During a lively and crowded ball hosted by Mr. Bingham at Ne…

During a lively and crowded ball hosted by Mr. Bingham at Netherfield Park, Miss Lydia Bennet stands to watch Mr. Wickham enter the room, then suddenly swoons. In preparing for the ball, she was determined to present the slimmest possible figure and instructed her maid to lace her corset with excessive zeal. Which of the following physiological mechanisms most directly explains her fainting spell?