Effect of the degree and speed of tilt on the immediate heart rate reaction.

The effect of the degree and speed of tilt on the immediate heart rate reaction measuring cardiac autonomic nerve function was evaluated in nine healthy subjects. The results showed that the tilt angle determined the immediate increase in heart rate. The increase in heart rate was maximal when a 90 degrees tilt was performed. After the immediate increase there was a transient decrease in heart rate after rapid tilts (2-5 s). A rapid 90 degrees tilt is preferred when automatic nerve function should be evaluated from the immediate heart rate response.