Lone pulmonary hypertension.

Lone (or primary), pulmonary hypertension (P.H.T.) may be defined as a condition of high pressure in the pulmonary artery associated with right ventricular hypertrophy for which no cause can be found outside the pulmonary vessels. The diagnosis is one which is made by exclusion of other diseases which are known to be potential or predisposing causes of P.H.T. The most important of these are chronic lung disease, mitral stenosis and congenital heart disease (Bedford, 195I). Less frequent causes are recurrent pulmonary embolism and pulmonary arteritis. The forms of lung disease most frequently associated with P.H.T. are emphysema and pneumoconiosis. Fibroid tuberculosis, cystic disease, sarcoidosis, secondary carcinomatosis and primary haemosiderosis are sometimes responsible. Kyphoscoliosis is another rare cause. The most important varieties of congenital heart disease are those which permit a left to right shunt, notably atrial septal defect, ventricular septal defect and patent ductus arteriosus. Repeated pulmonary embolism secondary to thrombosis in the systemic veins is an important and not very rare cause of P.H.T.; so also, in Egypt, is bilharzial pulmonary endarteritis; but rheumatic and syphilitic pulmonary arteritis are very uncommon. Under the diagnosis of primary pulmonary arteriosclerosis, occasional cases of Lone P.H.T. have been reported since the middle of the last century, but by I935 Brenner could find reports of only 15 pure and well authenticated cases. During the past 20 years, and particularly since the introduction of cardiac catheterization, many more cases have been described. The disease is nevertheless a rare one and there are still less than 0oo adequately reported cases with necropsy control in the world's literature. Dr. William Evans and Dr. Evan Bedford are about to publish a considerable series of cases which were carefully studied both during life and at necropsy. Through their courtesy the present author has had the opportunity of examining several of the patients during