HISTORY: The patient was an elderly male admitted to the hospital with a 10-year history of episodes of chest tightness, which had been exacerbated for 2 months. History of lower wall myocardial infarction for 10 years. Past history of type 2 diabetes mellitus for 3 years and hyperlipidemia. Denied hypertensive disease, smoker for 20 years. Family history denied. Outpatient imaging showed severe lesions in three branches and recommended treatment with coronary artery bypass grafting, which the patient refused. Diagnosis: coronary artery disease, unstable angina, old inferior wall myocardial infarction, type 2 diabetes mellitus, hyperlipidemia. Strategy: first deal with chronic occlusive lesions of the right coronary artery. Positive technique: apply a soft guidewire and then a hard guidewire, then deal with the left coronary artery at a later stage. The JL3.5 is more conducive to catheterization than the femoral route due to the angulation of the opening. The Trek balloon demonstrates unique passability that exceeds that of the Corsair microcatheter. The mother and daughter catheters are inserted deeper into the mid-coronary for increased support. The finecross microcatheter is further penetrated to increase distal support. Intravascular ultrasound clarifies the true lumen and helps to understand the hematoma. Ultimately, 3 stents were successfully implanted in the right crown, and the patient had a repeat coronary angiogram today with smooth vessels in the right crown. After handling the left crown today, the trunk and LAD were successfully completed, and the vessel area LM8.2mm2 was observed by IVUS.