Allemann Y, Saner H, Meier B
Departement Innere Medizin, Universitätsspital Bern.
Schweiz Med Wochenschr. 1998 Apr 25;128(17):671-8.
Acute exposure to high altitude produces hypoxia-associated stimulation of the sympathetic nervous system. This response is further enhanced by physical activity and induces an increase in heart rate and blood pressure. Consequently, cardiac work, myocardial oxygen consumption, and coronary blood flow are also increased. During the first 4 days of acute exposure to moderate or high altitude, coronary patients are at greatest risk of untoward events. Gradual ascent, early limitation of activity to a lower level than tolerated at low altitude, pre-ascent physical conditioning and rigorous blood pressure control should all help to minimise the cardiac risk. At altitudes of 2500 to 3000 m or lower, an asymptomatic coronary patient with good exercise tolerance, without exercise induced signs or symptoms of ischemia, and with an ejection fraction of the left ventricle > 50%, is at very low risk. However, several days' acclimatization before high-level activity at moderate or high altitude is recommended. High risk coronary patients should be investigated more carefully and precautionary measures should be more stringent. Left and right cardiac function and pulmonary artery pressure are the most helpful parameters for evaluation and counselling of patients with non-ischemic heart disease who plan to ascend to moderate or high altitudes. When advising patients who intend to fly as passengers in commercial aircraft, it is important to know that in-flight atmospheric pressure conditions in commercial jet aircraft approach altitude equivalents of 1500 to 2400 m. Propeller-driven planes are rarely pressurized but usually fly at altitudes below 3300 m. Relatively strict contraindications for air travel by coronary patients are uncomplicated myocardial infarction within the last 2 weeks, complicated myocardial infarction within the last 6 weeks, unstable angina, thoracic surgery within the last 3 weeks, and poorly controlled congestive heart failure, arrhythmia, or hypertension.
急性暴露于高海拔环境会引发与缺氧相关的交感神经系统刺激。这种反应会因体力活动而进一步增强，并导致心率和血压升高。因此，心脏做功、心肌耗氧量和冠状动脉血流量也会增加。在急性暴露于中度或高海拔环境的最初4天里，冠心病患者发生不良事件的风险最高。逐渐上升、将活动早期限制在低于低海拔耐受水平、 ascent前的身体锻炼和严格的血压控制都有助于将心脏风险降至最低。在海拔2500至3000米或更低的高度，无症状的冠心病患者，运动耐量良好，无运动诱发的缺血体征或症状，左心室射血分数>50%，风险非常低。然而，建议在中度或高海拔进行高强度活动前进行几天的适应。高危冠心病患者应进行更仔细的检查，预防措施应更严格。左、右心功能和肺动脉压是评估和咨询计划攀登至中度或高海拔的非缺血性心脏病患者最有用的参数。在为打算乘坐商业飞机的患者提供建议时，重要的是要知道，商业喷气式飞机飞行中的大气压力条件接近海拔1500至2400米的等效高度。螺旋桨驱动的飞机很少增压，但通常在海拔3300米以下飞行。冠心病患者航空旅行的相对严格禁忌症包括过去2周内未并发的心肌梗死、过去6周内并发的心肌梗死、不稳定型心绞痛、过去3周内的胸外科手术以及控制不佳的充血性心力衰竭、心律失常或高血压。
