Acceleration-induced atrioventricular dissociation: hemodynamic consequences.
A rest, compensatory mechanisms are able to make up for the loss of a properly timed atrial systole. At maximal stress or in a severely compromised patient, however, proper atrial function may be crucial for maintaining optimum cardiac output. We report a case of an apparently healthy male subject who developed A-V dissociation during +Gz stress and subsequently could not maintain vision at the higher (+7 Gz) levels. Anatomic, geometric, and physiologic considerations suggest that the loss of atrial function is probably associated with the loss of roughly 30 torr in arterial pressure during high +Gz stress. Since the subject was an avid jogger, the etiology of the A-V dissociation was considered to be due to physiologically enhanced vagal tone. This case, therefore, suggests that special attention should be given to the physical fitness programs designed for individuals in a unique profession, such as piloting single-seat high-performance fighter aircraft.
D000054:Acceleration / Q000009:adverse effects*; D000328:Adult; D000337:Aerospace Medicine; D001794:Blood Pressure; D006112:Gravitation; D006327:Heart Block / Q000209:etiology* / Q000503:physiopathology; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D013575:Syncope / Q000209:etiology; D014785:Vision, Ocular / Q000502:physiology