The electrocardiographic response of females to centrifuge +Gz stress.

Women continue to expand their participation in all areas of aviation, including flying high performance fighter aircraft. Acceleration (+Gz) stress is unique to fighter aviation, therefore it is important to thoroughly understand the electrocardiographic (ECG) response to +Gz stress since it reflects a portion of the cardiovascular +Gz tolerance. A comparison of the ECG response to centrifuge +Gz stress between 685 men and 94 women was made from data existing within a centrifuge data repository. The frequency of occurrence of specific types of atrial, ventricular, and the other most frequently observed ECG changes to +Gz stress were compared for females and males. Females had less atrial ectopy; essentially equivalent premature ventricular contractions (PVC's), multiformed PVC's, paired PVC's; less frequent ventricular and supraventricular tachycardia; and more frequent PVC's in a bigeminal pattern and QRS on T PVC's. Sinus arrhythmia, sinus bradycardia, and increased T-waves post +Gz stress were more frequent in males, with ectopic atrial rhythm and atrioventricular dissociation essentially equivalent in males and females. Although few women have participated in either simulated aerial combat maneuver type centrifuge profiles or centrifuge high-G training, they have shown similar ECG changes including conduction and rhythm disturbances infrequently seen in males, such as +Gz-induced right bundle branch block and high-G bradycardia. Based on the currently available ECG response data, women have no demonstrated unique susceptibility to +Gz-induced ECG changes. Therefore, no contraindication exists to initiating additional acceleration research to fully evaluate women's tolerance to the more stressful, higher levels of +Gz stress.