What is angina ?
The heart is a specialised muscle which pumps blood to the body. Like all tissues, it requires a constant supply of oxygen, which is provided by circulating blood. Oxygenated blood is carried to the heart by blood vessels called coronary arteries. Like all arteries, the coronary arteries have a special inner lining.
Coronary heart disease is the result of a process called atherosclerosis, which affects the inner lining of coronary arteries. This process involves scarring and furring of the arteries. When the arteries become partially blocked, less blood gets to the heart and when this happens, pain can occur. This pain is called angina.
Doctors can diagnose angina by taking a history and examining the patient. Investigations by cardiologists are needed, not only to determine whether disease is present but also to see how severe the disease is and which artery is affected. These will help decide on the best treatment for an individual patient. Blood tests can’t tell us whether furring of the arteries is present, but it can tell us whether you are at risk of developing it. A high blood cholesterol, for example, makes it more likely that a patient will have or develop coronary disease.
The following investigations can be used to confirm or refute the presence of coronary heart disease:
- ECG (heart trace) can often tell us whether you have had a heart attack.
- A CT of the coronary arteries (CTCA) provides images of the coronary arteries.
- An exercise ECG an help confirm whether partial blockages in the coronary arteries leads to diminished blood supply.
- A perfusion scan can help us confirm whether partial blockages in the coronary arteries leads to diminished blood supply. This can be done using nuclear techniques, which involve exposure to radiation, or with cardiac MRI perfusion scanning, which does not involve radiation.
- A stress echocardiogram can also be used to assess whether the heart is short of blood supply.
- A catheter angiogram provides the most detailed images of the coronary arteries.
None of these investigations is perfect and this is why we need to combine the results of the investigations with the clinical history, examination and individual characteristics of the patient.
Which artery is involved ?
Whether a narrowing in the coronary artery threatens survival or not depends on where it is. A narrowing in the main part of the left coronary artery (left main stem) is far more serious than a narrowing in a very distant branch of the artery. This is because blockage of the left main stem is likely to be fatal whilst blockage in a small branch leads to damage to a limited portion of the heart muscle. This situation is analogous to traffic jams: a traffic jam affecting the M1 is more serious than that of a country lane.
Investigations such as a CTCA, a catheter angiogram and a perfusion scan can identify which arteries are the cause of angina. Resting and exercise tests are not always helpful in identify which artery is affected.
The choice of treatment depends on the individual characteristics and circumstances of the patient. What may be appropriate for some may not be appropriate for others.
These are designed to relieve symptoms and to make people live longer. Here are some examples:
• Aspirin makes blood less sticky and reduces the likelihood of developing heart attacks and angina.
• Clopidogrel/prasugrel are alternatives if you develop side-effects to aspirin, such as indigestion. You may need to take both aspirin and clopidogrel or prasugrel after an angioplasty.
• Beta-blockers, such as atenolol and metoprolol relieve angina by reducing the heart rate. They also reduce the likelihood of developing heart attacks and angina.
• Calcium antagonists, such as amlodipine and diltiazem can also be used for angina.
• Nitrates, such as ‘GTN’ and isosorbide mononitrate relieve angina by opening up (dilating) the coronary arteries.
• Nicorandil, ivabradine and ranolazine can also be used.
• Statins, such as simvastatin, pravastatin and atorvastatin reduce blood cholesterol and slow down arteriosclerosis, reducing the likelihood of developing heart attacks and angina. The ideal total cholesterol in patients with coronary disease level is below 4 mmol/L. If you have coronary disease, make a point of remembering your cholesterol level.
Angioplasty / stenting
Angioplasty consists of introducing a small deflated balloon into the partially blocked artery and pushing the furring into the wall of the artery. This opens up the artery. Most angioplasty procedures also involve placing a small metal tube, or stent, into the artery. This stent is placed at the site of the blockage using a balloon. These procedures are very effective at relieving angina. Whether or not a patient should be treated with these procedures depends on many factors. One of them is how many arteries are affected by the furring up process. If there are too many blockages, angioplasty/stenting may not be suitable. Because these procedures involve a small risk, the possible benefits of the procedure needs to be weighed up against the risks.
Coronary artery bypass operations (CABG) involve taking a vein from your leg or an artery from the chest wall and using it as a bridge from the aorta to the area of the heart that requires more blood flow.