Combination of symptoms caused by a hormone-producing intestinal tumour. These rare tumours are malignant, but behave in a relatively benign fashion, growing slowly and metastasizing late. They can occur throughout the alimentary tract, but are ususally found in the appendix or the end of the small intestine. The characteristic symptoms of the carcinoid syndrome are caused by the production of serotin, histamine and related hormones. Serotin stimulates intestinal peristalsis and causes contraction of smooth muscle in the air passages, and it and other substances can be responsible for dilation of blood vessels. These substances are broken down in the liver, and because blood from the intestine (and the carcinoma) flows through the liver, and thus metastasizes in the liver, it causes the carcinoid syndrome, with the result that serotin can pass directly into the bloodstream. Irritation of the intestine causes diarrhoea, and contraction of the muscles in the air passages causes asthma. A characteristic of dilation of the blood vessels is increased facial flushing, sometimes spreading to the chest and limbs, and stimulated by emotion, bending, consumption of alcohol and effort. In the long run symptoms can occur like persisting redness of the skin and damage to the heart. The clinical picture is so clear that diagnosis is not difficult; it can be confirmed by measurement of the serotin level in the blood, and of breakdown products in the urine. Treatment is by removal of the tumour if possible. If this is not possible, as a result of metastasis for example, the symptoms should be treated by medication, possibly supplemented by cytotoxic drugs. With correct treatment, patients can live well into old age. Cardiac arrest Circulatory failure caused by non- contraction of the heart. This cuts off the oxygen supply to the brain and causes unconsciousness within ten seconds. After about three minutes brain cells begin to be destroyed and the patient finally dies. The commonest cause is ventricular fibrillation after a coronary infarction. Other causes are total failure of the impulse system in the heart, or serious heart block, in which impulses from the auricules do not reach the ventricles. The condition requires immediate treatment: cardiac massage, electric shock to the heart or extensive cardiac stimulation.