In this prospective study the investigators aim to evaluate the risk of acute renal failure post cardioversion. In addition the investigators would like to evaluate hemodynamic changes, fluid balance and sodium levels in patients post cardioversion as a potential mechanism for both acute renal failure and pulmonary edema post cardioversion. In order to assess hemodynamic changes the investigators will use a non-invasive FDA approved device called NICaS (Non-Invasive Cardiac System). This system calculates cardiac output, cardiac index and peripheral vascular resistance in a non-invasive, fast and accurate way.