At present two types of cor pulmonale are recognized—acute and chronic. The former is practically always the result of a single cause, pulmonary embolism; for a clearer understanding of its clinical manifestation one is indebted to the recent writings of Sylvester McGinn and Paul D. White.1 In this form, except in those relatively rare instances in which the patient survives repeated attacks over a long period (two months or longer), there is rarely significant hypertrophy of the right ventricle, since the condition either is rapidly fatal or quickly results in complete recovery.
The chronic type of cor pulmonale is of manifold etiology. The most important causes of primary chronic cor pulmonale are mitral stenosis, extensive pulmonary fibrosis and marked emphysema secondary to asthma, chronic bronchitis or some other pulmonary disease. In 14 per cent of a series of one hundred patients with heart failure White2 noted primary strain