Influence of Coronary Artery Disease on +Gz Tolerance: A Preliminary Study.

摘要

Current Air Force policy restricts pilots, with even minimal coronary artery disease (CAD), from flying high-performance aircraft. Liberalization of this policy is being considered, but additional data are needed for more informed decision. Eleven miniature swine (MS) were placed on a high cholesterol/high fat diet for 1 year. Five additional MS were maintained on a standard control swine diet (no cholesterol) over the same time. A vascular access port (VAP) was surgically placed into the superior vena cava. The 16 unanesthetized MS were placed under +Gz-stress one or two times each, using an alternating 4-8 +Gz simulated aerial combat maneuver (SACM) with 10 sec at each +Gz level. The MS were protected with an abdominal bladder anti-G suit. At the end of the SACM, Tc-99m was infused into the VAP and the MS were scanned for myocardial perfusion approximately 1 h later. Three MS died before data collection, one at 6 mos and two at 9 mos. Histopathology showed moderate-to-severe CAD in the three MS. Control and experimental plasma cholesterol levels (mg%) were: total = 77 and 422; ratio = 2.3 and 8.6; LDL = 35 and 353, respectively. Dysrhythmias and T-wave alterations during +Gz were seen equally in both the control and experimental MS. However, ST-T segment changes during +Gz were observed in all of the cholesterol MS, but not in the control MS.