Apan Vayu Mudra is used for healing and strengthening the heart. I find it good for calming down the heart rate when feeling stressed or anxious.
Bend the index finger and let the tip rest on the ball of your thumb, or what I like to call the drum stick. Then take the tips of your middle and ring fingers to touch the tip of the thumb. Extend the pinky finger. Do this on both hands. Use this mudra to find inner stillness.