Angina Pectoris and Pathophysiology
What is Angina Pectoris?
Angina pectoris is the medical term used to describe chest pains related to heart disease, particularly due to myocardial ischemia. The lack of adequate oxygen (ischemia) in the heart muscles (myocardium) due to a reduced blood supply brought about by diseases produces symptoms of:
- Chest tightness, discomfort or heaviness
- Squeezing, constricting or crushing pains behind the breastbone or sternum
- Prickling, stabbing or burning chest pain
- Choking sensation
These chest pains usually occur during exercise, when eating, when exposed to cold or experiencing emotional stress. The pain may originate from the epigastrium like an upper abdominal pain, and radiate to the neck, the jaw, the shoulder and the back. Angina can last for one to five minutes and is relieved by rest or nitroglycerin.
How Does Angina Pectoris Occur?
The heart is a powerful muscle that pumps blood to the rest of the body, including itself. As such it needs enough oxygen supply in its cells which it derives from the blood delivered to it by the coronary arteries.
Certain conditions and diseases can upset the balance between the oxygen demand and supply to the heart muscles (myocardium). The most common condition that can compromise blood and oxygen delivery to this organ is atherosclerosis, leading to coronary artery disease. It is characterized by deposits of excess cholesterol or fat in the walls of the arteries, including the heart arteries. This leads to a significant decrease in the diameters of these vessels. This leads to a reduction in the blood and oxygen supply to the myocardium, a condition called myocardial ischemia. If severe this can lead to a heart attack, or myocardial infarction, where a portion of the heart is permanently damaged from lack of oxygen. Other diseases that can lead to ischemia are hypertension, diabetes, congenital heart disease and lupus.
Angina pectoris and pathophysiology of myocardial ischemia are closely related, although not all patients who suffer from the heart condition will experience the symptom. The mechanism by which chest pains are brought about during myocardial ischemia or during a heart attack involves mechanical, metabolic and electrical changes during these episodes. Stimulation of nerve endings in the coronary arteries and the myocardium is transmitted along the thoracic and spinal nerves and finally into the brain, which is then perceived as pain.
A chemical mediator of pain called adenosine is mainly responsible for angina pectoris. This chemical comes from the degradation the ATP, the cells’ main source of energy. Adenosine diffuses outside the cells, dilates the coronary arterioles and stimulates cardiac nerve endings. This produces the chest pain referred as angina pectoris.
Other Causes of Chest Pains
Approximately 10 million Americans suffer from symptoms of heart attack like chest pains. The presence of possible precipitating factors like CAD, obesity, diabetes, high blood pressure and congenital heart disease should alert patients to take angina pectoris seriously. However, there are other possible causes of chest discomforts that should be distinguished from those of anginal attacks so that they can be managed appropriately. These include lung diseases, gastrointestinal diseases, chostochondritis and herpes zoster.
References
eMedicine, “Angina Pectoris”, https://emedicine.medscape.com/article/150215-overview
Merck Manuals, “Angina Pectoris”, https://www.merckmanuals.com/professional/sec07/ch073/ch073b.html
