CARDIOPULMONARY PHYSIOLOGY AFTER SURGICAL CLOSURE OF ASYMPTOMATIC SECUNDUM ATRIAL SEPTAL-DEFECTS IN CHILDHOOD - EXERCISE PERFORMANCE IS UNAFFECTED BY AGE AT REPAIR

Aims Most secundum atrial septal defects, once diagnosed, are correcte d at a young age. The evidence to justify early vs delayed or even non -closure is equivocal and little is known regarding long-term effects of later closure. This is particularly pertinent to those patients awa iting transcatheter closure of their defect for whom a device is only just becoming available. We examined the exercise cardiorespiratory ph ysiology of children surgically treated for an isolated secundum defec t. Methods and results One hundred and six healthy control children an d 22 children more than 6 months after surgical repair for an isolated secundum atrial septal defect were studied. All were asymptomatic. Me asurements of effective pulmonary blood flow, stroke volume, arteriove nous oxygen difference, minute ventilation, heart rate, oxygen consump tion and carbon dioxide production were made using a quadrupole mass s pectrometer during rest and graded exercise. Data from the normal chil dren allowed calculation of z scores for the atrial septal defect grou p matched for age, sex, pubertal stage and surface area. Maximal exerc ise performance was equal between control and atrial septal defect gro ups, however, the atrial septal defect group had a significantly great er effective pulmonary blood flow and stroke volume but a lower heart rate than controls at a given exercise stage. Stroke volume abnormalit ies were most closely related to duration of follow-up (29% of the var iance explained, P < 0.01) rather than age at surgery. Conclusions We were unable to show a medium term benefit from early surgery for an as ymptomatic secundum atrial septal defect during exercise. The clinical relevance of the haemodynamic differences that do exist remains uncle ar.