Your sister's death was caused by failure of the heart, sir, due to total shock. Literally, she died of fright.

9 seconds sound clip from the The Pit and the Pendulum (1961) movie soundboard.

You can hear this line at 00:16:33 in the Blu-ray version of the movie.

Quote context

[...]

- I want to hear it from you, Doctor.

- Her death was inevitable, I fear, under the circumstances. This castle, this odious atmosphere.

- What has the castle to do with it?

- It's too late now, Charles. I...I didn't want him to know.

- Know what?

- Your sister's death was caused by failure of the heart, sir, due to total shock. Literally, she died of fright.

- Why did you not tell me?

- I thought to spare you, sir.

- You thought to deceive me!

- That's not true.

[...]