Mild coronary artery stenosis has no impact on cardiac and vascular parameters in miniature swine exposed to positive acceleration stress.

Abstract

Exposure of pilots' heart to acceleration-associated stress (+Gz stress) is an adverse effect of high-performance aviation. The occurrence of coronary heart diseases is one of the most frequent medical causes leading to cessation of flying. To assess the effects of +Gz stress on coronary artery stenosis (CAS) in a minimally invasive miniature swine model with a fast recovery. The proximal left anterior descending branch was ligated in 20 swine using silk suture. CAS degree (mild, moderate, severe) was analyzed by quantitative computerized angiography. Five swine underwent a sham operation. +Gz stress exposure was performed and venous blood was collected before/after exposure. Plasma C-reactive protein (CRP), endothelin (ET)-1, angiotensin (Ang) II and urotensin 2 (U2) levels were measured. CAS models were successful in 18 animals. Two swine exhibited ventricular fibrillation during the procedure and died. Plasma CRP, ET-1, Ang II and U2 changed significantly after maximal tolerated +Gz stress exposure (all P < 0.05). After maximal tolerated +Gz stress exposure, plasma CRP, ET-1, Ang II and U2 levels increased in the moderate and severe stenosis groups, compared with the sham group (all P < 0.05), but there was no significant difference between the mild stenosis group and the sham group (all P > 0.05). The fully endoscopic operation method successfully generated animal models of different degrees of CAS. Plasma CRP, ET-1, Ang II and U2 levels increased after +Gz stress exposure with increasing CAS severity. Animals with mild stenosis showed no ill effect under +Gz stress, suggesting that pilots with mild stenosis might be allowed to continue flying, but it must be confirmed in humans.