Atheromas (fat deposits within the walls of arteries) form silently. The patient has no way of knowing they exist until they’re large enough to form a significant obstruction to the flow of blood through one or more coronary arteries. What does “significant” mean (Fig. 8-3)?

Seventy percent is the magic number. When the atheroma grows to about 70% of the diameter of a coronary artery, it may begin to produce symptoms. The reason is that at this point the blood flow to some area of heart muscle will be barely enough for the needs of that muscle when the patient is at rest and the heart isn’t working very
hard. When the heart has to beat faster or when it has to work against a higher pressure, it needs more fuel—blood. It can’t get the extra fuel it needs because of the narrowing in the coronary artery, and the syndrome called angina pectoris results. Study the diver in Figures 8-4, 8-5, and 8-6. Note that in Figure 8-5A he’s tugging on the hose pipe to let someone know he’s not getting enough air. Heart muscle that’s not getting enough blood will often send a message by means of a symptom. The symptom of angina pectoris is painful discomfort somewhere in the upper half of the body: the discomfort comes on with exertion and is relieved by rest.

Every health care worker must be prepared to recognize the symptoms of angina pectoris, as well as those of coronary insufficiency of any type.

Angina pectoris doesn’t actually mean “pain”: it refers to a sense of “smothering” localized in the front of the chest. It was first described by the English physician William Heberden back in the 18th century. Long before electrocardiograms or x-rays or modern pathology, Heberden deduced that this discomfort came from the heart. His younger colleague, Edward Jenner, wrote to him describing an autopsy he had carried out on a victim of angina at Bath. Jenner noted a “white, fleshy protuberance” blocking a coronary artery and guessed that this was the cause of the angina. (Jenner also discovered the smallpox vaccination, thereby saving more lives than anyone in the history of the human race.)

Here are the symptoms of anginal pain to look out for (Table 8-1):

One more time: The common denominator of all symptoms of the classic, typical form of angina pectoris is that the symptoms come on with exertion and are relieved by rest. Exertion like what? Exertion like walking, climbing stairs, or lifting or carrying loads, for instance. Isometric stress, or straining against a heavy weight, is especially dangerous. That’s why snow shoveling often brings on coronary pain. A large meal is a type of exertion most people overlook, but it can be important. A large meal throws about the same load on the heart as walking up three flights of stairs. King Henry VIII was said to have died of a “surfeit of lampreys.” In fact, he overstuffed the royal gullet and had a heart attack. Sudden emotional stress can cause the blood pressure to rise and the heart to beat faster. Angina can result.

Myron Prinzmetal, an American cardiologist, described another type of angina, commonly known as the “intern’s nightmare.” It doesn’t fit any logical pattern. The pain often comes on at rest, even though the patient doesn’t feel any discomfort during exercise. It may waken patients during the early morning hours. This kind of angina is usually caused by spasm or constriction of a coronary artery. Sometimes it happens in diseased arteries, but it can also take place in completely normal vessels. Fortunately, this type of angina is rare, and it can usually be diagnosed by changes in the electrocardiogram (Fig. 8-7).

When a musical score reads “crescendo,” it means “play louder and louder, progressively.” That’s a good description of this dangerous type of angina. The pain comes on more often, or it’s more severe, or it comes on with less effort—sometimes all three. In an especially dangerous form of crescendo angina, the pain comes on at rest or wakens the patient from sleep, especially in the early morning hours. It’s now clear that when this happens a blood clot has started to form at the diseased, narrowed spot in the artery. The clot doesn’t block the artery completely, but it cuts down flow below the danger point and there is the beginning of damage to the heart muscle (Fig. 8-8). Complete closure and sudden death are immediate risks. The patient with crescendo angina must be put in a hospital at once. The pain may last longer than in typical angina—sometimes as long as 30 minutes. The term coronary insufficiency is often used in these cases. Again, the combination of a clot and an atheroma is responsible and the risk is the same as in crescendo angina. Note the predicament of the diver in Figure 8-5 and you’ll have a good idea of what goes on in crescendo angina and coronary insufficiency.