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18105

Abnormal Heart Rate Characteristics Are Associated with Abnormal Brain Ultrasound and MRI In Extremely Low Birth Weight Infants

Friday, October 19, 2012
Room R02-R05 (Morial Convention Center)
F. Davalian, MD1, R.A. Sinkin, MD1, J. Matsumoto, MD2, D. Lake, PhD3, J.R. Moorman, MD4, J. Blackman, MD1 and K. Fairchild, MD1, (1)Pediatrics, University of Virginia, Charlottesville, VA, (2)Radiology, University of Virginia, Charlottesville, VA, (3)Statistics, University of Virginia, Charlottesville, VA, (4)Medicine, University of Virginia, Charlottesville, VA

Purpose

Brain injury may lead to autonomic nervous system dysfunction which is reflected by abnormal heart rate characteristics (HRC). An HRC monitor was developed to analyze heart rate variability and decelerations and predict catastrophic illness in NICU patients (HeRO monitor, Medical Predictive Sciences Corporation). We tested the hypothesis that the HRC index would be abnormally high in preterm infants with abnormal brain ultrasound and MRI.

Methods

We collected HRC data on extremely low birthweight infants who underwent brain MRI as part of a study of neurodevelopmental outcomes. Brain ultrasounds (US) were performed in the first week and as clinically indicated, and brain MRI was performed near discharge. US were scored as normal/mild (including grades 1-2 IVH) and moderate/severe (grades 3-4 IVH or cystic periventricular leukomalacia). MRI was scored 0-3 using an established scoring system for gray and white matter injury.

Results

45 ELBW infants with MRI performed had HRC data available. MRI was classified as 0 (normal, n=22), 1 (mild, n=14), 2 (moderate, n=5) or 3 (severely abnormal, n=4) and US as normal/mild (n=36) or moderate/severe (n=9). Average HRC index in the first 28 days after birth (aHRC28) was highly correlated with severity of abnormal brain US and MRI. aHRC28 for patients with normal/mild US abnormalities was 1.37±0.48 (mean±SD) and with moderate/severe 2.53±0.69 (p<0.001). For MRI, aHRC28 for patients with classes 0-3 was 1.24±0.44, 1.59±0.53, 2.49±0.68*, 2.72±0.82*, (*p<0.001 versus class 0). Differences persisted after adjustment for gestational age and birthweight.

Conclusion

HRC monitoring may be a useful adjunct test for severity of brain injury in NICU patients.

Figure 1. HRC monitor screen shot from an ELBW infant with severe IVH. HRC index over 5 days top orange tracing and heart rate (bpm) over 30 minutes bottom green tracing. HRC index (1.80) at time/date indicated is shown in upper right box.