What Is Percutaneous Coronary Intervention?

In 1844, Bernard inserted a catheter into the heart of an animal for the first time. In 1929, the German doctor Forssmann first inserted a urinary catheter from his elbow vein and sent it to the right atrium through the superior vena cava. First. Based on this, right heart catheter and left heart catheterization have been carried out successively. In 1953, Seldinger created percutaneous vascular puncture technology, thus ending the history of vascular incisions required for interventional procedures. In 1958, Sones inadvertently inserted a catheter into the right coronary artery during an aortic angiogram, and injected a contrast agent to the right coronary angiography. This accidental and dangerous event became the beginning of modern coronary intervention technology. In 1967, Judkins performed femoral artery puncture for coronary angiography. Since then, this technique has been further developed and promoted in the diagnosis of coronary heart disease. Gruentzig of Germany first performed percutaneous coronary angioplasty in 1977. Since then, PTCA technology has been rapidly promoted from Europe to the Americas, and its indications have continued to expand. Related industrial products are also developing rapidly, and various operating equipment (such as catheters and balloons) are continuously improved to adapt to the treatment of different lesions. In 1986, Puol and Sigmart implanted the first coronary stent into the human body. Intracoronary stent implantation can significantly reduce the restenosis of PTCA, can handle dissection and acute vascular occlusion, and has become another milestone in coronary intervention. In 2003, drug-eluting stent (DES) was put into clinical practice, which significantly reduced the restenosis rate of the stent, and made coronary interventional treatment enter a new era ^[1] .

Chen Yan	(Chief physician)	Coronary Heart Disease Diagnosis and Treatment Center of Fuwai Cardiovascular Hospital
Gao Zhan	(Deputy Chief Physician)	Coronary Heart Disease Diagnosis and Treatment Center of Fuwai Cardiovascular Hospital
Zhang Yin	(Attending physician)	Coronary Heart Disease Diagnosis and Treatment Center of Fuwai Cardiovascular Hospital

Percutaneous coronary intervention (PCI) refers to a method of transcatheter catheterization to clear narrow or even occluded coronary arterial lumen, thereby improving myocardial blood perfusion.

Development of percutaneous coronary intervention

In 1844, Bernard inserted a catheter into the heart of an animal for the first time. In 1929, the German doctor Forssmann first inserted a urinary catheter from his elbow vein and sent it to the right atrium via the superior vena cava, and took the first cardiac catheter chest radiograph in medical history, pioneering the development of human cardiac catheter technology First. Based on this, right heart catheter and left heart catheterization have been carried out successively. In 1953, Seldinger created percutaneous vascular puncture technology, thus ending the history of vascular incisions required for interventional procedures. In 1958, Sones inadvertently inserted a catheter into the right coronary artery during an aortic angiogram, and injected a contrast agent to the right coronary angiography. This accidental and dangerous event became the beginning of modern coronary intervention technology. In 1967, Judkins performed femoral artery puncture for coronary angiography. Since then, this technique has been further developed and promoted in the diagnosis of coronary heart disease. Gruentzig of Germany first performed percutaneous coronary angioplasty in 1977. Since then, PTCA technology has been rapidly promoted from Europe to the Americas, and its indications have continued to expand. Related industrial products are also developing rapidly, and various operating equipment (such as catheters and balloons) are continuously improved to adapt to the treatment of different lesions. In 1986, Puol and Sigmart implanted the first coronary stent into the human body. Intracoronary stent implantation can significantly reduce the restenosis of PTCA, can handle dissection and acute vascular occlusion, and has become another milestone in coronary intervention. In 2003, drug-eluting stent (DES) was put into clinical practice, which significantly reduced the restenosis rate of the stent, and made coronary interventional treatment enter a new era ^[1] .

Indications for percutaneous coronary intervention

1. For patients with chronic stable coronary heart disease with extensive myocardial ischemia, interventional therapy is one of the effective methods to relieve symptoms.

2. Patients at high risk of unstable angina pectoris and non-ST-elevation myocardial infarction are encouraged to intervene as soon as possible. High-risk patients mainly include: recurrent angina pectoris or myocardial ischemia or impaired activity tolerance during adequate drug treatment; elevated blood myocardial enzymes; new ST segment depression on electrocardiogram; heart failure or mitral regurgitation or original Worsened flow; hemodynamic instability; sustained ventricular tachycardia; received interventional therapy within 6 months; had coronary artery bypass grafting, etc.

3. The key to the early treatment of patients with acute ST-segment elevation myocardial infarction is to open the infarct-related blood vessels (IRA), save the dying myocardium as much as possible, reduce the risk of death and improve long-term prognosis in patients with acute phase. According to the timing of the patient's visit and the initial treatment, it is divided into different strategies:

(1) Direct PCI: IRA was performed directly within 12 hours of the onset of acute myocardial infarction. Direct PCI can enable IRA in a timely, effective and continuous manner. It is recommended that the "door-balloon opening" time be controlled within 90 minutes. For 12 hours (especially within 3-12 hours), especially for patients with contraindications to thrombolysis, direct PCI should be performed if possible. Direct PCI is also recommended for patients who have had onset for more than 12 hours but still have symptoms of ischemia, cardiac dysfunction, hemodynamic instability, or severe arrhythmia. For patients with cardiogenic shock, the time can be relaxed to 36 hours. For patients who have had onset for more than 12 hours and have no symptoms of ischemia, PCI is not recommended.

(2) Transit PCI : The first-patient hospital does not have the conditions for direct PCI, and the patients cannot be immediately thrombolytic, then they are transferred to a hospital with PCI conditions for direct PCI.

(3) Remedy PCI : IRA is still in occlusion after thrombolytic failure. For IRA PCI.

(4) Facilitating PCI : Within 12 hours of onset, patients planning to undergo PCI have planned use of thrombolytic or anti-platelet drugs before PCI in order to open IRA as soon as possible.

Classification of percutaneous coronary interventions

1. Percutaneous coronary angioplasty (PTCA)

Using the femoral or radial approach, the guide catheter is sent to the coronary artery to be expanded, and then a balloon of the corresponding size is sent along the guide wire to the narrow segment, with appropriate pressure and time according to the characteristics of the lesion Expansion to achieve the purpose of lifting stenosis ^[2] .

However, the incidence of acute coronary occlusion and restenosis in PTCA alone is higher. Acute occlusion is more common within 24 hours after surgery, and the incidence is 3% -5%, which can cause acute myocardial infarction and even death. Stenosis usually occurs within 6 months after surgery, with an incidence of 25% -50%. Patients will re-exist angina symptoms and need to be revascularized again. Due to the above limitations, it is rarely used alone.

2. Coronary stent implantation

Placing a stent made of stainless steel or alloy material with a gap into the coronary artery to support the vessel wall during the stenosis stage of the coronary artery to maintain blood flow. Generally, it can reduce the elastic contraction of the blood vessel after PTCA, and it is possible to close the PTCA. Dissection greatly reduces the occurrence of acute vascular occlusion during PTCA. However, due to the intimal hyperplasia of the stent placement site, restenosis within the stent is still a major problem. The early application was a bare metal stent (BMS) with a restenosis rate of 20% -30% within 6 months after surgery. Drug eluting stent (DES) adds a coating and drug with good biocompatibility on the metal surface of the bare stent. After this stent is placed, the proliferation of smooth muscle is inhibited and the restenosis is further reduced (10 %the following). However, DES delayed the endothelialization of blood vessels and caused a higher incidence of stent thrombosis.

3. Rotational atherectomy

Coronary rotatory grind is to use an olive-shaped spin grinder with diamond particles to selectively remove fibrotic or calcified atherosclerotic plaques based on the principle of "selective cutting" without cutting elastic tissue. And normal coronary arteries. It is mainly used for severe stenosis with severe calcification.

4.Intracoronary thrombus aspiration

A negative pressure suction catheter is used to remove the thrombus from the coronary arteries. Mostly used for thrombotic lesions or great saphenous vein vascular disease.

5. Cutting balloon formation

It is to install 3-4 mini blades longitudinally on the balloon. When the balloon begins to expand, the blade cuts the proliferative tissue in the vessel stenosis into 3-4 parts, and then the balloon fully expands the lesion. It is mainly used for in-stent restenosis or fibrous tissue hyperplasia.

6. Others: excimer laser angioplasty, intracoronary radiotherapy, etc. It can be used for the treatment of restenosis in stent, but it has less clinical application.

Percutaneous coronary intervention

1. Femoral artery path: The femoral artery is relatively large and the puncture success rate is high. Disadvantages are long bed rest time and high incidence of puncture-related complications, such as bleeding, hematoma, pseudoaneurysm, arteriovenous fistula, and retroperitoneal hematoma.

2. Radial artery path: The postoperative compression time is short, no bed rest is needed, the patient's discomfort is lighter than the femoral artery path, and there are fewer complications, so it has gradually become the current preferred path for PCI.

Drugs related to percutaneous coronary intervention

1. Aspirin: 3-5 days before surgery, 100-300mg per day. 100mg daily after operation, long-term administration.

2. Clopidogrel: Take 75mg daily 4-6 days before surgery or 300mg 6 hours before surgery. After taking 75mg per day after surgery, the duration varies from 1 month to 1 year, depending on the type of stent and the individual situation of the patient. There are still some similar new antiplatelet drugs under development, including prasugrel and ticagrelor.

3. Platelet IIb / IIIa receptor antagonists: abciximab, etibapin, and tirofiban. All are intravenous drugs.

4, heparin: intravenous application. It is mainly used in PCI.

5. Low-molecular-weight heparin: subcutaneous injection. Enoxaparin, Natraparin, Dalparin, etc.

6. Factor Xa inhibitor: subcutaneous injection. Fondaparinux sodium.

7, direct thrombin inhibitor: intravenous application. Bivalududin and Agagaban.

Complications of percutaneous coronary intervention

1. Coronary arterial spasm: During coronary angiography or intervention, the local or diffuse continuous contraction of the coronary arteries causes stenosis or even occlusion of the lumen. The incidence is between 1% -5%. Coronary spasm can be spontaneous or induced by contrast or device manipulation. Coronary spasm can be asymptomatic, or it can show obvious symptoms of ischemia, such as chest pain, myocardial infarction, and arrhythmia, which can cause death in severe cases. Coronary spasm can be intracoronally injected with nitroglycerin or a calcium antagonist.

2. Coronary artery perforation: It is relatively rare, but it is more harmful. It is manifested as extravasation of contrast medium into the pericardium, which can lead to pericardial hemorrhage and pericardial tamponade in severe cases. Most coronary perforations are related to interventional procedures, such as: the guide wire penetrates the blood vessel wall; rotary grinding causes damage to the blood vessel wall tissue; excessive balloon inflation leads to excessive stretching of the blood vessel wall. In addition, coronary artery tortuosity, calcification, angulation or occlusive disease can easily lead to coronary perforation during operation. Women, advanced age, diabetes, and renal insufficiency are also high risk factors for coronary perforation.

3, coronary dissection: more common in balloon pre-dilated lesions, is the main cause of acute coronary occlusion. Appearance is visible intraluminal filling defects, extraluminal contrast agent retention or visible endometrial slices.

4. Acute coronary occlusion: Blockage or slowing of coronary blood flow during or after PCI. It is one of the major complications in the PTCA era, which can lead to angina pectoris, myocardial infarction and even death. After stent application, the incidence of acute coronary occlusion was significantly reduced.

5. In-stent thrombosis: a rare but serious complication. Divided into acute thrombosis (within 24 hours after surgery), subacute thrombosis (within 24 hours and 30 days after surgery), advanced thrombosis (within 30 days and 1 year after surgery), and very advanced thrombosis (within 1 year after surgery) ).

6. Slow reflow or no reflow: refers to the phenomenon that the large epicardial coronary blood vessels have been released from stenosis during PCI, but the distal forward blood flow is significantly slowed or lost, and myocardial cell perfusion cannot be maintained. The reason is complex, and the exact mechanism is not yet clear. It may be caused by thrombus or plaque debris embolizing the distal microvessels.

7, stent fall off: less frequent. It is related to factors such as lesion characteristics, equipment and operator's operation.

8. Peripheral vascular complications: Complications seen by femoral artery puncture include thrombosis, embolism, bleeding, hematoma, retroperitoneal hematoma, pseudoaneurysm, and arteriovenous fistula. Radial artery pathway can be seen complications such as radial artery spasm, occlusion, forearm hematoma, local hemorrhage, and osteofascial compartment syndrome.

9 bleeding complications: due to the application of antiplatelet drugs before and after PCI, intravenous heparin needs to be given during surgery, so perioperative bleeding is a more common complication of PCI. Mainly include: bleeding at the puncture site, gastrointestinal bleeding, and even cerebral hemorrhage. Therefore, antithrombotic drugs should be reasonably applied to patients at high risk of bleeding, correct reversible risk factors, and try to prevent them before they occur.

10. Contrast nephropathy: After the application of iodine-containing contrast agents, renal damage may occur in some patients, with an incidence of less than 5%. It is more common within 2-3 days after operation, and the serum creatinine level is 25% or 0.5 mg / dl higher than that before the contrast agent. Most can recover on their own, with very few irreversible kidney injuries.