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 differential diagnosis of myocarditis, the main disease with a fast and weak pulse? 1, primary endocardial elastin fiber hyperplasia Similarities are heart enlargement, recurrent heart failure, visible cardiogenic shock, but the disease occurs mostly in small infants under 6 months of age, endocardial elastin fiber hyperplasia and myocardial degeneration and other lesions involving the entire heart, electrocardiography and echocardiography show left ventricular hypertrophy is predominant, clinical manifestations are recurrent symptoms of left heart failure, cardiac hypertrophy, heart sounds Weakened, no murmur or mild systolic murmur, no history or symptoms of viral infection, no laboratory test changes of viral myocarditis. 2, toxic myocarditis with a history of serious infection or drug poisoning, often complicated by severe pneumonia, typhoid, sepsis, diphtheria, scarlet fever and other diseases, often with the recovery of the symptoms of the original infection, the use of thujone base, antimony, etc. can cause myocarditis, with the reduction or discontinuation of drugs and gradually improve or recover. 3, rheumatic carditis with a history of recurrent respiratory infections, rheumatic activity symptoms such as high fever, multiple wandering arthritis, annular erythema and subcutaneous nodules, etc., with valvular lesions appear mitral valve area systolic and/or diastolic murmur, laboratory tests can be seen increased sedimentation, C-reactive protein positive, increased mucin and anti-hemolytic streptococcal “O “, increased potency of streptococcal kinase with positive pharyngeal swab culture and other evidence of streptococcal infection. 4, Keshan disease Similar points are heart enlargement, heart rhythm disturbance, heart failure or cardiogenic shock, but Keshan disease is endemic, the onset is often in an endemic area, there are more seasons (such as winter and spring in the northeast, southwest summer for more) and age object points (such as young women in the northeast, southwest 2-5 years old children), electrocardiogram to ST-T changes, right bundle branch conduction block, low voltage is more common; arrhythmia rhythm The heart rhythm is variable, fast-changing, and the heart rate is significantly increased or slowed down as a feature, the heart is more significantly enlarged on X-ray, the beat is significantly weakened, and it cannot be retracted to normal after controlling heart failure, and most of them become chronic after the acute period, sometimes it can cause cerebral embolism and convulsions or hemiparesis due to the detachment of blood clots attached to the wall in the heart. Thyroid nodules.