In a method of monitoring pulmonary edema in a human being, an electrical current is injected between a first electrode located in or around a heart and a housing of a medical device implanted in a chest region. A voltage potential is measured between a second electrode in a superior vena cava and a third electrode in the superior vena cava, where the voltage potential is created by the electrical current. Pulmonary edema is assessed based on an impedance value calculated from the electrical current and the voltage potential and a stored edema threshold impedance value.
