False-colour chest x-ray in a case of hyper- tension: abnormally high blood pressure, showing an enlarged heart at bottom right obscuring the lower lobe of the left lung. The cause of essential hypertension (the most common form) is still unknown, although it is closely associated with arteriosclerosis, the progressive build-up of fatty plaques on arterial walls. Other complications include heart failure, cerebral haemorrhage & kidney failure. Treatment is largely by long-term drug therapy to lower blood pressure, using thiazide diuretics, methyldopa, guanethidine, propanolol & others.