Final answer:
PCWP is a measure used to assess LV failure. In LV failure, excess fluid accumulates in the pulmonary capillaries, causing pulmonary edema.
Step-by-step explanation:
The PCWP (Pulmonary Capillary Wedge Pressure) is a measure used to assess LV (left ventricular) failure. In LV failure, the left ventricle of the heart is unable to pump sufficient blood into the systemic circulation, resulting in excess fluid accumulation in the pulmonary capillaries. This increased hydrostatic pressure within the capillaries causes fluid to be pushed out of them and into the lung tissues, leading to pulmonary edema.