Movement of post-operative pulmonary embolism (blood clots) from a surgical site in the left posterior knee, and moving through the popliteal vein, femoral vein, inferior vena cava, the heart and into the lungs. Additional images illustrate the path of the moving emboli as they pass through the heart and out to the periphery of the lungs, and the emboli passing deep into the lungs until they become lodged in the smaller vessels, causing tissue damage.