Alexander J K
Department of Medicine, Baylor College of Medicine, The Veterans Affairs Medical Center, Houston, TX 77030, USA.
Tex Heart Inst J. 1999;26(4):258-63.
To evaluate the effects of aging on cardiac rhythm at high altitude, I wore a Holter monitor at age 75 during a climb to 5,100 m on Mt. Kilimanjaro, then compared findings with those from my climb to 5,895 m at age 65. Holter leads were placed to identify left or right ventricular source of ectopy, and on the 2nd ascent arterial oxygen saturation was monitored by finger oximetry. Sea-level testing revealed no evidence of cardiac disease. During ascent from 4,710 to 5,100 m, when arterial oxygen saturation reached 70%, heart rate was higher (123 vs 116 beats per minute), and frequency of left ventricular premature complexes was greater (56 vs 50 per hour) than on the earlier ascent. Nine 3- to 5-complex runs of left ventricular tachycardia were recorded during climbing, resting, or sleeping, and there was 1 run of 14 complexes at 250 beats per minute during the climb near 5,100 m. These observations suggest that aging increases sympathetic response or sensitivity, or both, to hypoxia during exercise, and even during sleep. Also, our focus should perhaps be on sympathetic stimulation rather than on pulmonary hypertension as a cause of arrhythmia in unacclimatized older persons at high altitude.
为评估衰老对高海拔地区心律的影响，我在75岁攀登乞力马扎罗山至海拔5100米时佩戴了动态心电图监测仪，然后将结果与65岁攀登至海拔5895米时的结果进行比较。放置动态心电图导联以确定异位心律的左心室或右心室来源，在第二次攀登时通过手指血氧饱和度仪监测动脉血氧饱和度。海平面测试未发现心脏病迹象。在从4710米上升至5100米的过程中，当动脉血氧饱和度达到70%时，心率更高（每分钟123次 vs 116次），左心室早搏的频率也比早期攀登时更高（每小时56次 vs 50次）。在攀登、休息或睡眠期间记录到9次3至5个复合波的左心室心动过速发作，在接近5100米的攀登过程中，有1次发作14个复合波，心率为每分钟250次。这些观察结果表明，衰老会增加运动期间甚至睡眠期间对缺氧的交感神经反应或敏感性，或两者皆有。此外，对于未适应高海拔环境的老年人，我们或许应将关注重点放在交感神经刺激而非肺动脉高压作为心律失常的原因上。
