Allison Beth J, Nguyen Vivian, Yiallourou Stephanie R, Nitsos Ilias, Black Mary Jane, Polglase Graeme R
The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.
Department of Obstetrics and Gynecology, Monash University, Clayton, Victoria, Australia.
Exp Physiol. 2018 Jan 1;103(1):9-18. doi: 10.1113/EP086494. Epub 2017 Nov 9.
What is the central question of this study? Late preterm infants are often assumed to escape long-term morbidities known to impact earlier preterm offspring. Is this true for the cardiovascular system? What is the main finding and its importance? We show that late preterm birth is a risk factor for cardiovascular dysfunction in early adulthood and is influenced by sex. Early signs of cardiovascular dysfunction might predispose to heart disease in adulthood. Very preterm infants have an increased risk of cardiovascular disease; however, the effects of a late preterm birth on future cardiovascular function are not known. We hypothesized that after a late preterm birth, the well-described impairments in heart rate variability and baroreflex sensitivity would persist into adulthood. To test this hypothesis, sheep born preterm (0.9 gestation; nine male and seven female) or term (11 male and six female) underwent surgery at 14 months of age for insertion of femoral arterial and venous catheters and a femoral flow probe. After recovery, heart rate variability was assessed, followed by a baroreflex challenge (using the vasoactive agents phenylephrine and sodium nitroprusside) in conscious adult lambs. Our data demonstrate decreased low-frequency normalised units (LFnu) and low-frequency/high-frequency ratio in female but not male ex-preterm sheep at rest. When challenged, mature male ex-preterm sheep have an increased blood pressure response but dampened heart rate baroreflex response. We show that even a late preterm birth leads to cardiovascular dysfunction in adulthood. These early signs of cardiovascular dysfunction might underpin the later hypertension and increased risk of heart disease observed in adults born preterm. These findings are particularly important because late preterm infants are often assumed to escape the long-term morbidities known to impact on very preterm and extremely preterm offspring.
本研究的核心问题是什么？晚期早产儿通常被认为能避免出现那些已知会影响早期早产儿的长期疾病。心血管系统也是如此吗？主要发现及其重要性是什么？我们发现晚期早产是成年早期心血管功能障碍的一个风险因素，且受性别影响。心血管功能障碍的早期迹象可能会引发成年期心脏病。极早产儿患心血管疾病的风险增加；然而，晚期早产对未来心血管功能的影响尚不清楚。我们假设，晚期早产之后，心率变异性和压力反射敏感性方面广为人知的损伤会持续到成年期。为了验证这一假设，早产（妊娠0.9期；9只雄性和7只雌性）或足月出生（11只雄性和6只雌性）的绵羊在14月龄时接受手术，插入股动脉和静脉导管以及一个股血流探头。恢复后评估心率变异性，随后对清醒的成年羔羊进行压力反射激发试验（使用血管活性药物去氧肾上腺素和硝普钠）。我们的数据表明，静息状态下，雌性早产绵羊的低频标准化单位（LFnu）和低频/高频比值降低，而雄性则不然。受到激发时，成熟的雄性早产绵羊血压反应增强，但心率压力反射反应减弱。我们发现，即使是晚期早产也会导致成年期心血管功能障碍。这些心血管功能障碍的早期迹象可能是早产出生的成年人后期出现高血压和心脏病风险增加的原因。这些发现尤为重要，因为晚期早产儿通常被认为能避免出现那些已知会影响极早产儿和超早产儿的长期疾病。
