The kidney is a remarkably intricate organ with each kidney containing approximately 1 million nephrons.1 Our kidneys weigh less than 0.5% of our body weight but receive 20%–25% of our cardiac output at rest. Thus, per gram of tissue, they are among the most highly perfused organs in the body. Yet the kidney is susceptible to hypoxia which is a major pathophysiological feature of both acute kidney injury and chronic kidney disease.2
The primary vulnerability is due to the ischemic injury as the kidney is subjected to high metabolic and osmotic stress and it is supplied by an intricate microvascular circulation susceptible to local and systemic hypoperfusion.3
Patients with pre-existing chronic kidney disease and diabetes mellitus, have a reduced number of functioning nephrons and an impaired ability to regenerate tubular epithelial cells.4 Such patients, when exposed to contrast media (CM) enhanced imaging studies add a unique challenge to the already intense workload of the vulnerable kidney.
Iodinated CM are commonly used in modern medicine both intravenously with computerized tomography studies and arterially during angiographic procedures.5
Indians have the highest coronary artery disease (CAD) rates, and the conventional risk factors fail to explain this increased risk.6 Percutaneous coronary intervention (PCI) is thus a lifesaving procedure for many CAD patients in India and occupies a significant place in the practice of interventional cardiology.7
As per the data from National interventional Council of Cardiological Society of India, 2018 around 4,38,351 percutaneous coronary interventions are performed in India annually and are on a rising trend year by year.8 As the number of coronary interventions increase, so do the consequent complications such as contrast associated acute kidney disease (CA-AKI) which contribute to significant morbidity and mortality after PCI. Hence, identification of high-risk patients by risk stratification is indispensable.7
Diabetes associated with microvascular consequences like retinopathy or neuropathy are strong predictors of CA-AKI in Indian patients undergoing PCI. Other established risk factors include renal impairment, peripheral vascular disease, high contrast volume, albuminuria, hypotension and anemia. 7
Among patients undergoing PCI, the burden of co-morbidity is very high9,10 which can further increase the risk of post-contrast cardio-renal adverse events.10
Since there are lack of treatment options for CA-AKI,11 all patients undergoing iodinated contrast exposure should be risk stratified and preventive measures should be employed in high-risk population.12. Calculated glomerular filtration rate (eGFR) is more accurate than is serum creatinine at predicting true GFR and is gaining attention as a potentially better marker of CA-AKI risk.13
Prior to contrast medium administration, adequate patient assessment is important. The major preventive action to mitigate the risk of CI-AKI is to provide intravenous volume expansion prior to contrast medium administration, preferably with isotonic fluid such as 0.9% normal saline (NS). Typical prophylaxis regiments begin 1 hour prior to the exam and continue 3-12 hours after with longer regiments (approximately 12 hours) shown to lower the risk of CA-AKI compared with shorter regiments. Typical doses may be fixed volume (e.g., 500 mL NS) before and after or weight-based volumes (1-3mL/kg per hour). 13
Standard contrast dosing is recommended if the benefits have been deemed to outweigh the risks for intravenous iodinated contrast media administration in high-risk patients for CA-AKI. Dosing intervals shorter than 24 hours be avoided except in urgent situations. 13
Another important measure for prevention of CA-AKI is the correct choice of contrast media.14
Available evidence suggests that the use of low-osmolar contrast media (LOCM) and Isosmolar contrast media (ICOM) should be preferred. IOCM may help comorbid patients undergoing intra-arterial interventional procedures achieve better clinical outcomes.15
Recent publications on real world data have reported both clinical and economic benefits of IOCM in patients undergoing PCI in an inpatient setting.16 Currently, iodixanol is the only IOCM with osmolarity same as the blood.17 Real-world evidence confirms that iodixanol may help to reduce post-contrast major adverse renal or cardiovascular events in co-morbid, at-risk patients.18
As the number of vulnerable patients exposed to CM- enhanced imaging studies continue to rise, effective intervention and rapid detection to prevent adverse cardiorenal outcomes is of paramount importance.
CA-AKI: contrast-associated acute kidney injury
CM: contrast media
CAD: coronary artery disease
eGFR: estimated glomerular filtration rate
GFR: glomerular filtration rate
IOCM: isoosmolar contrast media
LOCM: low-osmolar contrast media
NS: normal saline
PCI: percutaneous coronary intervention
Adapted from https://radiologykey.com/functional-renal-anatomy-renal-physiology-and-contrast-media-2/, last accessed on 12th Sept. 2022
Evans RG, Smith DW, Lee CJ, Ngo JP, Gardiner BS. What Makes the Kidney Susceptible to Hypoxia? Anat Rec (Hoboken). 2020 Oct;303(10):2544-2552.
Rear R, Bell RM, Hausenloy DJ. Contrast-induced nephropathy following angiography and cardiac interventions. Heart. 2016 Apr;102(8):638-48.
McCullough PA, Choi JP, Feghali GA, et al. Contrast-Induced Acute Kidney Injury. J Am Coll Cardiol. 2016 Sep 27;68(13):1465-1473.
Lakhal, K., Ehrmann, S. & Robert-Edan, V. Iodinated contrast medium: Is there a re(n)al problem? A clinical vignette-based review. Crit Care 24, 641 (2020).
Sreeniwas Kumar A, Sinha N. Cardiovascular disease in India: A 360-degree overview. Med J Armed Forces India. 2020 Jan;76(1):1-3.
Victor SM, Gnanaraj A, S V, Deshmukh R, et al. Risk scoring system to predict contrast induced nephropathy following percutaneous coronary intervention. Indian Heart J. 2014 Sep-Oct;66(5):517-24
Arramraju SK, Janapati RK, Sanjeeva Kumar E, Mandala GR. National interventional council data for the year 2018-India. Indian Heart J. 2020 Sep-Oct;72(5):351-355
Potts J, Kwok CS, Ensor J, et al. Temporal Changes in Co-Morbidity Burden in Patients Having Percutaneous Coronary Intervention and Impact on Prognosis. Am J Cardiol. 2018 Sep 1;122(5):712-722.
Mehran R, Aymong ED, Nikolsky E, et al. A simple risk score for prediction of contrast-induced nephropathy after percutaneous coronary intervention: development and initial validation. J Am Coll Cardiol. 2004 Oct 6;44(7):1393-9.
Finn WF. The clinical and renal consequences of contrast-induced nephropathy. Nephrol Dial Transplant. 2006 Jun;21(6): i2
Reddan D, Laville M, Garovic VD. Contrast-induced nephropathy and its prevention: What do we really know from evidence-based findings? J Nephrol. 2009 May-Jun;22(3):333-51.
Adapted from ACR manual on Contrast Media, 2022, available at https://www.acr.org/-/media/ACR/files/clinical-resources/contrast_media.pdf, last accessed on 15th Sept. 2022
Andreucci M, Faga T, Serra R, De Sarro G, Michael A. Update on the renal toxicity of iodinated contrast drugs used in clinical medicine. Drug Healthc Patient Saf. 2017 May 22; 9:25- 37
Jo SH, Youn TJ, Koo BK, Park JS, et al. Renal toxicity evaluation and comparison between visipaque (iodixanol) and hexabrix (ioxaglate) in patients with renal insufficiency undergoing coronary angiography: the RECOVER study: a randomized controlled trial. J Am Coll Cardiol. 2006 Sep 5;48(5):924-30
Amin AP, Prasad A, Ryan MP, et al. Association of Iso-Osmolar vs Low-Osmolar Contrast Media With Major Adverse Renal or Cardiovascular Events in Patients at High Risk for Acute Kidney Injury Undergoing Endovascular Abdominal Aortic Aneurysm Repair. J Invasive Cardiol. 2021 Aug;33(8): E640-E646. Epub 2021 Jul 16.
Ronco F, Tarantini G, McCullough PA. Contrast induced acute kidney injury in interventional cardiology: an update and key guidance for clinicians. Rev Cardiovasc Med. 2020 Mar 30;21(1):9-23
McCullough P, Ng CS, Ryan M, et al. Major Adverse Renal and Cardiovascular Events following Intra-Arterial Contrast Media Administration in Hospitalized Patients with Comorbid Conditions. Cardiorenal Med. 2021;11(4):193-199.