本文由小咖机器人翻译整理

期刊来源：Ann Intern Med

原文链接：https://doi.org/10.7326/M24-3504

摘要内容如下：

背景

极端高温与更大的心血管死亡风险相关。介导这种联系的病理生理机制尚不清楚。

客观

量化热暴露对心肌血流量（MBF）的需求。

设计

实验研究。（ClinicalTrials.gov：NCT04549974）

设置

基于实验室。

参与者

61名参与者，包括20名健康的年轻人（平均年龄28岁）、21名健康的老年人（平均年龄67岁）和20名患有冠状动脉疾病（CAD）的老年人（平均年龄70岁）。

干预

参与者被加热，直到他们的核心温度上升1.5°C；在热暴露前和核心温度每增加0.5°C时测量MBF。

测量

主要结果是通过正电子发射断层扫描-计算机断层扫描测量的MBF。次要转归包括心率、血压和体重变化。

结果

当核心温度升高1.5°C时，健康年轻人（变化，0.8 mL/min/G[95%CI，0.5至1.0 mL/min/G]）、健康老年人（变化，0.7 mL/min/G[CI，0.5至0.9 mL/min/G]）和患有CAD的老年人（变化，0.6 mL/min/G[CI，0.3至0.8毫升/分钟/克]）。与暴露前的值相比，分别变化了2.08倍（CI，1.75至2.41倍）、1.79倍（CI，1.59至1.98倍）和1.64倍（CI，1.41至1.87倍）。在事后分析中，7名成年CAD患者（35%）有无症状热诱导心肌缺血的影像学证据。

局限性

在这项基于实验室的研究中，加热时间被限制在100分钟左右，参与者的运动和液体摄入也受到限制。参与者避免剧烈运动和吸烟；停止酒精和咖啡因的摄入；并在加热前停用β受体阻滞剂、钙通道阻滞剂和硝酸甘油。

结论

热暴露使核心温度增加1.5°C，几乎使MBF加倍。MBF的变化并不因年龄或CAD的存在而不同，但一些患有CAD的老年人可能会出现无症状性心肌缺血。

主要资金来源

加拿大卫生研究院。

英文原文如下：

Abstracts

BACKGROUND  Heat extremes are associated with greater risk for cardiovascular death. The pathophysiologic mechanisms mediating this association are unknown.

OBJECTIVE  To quantify the myocardial blood flow (MBF) requirements of heat exposure.

DESIGN  Experimental study. (ClinicalTrials.gov: NCT04549974).

SETTING  Laboratory-based.

PARTICIPANTS  61 participants, comprising 20 healthy young adults (mean age, 28 years), 21 healthy older adults (mean age, 67 years), and 20 older adults with coronary artery disease (CAD) (mean age, 70 years).

INTERVENTION  Participants were heated until their core temperature increased 1.5 °C; MBF was measured before heat exposure and at every increase of 0.5 °C in core temperature.

MEASUREMENTS  The primary outcome was MBF measured by positron emission tomography-computed tomography. Secondary outcomes included heart rate, blood pressure, and body weight change.

RESULTS  At a core temperature increase of 1.5 °C, MBF increased in healthy young adults (change, 0.8 mL/min/g [95% CI, 0.5 to 1.0 mL/min/g]), healthy older adults (change, 0.7 mL/min/g [CI, 0.5 to 0.9 mL/min/g]), and older adults with CAD (change, 0.6 mL/min/g [CI, 0.3 to 0.8 mL/min/g]). This represented a 2.08-fold (CI, 1.75- to 2.41-fold), 1.79-fold (CI, 1.59- to 1.98-fold), and 1.64-fold (CI, 1.41- to 1.87-fold) change, respectively, from preexposure values. Imaging evidence of asymptomatic heat-induced myocardial ischemia was seen in 7 adults with CAD (35%) in post hoc analyses.

LIMITATIONS  In this laboratory-based study, heating was limited to about 100 minutes and participants were restricted in movement and fluid intake. Participants refrained from strenuous exercise and smoking; stopped alcohol and caffeine intake; and withheld β-blockers, calcium-channel blockers, and nitroglycerin before heating.

CONCLUSION  Heat exposure that increases core temperature by 1.5 °C nearly doubles MBF. Changes in MBF did not differ by age or presence of CAD, but some older adults with CAD may experience asymptomatic myocardial ischemia.

PRIMARY FUNDING SOURCE  Canadian Institutes of Health Research.

-----------分割线---------

点击链接：https://www.mediecogroup.com/community/user/vip/categories/ ，成为医咖会员，获取12项专属权益。