P21 Multi-modality imaging of the pulmonary blood supply in infants with pulmonary atresia with ventricular septal defect: Accuracy, cumulative radiation dose and anaesthetic time

Aims In newborns with pulmonary atresia with ventricular septal defect (PA/VSD), the pulmonary arteries (PAs) may be either hypoplastic or absent, with or without highly variable aortopulmonary collaterals. Comprehensive imaging of the native pulmonary blood supply is important to inform initial management. We sought to describe the accuracy, cumulative radiation dose and anaesthetic time associated with multi-modality imaging in newly diagnosed patients with PA/VSD prior to their first intervention. Methods The records of all patients diagnosed with PA/VSD between 2004 and 2014 were reviewed retrospectively, excluding all patients over 100 days old at the time of diagnosis. We determined the accuracy and benefits (if any) of serial investigations up to the time of the first intervention, comparing the results to the anatomical findings at operation. We then calculated the cumulative radiation dose and anaesthetic time per patient. Results 30 patients were identified, of which 13 were excluded (7 had no further imaging and 6 were >100 days old at diagnosis). In total, there were 13 catheters and 4 CT scans performed in the whole group before intervention. All were within 100 days of life. Aside from one patient with 2 MRI scans, no investigation was repeated. Echocardiography correctly identified PAs in 12/17 patients (71%), MRI in 9/13 patients (69%), CT in 1/4 patients (25%), and in all patients who underwent catheterisation (13/13, 100%). In the 4 patients who underwent cross-sectional imaging only (3 MRI, 1 CT), PAs were also correctly identified. The mean radiation dose during catheterisation was 119mGy*cm2 (47–231mGy*cm2), and for CT was 92mGy*cm2 (66–123mGy*cm2). 3 patients underwent both catheterisation and CT, with a mean cumulative dose of 297mGy*cm2 (191–461mGy*cm2). 3 underwent MRI only with no ionising radiation. The mean total anaesthetic time before intervention was 111 min (33–185 min). In the one child who had CT only, no anaesthetic was used. The mean age of those undergoing primary catheterisation was 3 days (1 – 6 days, n = 3). In those undergoing primary MRI or CT, the mean age at subsequent catheterisation was 35 days (8–86 days, n = 10, P = 00.09); however, there was no difference in the mean radiation dose or anaesthetic time of these procedures. Over the ten year period of our study, the maximum cumulative radiation dose in a single patient was 8022mGy/cm2 at the age of 6 years (via 5 catheters), and 1263 min of anaesthetic time at 5 years (via 5 catheters, 1 CT and 4 MRIs). Conclusions Echocardiography may not identify native PAs in all neonates and infants with PA/VSD. Catheterisation is highly accurate, but also carries the highest risk. Cross-sectional imaging alone may be appropriate in some cases; in others, it may allow for delayed catheterisation, but may not reduce the radiation dose or anaesthetic time. The cumulative effects of repeated diagnostic and interventional procedures can lead to large radiation doses and anaesthetic times, both before and after primary intervention. These risks are an important consideration when planning management in this complex patient group.