1 Cardiovascular Division Rayne Institute St Thomas' Hospital King's College London London United Kingdom.
2 Population Health Research Institute St George's University of London United Kingdom.
J Am Heart Assoc. 2018 Jul 17;7(14):e008837. doi: 10.1161/JAHA.118.008837.
Background Cold air inhalation during exercise increases cardiac mortality, but the pathophysiology is unclear. During cold and exercise, dual-sensor intracoronary wires measured coronary microvascular resistance ( MVR ) and blood flow velocity ( CBF ), and cardiac magnetic resonance measured subendocardial perfusion. Methods and Results Forty-two patients (62±9 years) undergoing cardiac catheterization, 32 with obstructive coronary stenoses and 10 without, performed either (1) 5 minutes of cold air inhalation (5°F) or (2) two 5-minute supine-cycling periods: 1 at room temperature and 1 during cold air inhalation (5°F) (randomized order). We compared rest and peak stress MVR , CBF , and subendocardial perfusion measurements. In patients with unobstructed coronary arteries (n=10), cold air inhalation at rest decreased MVR by 6% ( P=0.41), increasing CBF by 20% ( P<0.01). However, in patients with obstructive stenoses (n=10), cold air inhalation at rest increased MVR by 17% ( P<0.01), reducing CBF by 3% ( P=0.85). Consequently, in patients with obstructive stenoses undergoing the cardiac magnetic resonance protocol (n=10), cold air inhalation reduced subendocardial perfusion ( P<0.05). Only patients with obstructive stenoses performed this protocol (n=12). Cycling at room temperature decreased MVR by 29% ( P<0.001) and increased CBF by 61% ( P<0.001). However, cold air inhalation during cycling blunted these adaptations in MVR ( P=0.12) and CBF ( P<0.05), an effect attributable to defective early diastolic CBF acceleration ( P<0.05) and associated with greater ST -segment depression ( P<0.05). Conclusions In patients with obstructive coronary stenoses, cold air inhalation causes deleterious changes in MVR and CBF . These diminish or abolish the normal adaptations during exertion that ordinarily match myocardial blood supply to demand.
运动时吸入冷空气会增加心脏死亡率，但病理生理学尚不清楚。在寒冷和运动期间，双传感器冠状动脉内导线测量冠状动脉微血管阻力（MVR）和血流速度（CBF），心脏磁共振测量心内膜下灌注。
42 名（62±9 岁）接受心导管检查的患者，其中 32 名患有阻塞性冠状动脉狭窄，10 名没有，分别进行了以下两种操作之一：（1）5 分钟冷空气吸入（5°F）或（2）2 个 5 分钟仰卧位循环周期：1 个在室温下，1 个在冷空气吸入（5°F）（随机顺序）。我们比较了休息和峰值应激 MVR、CBF 和心内膜下灌注测量值。在无阻塞性冠状动脉狭窄的患者（n=10）中，休息时冷空气吸入使 MVR 降低 6%（P=0.41），增加 CBF 20%（P<0.01）。然而，在有阻塞性狭窄的患者（n=10）中，休息时冷空气吸入使 MVR 增加 17%（P<0.01），CBF 减少 3%（P=0.85）。因此，在接受心脏磁共振方案的有阻塞性狭窄的患者（n=10）中，冷空气吸入降低了心内膜下灌注（P<0.05）。仅对有阻塞性狭窄的患者进行了此方案（n=12）。室温下循环使 MVR 降低 29%（P<0.001），增加 CBF 61%（P<0.001）。然而，循环时冷空气吸入使 MVR 和 CBF 的这些适应性降低（P=0.12），这一效应归因于早期舒张期 CBF 加速的缺陷（P<0.05），并与更大的 ST 段压低（P<0.05）相关。
在有阻塞性冠状动脉狭窄的患者中，冷空气吸入会导致 MVR 和 CBF 的有害变化。这些变化削弱或消除了运动期间通常使心肌血液供应与需求相匹配的正常适应性。
