The American Journal of Medicine. Volume 122, Issue 11, Page e1, 2009.

Extraordinary Hypertension after a Lunar Mission

To the Editor:

“The farther backward you can look, the farther forward you are likely to see.”

Winston Churchill

According to information obtained in 2006 through the Freedom of Information Act, 41-year-old James Irwin returned from his 12-day Apollo 15 mission in 1971 with extraordinary stress test hypertension (>275/125 mm Hg) by the third minute of exercise, probably the day after return, because there was a drop in stress test blood pressures subsequently.1. NASA (National Aeronautics and Space Administration) had not published this. There was no evidence of an acute renal insult. On the day of return, Irwin showed cyanosis of the fingernails from minutes 18-21 of a stress test; this supports my Apollo 15 Space Syndrome, in which I postulated that the severe fingertip pain experienced by both Irwin and Scott on the lunar surface, before exposure to dust inhalation in the lunar module, was triggered by endothelial dysfunction with peripheral vasospasm. 1.Irwin's heart rate climbed to 167 beats per minute, whereas Scott's was 130 beats per minute while configuring the lunar rover. Irwin had an episode of syncope complicating brief bigeminy after return to the command module. While asleep, either Irwin or Scott experienced a heart rate down to 28 beats per minute. During reentry, Irwin experienced classical angina and such severe dyspnea he was unable to talk during the 4-minute radio blackout at 7 Gs. Twenty-one months later, Irwin experienced the first of 4 myocardial infarctions, and he died 20 years later. 1.

The mechanisms for Irwin's apparent spontaneous recovery with return in a few days to pre-mission blood pressure levels—with, however, hypertension before his mission (145/110 mm Hg) 1.—are postulated to be related to return to pre-mission levels of a protective vasodilator, atrial natriuretic peptide—reduced with space flight because of invariable reductions of plasma volume. Also, with invariable malabsorption and loss of skeletal muscle storage sites, even after this brief 12-day mission, there are significant reductions of magnesium ions required for atrial natriuretic peptide release. 2., 3.

This case demonstrates the usefulness of stress tests in patients with suspected endothelial dysfunction. 4. Furthermore, it shows the importance of atrial natriuretic peptide, because on earth, with exposure to dust, hypertension either might not occur, or is likely to be less severe than the degree of hypertension postulated to be triggered by heavy dust exposure 1.—brought in on the space suits—in the habitat for a total of about 40 hours, an additional 2 days orbiting the moon on Apollo 15, and during the 3-day journey home. Having monitored over 5000 symptom-limited maximum stress tests (Bruce protocol), I have never seen hypertension to this degree nor observed cyanosis developing during a stress test. With space flight there is a loss of at least 3 antioxidants: water, red blood cells, and magnesium, 2. with, in turn, the potential for endothelial dysfunction. 1.Magnesium deficits contribute to hypertension along with the potential for arrhythmias, clots, and endothelial dysfunction from catecholamine elevations and increased angiotensin effect, with potential vicious cycles involving the latter 2. 1. Because of invariable malabsorption, a reliable subcutaneous delivery device must be developed. Furthermore, because of space flight-malabsorption, deterioration of some pharmaceuticals, and potential liver and kidney dysfunction, there is, at this time, no option for pharmaceutical use, particularly for very long space flight. This raises the question as to whether gene therapy studies 5. should begin at this time if we are to succeed in space.

Acknowledgement 

I am greatly indebted to Lee Saegesser (former archivist of NASA) who provided me with a wealth of information.

William J. Rowe, MD, FBIS
Former Assistant Clinical Professor of Medicine, Medical University of Ohio at Toledo, Toledo, Ohio

References 

1. Rowe WJ. Moon dust may simulate vascular hazards of urban pollution. J Br Interplanet Soc. 2007;60:133–136.

2. Leach Huntoon CS, Grigoriev AI, Natochin YV. American Astronautical Society. Fluid and Electrolyte Regulation in Spaceflight. San Diego, CA: Univelt; 1998.

3. Wong NLM, Hu DDK, Wong EFC. Effect of dietary magnesium on atrial natriuretic peptide release. Am J Physiol. 1991;261:H1353–H1357.

4. Chang H-J, Chung J, Choi SY, et al. Endothelial dysfunction in patients with exaggerated blood pressure response during treadmill test. Clin Cardiol. 2004;27:421–425.

5. Lin K-F, Chao J, Chao L. Human atrial natriuretic peptide gene delivery reduces blood pressure in hypertensive rats. Hypertension. 1995;26:847–853.