[Clinico-histologic-morphometric correlations in pulmonary arteries among patients with heart malformations ]

To improve the evaluation of grades of pulmonary vascular lesions in congenital heart malformations, we studied the extent to which there is a measurable relationship between pressure conditions in the pulmonary circulation and the area of the media in small and medium-sized pulmonary arteries, and the possibility of a correlation between the subjective evaluation of grades of hypertensive pulmonary vascular lesions according to Heath and Edwards (1958). Material and methods. The lungs in 68 children (mean age, 22.7 months) with congenital malformations of the heart or great vessels resulting in pulmonary hypertension were examined. The lungs were fixed in a 4% formalin solution passed via the trachea under a constant filling pressure of 150 cm H2O. Peripheral as well as central tissue was removed from all lobes of the lungs; the specimens were stained with Elastica-van Gieson. The extent of hypertensive pulmonary vasculopathy was staged, without knowledge of the pressure conditions, according to the grading system developed by Heath and Edwards. The diameter and the area of all muscular arteries with diameters smaller or larger than 100 micron were measured using a semiautomatic measurement device for quantitative morphometric analysis (MOP/AM 01). Cardiac catheter values were available for all cases. The quotient of systolic pressures in the pulmonary artery and the aorta was taken as the measure of hemodynamic conditions in the pulmonary circulation. The Pearson-Bravais correlation coefficient (r) was computed from the respective area quotient and the corresponding pressure values. In addition, the coefficient of determination (r2) and regression functions were determined. Results. A linear correlation (r = 0.70) exists between the pressure quotient (Psyst. pulm. art./ Psyst. aorta) and the vessel area quotient (media area/total area). The correlation is expressed by the following functions: x = 1.89 y - 0.08 y = 0.26 x + 0.24 Using the Heath and Edwards grading, the following frequencies were obtained: Grade 0: 21, Grade I: 7, Grade II: 16, Grade III: 15, Grade IV: 6, and 3 children were undeterminable. No relationship exists between the grades and certain heart malformations. In spite of the fact that hypertensive vasculopathy becomes progressively more severe as the child grows older, we found four cases of Grade IV in children under the age of one. On the whole, a comparison of the measured area quotients and the Heath and Edwards grading showed a good correlation. Although we considered only pressure quotients and no other hemodynamic parameters, conclusions can be drawn about the operability of congenital heart malformations based on these findings. Using measured pressure values, the morphologic state of the pulmonary arteries can be approximately evaluated.