Medicines for the heart
ACE inhibitors are very effective in treating high blood pressure and can be used on their own or along with a calcium channel blocker. After a heart attack, many patients may benefit from taking an ACE inhibitor. ACE inhibitors are also very effective in treating and helping to prevent heart failure and are recommended for most people with heart failure.
‘ACE’ stands for ‘angiotensin converting enzyme’. Angiotensin is a natural substance produced by the kidneys. It has a powerful narrowing effect on the blood vessels, which increases blood pressure. It is produced as a result of the actions of an enzyme in the blood called angiotensin-converting enzyme (ACE).
The group of drugs known as ACE inhibitors (‘angiotensin converting enzyme inhibitors’) can reduce the activity of this enzyme, making the arteries relax and widen, and lowering blood pressure.
ACE inhibitors are generally tolerated well by patients than most other drugs used for similar purposes. However, they can cause a marked fall in blood pressure, especially when first used by people who are also taking other heart medicines. When your doctor starts the treatment, he or she may start you on a low dose and then gradually increase it. They will regularly check your blood pressure, and will check your kidney function by taking a blood test. You will need to have more blood tests from time to time to make sure that you don’t have too much potassium in your blood – another possible side effect when taking this type of medication.
ACE inhibitors can cause skin rashes and, very occasionally, a major allergic reaction. Some people develop a persistent, dry, irritating cough. If this happens, you should tell your doctor about it. He or she can prescribe another medicine known as an angiotensin II antagonist (see below).
ANGIOTENSIN RECPTOR BLOCKER
These act in a similar way to ACE inhibitors, but do not cause the persistent dry cough that ACE inhibitors can sometimes cause. So they are a useful alternative to ACE inhibitors. As with ACE inhibitors, if you take angiotensin II antagonists you will need to have regular blood tests to check the levels of salts in your blood and to test your kidney and liver function.
ANTI- ARRHYTHMIC DRUG
Anti-arrhythmic drugs are drugs for controlling the rhythm of the heart. Beta-blockers and the calcium channel blocker verapamil are often used to treat disturbances of the heart rhythm (arrhythmias), but there are several other drugs that are used almost exclusively for this purpose.
Amiodarone is very effective in controlling disturbances of the heart rhythm, especially atrial fibrillation. (Atrial fibrillation is a common heart rhythm disorder which makes the heart beat quickly and irregularly, and which may lead eventually to heart failure.
At low doses, amiodarone is well tolerated, but it has important side effects. It may produce headache, flushing, dizziness and stomach upsets. More seriously, and more rarely, it may cause disorders of the thyroid gland, lungs and liver. To avoid these complications, you will need to have regular blood tests. You may also have chest X-rays and tests to see how your lungs are working.
Digoxin is often used to treat atrial fibrillation, a common heart rhythm disorder. Digoxin slows the heart rate but does not restore its regularity. This may be enough to relieve the symptoms of breathlessness and palpitation, but you may need other treatment to return your heartbeat to normal.
Digoxin may cause loss of appetite and nausea. Less frequently it can cause vomiting, painful or enlarged breasts, palpitation, and fainting. Too much digoxin can also make everything you see look yellowish. You should tell your doctor if you get any of these symptoms, as it may be necessary to adjust the dosage. You may need to have blood tests to make sure that the correct level of drug is present in your blood.
Clots are made up of platelets (tiny blood cells) clumped together, and a protein called fibrin. Anticoagulants prevent fibrin from forming and so prevent clots from forming too. However, in doing so, they may cause internal bleeding or make bleeding from a minor injury worse.
Heparin is injected into a vein and has an immediate effect in preventing further blood clots from forming. This is known as intravenous heparin and is only given in this way if you are in hospital. Another form of heparin called ‘low molecular weight heparin’ may be given subcutaneously (by injection just under the skin) over a longer period of time.
WARFARIN (or another oral anticoagulant- like ACITROM) is given when long-term prevention of clotting is needed. This drug is most often used for people with disease of the heart valves, especially those who have been given an artificial heart valve, or for some people with an irregular heart rhythm such as persistent atrial fibrillation.
Anticoagulants are also particularly valuable in treating clots in the veins of the legs (deep-vein thrombosis) and in preventing these clots from travelling through the blood to the lungs (pulmonary embolism).
Because the desired effect of these drugs is to make the blood thinner so that it doesn’t clot so easily, you will need regular blood tests to make sure that the clotting activity of the blood is within safe but effective levels.
If you are taking oral anticoagulants, you should check with your doctor before taking any other drugs. This is because oral anticoagulants interact with many medicines including antibiotics, aspirin and cimetidine, and with some drugs that are used to treat arthritis, gout, epilepsy, high blood cholesterol and disorders of heart rhythm.
ASPIRIN (and other anti-platelet drugs)
Aspirin has been used for relieving pain for more than 100 years, but it is also effective in preventing blood from clotting. It achieves this by reducing the ‘stickiness’ of platelets – the small blood cells that can clump together to form a clot. The dose you would need for this effect is smaller than the dose you would need to relieve a headache.
Aspirin reduces the risk of having a heart attack or stroke through its anticoagulant action (preventing fibrin from forming and so helping to prevent clots from forming). It is also useful for people with angina, and is used to prevent blood clotting in the vein grafts used in coronary artery bypass surgery. So, it is used for most people with known coronary heart disease, and for certain people who are at risk of coronary heart disease or stroke.
CLOPIDOGREL is another anti-platelet medication. It is sometimes given along with aspirin. It is useful for people with unstable angina or for those who have recently had a coronary angioplasty with stenting (a procedure which helps to keep the coronary artery open). Sometimes, clopidogrel is used for people who can’t take aspirin because they have a condition such as asthma or a history of ulcers in the stomach or intestine.
Anti-platelet drugs can cause indigestion, nausea and vomiting. More seriously, they can provoke or worsen bleeding from the stomach. Occasionally, aspirin can bring on an asthma attack.
The unwanted effects described above are not common, but because of them anti-platelet drugs are only recommended as a way to help prevent heart attacks or strokes in people who are known to be at risk from these conditions. They are not given routinely to healthy people as a way of preventing heart attacks or strokes.
Beta-blockers act by slowing the heart rate. This reduces the amount of work the heart has to do, so that it needs less oxygen, blood and nutrients. Beta-blockers are very effective in preventing attacks of angina, but work too slowly to be useful in relieving an attack of angina. They are also effective in lowering high blood pressure and in reducing the risk of a further heart attack in people who have already had one. Some beta-blockers can help control abnormal heart rhythms and heart failure.
Beta-blockers are not usually suitable for people with asthma or bronchitis. If you have diabetes, your doctor may prefer not to give you beta-blockers, as they may mask (hide) the symptoms of low blood sugar. However, so-called ‘selective’ beta-blockers have fewer effects on the lungs and are also less likely to mask the symptoms caused by low blood sugar.
Because beta-blockers reduce the force of the heartbeat, they need to be used carefully in people with heart failure. However, many people with mild to moderate heart failure can benefit from taking beta-blockers.
Many preparations of beta-blockers are available, but they differ only slightly from each other. If you take beta-blockers for heart failure, you will start with a very low dose which your doctor will gradually increase over several weeks, while closely monitoring you.
Serious side effects are rare if beta-blockers are used carefully. Minor side effects are Common but they tend to lessen as time goes by. The minor side effects include tiredness, fatigue, and cold hands and feet. Other less frequent effects include feeling sick, diarrhoea, skin rashes, impotence, nightmares and dizziness.
You should not stop taking beta-blockers suddenly without medical advice, as coming off them too quickly can make angina worse.
CALCIUM ANTAGONISTS (CALCIUM CHANNEL BLOCKERS)
You need a regular inflow of calcium for the muscle cells in the heart to work normally. Calcium channel blockers reduce the amount of calcium entering the muscle cells of the arteries (including the coronary arteries) and cause them to relax and widen. As a result of this, the ‘resting phase’ of the heart’s pumping cycle lasts longer. (The resting phase is when the heart rests in between heartbeats and the coronary arteries fill up and supply the heart muscle with blood.) This means that the heart receives a better blood supply and has to do less work to pump enough blood around the body.
Some calcium channel blockers may increase or reduce the heart rate at rest while others may have no effect on the heart rate. So different calcium channel blockers are used for different heart conditions. For example, the combination of nifedipine and beta-blockers may be effective in relieving symptoms of angina but there is a danger that the heart rate may become too slow if beta-blockers are combined with diltiazem or verapamil.
Serious side effects are not common. Minor effects include flushing, headache, dizziness, faintness, swollen ankles, indigestion, feeling sick and vomiting.
Diuretics, or water tablets, increase the output of water and salt in the urine. They are particularly valuable in treating heart failure, a condition in which the body holds too much water and salt.
Diuretics can also help to lower blood pressure. If you have too much fluid in your body, your heart has to work harder to pump it around the body and the extra workload increases your blood pressure.
There are three main types of diuretic – thiazide diuretics, loop diuretics and potassium sparing diuretics. Thiazide diuretics (such as bendroflumethiazide) and loop diuretics (such as furosemide and bumetanide) can cause you to lose potassium, so your doctor will arrange a blood test a few weeks after starting your tablets to check the potassium level in your blood. If this is getting low, you may be given potassium supplements or a potassium sparing diuretic instead, to correct the problem with the potassium level.
SPIRINOLACTONE is a potassium sparing diuretic, which is being used more and more to treat heart failure. In treating heart failure, diuretics are often combined with digoxin or ACE inhibitors, or both, and they are increasingly used with a small dose of a beta-blocker.
To treat high blood pressure, diuretics may be used alone or with beta-blockers, calcium channel blockers ACE inhibitors, or other drugs.
If you are taking a diuretic, you should not have too much salt in your food as this will counteract the effects of the diuretics. Don’t add any salt to food during cooking or at the table, and avoid salty foods. Many processed foods and ready meals contain high levels of salt. It is also important to avoid using salt substitutes as these contain potassium which may have an effect on your blood test results.
Some diuretics can affect your potassium levels. So, if you are taking diuretics, you may need to have tests from time to time to check the levels of various salts in your blood.
People with diabetes may find that diuretics raise their blood sugar. People with gout may find that diuretics make their condition worse. The diuretic spironolactone can cause the breasts to become larger and painful, and may also make you feel sick. A newer diuretic called eplerenone can help to overcome the problem of enlarged breasts. It is important to tell your doctor about any symptoms that you may be having so that he or she can adjust your medication if necessary.
Nitrates relax the muscles in the walls of the veins and arteries, including the coronary arteries. This improves the blood supply to the heart muscle by widening the arteries that take oxygen-containing blood to the heart.
Nitrates are useful in relieving angina pain and in preventing ‘predictable’ attacks. This means, for example, if you take them just before doing something that usually brings on an angina attack. You should only do this if you have previous experience of getting chest pain while doing that activity. Nitrates are also valuable in preventing angina in the long term, but they may become less effective if they are used continuously over a long period.
Glyceryl trinitrate tablets
Also called GTN, trinitrate or nitroglycerin tablets
Tablets of glyceryl trinitrate (GTN tablets), put under the tongue, relieve angina quickly. They are particularly effective when used to prevent a predictable attack. But, as mentioned above, you should only do this if you have previous experience of getting chest pain while doing that activity.
You should let the tablets dissolve under your tongue. They are not effective if you swallow them. Keep your tablets in the container in which they are given to you. The tablets lose their strength quite quickly and you should replace them with a fresh supply after eight weeks.
You may get a throbbing headache when you first take GTN tablets, but after you have been taking them for a while this side effect usually lessens or disappears. They may also cause flushing, dizziness or even fainting, so it is best to sit down when taking your first tablet.
Glyceryl trinitrate can be given in an aerosol spray (a GTN spray). You need to take one or two doses under your tongue and then close your mouth after each dose. You don’t need to shake the canister before spraying. The spray has the advantage of having a longer lifespan than GTN tablets. You can keep it for up to two years.
Common examples: isosorbide mononitrate, isosorbide dinitrate.
Isosorbide mononitrate and dinitrate are effective drugs in preventing angina. These are usually prescribed once a day (as a slow-release preparation) or sometimes twice a day. If
you take nitrates twice a day, it is important to take the two doses about six hours apart (at breakfast and after lunch) so that the total amount you take each day is properly divided up and you are not getting too much at any one time. This means that the drug will remain more effective. If you find that the tablets become less effective or your angina is becoming uncontrolled, tell your doctor as soon as possible.
Oral nitrates are sometimes used for people with heart failure, along with another drug that dilates the blood vessels called hydralazine. Hydralazine is often used for people with heart failure who cannot take ACE inhibitors or angiotensin receptor blockers.
This combination of oral nitrates and hydralazine can help people who have heart failure but can also cause flushing and dizziness if the dose is too high.
GTN skin patch
Self-adhesive skin patches containing glyceryl trinitrate are effective in relieving or preventing angina, but they may become less effective if they are used continuously for a 24-hour period. So, it may be helpful to leave the patches off for several hours in each 24-hour period. You can still use your spray or tablets under your tongue in you have an angina attack.
Unwanted effects of nitrates
Headache, flushing, dizziness and faintness can happen with all nitrates, but are most common with GTN tablets. These symptoms tend to lessen with continued use. If you are taking a long-acting nitrate such as isosorbide mononitrate or isosorbide dinitrate, you should not take Viagra. Speak to your doctor if you are not sure about this.
POTASSIUM CHANNEL ACTIVATORS
Potassium channel activators are a type of drug given to relieve angina. They have a similar effect to nitrates as they relax the walls of the coronary arteries and so improve the flow of blood to the heart. Unlike nitrates, they do not appear to become less effective with continued use.
Unwanted effects of potassium channel activators may include a headache when you first take them, and also flushing, indigestion or dizziness. If you are taking a potassium channel activator, you should not take Viagra.
These drugs are used only when there is an urgent need to dissolve a clot. This is normally following a heart attack. The sooner they are given after the start of the heart attack, the better. They can be given either as a single dose or diluted in a drip.
Thrombolytic drugs may cause serious bleeding so, before you are given the drug, the doctor or nurse will assess whether it is suitable for you and whether you have a high risk of bleeding. For example, you would not be given a thrombolytic drug if you had recently had surgery or a stroke.
If you receive thrombolytic drugs, you should be given a card to carry with you, describing the type of thrombolytic drug given and when it was given. If you have already had streptokinase and your dose was given more than four days ago, you should not have another dose of it. This is because, by that time, your body will have developed antibodies to the drug. If you have another heart attack, a different thrombolytic drug can be given.
OTHER DRUGS FOR HYPERTENSION
High blood pressure can usually be controlled successfully with one or more of the drugs mentioned earlier – diuretics, beta-blockers, calcium channel blockers, or ACE inhibitors. Sometimes these are not enough, or may have unacceptable side effects, and other drugs are added or given instead. Among these are alpha-blockers, methyldopa and moxonidine.
These may cause a large fall in blood pressure when they are first used. They can also cause tiredness.
This is used, with diuretics, to reduce blood pressure. It can cause a dry mouth, and drowsiness which can interfere with skilled tasks including driving.
This is a drug to lower blood pressure. It may be prescribed if other drugs are not suitable or have failed to control high blood pressure.