Cardiac arrhythmias during aerobatic flight and its simulation on a centrifuge.

INTRODUCTION: It is well known that accelerations during centrifuge training and during flight can provoke cardiac arrhythmias. Our study was designed to investigate both the similarities and differences between heart rhythm disturbances during flights and centrifuge tests. METHOD: There were 40 asymptomatic, healthy pilots who performed two training flights and were also tested in a human centrifuge according to a program of rapid onset rate acceleration (ROR) and of centrifuge simulation of the actual acceleration experienced in flight (Simulation). During the flight and centrifuge tests ECG was monitored with the Holter method. ECG was examined for heart rhythm changes and disturbances. RESULTS: During flights, premature ventricular contractions (PVCs) were found in 25% of the subjects, premature supraventricular contractions (PSVCs) and PVCs with bigeminy in 5%, and pairs of PVCs in 2.5% of subjects. During the centrifuge tests, PVCs were experienced by 45% of the subjects, PSVCs and pairs of PVCs by 7.5%, and PVCs with bigeminy by 2.5%. Sinus bradycardia was observed during flights and centrifuge tests in 7.5% of subjects. DISCUSSION: Comparative evaluation of electrocardiographic records in military pilots during flights and centrifuge tests demonstrated that: 1) there were no clinically significant arrhythmias recorded; and 2) the frequency and kind of heart rhythm disturbances during aerobatic flight and its simulation on a centrifuge were not identical and did not occur repetitively in the same persons during equal phases of the tests.

Centrifuge braking effects on cardiac arrhythmias occurring at high +Gz acceleration.

Abrupt onset and offset of acceleration induces hemodynamic changes that activate a number of reflex cardiovascular responses. At high +Gz on a centrifuge, apparently healthy subjects occasionally develop a serious cardiac arrhythmia such as supraventricular tachycardia or asystole. We report on four such cases and examine the effect of rapid centrifuge braking (1 G x s(-1)) on the arrhythmia. It appears that the hemodynamic consequences and reflex responses produced by rapid deceleration may have a positive effect on paroxysmal supraventricular tachycardia, slowing the heart rate or terminating the arrhythmia. On the other hand, deceleration tends to intensify sinus bradycardia. If further study confirms these findings, medical monitors and centrifuge operators may want to consider using gradual braking in cases of bradycardia.