Haemodynamic findings at rest before and after operation in 107 patients

Summary The oxygen saturation and pressure conditions at rest before and, on the average, 17 months after surgical repair of ASD sec in 107 patients are reported. The left‐to‐right shunt was preopera‐tively, on the average, 61 % of the pulmonary blood flow. No significant correlation was found between the size of the left‐to‐right shunt, expressed in % of the pulmonary blood flow, and the preoperative roentgenological heart volume, expressed in ml/m 2 body surface area, in any of the age groups. No residual shunts were found on recatheterization. The oxygen saturation in the superior vena cava was normal, and significantly higher (***) postoperatively, indicating pre‐operatively increased peripheral utilization of the oxygen content. At the follow‐up examination no statistically certain correlation was found between shunt reduction and reduction of the relative heart volume. Preoperatively, the pressures in the pulmonary circulation were high but within the normal range; only three patients had pulmonary hypertension. On recatheterization the pressures were significantly lower in the right atrium (**), right ventricle (***) and the pulmonary artery (*), which shows that preoperatively the left‐to‐right shunt gave rise to a pressure increase to high normal but not pathological values. Only in the older adults, was there a significant correlation (*) between shunt size and systolic right ventricular pressure. At the follow‐up examination no statistically certain correlation was found between shunt reduction and reduction of systolic right ventricular pressure, in the different age groups. The mean PCV pressure was normal and showed no significant change postoperatively, and therefore the pressure gradient across the pulmonary capillary bed was essentially independent of the pulmonary blood flow. On comparing the filling pressures of the ventricles pre‐and postoperatively, it was found that before the operation, because of the defect, this pressure was increased for the right ventricle and, in many cases, was decreased for the left, compared with normal values. The pressure relationships and the functional mechanisms of both the right and the left ventricle were unphysiological and were prerequisite conditions for the occurrence of a left‐to‐right shunt, and possibly also for reduced systemic flow. Postoperatively, a normal pressure difference between the atria, and prerequisite conditions for normal filling pressure, were noted.