PULMONARY HYPERTENSION IN MITRAL STENOSIS

Abstract

Pulmonary vascular changes were studied in 24 patients in whom mitral stenosis was confirmed at necropsy by means of pulmonary arteriograms and histological sections. Pulmonary arterio-grams in each of 12 cases revealed changes of two kinds: focal changes consisting of thrombotic obstruction of segmental arteries, areas of infarction, and abnormal arterial anastamoses; and diffuse changes consisting of an absence of opaque material from the finest branches throughout the lungs. The latter changes occurred only in those in whom subsequent examination revealed severe arterial disease. Histological examination also showed two kinds of abnormalities: subsidiary changes which included intimal thickening and thrombosis within the large arteries and subintimal thickening of the venules; and salient changes consisting of widespread intimal proliferation within the arterioles and diffuse refractory arterial contraction. The salient changes were neither related to the degree of mitral stenosis nor to the age of the patient, but in the 12 of the 24 patients in whom they were found, there was marked hypertrophy of the right ventricle. Comparison of clinical features in the cases showing salient pulmonary arterial changes and pulmonary hypertension with the other cases, showed that the presence of pulmonary hypertension in mitral stenosis presents signs consisting of a small pulse, raised venous pressure, a prominent auricular wave in the neck, a loud pulmonic second sound and a sound in early systole. Ecg shows right ventricular preponderance as manifested by a diphasic P wave 2.5 mm high in CR-1 pointed or bifid with a prominent trial peak. On fluoroscopy, the pulmonary trunk and its branches were prominent. It is concluded that pulmonary hypertension can be diagnosed during life on the basis of clinical, ecg and radiological examination without recourse to pulmonary arterial catheterization. The investigation has established that vascular obstruction accounts for persistent pulmonary hypertension in mitral stenosis. Since the arterial changes appear to be progressive and irreversible, it is concluded that mitral valvotomy in the patients with pulmonary hypertension is unlikely to produce material or lasting benefit.