Effects of hyperbaric oxygen preconditioning on cardiac stress markers after simulated diving

• Published in: Physiological reports Vol. 1; no. 6; pp. e00169 - n/a
• Main Authors: Jørgensen, Arve, Foster, Philip P., Brubakk, Alf O., Eftedal, Ingrid
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01-11-2013; Blackwell Publishing Ltd
• Subjects: Biomarkers; Calcium-binding protein; Cardioprotection; Cardiovascular system; Congestive heart failure; Crystallin; decompression illness; Diving; Embolisms; gas embolism; Gene expression; Heart failure; Hyperbaric oxygen; hyperbaric oxygen preconditioning; Ischemia; Laboratory animals; Original Research; Physiology; Pressure; Proteins; Pulmonary arteries; Studies; Troponin; Troponin T; Ultrasound; diving; Cardioprotection; hyperbaric oxygen preconditioning; decompression illness; gas embolism
• ISSN: 2051-817X; 2051-817X
• DOI: 10.1002/phy2.169

Hyperbaric oxygen preconditioning (HBO‐PC) can protect the heart from injury during subsequent ischemia. The presence of high loads of venous gas emboli (VGE) induced by a rapid ambient pressure reduction on ascent from diving may cause ischemia and acute heart failure. The aim of this study was to investigate the effect of diving‐induced VGE formation on cardiac stress marker levels and the cardioprotective effect of HBO‐PC. To induce high loads of VGE, 63 female Sprague–Dawley rats were subjected to a rapid ambient pressure reduction from a simulated saturation dive (50 min at 709 kPa) in a pressure chamber. VGE loads were measured for 60 min in anesthetized animals by the use of ultrasonography. The animals were divided into five groups. Three groups were exposed to either diving or to HBO‐PC (100% oxygen, 38 min at 303 kPa) with a 45 or 180 min interval between HBO‐PC and diving. Two additional groups were used as baseline controls for the measurements; one group was exposed to equal handling except for HBO‐PC and diving, and the other group was completely unexposed. Diving caused high loads of VGE, as well as elevated levels of the cardiac stress markers, cardiac troponin T (cTnT), natriuretic peptide precursor B (Nppb), and αB‐crystallin, in blood and cardiac tissue. There were strong positive correlations between VGE loads and stress marker levels after diving, and HBO‐PC appeared to have a cardioprotective effect, as indicated by the lower levels of stress marker expression after diving‐induced VGE formation.
e00169
Cardiac ischemia and acute heart failure may develop from exposure to high loads of vascular gas emboli due to a rapid ambient pressure reduction (e.g., diving, aviation, spaceflight) or as a result of gas entry into the vasculature during inhospital procedures (e.g., extracorporal bypass and invasive catheters). This study shows that hyperbaric oxygen preconditioning appears to prevent cardiac injury induced by vascular gas embolism in rats.