1
My heartbeat is very fast.
Start by signing 'my', then perform the sign for 'heartbeat'. To convey the meaning effectively, you can actually tap your chest more rapidly to show the fast pace, and then finish with the sign for 'fast'. Your facial expression should also reflect a sense of urgency or excitement.
2
I can feel your heartbeat.
Point to yourself for 'I', sign 'feel' by brushing your middle finger up your chest, point to the other person for 'your', and then sign 'heartbeat' over your own chest. This is a great phrase to practice combining pronouns with sensory verbs and body-related vocabulary.
3
The doctor listened to my heartbeat.
Sign 'doctor' by tapping your wrist, then sign 'listen'. Follow this by signing 'my', and finally perform the sign for 'heartbeat'. You can use your eye gaze and body language to show the interaction between the doctor and yourself during the examination.