The pathogenesis of the two forms of hypertensive pulmonary vascular disease.

Autopsy observations suggested that lesions of hypertensive pulmonary vascular disease (HPVD) due to elevated venous pressure differ from those with arterial hypertension only. Clinical and pathologic features were reviewed in patients from the Hopkins autopsy files with proved pulmonary hypertension; 50 had venous HPVD due to left-sided congestive heart failure, 50 had arterial HPVD due to congenital malformations, and 15 had idiopathic pulmonary hypertension (IPH). The two forms of HPVD have consistent distinctive histologic changes. In venous HPVD intimal fibroelastosis (IFE) develops in veins and arteries with retention of normal lumen diameters. Intensity of IFE correlates with severity and duration of venous hypertension. Arterial HPVD has IFE in conducting arteries, but the characteristic lesion is cellular intimal proliferation in regulatory arterioles, producing progresssive irreversible lumenal narrowing. Glomoid and angiomatoid lesions appear with prolonged severe arterial hypertension. They do not occur in venous HPVD. Hypertensive arteritis may develop with either form of HPVD. IPH has arterial-type HPVD. IFE of venous HPVD appears to be a response to increased mural tension. Arteriolar intimal cellular proliferations seen in arterial HPVD may be produced by blood flow boundary layer separations. IPH may be explainable as protracted inappropriate pulmonary arteriolar constriction.