Pectoral-qi is a kind of essential qi in the body. Which accumulates in the chest. When transported from the chest, it is divided into ying-qi (the nutrient qi) and wei-qi (the defensive qi), which are then distributed to the rest of the body.
Pectoral-qi has two functions. One is to warm and nourish the heart vessels to maintain their functions in transporting qi and blood. The other is to warm and nourish the lung and the upper respiratory tract to maintain their function in governing respiration and vocalization. If the pectoral-qi is insufficient, it will lead to palpitations, shortness of breath and weak voice, etc.