Autonomic function and blood pressure in adolescents born preterm
Authors: Harradine Rachel , Haraldsdottir Kristin , Pegelow David , Goss Kara , Watson Andrew , Eldridge Marlowe 
Published: June 2021

IntroductionPreterm birth affects 10% of births in the United States. The nervous and cardiovascular systems undergo significant development in the third trimester. The autonomic nervous system (ANS) plays a significant role in regulating heart rate and blood pressure. Parasympathetic nervous activity (PNA) increases throughout the third trimester, and preterm birth is known to result in lower PNA during infancy. Preterm birth is known to put young adults at greater risk of cardiac autonomic dysfunction, hypertension and cardiac hypertrophy. However, little is known about the onset of these cardiovascular abnormalities. Autonomic dysfunction and high blood pressure are associated with increased risk of cardiovascular disease. The purpose of our research is to investigate the long term effects of preterm birth on autonomic function and blood pressure at rest in adolescents born preterm and age‐matched term‐born controls. We hypothesize that preterms will have lower autonomic function, as determined by heart rate variability at rest, and elevated blood pressure compared to term‐born adolescents.Methods21 children born preterm (birthweight <1500 g, gestational age <32 weeks) and 20 children born full term (gestational age >38 weeks) were studied. Heart rate variability measurements were obtained during a 15 minute supine resting period using a 3‐lead ECG. The standard deviation of R‐R interval (SDRR) and the root mean squared of successive differences (RMSSD) were calculated using PowerLab software. Blood pressures were obtained every 2 minutes during a 10 minute supine rest period using a brachial artery cuff, and the mean arterial blood pressure (MABP), systolic blood pressure (SBP), diastolic blood pressure (DBP) were determined. The relationship between MABP and RMSSD was determined using a linear regression. Results between groups were compared using Mann‐Whitney tests.ResultsPreterms had significantly lower birthweights than the controls (1097 ± 274 v 3497 ± 366 g, respectively, p<0.001) and had lower gestational age (27.86 ± 2.10 v 39.74 ± 0.87 weeks, respectively, p<0.001). Preterms had significantly higher MABP (82.2 ± 3.7 v 76.4 ± 4.0 mmHg, respectively, p<0.001), DBP (65.8 ± 4.7 v 59.6 ± 5.1 mmHg, p=<0.001), and SBP than controls (114.8 ± 5.7 v 109.9 ± 4.8 mmHg, p=.009). Preterms had lower HRV, SDRR (69.1 ± 33.8 v 110.1 ± 33.0 ms, p=.008), and RMSSD (58.8 ± 38.2 v 101.5 ± 36.2 ms, p=.012). There was a negative relationship between RMSSD and MABP (r2=0.324, p=0.007).DiscussionOur results demonstrate that adolescents born prematurely have lower HRV and higher resting blood pressure. Both autonomic dysfunction and elevated blood pressure are known to be correlated with increased risk of cardiovascular disease. Furthermore, we found a negative relationship between HRV and blood pressure in our population. Our results suggest that preterm individuals have higher sympathetic activity, and the inverse relationship between HRV and BP suggests that higher sympathetic vascular tone due to autonomic dysfunction leads to elevated BP. The individuals in our study were free of known cardiovascular or respiratory disease, and both groups were very active. Our results suggest that otherwise healthy preterm adolescents are potentially at increased risk of developing cardiovascular disease and further study is warranted.Support or Funding InformationNIH‐NHLBI R01–HL115061This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.