Percutaneous Coronary Intervention (PCI) is a treatment that improves myocardial perfusion by unblocking the lumen of a narrowed or even occluded coronary artery via a cardiac catheter technique. History In 1844, Bernard first inserted a catheter into the heart of an animal, and in 1929, Forssmann, a German physician, first inserted a urinary catheter through his own elbow vein into the right atrium via the superior vena cava, and took the first cardiac catheterization chest film in medical history, pioneering the development of cardiac catheterization technology in humans. In 1953, Seldinger created the technique of percutaneous vascular puncture, thus ending the history of interventional operations requiring vascular dissection. 1958, during an aortogram, Sones inadvertently inserted a catheter into the right coronary artery and injected a contrast medium to visualize the right coronary. In 1967, Judkins performed coronary angiography using femoral artery puncture, and this technique was further developed and promoted in the diagnosis of coronary artery disease. Percutaneous coronary angioplasty was first performed by Gruentzig in Germany in 1977. Since then, the PTCA technique has rapidly spread from Europe to the Americas, and the indications have been expanding. In 1986, Puol and Sigmart placed the first coronary stent in the human body. In 2003, Drug-eluting Stent (DES) was introduced into the clinic, which significantly reduced the restenosis rate of stents and brought coronary intervention into a new era. PCI treatment indications 1. Chronic stable angina For patients with chronic stable coronary artery disease with evidence of a large range of myocardial ischemia, interventional therapy is one of the effective methods to relieve symptoms. Unstable angina and non-ST-segment elevation myocardial infarction Patients at high risk for unstable angina and non-ST-segment elevation myocardial infarction are advocated for early intervention. Patients at high risk include: recurrent angina or myocardial ischemia or low activity tolerance on adequate drug therapy; elevated blood cardiac enzyme index; new ST-segment depression on ECG; development of heart failure or mitral regurgitation or worsening of existing regurgitation; hemodynamic instability; persistent ventricular tachycardia; intervention within 6 months; previous coronary artery bypass grafting, etc. 2. Acute ST-segment elevation myocardial infarction The key to early treatment of patients with acute ST-segment elevation myocardial infarction is to open the infarct-related vessels (IRA), save the dying myocardium as much as possible, reduce the risk of death in the acute phase and improve the long-term prognosis. Depending on the timing of the patient’s visit and the initial treatment, there are different strategies: (1) Direct PCI: PCI is performed within 12 hours of the onset of acute myocardial infarction to open the IRA directly, which allows for timely, effective and sustained opening of the IRA. For patients with ischemic symptoms, cardiac dysfunction, hemodynamic instability, or severe arrhythmias beyond 12 hours of onset, direct PCI is also recommended; for patients with cardiogenic shock, the time can be extended to 36 hours. PCI is not recommended for patients who have been onset for more than 12 hours and have no ischemic symptoms. (2) Transfer PCI: If the first hospital is not available for direct PCI and the patient cannot be thrombolized immediately, the patient will be transferred to a hospital that is eligible for PCI for direct PCI. (3) Remedial PCI: PCI performed for IRAs that are still occluded after thrombolysis failure. (4) Easy PCI: Within 12 hours of the onset of the disease, patients who are to undergo PCI are planned to use thrombolytic or antiplatelet drugs before PCI to open the IRA as early as possible. PCI technique classification 1. Percutaneous coronary balloon angioplasty Using the femoral route or radial route, a guiding catheter is sent to the coronary artery opening to be dilated, and then a balloon of the appropriate size is sent along the guiding wire to the stenotic segment. The balloon is then delivered to the stenotic segment along the guidewire and dilated with the appropriate pressure and time according to the characteristics of the lesion, in order to release the stenosis. However, PTCA alone has a high incidence of acute occlusion and restenosis of the coronary artery. Acute occlusion is usually seen within 24 hours after surgery, with an incidence of 3-5%, and can lead to acute myocardial infarction and even death. In stenosis, which usually occurs within 6 months after surgery, with an incidence of 25%-50%, patients will again develop anginal symptoms and mostly require revascularization. Due to the above limitations, it is rarely used alone anymore. Coronary artery stent implantation places a mesh stent made of stainless steel or alloy with gaps into the stenotic phase of the coronary artery to support the vessel wall and maintain the usual blood flow, which can reduce the elastic retraction of the vessel after PTCA and close the possible entrapment of PTCA, greatly reducing the occurrence of acute vessel occlusion during PTCA. However, postoperative in-stent restenosis is still a major problem due to proliferative changes in the intima at the stent placement site. The early application was Bare Metal Stent (BMS) with a restenosis rate of 20%-30% within 6 months after surgery. Drug Eluting Stent (DES) adds a biocompatible coating and drugs to the metal surface of the bare stent, and after placement of this stent, smooth muscle proliferation is inhibited, resulting in a further reduction in restenosis (below 10%). However, DES has a higher incidence of in-stent thrombosis due to delayed endothelialization of the vessel. 2.Coronary artery spinning The coronary artery spinning procedure is based on the principle of “selective cutting” by using an olive-shaped spinning head with diamond particles to selectively remove fibrotic or calcified atherosclerotic plaques without cutting the elastic tissue and normal coronary arteries. It is mainly used for severe stenosis with heavy calcification. 3.Intracoronary thrombus aspiration The thrombus is extracted from the coronary artery with a negative pressure aspiration catheter. It is mostly used for thrombotic lesions or saphenous vein bridge vascular lesions. Cutting balloon generation is a procedure in which 3-4 miniature blades are installed longitudinally on the balloon. When the balloon starts to expand, the blades cut the hyperplastic tissue at the stenosis into 3-4 parts, and then the balloon fully expands the lesion. It is mainly used for in-stent restenosis lesions or lesions with predominantly fibrous tissue hyperplasia. 4.Other Excimer laser angioplasty, intracoronary radiation therapy, etc. They can be used for the treatment of in-stent restenosis, but are less commonly used in clinical practice. PCI interventional route 1.Femoral artery route The femoral artery is thicker and has a high success rate of puncture. The disadvantages are long postoperative bed rest and high incidence of puncture-related complications, such as bleeding, hematoma, pseudoaneurysm, arteriovenous fistula and retroperitoneal hematoma. 2, radial artery route The postoperative compression time is short, no bed rest is required, patient discomfort is less than that of the femoral artery route, and there are fewer complications, so it is gradually becoming the preferred route for PCI treatment. PCI-related drugs 1.Aspirin 100-300mg per day 3-5 days before surgery, 100mg per day after surgery, for a long time. 2.Clopidogrel 75mg daily 4-6 days before surgery or 300mg 6 hours before surgery. 75mg daily after surgery for 1 month to 1 year, depending on the type of stent and individual patient’s condition. There are also some similar new anti-platelet drugs in development, including Pragrel, Tegretol, etc. 3. Platelet IIb/IIIa receptor antagonists Aximab, etidiotide, and tirofiban, etc. All are intravenous drugs. 4.Heparin Intravenous application. Mainly used in PCI. 5.Low molecular heparin subcutaneous injection. Enoxaparin, natriuretic heparin, dalteparin, etc. 6.Coagulation factor Xa inhibitor Subcutaneous injection. Fondaparinux sodium. 7.Direct thrombin inhibitors Intravenous application. Bivalirudin, Argatroban.