Despite 50 years of experience in space, only about 530 individuals have ventured into this dangerous environment, and only 12 have been subjected to the hazards of the moon. With the recent loss of Neil Armstrong, who, on Apollo 11 was the world’s first moon walker, vital information has now become available.
Due to the National Aeronautic and Space Administration’s (NASA’s) restriction of independent access to medical data, there could be no independent analysis of the 8 moon walkers who remain alive. Now, for the first time, a comparison can be made between the shortest lunar mission and one of the longest missions—Apollo 15, involving James Irwin—with, in turn, greater dust exposure for much longer durations in the habitats until return back to Earth, and significant differences in predisposing factors for endothelial dysfunction.
The combination of dust inhalation and invariable reductions of a vessel dilator, atrial natriuretic peptide, could have been responsible for Irwin’s severe stress test hypertension of blood pressure (BP) >275/125 mm Hg on the day after return.(1, 2) But also, Irwin showed a single resting blood pressure of 145/110 mm Hg a month before his mission. A contributing factor, conducive to magnesium (Mg) loss with heat exposure, is that Irwin did not properly set the cooling temperature of his space suit (personal communication, Mary Irwin), while experiencing noon temperatures of 121.1°C (250°F). In addition, Apollo 15 astronauts in training were exposed to “intense summer heat” conducive to an Mg loss from sweating and renal Mg loss—compounding invariable Mg deficits with space flight. In addition, there was no access to water due to a malfunction of Irwin’s in-suit water device.1, 2 Neil Armstrong, on the other hand, showed a significantly elevated stress test—diastolic BP during a bicycle stress test, providing greater BP accuracy by arm support than on a treadmill—the day after splashdown (up to 160/135 mm Hg); this is consistent with ischemic left ventricular dysfunction with a specificity of 100% in a study of 102 subjects.(3) This necessitates comparison with a resting BP of 110/85 mm Hg a month before lift-off, with no resting BP after return available—before the stress test; a difference of diastolic BP in comparison with the resting level, far above the cut-off abnormal level >15 mm Hg.
When I discovered 6 years ago that Irwin returned from his Apollo 15 mission with a stress test BP of >275/125 in just 3 minutes on the day after return from his 12-day mission, and that both David Scott and Irwin experienced several cardiovascular complications from inhaling dust brought into the habitats on their space suits—with impairment in cardiac function, manifested by abnormal stress tests in both4—I was puzzled because these complications had not been reported with the other 5 Apollo missions. I had attempted to explain this with the assumption that the variation in the quantity/quality of dust was responsible; that this was triggered by the variations of the 6 lunar locations. NASA apparently was puzzled as well, and considered Apollo 15 an “anomaly.” Now, with the discovery, via information provided by NASA through the Freedom of Information Act (FOIA), that Neil Armstrong had also experienced, following his 8-day mission at age 38, evidence consistent with impairment in left ventricular function, I realize that I had been mistaken.
Now we have evidence, which I also obtained through the FOIA, that a 4th astronaut, Alan Shepard, the oldest at age 47 years, also showed an abnormal stress test, with a drop in his BP from a maximum stress test level of 210/85 mm Hg at the 16th minute, down to 185/70 mm Hg (Table).
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– William Rowe, MD
This article originally appeared in the July 2013 issue of The American Journal of Medicine.
