It's likely that, after the initial fall, the patient was immobilised for several days. This lack of movement predisposes to the formation of deep vein thrombosis in the legs. Diagnosis of DVT is difficult, but the presence of ankle swelling may suggest the diagnosis. The thrombus then fragments and pieces pass through the right side of the heart, lodging in the pulmonary arteries and blocking flow to the lungs. This leads to the infarction seen in this patient and also leads to venous congestion of the liver as the pressure in the right side of the heart rises.
This condition can be prevented by giving prophylactic heparin treatment to stop thrombus formation, and by giving physiotherapy to the legs. This man suffered some smaller pulmonary emboli initially which led to pulmonary infarction. Finally he suffered a massive pulmonary embolism which led to death.
He also had several co-existing diseases at the time of death - i.e. he died with them, rather than of them. These included: