Understanding angina pectoris

Decoded content
23/08/2018

The angina pectoris or angina is characterized by chest pain which usually occurs during exertion. It is the symptomatic manifestation of myocardial ischemia, i.e. when the heart cells (cardiomyocytes) are not receiving enough oxygen-rich blood.

The main cause of Angina is Atherosclerosis which is a potentially serious condition where arteries become clogged with fatty substances called plaques, or atheroma. These plaques cause the arteries to harden and narrow, restricting the blood flow and oxygen supply to heart.

Although it concerns approximately 2% of the population in industrialized countries, angina normally occurs in people over 50 years old and is more common in men.

Its development is promoted by risk factors such as diabetes, dyslipidemia, smoking, high blood pressure, obesity and heredity.

 

The heart needs energy

The heart beats more than 100,000 times every day and pumps almost 9,000 liters of blood to supply our organs with oxygen and nutrients. Thanks to this natural pump, we can do the things we do every day, such as walking, running and thinking, etc.

The heart must constantly produce its own energy to operate continuously 24 hours a day, 7 days a week. This energy is ATP or adenosine triphosphate; it is an energy molecule that is present in the cells and which enables them to operate. In order to continuously produce ATP, the blood transports sugars and lipids, taken from food, to the cells. These are then “burnt” using the oxygen from respiration, in the same way that a log burns in a fireplace by using the oxygen in the air around it to produce heat. It is thanks to the ATP that the cardiomyocytes contract and allow the heart to beat.

Under normal conditions, i.e. when a person is in good health, the heart receives enough oxygen to produce the energy required, appropriate to the effort being expended. For example, when at rest, less ATP energy needs to be provided than during exertion, when the muscles are going to consume more energy.

So the body needs more oxygen during physical exertion so as to produce more ATP and this is why we breathe faster. The body is therefore able to regulate its consumption and production of ATP, subject to its requirements.

 

The energy deficit or myocardial ischemia

In some pathologies that reduce blood flow, not enough oxygen gets to the heart. The latter, as a result, can no longer produce enough ATP so as to be able to operate as a pump. This ATP deficit is all the more visible during physical exertion, during which it needs more energy. An imbalance is thus created between the energy supply and energy requirements in the heart – this is known as myocardial ischemia.

Myocardial ischemia results in chest pain – angina – which is also known as angina pectoris. If left untreated, this heart malfunction may, in the long term, cause a part of it to die.

Understanding the mechanisms that cause angina pectoris

 

Prevention and treatment of angina pectoris

Whatever the reason for this energy deficit, those who suffer from angina must, above all, be careful to follow some lifestyle rules. Where possible, the patient must stop smoking, have a balanced diet, keep an eye on their weight and exercise regularly.

The treatment strategy, for its part, consists in re-establishing this balance between energy supply and energy requirements so that the heart may constantly carry out its contraction operations, whether at rest or during exertion.

10 or so drugs are currently prescribed to treat angina. Those that are most commonly used slow down the heart rate to reduce its energy requirements, thus relieving patients and protecting the heart in a reduced-oxygen environment. They are often combined with other drugs to obtain a synergistic effect. Some of the drugs with which they are combined directly increase ATP production and therefore the energy for the heart. Others are vasodilators and increase the size of the blood vessels that supply the heart.

Cardiomyocytes

  An appropriate combination of these drugs relieves patients and improves their day-to-day lives. For example, it allows patients to resume reduced physical activity without causing any chest pain or, more simply, avoid getting out of breath after a short period of exertion, such as climbing stairs.

Surgical treatment may be necessary in some cases, in particular when the vessels that supply the heart are excessively obstructed (e.g. during dyslipidemia), mainly to unblock the vessels and allow the blood to supply the heart normally.