Catheter treatment of narrowings and blockages in the coronary arteries
Percutaneous coronary intervention (PCI), also known as coronary angioplasty, is a catheter-based procedure used to treat the narrowed coronary arteries in patients with ischaemic heart disease. PCI is performed by an interventional cardiologist, a specially trained heart specialist, usually following a diagnostic coronary angiography. During PCI, a cardiologist places a tiny deflated cylinder-shaped balloon at the tip of a catheter under the X-ray control to the site of blockage in the coronary artery. The balloon is then inflated to crush the plaque into the artery walls. The procedure usually involves implantation of stents (metallic mesh) to the site of original narrowing or blockage to prop it open. Traditional ("bare-metal stents", BMS) have been largely superseded by drug-eluting stents (DES), which release certain drugs to prevent restenosis of the coronary artery. Bioresorbable stents are so far the newest devices, which aim to provide mechanical support to the vessel in the acute stage and then disappear, avoiding the long-term problems with implanted foreign material.
An alternative to PCI is coronary artery bypass grafting (CABG), which bypasses stenotic arteries using arteries (most commonly LIMA, left internal mammary artery) and veins (usually harvested from legs). The choice of revascularisation between PCI and CABG depends on many factors, including number, complexity, location and functional impact of coronary artery lesions, diabetes mellitus and age. Syntax score based on angiographic classifications of coronary lesions allows calculation of the risk of major adverse cardiac events (MACE), i.e. cardiac death, nonfatal myocardial infarction, or target lesion revascularisation. Studies showed that patients with low Syntax score (less advanced disease) do prognostically well with both PCI and CABG, but patients with high Syntax score (more advanced disease) are better off with CABG. Often in the absence of prognostic difference, coronary revascularisation with PCI is considered as less invasive, with a lower risk of stroke but more often needs to be repeated in the future, whereas CABG is a more extensive initial undertaking but with less need for repeated procedures.
Coronary angioplasty is a safe and routine procedure with a risk of major complications less than 1% in elective patients. Common mild problems are transitory chest discomfort during the procedure because the balloon briefly blocks off the blood supply to the heart muscle and some bruising at the insertion point in the wrist or groin, partly due to the use of antiplatelet drugs; significant haematoma or pseudoaneurysm requiring surgical repair is uncommon. Allergic reaction to the contrast dye is rare with newer agents. Mild transitory deterioration of kidney function is common, but kidney failure requiring dialysis is rare. Vascular access complications are less common and less severe when the procedure is performed via the radial artery (the artery in the wrist). Sometimes, angioplasty is not successful in opening up the blockages, especially in chronically occluded arteries.
Major complications are death, stroke, myocardial infarction and aortic dissection. A heart attack during angioplasty may require emergency CABG. A cardiac surgeon with a complete surgical team is on standby during PCI at the Alexandra Hospital to cover this unlikely scenario. The risk of complications in PCI is higher in elderly patients, the presence of kidney disease and diabetes, women, patients with heart failure and complex coronary artery disease.
Please bring all your medications with you on the day of the procedure. If you have diabetes, please follow the instructions given to you. If you take warfarin or other anticoagulants (apixaban, edoxaban, rivaroxaban, dabigatran), you will be given advice for managing your medication before, during and after the procedure. If you have diabetes and are taking metformin, you should stop taking the tablets the day before your procedure. Do not stop taking other diabetic pills. Bring your glucose tablets or a snack with you on the day of your procedure. You can drink water, clear tea and black coffee (without milk) up to 2 hours before the procedure. Milk, food, sweets, tea or coffee with milk can be consumed up to 6 hours before the procedure. Chewing gum and smoking is not permitted on the day of surgery. Please take all your regular medication (except metformin) as usual with a sip of water.
Please bring your dressing gown and slippers with you. You will be asked to put on a gown and paper pants during your admission. Your details will be checked and a name band placed on your wrist. The procedure is performed in the cath lab (catheter laboratory), a special x-ray room that looks like a small operating theatre.
There will be several members of staff in the room during the procedure, including a doctor, nurses, cardiac physiologists, a radiographer. During a coronary angiogram, you will be lying on an x-ray table. Your heartbeat will be monitored using electrodes and an ECG machine. The radiographer will move the table and camera into position to take the x-ray pictures. A local anaesthetic will be used to numb the wrist (less often groin), and usually, sedation will be given to help you relax. Once numb, the doctor will insert a small tube, called a sheath, into the artery. A guiding catheter is then inserted through the sheath and passed through the artery until it reaches the heart and the origin of the coronary arteries. Low dose x-rays are used to guide the catheter into the correct position. Once the catheter is in place, a special dye will be injected into the catheter, which will flow through your coronary arteries and outline them on an x-ray.
The coronary guidewire is then inserted through the guiding catheter into the coronary artery and passed across the narrowing or blockage. With the guidewire in place, the doctor inserts the balloon catheter on the guidewire and gently pushes it forward until it reaches the blockage. Then the balloon is inflated to compress the plaque and expand the coronary artery to improve the blood flow. Usually, a mesh tube (stent) mounted on the balloon catheter is left in the artery to keep it open. When the procedure is over, the balloon catheter, guidewire and sheath are removed, and an inflatable plastic band is placed on the wrist or pressure device on the groin to keep the puncture site clean and dry.
After the procedure, you will return to the ward, where nursing staff will monitor your blood pressure and pulse. They will also check the wound. After a period of resting in bed, you will be allowed to mobilise. Your nurse will keep you informed of your progress. The interventional cardiologist will explain the results to you and schedule a follow-up. A letter will be sent to your GP confirming this information. You will be able to eat and drink; it is vital to drink plenty of fluid as this will help to flush the contrast dye from your body. Providing there are no complications, you will be allowed to go home approximately 2-3 hours after the procedure. If the test was performed via the wrist artery, the dressing could be removed in 24 hours.
During the first 48 hours after your angiogram, you should not do anything strenuous to prevent bruising and bleeding. It is normal to feel some discomfort in the wound and a simple painkiller, such as Paracetamol, is usually helpful. You must not drive for 24 hours after discharge. Please arrange for a responsible adult to drive you home and stay with you for 24 hours. If the wound begins to bleed, you should press firmly over the area for 10 minutes.