Lady Chen's heart palpitations.

Chen Lihua was flushed red with embarrassment as she touched the kiss marks Liu Longwei left on her neck. She started cursing him and only stopped when she felt better. Then she used a concealer to cover the faint mark left as an aftermath of their actions, the previous night.

Back at the Chen Villa, after the devastated Aunt Lin left crying with her daughter, Old Master Chen asked Butler Li to make a call to Lady Chen's assistant so he could reschedule the meeting at the company, with the excuse that Lady Chen was down with a fever.

An hour later, Lady Chen woke up. 

At first, when she regained consciousness, she didn't open her eyes. Instead, she had her eyes closed as she listened to her surroundings. She could hear the sound coming from the heart monitor in the room, and the sound caused by the dripping drops of the drip connected to her vein.

Lady Chen has a sharp hearing, and thus very sensitive to sounds, and Chen Lihua got that trait from her.