What comes first pulmonary edema or pedal edema and why does it come first?

It depends : Most heart failure is left heart failure, which is weakness, or inefficient pumping of the left ventricle. This causes back-up initially in the lungs, which will manifest itself as pulmonary congestion, or in more sever cases, pulmonary edema. The high pressure is then transmitted to the right heart, causing abdominal distinction and edema. Pure right heart failure exits, which causes edema.