Treatment Of Heart Disease - Drugs (Diuretics, Anti-Anginal Agents)

These represent the second major group of drugs aimed at aiding the heart whose function has lessened. For reasons still not entirely understood, the failing heart causes the kidneys to retain too much salt and water, and this extra fluid, instead being excreted, can cause problems for the suffer. Diuretics help the kidneys to excrete this unwanted salt and water.

Diuretics have a side-effect on the kidney; some cause a loss of the metallic element potassium in the urine and others cause a retention. The latter type therefore should not be used alone, but can be given together with one of the former so that potassium balance is more likely. If the former are used alone, additional potassium-containing pills should taken, as long-term potassium loss may detrimental to general well-being as well as to the heart's action. Diuretics also have a small blood-pressure-lowering action and may be used primarily for that purpose.

Anti-anginal agents

As most of the narrowings of the coronary arteries are permanent, there is no medical (as opposed to surgical) method of relieving them; most anti-anginal agents act by decreasing the amount of work that the heart has to do.

Nitrites, such as glyceryl trinitrate, cause the widening of the smaller blood vessels in the body, which reduces the resistance to blood flow and, therefore the effort by the heart. They also reduce the amount of blood returning to the heart and, consequently, the amount of blood filling the heart. This in turn reduces the blood pressure within the heart itself during its relaxation phase.

Beta-blockers (properly called 'beta-adrenergic blocking drugs') block the effects of adrenaline and the effects of those nerve mechanisms, governed by adrenaline, which drive the heart stronger and faster. They also reduce the amount of work of, and thus the fuel required by, the heart at any given time. Therefore,  less energy, oxygen and blood need to be delivered through the coronary arteries. However, as a side-effect they naturally reduce the maximum amount of work of which the heart is capable, and they may therefore cause heart failure or make it worse when there is something else wrong with the heart; they may also cause asthma and reduce blood flow to the legs. They are nevertheless extremely useful in controlling angina, provided that they are administered with care and supervision. Examples of of drug are propranolol and oxprenolol, also there are many others. Beta-blockers may also used in the treatment of hypertension and  abnormal heart rhythms.