This refers to a pathological phenomenon in which the pulse rhythm is normal but the beat is alternately strong and weak. That is, a strong pulse is touched, followed by a weak pulse, then a strong pulse, then a weak one. The alternating pulse is an important and serious sign of cardiovascular system disease and is a manifestation of myocardial damage, which is evident in the sitting position. It is caused by the left ventricle showing alternating changes in the strength of contraction, which is a valuable clue for the diagnosis of left heart failure and often indicates left heart insufficiency. It may appear or become larger if the patient is supine with the head tilted upward. The examiner should ask the patient to hold his or her breath to be sure that the alternating strong and weak pulse palpated at this time is not related to breathing. The alternating pulse diet is as follows. 1. antibacterial and anti-inflammatory foods are desirable; 2. diuretic and dehydrating foods are desirable; 3. foods rich in high quality protein are desirable.