For once, it’s not the heart! Exercise limitation in children from breathing pattern disorders post cardiac-surgery

Introduction: Children with congenital cardiac disease may require surgery via sternotomy. Residual cardiac pathology can limit exercise, but sternotomy may alter thoracic cage dynamics, causing breathing pattern disorders (BPD) and exercise limitation. Cardiopulmonary exercise testing (CPET) allows objective assessment of exercise capacity and BPD. Aim: To assess if BPDs contribute to exercise limitation in patients with total cavopulmonary connection (TCPC). Methods: Retrospective audit of children with TCPC who underwent incremental maximal CPET for exercise limitation over 5 years (2011-2015) at Royal Brompton Hospital, London. Medical record data was extracted & analysed via SPSS software. Results: 13 patients (8 male; mean age 10.7yrs [7-15]) had TCPC & subsequent CPET (treadmill; Bruce protocol). All reached AT but 8 (62%) had exercise limitation with early AT & low VO2 peak. 3 (23%) had low ventilatory reserve, indicating ventilatory limitation; all others were cardiovascularly limited. 6 (46%) demonstrated BPD: 4 (67%) had hyperventilation syndrome; 2 (33%) had large VT without tachypnoea. Baseline spirometry & ventilatory limitation did not predict BPD on CPET. Conclusions: Our data shows nearly 50% of children with TCPC have BPD, possibly adding to exercise limitation. BPD are under-recognized in this group and longitudinal studies are required to assess specialist physiotherapy intervention.