How does Poe create suspense in this excerpt?

excerpt from “The Pit and the Pendulum” by Edgar Allan Poe

So far, I had not opened my eyes. I felt that I lay upon my back, unbound. I reached out my hand, and it fell heavily upon something damp and hard. There I suffered it to remain for many minutes, while I strove to imagine where and what I could be. I longed, yet dared not to employ my vision. I dreaded the first glance at objects around me. It was not that I feared to look upon things horrible, but that I grew aghast lest there should be nothing to see. At length, with a wild desperation at heart, I quickly unclosed my eyes. My worst thoughts, then, were confirmed. The blackness of eternal night encompassed me.I struggled for breath. The intensity of the darkness seemed to oppress and stifle me. The atmosphere was intolerably close. I still lay quietly, and made effort to exercise my reason. I brought to mind the inquisitorial proceedings, and attempted from that point to deduce my real condition. The sentence had passed; and it appeared to me that a very long interval of time had since elapsed.