Radio Contrast Induced Nephropathy (RCIN) remains a well recognized complication in patients undergoing diagnostic or interventional procedures requiring radiographic contrast agents. Recent studies have shown benefit in administering Sodium Bicarbonate over normal saline( the uniformly accepted prophylaxy) in preventing RCIN.But most studies have excluded patients with history of pulmonary edema, severe heart failure(NYHA 3-4), uncontrolled hypertension or ejection fraction less than 30%. Therefore the aim of this study is to evaluate the efficacy of sodium bicarbonate solved in half saline compared with infusion of half saline in prevention of RCIN in these groups of patients.