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Coronary angioplasty and stenting

 
The purpose of a coronary angioplasty (angio = artery and plasty = opening) is to restore or improve blood flow to the heart muscle in order to address coronary heart disease which can cause angina or heart attack. The procedure widens areas in coronary arteries (the arteries supplying blood to the heart muscle) that have been narrowed as a result of the build up of fatty deposits (plaques) inside the artery. Stents are positioned inside the artery as a scaffold to help keep the artery open. The procedure doesn’t usually require an overnight stay in hospital and patients. 

Introduction

Coronary angioplasty and coronary artery stenting are both forms of percutaneous coronary intervention (PCI) and were previously referred to as percutaneous coronary angioplasty (PTCA). The balloon coronary angioplasty procedure was developed in the late 1970s and was first performed in New Zealand in 1981 at Auckland’s Green Lane Hospital. Coronary artery stents were first used in New Zealand in the early 1990’s.

Balloon coronary angioplasty alone was once the main non-surgical technique for treating narrowed coronary arteries (a narrowed area in an artery is referred to as a stenosis; plural = stenoses). However, today approximately 99% of all coronary angioplasty procedures involve the use of a coronary stent. A stent is a small metal mesh tube that is positioned inside a narrowed area in an artery and acts as a scaffold to help keep the artery open. The majority of stents used have a medication coated on them. Once the stent is deployed in the artery the medication is slowly released into the surrounding area to help reduce the chance of the artery renarrowing (known as re-stenosis). Stents with a medication coating are known as drug-eluting stents (DES). Stents without a medication coating are known as bare metal stents (BMS). Most stents are made of metal; however some drug-eluting bioabsorbable stents made of a dissolvable polymer are now in clinical use.

Coronary angioplasty and stenting can be performed on an emergency basis during a heart attack to open a blocked or narrowed artery in order to restore blood flow; or they can be performed as a planned procedure. 

The procedure

Coronary angioplasty and stenting are usually able to be performed as a day-stay procedure, though sometimes an overnight stay in hospital may be required. On admission, the doctor or nurse will take a medical history and perform a physical examination. An electrocardiogram (a tracing of the heart’s electrical activity) and blood tests (to check kidney function and blood counts) will be performed. On some occasions a chest x-ray may also be taken.

Baseline measurement of the blood pressure, heart rate and temperature will be recorded. The enrty site for the procedure will be shaved. The patient cannot eat or drink anything for a few hours before the procedure.

The patient will be taken to the cardiac catheter laboratory and positioned on a specialised procedure table. The patient will be mildly sedated but awake during the procedure and staff in the cardiac catheter laboratory will monitor heart rhythm and rate, blood pressure and blood oxygen levels.

A narrow plastic tube (an introducer sheath) will be inserted into an artery in the wrist (radial approach) or the groin (femoral approach). The area where the introducer sheath is to be inserted will first be cleaned with a sterile solution, before large drapes are positioned to maintain sterility. A local anaesthetic is used to numb the insertion site before the introducer sheath is positioned in the artery. A catheter (a thin flexible tube) is inserted though the introducer sheath and is positioned at the entrance to the coronary arteries. The cardiologist injects x-ray dye through the catheter into the coronary arteries, enabling them to be seen on an x-ray screen. This procedure is known as a coronary angiogram.

A specialised x-ray camera is positioned over the chest during the procedure and is able to move to a number of positions in order for x-ray pictures to be taken from different angles. If a narrowed area is identified, and it is deemed to be suitable for treatment with coronary angioplasty and stenting, this is usually able to be done straight away.

A balloon-tipped catheter is passed through the introducer sheath and is threaded up into the coronary arteries. It is positioned within the narrowed portion of the artery and is checked on the x-ray screen. Once correctly positioned, the balloon is inflated. The inflated balloon opens up the narrowed artery by compressing the plaque and slightly stretching the artery wall. Each balloon catheter is selected to be approximately the same size as the artery and the balloon is made to only inflate to a specific size.
 
Coronary Angioplasty
 
Coronary angioplasty 1
Graphic courtesy of A. Bonsall and MedicineNet.com
 
A stent is deployed in a similar way. The unexpanded stent is tightly crimped on a balloon tipped catheter. The stent is positioned within the narrowed portion of the artery and the balloon is expanded, opening the stent and pushing it up against the artery wall. The balloon is then deflated and removed, leaving the stent behind to act as a scaffold to keep the artery open. Once the stent is in place, it cannot be removed.

Occasionally another balloon tipped catheter is inflated inside the stent to ensure that it is fully expanded. When the cardiologist is satisfied that the artery has been opened sufficiently, and the stent is adequately deployed, more x-ray pictures of the artery will be taken to see how blood flow through the artery has improved. The catheter is then removed.

If the procedure was performed via the wrist artery the introducer sheath is removed at the end of the procedure and a pressure band is applied to help seal the incision site. If the procedure was performed via the groin artery the introducer sheath will be removed on the ward two to four hours after the procedure.

Recovery

Following the procedure, the patient is returned to the ward and blood pressure, heart rate and heart rhythm will be monitored. A nurse will check the insertion site frequently and also check the pulses in the hand (for radial approach) or the foot (for femoral approach). They will advise when the patient can get out of bed and move around. This can occur more quickly with a radial approach.

Fluids may be given intravenously through a small needle (drip) inserted in the hand or arm. This fluid will help to flush the x-ray dye from the kidneys.

Prior to discharge a further ECG and blood tests may be taken. A doctor or nurse will advise about recovery and activity guidelines following discharge from hospital. Some activities, such as heavy lifting, should be avoided for at least a week. Land Transport Safety Authority (LTSA) guidelines prohibit driving for at least two days after a coronary angioplasty. The patient will therefore need someone to drive them home after the procedure.

Medications will be prescribed before the patient is discharged. These may or may not be the same medications that the patient was taking before admission to hospital. If a stent has been deployed it is usual to have dual anti-platelet therapy. This consists of aspirin and an anti-platelet medication such as clopidogrel or ticagrelor. It is very important to take these medications as prescribed as they help to prevent blood clots forming within the stent. Dual anti-platelet therapy may be prescribed for a duration of up to 12 months.

A follow up appointment with the cardiologist is usually made in order to assess recovery and progress.

Complications

The risks associated with coronary angioplasty are very small. It is important to discuss these with the cardiologist prior to signing the consent form for the procedure. Risks of coronary angioplasty include:

  • Abrupt closure of the coronary artery 
  • An allergic reaction to the x-ray dye 
  • Heart attack or stroke 
  • Damage to the coronary artery 
  • Damage to the catheter insertion site.
In a small percentage of cases the coronary artery narrows again soon after the angioplasty. This is called re-stenosis and usually occurs within the first six months after the angioplasty is performed. In these cases a repeat angioplasty or coronary artery bypass surgery may be recommended.  In a small number of cases (about one to two per cent) emergency coronary bypass surgery is necessary as a result of complications of the coronary angioplasty and stenting procedure.

References

MedicineNet (2010) Coronary Balloon Angioplasty and Stents (Percutaneous Coronary Intervention, PCI). Foothill Ranch: MedicineNet.Inc
http://www.medicinenet.com/Script/Main/Art.asp?li=MNI&ArticleKey=271
National Heart Foundation (2009) A guide to angioplasty. Booklet. National Heart Foundation of New Zealand. Wellington.
National Heart Foundation (2013) Angioplasty and Stents. National Heart Foundation of New Zealand. Wellington. http://www.heartfoundation.org.nz/know-the-facts/treatments/angioplasty-and-stents
Proseus E. R. (2006) Angioplasty. Gale Encyclopaedia of Medicine, Third Edition. Jacqueline L. Longe. Editor. Infotrac Health and WellnessResourceCenter. Farmington Mills, MI. Gale

Last Reviewed – 22 August 2013 

 

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