How does hyperventilation cause coronary vasospasm?

Hyperventilation may be an important cause of coronary vasospasm and chest pain. 1 The mechanism likely revolves around the competition between the effects of hydrogen and calcium ions on the smooth muscle of coronary arteries. 2

Respiratory alkalosis induced by hyperventilation causes a reduction of hydrogen ions which, under physiologic conditions, compete with calcium ion, an important trigger for arterial smooth muscle contraction. Lower hydrogen ion concentrations tips the balance in favor of calcium’s effects on transmembrane channels and myofibrillar ATP-ase of the smooth muscle and causes vasoconstriction.2

In fact, hyperventilation has been used to reproduce coronary spasm during angiography in patients with non-obstructive coronary artery disease and angina symptoms.The efficacy of hyperventilation in inducing an alkalotic state during this test is verified by obtaining an arterial blood gas after 6-minutes of hyperventilation.  A basic Tris-buffer to enhance alkalotic provocation was also used in earlier studies. 2

In addition to producing spasm and angina, hyperventilation-induced alkalosis has been associated with frank transmural myocardial infarction and ischemia-related arrhythmias such as ventricular tachycardia. 2,4,5

So in the appropriate context, hyperventilation may not be so benign!

References:

  1. Freeman LJ, Nixon PGF. Chest pain and the hyperventilation syndrome-some aetiologic considerations. Postgrad Med J 1985;61:957-61. http://pmj.bmj.com/content/postgradmedj/61/721/957.full.pdf
  2. Yasue HM, Nagao S, Omote A, et al. Coronary arterial spasm and Prinzmetal’s variant form of angina induced by hyperventilation and Tris-buffer infusion. Circulation 1978;58:56-62. https://www.ncbi.nlm.nih.gov/pubmed/25720
  3. Zaya M, Mehta PK, Merz NB, etal. Provocative testing for coronary reactivity and spasm. J Am Coll Cardiol 2014; 63:103-9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3914306/pdf/nihms549572.pdf
  4. Magarian GJ, Jones S, Calverley T. Hyperventilation testing for coronary vasospasm: induction of spontaneous ventricular tachycardia in association with transmural ischemia without obstructive coronary disease. 1990; 120:1447-49. http://journal.chestnet.org/article/S0012-3692(16)52837-2/pdf
  5. Chelmowski MK, Keelan MH. Hyperventilation and myocardial infarction. Chest 1988;93:1095-96. https://www.ncbi.nlm.nih.gov/pubmed/3359829

 

 

Contributed by Ramya Chitra Mosarla, Medical Student, Harvard Medical School

How does hyperventilation cause coronary vasospasm?

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