CO Pulmonary Diffusing Capacity in Heart Diseases

　CO pulmonary diffusing capacity by the　breath holding technique and hemodynamics　by right heart catheterization were perform—ed in 26 cases with various heart diseases and　the clinical significance of the determination　of DLco and the relationship between the pul—monary diffusing capacity and hemodynamics　were discussed.

　Diffusing capacity of the pulmonary mem—brane　(DM)　and the pulmonary capillary　blood volume　(Vc)　were also measured for　selected cases and its clinical significance was　discussed.

　1)　An increase of DLco and Vc was found　in case with intracardial septal defect when　the pulmonary blood flow is increased by the　left to right shunt.

　2)　A tendency of decrease of DLco was　found in case with pulmonic stenosis as pul—monary blood flow is decreased.

　3)　Patient with increased pulmonary blood　flow in patent ductus arteriosus tends to have　an increase of DLco, however, the grade of　increase was slight compared with intracard—iac septal defect.

　4)　DLco showed the significant variation　according to the stage of disease in mitral　stenosis.

　5)　Significant positive correlation was ob—tained among DLco, pulmonary blood flow　and an amount of left to right shunts, and no　significant correlation was obtained among　DLco, pulmonary arterial pressure and total　pulmonary resistance in heart diseases.

　6)　As not only the diagnosis of the increase　and decrease of the pulmonary blood flow and　the existence of the left to right shunt could　be presumed but also the diagnosis of intra—cardiac septal defect the stage of mitral steno—sis and the grade or stage of heart disease　could be made, the measurement of DLco, DM　and Vc are quite important method as clinical　test.