Grading of pulmonary vascular lesions-a reappraisal

Grading of pulmonary vascular alterations, introduced by Heath & Edwards (1958), has been widely used for assessment of the severity of hypertensive pulmonary vascular disease. Two factors call for a reappraisal of the grading principle: an increasing awareness of the complexity of the vascular lesions and an increasing use of lung biopsies for the pre-operative evaluation of the operability of an underlying cardiac defect. We suggest that the grading system, as well as the previously proposed variations of it, no longer fulfil the requirements of unambiguous assessment of the severity of vascular disease. The degree and extent of the various lesions, the different types of intimal fibrosis, and the eventual decrease in number and size of vessels should all be assessed, not only for arteries but also for other vessels. Careful consideration and weighing of all these features are necessary in order to form an opinion on diagnosis and prognosis. This cannot be achieved by using a single grade.