidase as an early marker of contrast-induced nephropathy

Early detection and timely intervention are important for improving contrast-induced nephropathy (CIN) prognosis. Whether urinary N-acetyl-β-glucosaminidase (NAG) is a useful marker for early detection of CIN was investigated in 590 patients undergoing diagnostic coronary angiography (CA) and/or therapeutic percutaneous coronary intervention (PCI) for acute coronary syndromes or stable angina, and who received low-osmolality nonionic contrast agent. Urinary NAG, osmolality and serum creatinine were measured before and 1, 2 and 6 days after contrast agent exposure. CIN occurred in 33 patients; its incidence in high-risk patients (pre-existing renal dysfunction with/without diabetes mellitus) was significantly higher than in others. In patients with CIN, urinary NAG and serum creatinine levels on days 1 and 2 were significantly higher than at baseline and compared with patients without CIN; mean levels were gradually returning to baseline by day 6. Compared with serum creatinine, urinary NAG levels peaked earlier in CIN patients and increased much more. The results suggest that, following CA and/or PCI, CIN occurs to a certain degree and that NAG may be a useful early CIN marker as it is noninvasive, simple, inexpensive and sensitive.

Effects of Intra-Arterial and Intravenous Iso-Osmolar Contrast Medium (Iodixanol) on the Risk of Contrast-Induced Acute Kidney Injury: A Meta-Analysis

BACKGROUND: The iso-osmolar contrast agent iodixanol may be associated with a lower incidence of contrast-induced acute kidney injury (CI-AKI) than low-osmolar contrast media (LOCM), but previous meta-analyses have yielded mixed results. Objectives: To compare the incidence of CI-AKI between iodixanol and LOCM. METHODS: Studies were identified from literature searches to December 2009, clinicaltrials.gov, and conference abstracts from the past 2 years including 2010. Only prospective, randomized comparisons between iodixanol and LOCM with CI-AKI [increase in serum creatinine (sCr) ≥0.5 mg/dl or ≥25% from baseline, as defined in the trial] as a primary and/or secondary endpoint and a Jadad score ≥2 were included. A random-effects model was used to obtain pooled relative risks (RRs) for CI-AKI in analyses based on route of administration [intra-arterial (IA) or intravenous (IV)], definition of CI-AKI, and timing of sCr measurements. RESULTS: 145 potential articles were identified, of which 25 were included in the meta-analysis. Following IA administration (n = 19), the RR for CI-AKI (≥0.5 mg/dl definition) with iodixanol, compared with LOCM, was 0.462 [95% confidence interval (CI): 0.272-0.786, p = 0.004, 15 studies]. Using the ≥25% definition, there was a lower incidence of CI-AKI with iodixanol versus LOCM, but the difference was not statistically significant (RR: 0.577, 95% CI: 0.297-1.12, p = 0.104, 11 studies). In the IV trials, there was no significant difference in the incidence of CI-AKI using either definition (≥0.5 mg/dl definition: RR: 0.967, 95% CI: 0.188-4.972, p = 0.968, 3 trials; ≥25% definition: RR: 0.656, 95% CI: 0.316-1.360, p = 0.257, 4 trials). CONCLUSIONS: IA but not IV administration of iodixanol is associated with a significantly lower risk of CI-AKI than LOCM.

Colorimetric assay for the quantification of serum iodixanol concentration and its application on estimation of glomerular filtration rate in cattle

A colorimetric assay used to quantify the non-ionic contrast medium iodixanol in sera was validated and compared with high-performance liquid chromatography. The application of this assay to estimate glomerular filtration rates (GFR) in cattle was examined. Serum iodixanol was de-iodinated by alkaline hydrolysis and the amount of released iodine was subsequently determined using a ceric arsenite method. There was a close correlation between the two methods using identical specimens. In clinically healthy cattle with different body weights, the reference value (166.3-178.8 mL/min/m(2)) based on body surface area was fairly stable as compared with that (2.13-3.63 mL/min/kg) based on body weight. Based on GFR data in healthy and renal-impaired cattle, when the GFR decreased to more than 60% of the reference value, serum urea nitrogen and creatinine concentrations increased. The colorimetric assay is a simple method for the estimation of GFR in cattle and requires no expensive equipment.

Diagnostic Accuracy of Sixty Four Multi-Slice CT Angiography in Assessment of Arterial Cut-Off and Run-Off in Comparison with Surgical Findings

BACKGROUND/OBJECTIVE

The accurate anatomic mapping and determination of the severity of arterial disease, an important health problem of the elderly, is of great significance. We aimed to determine the diagnostic value of 64-multislice CT angiography (MSCTA) in run-off and cut-off sites of arterial disease.

PATIENTS AND METHODS

Throughout the study, MSCTA followed by an operative intervention was carried out on a total of 38 patients with clinical signs and symptoms suggestive of arterial disease (AD) all of whom had the indication for vascular surgery. The mean age of patients was 34±15.86 (range, 23 to 93) years. MSCTA was executed using a 64-slice CT scanner, during the arterial phase of injecting the nonionic, contrast medium with a power injector at the rate of 5 ml/sec into the antecubital vein and exploration and revascularization of peripheral arterial disease was performed intraoperatively.

RESULTS

Atherosclerosis and arterial disease, the most common causes of vascular occlusion, were more common in the lower extremities. According to MSCTA findings, the most frequent site of stenosis was the superficial femoral artery. Spearman's correlation coefficient showed a high degree of agreement amongst the raters. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the accuracy of MSCTA compared to surgery were 83.8%, 96%, 96.8%, 81.3% and 89%, respectively. MSCTA findings were compared with surgery as a standard of reference, which showed concordance in the majority of cases (81.6%). Cut-off sites were correctly identified by MSCTA in 97.3% of the patients and the most common sites of discordance were the run-off sites (18.2%).

CONCLUSION

MSCTA angiography as a novel diagnostic modality may be a suitable alternative and a viable choice for routine clinical diagnosis.

Contrast induced nephropathy: updated ESUR Contrast Media Safety Committee guidelines

PURPOSE

The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN).

AREAS COVERED

Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic measures used to reduce the incidence of CIN, and the management of patients receiving metformin. Key Points • Definition, risk factors and prevention of contrast medium induced nephropathy are reviewed. • CIN risk is lower with intravenous than intra-arterial iodinated contrast medium. • eGFR of 45 ml/min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR ≥ 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally.