The early and late effects of surgical closure of ventricular septal defects on pulmonary vascular dynamics.

In sixty patients who underwent closure of ventricular septal defect (VSD), cardiac catheterizations were performed before and late after surgery together with pressure measurements immediately after closure of the VSD during surgery. Pulmonary arterial mean pressure (PAm), pulmonary arterial systolic pressure to systemic arterial systolic pressure ratio (Pp/Ps), and pulmonary vascular resistance to systemic vascular resistance ratio (Rp/Rs) were measured and calculated. The patients were classified into 5 groups according to the preoperative Rp/Rs and Qp/Qs as was reported by Nakada: Group A: Rp/Rs less than 0.15, Qp/Qs larger than or equal to 1.8, Group B: Rp/Rs less than 0.15, Qp/Qs less than 1.8, Group C: 0.15 less than or equal to Rp/Rs less than 0.50, Group D: 0.50 less than or equal to Rp/Rs less than 0.85, Group E: 0.85 less than or equal to Rp/Rs. These groups were further divided into 3 groups respectively according to age at operation (less than or equal to 2 years, 3 or 4 years, 5 years less than or equal to). The averages of PAm, Pp/Ps, and Rp/Rs were within the normal range in Group A and B patients (normal pulmonary vascular resistance groups) irrespective to the age at operation except the average of PAm before surgery. In Group C, D and E patients (elevated pulmonary vascular resistance group), these variables decreased immediately after closure of VSD, and further decreases were noted at the time of late catheterization. These variables, however, did not completely normalize even at that time. Among the patients operated upon at 2 years of age or less, the averages of these variables normalized immediately after closure of the VSD. When operated upon at 3 or 4 years of age, these variables decreased but did not normalize immediately after closure of the VSD and were found to be within the normal range at the time of late catheterization. When operated upon at 5 years of age or more, these variables decreased immediately after closure of the VSD, and further decrease was found at the time of late catheterization but mostly remained in the abnormal range even at this time. From the data obtained herein, the factors producing the pulmonary vascular resistances in respective age groups were discussed. The closure of VSD in patients with elevated pulmonary vascular resistance is recommended at the latest 4 years of age and preferably at 2 years of age or less, in order to obtain normal pulmonary circulatory dynamics after surgery.