Kawasaki Disease (Kawasaki Disease), also known as cutaneous mucocutaneous lymph node syndrome (MCLS), was first reported by the Japanese Kawasaki Fusaku in 1967, is a vasculitis syndrome of undetermined etiology; 50% of the disease develops within the age of 2 years, and 80% of the disease develops within the age of 4 years; it is more common in boys than girls, and the ratio of male to female is 1.6:1, and it is the main cause of ischemic heart disease in pediatrics. It is the main cause of ischemic heart disease in pediatrics and may be a risk factor for coronary atherosclerosis in adulthood, and is one of the most common causes of acquired heart disease in children. [Etiology and pathogenesis] The cause of this disease is unknown, and a large number of epidemiologic and clinical observations indicate that Kawasaki disease is caused by infectious factors. At present, it is believed that TSST-1, SPE and other microbial toxins such as super antigen pathogenic theory and bacterial HSP65 mimic the host’s own antigen pathogenic role may play an important role in its pathogenesis. High activation of the immune system and immunoinjurious vasculitis are the prominent features of Kawasaki disease, and the cascade of cytokine amplification and aberrant T-cell-mediated immune responses are the basis of the vasculitic damage in Kawasaki disease. Clinical manifestations] Kawasaki disease can be clinically divided into 3 phases, i.e., acute, subacute and recovery phases. (I) Acute phase From onset to about 2 weeks. About 95% of the children have fever, mostly persistent fever, may be flaccid fever, more than 5 days, usually 4-30 days or longer, a few fever lasts less than 5 days, often mild children, the average duration of about 2 weeks; the application of antibiotic treatment is ineffective. Very few children with fever lasting more than 30 days, often drug-resistant Kawasaki disease, or easily combined with coronary artery aneurysm. Conjunctival congestion in both eyes About 90% of the children have obvious conjunctival congestion in both eyes after 3-4 days of fever, and a few children have bulging blood vessels in the bulbar conjunctiva, but the above manifestations disappear after the fever subsides. Attention should be paid to observe whether there is subconjunctival hemorrhage, if necessary, the fundoscopy and slit lamp can be used to check whether there is optic nerve papillary edema, uveitis, vitreous clouding, corneal precipitates. 3, oral mucosal changes More than 90% of children with chapped or crusted lips, bright red, oral mucous membrane flushing, tongue papillae obviously protruding, a typical prune tongue. Diffuse pharyngeal congestion, tonsils may be enlarged or have oozing, but oral ulcers are rare. 4, changes in the ends of the limbs early 75% of children with extensive hard edema of the hands and feet, 90% of children with palmar-plantar and phalangeal skin flushing, or erythema. In the second week of the disease, about 98% of the children may have membrane-like peeling of the skin of the nail bed at the skin migration, which is a typical clinical feature of Kawasaki disease. Rash: About 95% of children with Kawasaki disease have fever for 1~3 days, which may be polymorphic erythema or urticaria-like, measles-like, maculopapular rash or scarlet fever-like rash, with more in the trunk, and the rash may subside after the fever subsides, and blisters and scabs do not occur. 6, lymphadenopathy 50% ~ 70% of the children at the same time or within 3 days of the onset of cervical lymph node enlargement, the diameter can be greater than 1.5cm; hard, painful to the touch, but the surface is not red, not pus; can be unilateral or bilateral, disappear after the fever subsides. This period is often complicated by myocarditis, pericarditis, mitral valve insufficiency, congestive heart failure, etc., and the cause of death is mostly severe heart failure and arrhythmia. (B) subacute stage 2 to 3 weeks after the onset of the disease, in this period, except for a small number of children still have fever, most of the children with all the symptoms gradually disappeared, but arthritis symptoms can occur, the nail bed of the skin at the skin grafts of the characteristic membrane-like peeling phenomenon. This period is often complicated by coronary artery aneurysm, mitral valve insufficiency, delayed arthritis, gallbladder edema, thrombocytosis, etc. The causes of death are mostly myocardial infarction, aneurysm rupture and myocarditis. (C) Recovery period 4-8 weeks after the onset of clinical symptoms disappeared, the vast majority of children 8 weeks after the disease to restore health, but the physical examination should pay attention to the scalp with or without aneurysmal dilatation and vascular murmur and scalp detachment. This period can be complicated by coronary artery and peripheral artery aneurysm, the cause of death is mostly myocardial infarction, ischemic heart disease. [Complications] (a) cardiovascular complications heart and coronary artery involvement occurs mostly in the beginning of the disease 1 ~ 6 weeks, cardiovascular lesions mainly involved in the systemic small and medium arteries and the heart, the incidence of which is about 70% ~ 90%; cardiovascular complications are coronary arteries transient dilatation, coronary artery aneurysm, systemic artery aneurysm, pericarditis or pericardial effusion, myocarditis and myocardial infarction, and in severe cases can be sudden death. (B) non-cardiovascular system complications 1, lung damage Kawasaki disease autopsy showed that 45% to 70% of children with pulmonary arteritis, 30% to 90% of children with interstitial pneumonia changes, and occasional occurrence of pulmonary infarction. Clinically, we can hear the wet shirts and ulcers urinate, pregnant, naiヒ act 2. Digestive system damage: about 25% of children with Kawasaki Disease have mild digestive reactions, some children may have gallbladder edema, and a few severe cases may have paralytic intestinal obstruction or intestinal hemorrhage. Clinical vomiting can be seen, may be accompanied by bile, usually lasts for 1 to 3 days; diarrhea, appearing 2 to 3 days after the disease, for watery, egg drop soup or bile-like stools, lasting for 3 to 7 days, microscopy and culture are normal; abdominal pain, abdominal distension and jaundice, electrolyte disorders and acid-base disorders, etc.. Gastrointestinal symptoms resolve on their own or improve as the condition improves. Right upper abdominal distension is seen in hepatomegaly. There are also reports of pseudo-intestinal obstruction, mechanical intestinal obstruction and appendicitis as the first manifestation. 3.Neurological damage In acute stage, aseptic cerebrospinal meningitis, facial nerve paralysis, acute encephalopathy and febrile convulsions can occur, mostly transient, with good prognosis. In the recovery period, limb paralysis caused by cerebrovascular stenosis or occlusion may occur, but it is rare. Facial nerve palsy is a rare neurological complication of KD. Facial nerve palsy is a self-limiting disease, and can recover on its own in surviving cases, and IVIG can accelerate the recovery process. 4, arthropathy about 30% of children can appear arthritis manifestations, early-onset arthritis more than 1 week after the onset of the sudden emergence of multiple arthropathy, non-steroidal anti-inflammatory drugs react poorly; the joint cavity fluid is purulent, joint fluid leukocytes elevated, up to 35 × 109 / L. Delayed arthritis joint fluid can be seen in the immune complex, and occasional joint hemorrhage. 5, skin and mucous membrane changes in the acute phase can have urethritis, urine routine examination can be seen leukocytosis, mild proteinuria, etc.; male children can have small ulcers in the urethra. May appear psoriasis-like changes; 1 week after the disease, a few children may appear pustule-like granulomatous rash, often distributed in the knee, elbow extension side. One to three months after the disease, individual children’s nail growth stops or appear Beau’s line (Beau’s line). (Auxiliary examination) (a) Laboratory examination 1, blood routine Mild anemia, increased total white blood cells and neutrophils, platelets in the second to third week of the course of the disease increased significantly, the maximum can reach more than 1,000 × 109/L. 2, urine routine About 30% of the children with the disease, the total white blood cells and neutrophils are increased. Urine routine Mild proteinuria and leukocytosis in urine sediment can be found in about 30% of the children. Blood sedimentation: Most of the children have a significant increase in blood sedimentation, with an average of about 70mm/h and a maximum of 180mm/h. C-reactive protein: About 50% of the children have a significant increase in C-reactive protein. 5, immune function Acute IgM, IgG rise, complement generally no change, about 50% to 70% of children with increased immune complexes, while autoantibodies can be seen, such as anti-endothelial cell antibodies, anti-cardiolipin antibodies. 6.Other Acute blood cholinesterase, prealbumin and plasma fibronectin can be reduced, suggesting that coronary aneurysm may occur. (B) X-ray examination: lung texture is increased, a few children have flaky shadow or pleural reaction; heart shadow is often mildly enlarged, and coronary artery calcification can be seen in a few children. (C) Electrocardiography: sinus tachycardia or bradycardia, prolonged P-R interval, prolonged Q-T interval, ST-T changes, QRS wave undervoltage and arrhythmia, etc. When combined with myocardial infarction, typical myocardial infarction-like electrocardiographic features or abnormal Q waves in leads II, III, aVF, and the Q wave/R wave ratio is greater than 0.3, or the QS waveform is presented. (Echocardiography Normal pediatric coronary arteries show two parallel echoes with a continuous echo-less area between them. Normal pediatric coronary artery diameter and age and body surface area is positively correlated, 3 years of age (body surface area of less than 0.5m2) coronary artery diameter less than 2.5mm; 3 ~ 9 years of age (body surface area of 0.5 ~ 1.0m2) coronary artery diameter less than 3.0mm; 9 years of age or older coronary artery diameter less than 3.5mm. coronary artery diameter and the root of the aorta diameter ratio of the age and surface area of the body. The average value is 0.18, the maximum value is 0.25, all less than 0.3. Coronary artery inner diameter is greater than the above normal value or the ratio of coronary artery inner diameter and aortic root inner diameter is greater than 0.3, especially when the expansion of a certain segment exceeds the inner diameter of the neighboring segments by 1.5 times, i.e., coronary artery dilatation, which is mostly transitory, and the course of the disease returns to normal in 3 to 4 weeks. Coronary artery dilatation with an internal diameter of less than 4.0 mm is considered mild dilatation, 4.0 mm to 8.0 mm is considered moderate dilatation, and more than 8.0 mm is considered severe dilatation. If the disease duration is more than 4 weeks, it is still dilated or shows tumor-like changes, then it is an aneurysm. If the internal diameter is greater than 8 mm, it is considered a giant aneurysm. Coronary artery aneurysm in two-dimensional echocardiography shows in the corresponding part of the coronary artery appeared in the tumor-like, clear boundary of the anechoic area; such as coronary artery internal diameter narrowing, the two walls of the wall of the echoes are irregular, asymmetric, the lumen of the continuous anechoic area of the irregular or interrupted, etc. suggests that the coronary artery stenosis and obstruction. The acute stage of Kawasaki disease may show pericardial effusion, enlargement of the heart cavity, diminished amplitude of motion of the septum and the posterior wall of the left ventricle, and sometimes mitral valve prolapse. In the late stage, ischemic heart disease can be seen in the ventricles with segmental abnormal motion. (E) coronary angiography coronary angiography is the most accurate method of diagnosing coronary artery disease, but it is a traumatic test, the indications are: ① history of myocardial ischemia; ② long-term mitral valve insufficiency; ③ chest X-ray shows coronary artery atherosclerosis; ④ echocardiography repeated examinations still have coronary aneurysms. (F) Other tests Electron beam (ultra-high-speed) CT (EBCT) can show the main branches of the coronary arteries, and after silhouette can show the projection image of the coronary arteries alone, in order to clarify the type and location of coronary artery aneurysm.