The death of 38-year-old Prateek Yadav , son of Samajwadi Party (SP) founder Mulayam Singh Yadav, due to pulmonary embolism and heart complications has once again spotlighted a medical emergency that is often sudden, difficult to detect and, if missed, can be fatal. Unlike a heart attack, which occurs when blood flow to the heart muscle is blocked, a pulmonary embolism happens when a blood clot blocks one of the arteries supplying blood to the lungs. “This is like a pileup in one of the body’s most critical highways. And because the lungs are central to oxygenating blood, even a single large clot there can quickly trigger collapse of all body systems,” says Dr Nishith Chandra, principal director, cardiology, Fortis Escorts Heart Institute Research Centre, New Delhi . Excerpts: What is pulmonary embolism? To understand pulmonary embolism or lung clots , it helps to understand how quickly the body’s circulation works. The heart beats about 60 to 70 times every minute.…