Wyss Christophe A, Koepfli Pascal, Fretz Gregory, Seebauer Magdalena, Schirlo Christian, Kaufmann Philipp A
Department of Cardiology, University Hospital, Zurich, Switzerland.
Circulation. 2003 Sep 9;108(10):1202-7. doi: 10.1161/01.CIR.0000087432.63671.2E. Epub 2003 Aug 25.
Although no data exist on the effect of altitude exposure on coronary flow reserve (CFR), patients with coronary artery disease (CAD) are advised not to exceed moderate altitudes of approximately 2500 m above sea level. We studied the influence of altitude on myocardial blood flow (MBF) in controls and CAD patients.
In 10 healthy controls and 8 patients with CAD, MBF was measured by positron emission tomography and 15O-labeled water at rest, during adenosine stress, and after supine bicycle exercise. This protocol was repeated during inhalation of a hypoxic gas mixture corresponding to an altitude of 4500 m (controls) and 2500 m (CAD). Workload was targeted to comparable heart rate-blood pressure products at normoxia and hypoxia. Resting MBF increased significantly in controls at 4500 m (+24%, P<0.01) and in CAD patients at 2500 m (+24%, P<0.05). Altitude had no influence on adenosine-induced hyperemia and CFR. Exercise-induced hyperemia increased significantly in controls (+38%, P<0.01) at 4500 m (despite a reduction in workload, -28%, P<0.0001) but not in CAD patients at 2500 m (moderate decrease in workload, -11%, P<0.05). Exercise-induced reserve was preserved in controls (+10%, P=NS) but decreased in CAD patients (-18%, P<0.005).
At 2500 m altitude, there is a significant decrease in exercise-induced reserve in CAD patients, indicating that compensatory mechanisms might be exhausted even at moderate altitudes, whereas healthy controls have preserved reserve up to 4500 m. Thus, patients with CAD and impaired CFR should be cautious when performing physical exercise even at moderate altitude.
尽管目前尚无关于海拔暴露对冠状动脉血流储备（CFR）影响的数据，但建议冠状动脉疾病（CAD）患者不要超过海拔约2500米的中度海拔高度。我们研究了海拔对对照组和CAD患者心肌血流（MBF）的影响。
在10名健康对照者和8名CAD患者中，通过正电子发射断层扫描和15O标记水在静息、腺苷负荷及仰卧位自行车运动后测量MBF。在吸入相当于海拔4500米（对照组）和2500米（CAD患者）的低氧混合气体期间重复该方案。将常氧和低氧时的工作量目标设定为可比的心率-血压乘积。4500米海拔时对照组静息MBF显著增加（+24%，P<0.01），2500米海拔时CAD患者静息MBF显著增加（+24%，P<0.05）。海拔对腺苷诱导的充血和CFR无影响。4500米海拔时对照组运动诱导的充血显著增加（+38%，P<0.01）（尽管工作量减少，-28%，P<0.0001），但2500米海拔时CAD患者运动诱导的充血未增加（工作量适度减少，-11%，P<0.05）。对照组运动诱导储备得以保留（+10%，P=无显著性差异），但CAD患者运动诱导储备下降（-18%，P<0.005）。
在2500米海拔高度，CAD患者运动诱导储备显著下降，这表明即使在中度海拔高度，代偿机制可能也已耗尽，而健康对照者在高达4500米海拔时仍保留储备。因此，CFR受损的CAD患者即使在中度海拔进行体育锻炼时也应谨慎。
