Background There is a significant body of adult congenital patients born with transposition of the great arteries (TGA) who have undergone Mustard or Senning procedures requiring follow up. Long-term complications relating to the intra atrial baffles are frequent and baffle leaks may cause significant desaturation, exercise intolerance and increased risk of paradoxical emboli. However the clinical consequence of a baffle leak is often poorly understood and in some cases their presence may prove beneficial to the patient. We describe four cases in whom the decision to eliminate an atrial baffle leak was not clear-cut.

Findings Four male patients, mean age 27 years, with a history of TGA underwent a Senning procedure in infancy (mean age 8 months). All patients were NYHA class 1, in sinus rhythm with no history of embolic events. Significant baffle leaks were identified on MRI and confirmed at cardiac catheterisation. Calculated Qp:Qs ranged from 1.5–3:1. Pulmonary artery pressure was normal in all cases. All 4 patients had a dilated left ventricle with well-preserved function and, interestingly, had a systemic right ventricle of relatively normal size with good function.

Discussion A significant baffle leak, which behaves like an atrial septal defect, places a volume load on the posterior subpulmonary left ventricle. We postulate that this may actually be beneficial in supporting systemic right ventricular function. For a subset of patients intervention to abolish the leak could potentially precipitate right ventricular dysfunction. This must be offset against the potential implications of a significant left to right shunt. Careful investigation is required to appropriately diagnose, counsel and follow this patient group.