National space agencies and private corporations aim at an extended presence of humans in space in the medium to long term. Together with currently suboptimal technology, microgravity and cosmic rays raise health concerns about deep-space exploration missions. Both of these physical factors affect the cardiovascular system, whose gravity-dependence is pronounced. Heart and vascular function are, therefore, susceptible to substantial changes in weightlessness. The altered cardiovascular function in space causes physiological problems in the postflight period. A compromised cardiovascular system can be excessively vulnerable to space radiation, synergistically resulting in increased damage. The space radiation dose is significantly lower than in patients undergoing radiotherapy, in whom cardiac damage is well-documented following cancer therapy in the thoracic region. Nevertheless, epidemiological findings suggest an increased risk of late cardiovascular disease even with low doses of radiation. Moreover, the peculiar biological effectiveness of heavy ions in cosmic rays might increase this risk substantially. However, whether radiation-induced cardiovascular effects have a threshold at low doses is still unclear. The main countermeasures to mitigate the effect of the space environment on cardiac function are physical exercise, antioxidants, nutraceuticals, and radiation shielding.

中文翻译：

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太空中的心脏：地外环境对心血管系统的影响

国家太空机构和私人公司的目标是在中长期内扩大人类在太空中的存在。微重力和宇宙射线与当前欠佳的技术一起引发了人们对深空探索任务的健康担忧。这两种物理因素都会影响心血管系统，其引力依赖性非常明显。因此，心脏和血管功能容易发生失重的实质性变化。太空中心血管功能的改变会在飞行后引起生理问题。受损的心血管系统可能极易受到空间辐射的影响，从而导致损害增加。空间辐射剂量明显低于接受放射治疗的患者，在胸腔区域接受癌症治疗后，心脏损伤得到了有据可查的记录。尽管如此，流行病学调查结果表明，即使低剂量的辐射，晚期心血管疾病的风险也会增加。而且，重离子在宇宙射线中的特殊生物学效力可能会大大增加这种风险。但是，目前尚不清楚低剂量时辐射诱发的心血管效应是否有阈值。减轻空间环境对心脏功能的影响的主要对策是体育锻炼，抗氧化剂，营养保健品和辐射屏蔽。重离子在宇宙射线中的特殊生物学效力可能会大大增加这种风险。但是，目前尚不清楚低剂量时辐射诱发的心血管效应是否有阈值。减轻空间环境对心脏功能的影响的主要对策是体育锻炼，抗氧化剂，营养保健品和辐射屏蔽。重离子在宇宙射线中的特殊生物学效力可能会大大增加这种风险。但是，目前尚不清楚低剂量时辐射诱发的心血管效应是否有阈值。减轻空间环境对心脏功能的影响的主要对策是体育锻炼，抗氧化剂，营养保健品和辐射屏蔽。