Abstract 6079: Memory Impairment And Hippocampal Pathology In Survivors Of The Arterial Switch Operation For Transposition Of Great Arteries
The hippocampus is vulnerable to perinatal hypoxic/ischaemic insults with potential memory impairment in later life. We measured memory and hippocampal integrity in survivors of the Arterial Switch Operation (ASO) for Transposition of Great Arteries (TGA).
Methods We recruited 35 neurodevelopmentally normal children [mean (SD) age 10.9 (0.4) years] who had ASO and 21 age-matched healthy controls [11.6 (0.3) years]. Preterms and those with genetic syndromes and additional heart abnormalities were excluded. Clinical and intra-operative variables were analysed. All had standardised tests of intelligence, general memory and learning, academic achievements, and a special test of episodic memory (Rivermead Behavioural Memory Test). Hippocampal volumes (mm3) were measured using MRI corrected for intracranial volume.
Results In the 35 studied, 2 groups were identified: 25 with intact ventricular septum (TGA-IVS) and 10 with ventricular septal defect (TGA-VSD); median (IQR) age at ASO was 13 (9.5, 17.5) and 11.5 (10, 39) days, respectively. There were no group differences in median pre-operative oxygen saturations (p=0.1) or arterial PaO2 (p=0.7), but median (IQR) duration (minutes) of cardiopulmonary bypass [119 (110, 135) vs. 138 (133, 173)] and median circulatory arrest [8 (6.5, 10) vs. 22.5 (9.1, 34.8)] were significantly longer in TGA-VSD (p=0.03). In all, the mean IQ, academic achievements, and factual knowledge were within the normal standard average range but below controls. Memory deficit was identified in 23%, with memory quotient (MQ) ≤1.5 SD below the standard average and the controls. The proportion of those with memory deficit was higher in VSD group [4/10 (40%)] with significantly lower MQ (p<0.01) and episodic memory (p<0.02) relative to standard average and controls. On MRI, bilateral mean (SD) hippocampal volumes were reduced in the TGA-VSD group [12 (10)%] compared to controls (p<0.01) and TGA-IVS (p<0.01) group.
Conclusions Memory was adversely affected in 23% despite preserved general cognitive abilities and was accompanied by hippocampal injury, especially in TGA-VSD group. The intra-operative variables may have a specific, isolated impact on memory, which appears to be independent of general cognitive function.
This research has received full or partial funding support from the American Heart Association, AHA Greater Southeast Affiliate (Alabama, Florida, Georgia, Louisiana, Mississippi, Puerto Rico & Tennessee).