Blood Pressure and Stroke Volume Response to Exercise in Adolescent Children Born Very Preterm

IntroductionMultiple studies have shown that adolescents born preterm have exercise intolerance. The etiology of the intolerance remains controversial. It has been demonstrated that infants and young adults born preterm have higher blood pressure (BP) than term‐borns of the same age. Very little is known about the effects of premature birth on cardiovascular function in adolescent children. The purpose of this study was to investigate BP and stroke volume responses to exercise in children. We hypothesized that adolescent children born prematurely would have an augmented BP response with a lower stroke volume response to exercise compared to children born at term.MethodsSubjects were adolescent children born in 2003 and 2004. Preterm subjects were born <33 weeks gestation, and term‐born subjects were born >38 weeks gestation. 21 adolescent children born premature and 20 term‐born controls completed the study. Measurements of systolic BP (SBP) and diastolic BP (DBP) were recorded at rest and during supine submaximal exercise (70% of predetermined maximal wattage). BP data was obtained using a brachial artery cuff every 2 minutes during a 10 minute rest period, and during a 10 minute submaximal exercise period. Rest and exercise mean arterial BP (MABP), SBP and DBP were averaged for every subject. A 3T cardiac MRI was used to determine left ventricular stroke volume using aortic blood flow from a 2D flow cine sequence during rest and exercise using Segment post‐processing software. Stroke volume was calculated the average of aortic flow waveforms from one cardiac cycle. Unpaired t‐tests were used to compare results between controls and preterms.ResultsChildren born preterm had higher SBP (114.8±5.7 mmHg vs. 109.7±4.7 mmHg respectively: p = 0.006), DBP (65.8±4.7 mmHg vs. 60.0±5.3 mmHg respectively: p = 0.001) and MABP (82.2±3.7 mmHg vs. 76.6 ±4.0 mmHg respectively: p < 0.001) compared to term born children at rest. Contrary to our hypothesis, there was no difference in BP response to exercise. There was no difference in SV at rest between preterm and term‐born adolescents (73.0±22.7 vs. 81.6±9.6 ml respectively: p = 0.30). SV during exercise was significantly lower in preterms than controls (66.3±9.0 vs. 99.1±15.6 ml respectively: p = 0.02), resulting in a blunted SV response to exercise in preterms compared to controls (ΔSV; 2.4±1.8 vs. 17.5±6.6 ml respectively: p = 0.02).DiscussionWe found that adolescent children born preterm have higher BP at rest than term‐born controls, with no significant difference during exercise. Elevated BP, while not considered hypertensive, was in the upper limits of what is considered normal for this age group. While we did not find a difference in SV between preterm and term‐born controls at rest, we found that there was a blunted SV response to exercise in preterms. The inability to augment SV appropriately to exercise is indicative of cardiovascular or autonomic dysfunction. In combination, the higher BP and blunted SV response to exercise suggests a need for further cardiovascular investigations in this population.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.