③ Acute Aortic Dissection — Sudden severe chest or back pain The third is acute aortic dissection. The aorta is the largest blood vessel in the human body and the first vessel through which blood pumped out of the heart passes. An aortic dissection occurs when the wall of the aorta suddenly tears, allowing blood to enter the layers of the vessel wall. “The typical symptom is sudden, extremely severe pain in the chest or back. People may describe it as pain unlike anything I’ve ever experienced or suddenly feeling as though my chest or back was being torn apart. As the dissection spreads, the pain may move from the chest to the back and even down to the lower back.” The symptoms are not necessarily limited to the chest or back. “If blood flow through the vessels supplying the brain is disrupted, it can cause impaired consciousness or paralysis of the limbs. If the blood vessels of the heart are affected, it can result in a condition resembling a myocardial infarction. “If the aorta ruptures, or if blood accumulates inside the membrane surrounding the heart (the pericardium), preventing the heart from functioning properly—a condition known as ‘cardiac tamponade’—it can lead to sudden death. High blood pressure is a major risk factor for aortic dissection. Aortic dissection is a medical emergency in which every moment counts. Do not ignore sudden, severe chest or back pain by thinking, ‘It’ll probably go away if I rest for a while.’” ④ Pulmonary Thromboembolism — Suddenly having trouble breathing requires caution The fourth is pulmonary thromboembolism. A blood clot that forms in a vein in the leg or elsewhere can travel through the bloodstream to the lungs and block a pulmonary artery. When this occurs after remaining in the same position for a long period, it is commonly known as economy-class syndrome. “The characteristic symptoms are sudden difficulty breathing and chest pain. In severe cases, insufficient blood can reach the lungs, causing blood pressure to drop, which can result in loss of consciousness or cardiac arrest.” Caution is necessary when someone is in a situation that makes blood clots more likely to form, such as after surgery, prolonged bed rest, or having cancer. In some cases, this condition first causes abnormalities in the legs before affecting the lungs. “One leg may suddenly become swollen or painful. If you then suddenly develop difficulty breathing or chest pain, pulmonary thromboembolism should be considered.” ⑤ Subarachnoid Hemorrhage — A headache unlike anything you’ve ever experienced Brain disorders can also lead to sudden death. A representative example is subarachnoid hemorrhage. This occurs when an aneurysm or other abnormality in a blood vessel in the brain ruptures, causing bleeding into the subarachnoid space beneath the arachnoid membrane, one of the three layers of membrane covering the brain. “One extremely important warning sign is a sudden, severe headache. It is often described as a headache unlike anything I’ve ever experienced. It may be accompanied by nausea or vomiting, and in severe cases, the person may lose consciousness on the spot. A relatively mild headache known as a warning headache can also occur before a major hemorrhage.” People who frequently suffer from headaches need to be particularly cautious. “It is easy to think, ‘It’s probably just my usual headache again,’ but is it really the same as your usual headache? If the headache is clearly different from what you normally experience, it is important not to simply take a painkiller and wait to see what happens, but to seek medical attention immediately.”