A fast pulse means a pulse rate greater than one breath and four to. A weak pulse is a modern term, a proper noun, referring to a pulse that comes to be thin, soft and sunken, soft and slippery. Weak pulse is mostly seen in deficiency evidence of Qi and blood deficiency. Blood deficiency pulse channel is not full, then the pulse is thin; qi deficiency then the pulse is weak, then the pulse is sunken and soft and weak. When the pulse is significantly weakened or even disappears when inhaling, it is called odd pulse. The odd pulse is one of the important signs of pericardial tamponade, mainly due to the reduction of left ventricular beat volume. During pericardial tamponade, the increase in negative thoracic pressure during inspiration increases the blood volume of the pulmonary circulation, but the return flow from the body circulation to the right ventricle cannot increase accordingly because of the restricted diastole of the heart. What is the main cause of a fast and weak pulse? A weak pulse is due to insufficient expansion of the heart, which is mainly due to insufficient strength of the heart muscle, weakness, small heart, etc. Because the heart is the “blood pump”, the heart power is not enough, the natural blood supply is not enough, just like the water pressure is not enough, a higher place is easy to stop the water. It is not excluded that the blood volume itself is not enough, it is a sign of weakness. The causes of tachycardia vary widely, the most common is the heart itself has a disease, such as various types of heart disease, myocarditis, heart failure, etc.. Tachycardia can also be caused by systemic diseases such as anemia, fever, acute and chronic infections, shock, hyperthyroidism, and gas poisoning. In normal people, tachycardia can be accelerated by exercise or emotional excitement, by taking strong alcohol, strong tea, strong coffee or smoking, and by taking certain drugs.