The purpose of this clinical trial is to investigate the relationship between the gene polymorphism of aldehyde dehydrogenase 2 and contrast induced nephropathy and its mechanism.

Patients undergoing coronary angiography or percutaneous coronary intervention will be recruited in this study after they sign the informed consent.5ml venous blood was extracted from the peripheral vein before the operation to detect the renal function, the genotype and enzyme activity of aldehyde dehydrogenase 2 ,and the levels of oxidative stress and inflammation.Another 5ml venous blood was extracted from the peripheral vein 24-72 hours after the operation to detect the renal function and the levels of oxidative stress and inflammation.Activated oxygen protein products , 4-HNE and hs-CRP as markers for oxidative stress and inflammation.The renal function index contains serum creatinine，urea nitrogen and cystatin C.

Inclusion Criteria:

• Patients undergoing elective coronary intervention or coronary angiography at Yu Qilu hospital.
• All the patients or their guardians must sign the consent form before entering the trial.

Exclusion Criteria:

• Patients with acute renal failure, renal transplantation, end-stage renal disease, or dialysis treatment, GFR < 15ml/min.
• Use of renal toxicity drugs during the treatment, such as non steroidal anti-inflammatory drugs, etc.
• Patients who has used contrast agent 10 days before the operation.
• Cardiac shock, hypotension (systolic blood pressure < 95mmHg),or hyper- tension with difficulty to control.
• Allergy to contrast media.
• Congestive heart failure (left ventricular ejection fraction<40%), cardiac function NYHA grade IV.
• Pregnancy or lactation.

Patients undergoing elective coronary intervention or coronary angiography in Qilu hospital from December 2015 to December 2016