Pulmonary Hypertension and Its Relation to Congenital Heart Disease

¹ The Department of Medicine, Stanford University School of Medicine.

Of the various types of pulmonary hypertension the primary, "vascular" form is frequently associated with congenital heart disease. Primary pulmonary hypertension can usually be demonstrated in children and is presumed to be related to a maladjustment of the pulmonary circulation during the postnatal adaptive period. In such cases equal resistances within the pulmonary and systemic circuits, which are essential in the fetal circulation, persists into postnatal life. This form of severe pulmonary hypertension appears in three clinical types: (1) a "primary" form in which it is not associated with any other cardiac malformation; (2) a type in which the persistence of the fetal-like equalization of pulmonary and systemic resistance exerts an important protective function by preventing an unequal distribution of the blood and, (3) the type in which pulmonary hypertension is found occasionally in association with congenital syndromes causing a left-to-right shunt, which ordinarily show normal pulmonary arterial pressures. In the second type a causal relationship between the cardiac malformation and the persistence of high pulmonary resistance has not been demonstrated but appears highly probable. In the third type pulmonary hypertension is probably a coincidental complication of the cardiac defect as it appears to be unrelated to the magnitude of the shunt and to the large pulmonary blod flow.