Paravertebral Block for Postoperative Analgesia in Children Undergoing Lateral Incision Cardiac Surgery With CBP

Inclusion Criteria: 1. Children aged 6-14 years old; 2. Children who have atrial septal defect or ventricular septal defect scheduled for lateral incision cardiac surgery with cardiopulmonary bypass; 3. Inform consent signed by the parent or legal guardian. Exclusion Criteria: 1. Patients who were intubated, on mechanical circulatory support, or with intravenous inotropes before surgery; 2. Emergency surgery or redo cardiac surgery; 3. Body weight more than 50kg; 4. Diagnosed as severe pulmonary hypertension; 5. Left ventricular ejection fraction less than 45% in most recent echocardiography before surgery; 6. Allergic to ropivacaine or other regular anesthetics, analgesics or other medications regularly used in the study; 7. Preoperative platelet counts less than 100\*109/L, coagulopathy or bleeding tendency ; 8. Preoperatively using antiplatelets or anticoagulants; 9. Diagnosed with scoliosis or other contraindications for PVB.