Anti-Anginal Drugs

Coronary insufficiency is a very common disease, and is responsible for the end of life of many people. Arteriosclerosis can be in many arteries, but the cardiac arteries cause the most problems. At rest, more or less, the heart muscle uses 70% of the oxygen available to the coronary blood flow—so this means that when you exercise and need 4 or 5 times more oxygen, there is no way to compensate for this need unless you increase the coronary threshold. If you have a coronary arteriosclerotic plaque that obstructs about 50% of the lumen of the artery, when you exercise you cannot compensate and thus have angina. On the other hand, to have angina at rest requires a greater obstruction of the arteries. When we talk about angina, it represents an acute shortage of oxygen resulting as chest pain (due to insufficient oxygen supplied to the myocardium). Angina can occur during exercise or stress.

Chronic stable angina is caused by a fixed coronary stenosis. Unstable angina occurs even at rest and has some spastic components. Then, there is one rare variant of angina that occurs even without coronary occlusion and sometimes even at rest due to some spasm—like a charley-horse of the heart.

It is important to distinguish the angina episode from a myocardial infarction. It is a question of timing, how long it lasts, and how much damage is caused to the myocardium. If the occlusion lasts long enough to cause death to the muscle, it is a myocardial infarction.

Category: Pharmacology Notes