What is the main cause of angina?

Written by Yara Patrice Formento

Edited and Reviewed by Reuben J C. Los Baños, Ph.D.

Angina pectoris, or angina, is chest pain caused by reduced blood flow to the heart. It is not a disease, but it is a symptom of underlying cardiovascular conditions such as coronary artery disease (CAD).

Angina manifests when the myocardium does not receive enough oxygen-rich blood. Angina occurs either when the heart is pumping hard or at rest, depending on the severity of the underlying factor.

Mayo Clinic describes angina as squeezing, pressure, tightness, and burning in the chest as if something heavy is pressing against the chest. It may also feel like indigestion or heartburn.

The discomfort can radiate to the shoulders, arms, neck, jaw, and back, similar to a heart attack. However, angina subsides with rest or specific medication, unlike a heart attack.

According to Hermiz and Sedhai (2023), chronic stable angina affects approximately 30,000 to 40,000 people per million people in Western countries. It is important to note that not all chest pain is angina and that it manifests differently for everyone.

Generally, when the myocardium lacks oxygen due to inadequate blood supply, this results in angina pectoris.

When the heart beats rapidly, the myocardium may receive inadequate oxygen-rich blood supply because relaxation periods (when the blood can flow to the heart tissue) are short-ended.

It can also be due to the narrowing and blocking of coronary arteries by atherosclerotic or lipid plaque. This condition is called coronary artery disease (CAD). As a consequence, a rupture or blood clot may occur.

Additionally, when the heart muscle does not receive enough oxygen, it causes ischemia.

1. At the cellular level, ischemia causes an increase in anaerobic glycolysis. Anaerobic glycolysis refers to the production of energy in the cells without oxygen. The end product of anaerobic glycolysis is two pyruvate molecules, which are then converted to lactic acid (lactate) for glycolysis to continue.
2. Anaerobic glycolysis increases the levels of hydrogen (pH), potassium, and lactate in the affected area of the myocardium.
3. The hydrogen ions compete with calcium ions, causing hypokinesia (reduced movement) or akinesia (no movement) in the affected area.
4. The affected cells also release adenosine and bradykinin. These chemicals stimulate nearby pain receptors (nociceptors).
5. The build-up of carbon dioxide and a drop in the pH due to anaerobic metabolism contributes to the sensation of pain.
6. Next, the pain signals travel along sympathetic nerve fibers and the vagus nerve, which send these signals to the brain, resulting in the perception of chest pain.
7. The activated sympathetic nervous system causes secondary symptoms such as sweating, anxiety, increased heart rate, and distress.

One should not ignore angina. The oxygen-deprived heart cells may die when prolonged, forming an infarct area. This results in myocardial infarction, more commonly known as heart attack.

What can trigger angina?

When a person is at risk for heart disease or coronary artery disease, he or she is also at risk for angina. Risk factors for people to develop coronary artery disease (CAD) include:

• Smoking and tobacco use
• High blood pressure
• Increasing age
• Diabetes
• High cholesterol levels
• Obesity
• Type “A” or Alpha personalities (refers to individuals who are consistently working and experience higher stress levels than most individuals)
• Emotional stress
• Drug abuse
• Sedentary lifestyle
• Genetics
• Medicines
• Cold temperatures
• Other health conditions such as chronic kidney disease, peripheral artery disease, metabolic syndrome, or stroke history

Most of these risk factors can be modified by changing diet and sedentary habits and controlled through medication. However, some risk factors are uncontrollable, such as genetics, age, and gender.

For instance, according to Tortora and Derrickson (2009), adult males are more likely than adult females to develop CAD. However, after age 70, all the risk factors are roughly equal. Smoking is the leading risk factor in all CAD-associated diseases, increasing the risk of morbidity and mortality.

What are the symptoms of an angina attack?

According to the Mayo Clinic, symptoms of angina include:

• Chest pain or pressure
• Intense sweating
• Difficulty catching breath
• Pain in the arm, neck, jaw, and shoulder
• Nausea
• Fatigue
• Feeling of gas or indigestion
• Fluctuating chest pain

Chest pain occurring with angina can make executing simple activities uncomfortable, but the most dangerous complication is a heart attack. The warning symptoms of a heart attack include:

• Pressure, fullness, or a squeezing pain in the chest that lasts for more than a few minutes
• Pain extending beyond the chest to the shoulder, arm, or back, and even to the teeth and jaw
• Fainting
• Threatening sense of doom
• Nausea and vomiting
• Continued pain in the upper belly area
• Shortness of breath
• Sweating

A person experiencing these symptoms must seek immediate medical help from a healthcare professional. The healthcare professional will perform a physical exam and ask about symptoms and risk factors, such as the family history of heart disease and other health conditions.

Where is angina pain located?

Angina pain primarily occurs in the chest area, yet it may also radiate to the neck, shoulders, and arms, especially the left arm, back, and jaw.

How long does angina pain last?

The duration of angina pain varies depending on its type. Angina due to the blockage of coronary arteries is classified into three categories:

1. Stable angina is the most common form of angina during exertion or activity. It disappears with rest or by taking medicine for angina. It is also predictable, similar to previous episodes of chest pain, and lasts a short time, approximately five minutes or less.
2. Unstable angina is unpredictable and occurs at rest. It is typically severe and lasts longer than stable angina, approximately for more than 20 minutes. Prolonged unstable angina can lead to myocardial infarction or heart attack due to the lack of oxygen in the heart. Generally, it is dangerous and requires emergency treatment.
3. Variant angina, or Prinzmetal angina, is caused by spasms in the heart’s arteries rather than coronary artery disease (CAD). The spasm temporarily reduces blood flow, with severe chest pain as the main symptom. It often occurs in cycles, from rest and overnight. It can be relieved by taking angina medicine.

Moreover, suppose a healthcare professional thinks that a patient has unstable angina or a severe underlying factor. In that case, tests such as an electrocardiogram, stress test, blood tests, chest x- rays, coronary angiography, cardiac catheterization, and computer tomography angiography may be done.

• Electrocardiogram. It records the heart’s electrical activity and shows whether a person is at an increased risk for heart attack.
• Stress test. A person walks on a treadmill to elevate their heart rate while receiving an electrocardiogram. The test reveals whether the heart gets enough oxygen-rich blood when physically exerted.
• Blood test The presence of substances in the blood, such as troponin, can indicate whether a person is at an increased risk for a heart attack. High levels of troponin indicate whether a person is having or has had a heart attack.
• Chest x-ray.
• CT scan. It assesses the calcium build-up or blood flow in the coronary arteries.
• Holter monitor. A device is worn for 24 hours or longer to record and look for abnormalities in the heart rhythm.
• Coronary angiography. A procedure wherein contrast dye is injected into the bloodstream to reveal, through X-ray images, possible blockages within coronary arteries.
• Cardiac catheterization. A general procedure wherein a doctor inserts a catheter into a large blood vessel. It can be used for angiography, angioplasty (when the catheter is used to clear a blocked artery and valvuloplasty (when the catheter is used to widen a narrow heart valve).

What is the fastest way to stop angina?

The fastest way to stop an angina attack is through medication, specifically nitroglycerin. Nitroglycerin is a nitrate that causes the coronary arteries to widen, increasing blood flow.

Nitroglycerin is placed under the tongue when a person first feels discomfort and pain and should relieve angina within 5 minutes. Long-acting nitrates, diagnosed by physicians for patients to take daily, help prevent angina attacks.

Other medications to stop angina include:

• Beta blockers. They decrease the heart rate, reduce the risk of abnormal heart rhythms, and decrease blood pressure.
• Calcium channel blockers. An alternative to beta blockers for people with asthma or chronic obstructive lung disease, heart block and related conduction system abnormalities, and peripheral artery disease. They lower blood pressure and widen coronary arteries.
• Aspirin. It prevents the formation of blood clots in diseased blood vessels, which are the leading cause of heart attack and stroke.
• Statins. An umbrella term for drugs used to lower cholesterol. They also reduce inflammation in blood vessels and prevent plaque from breaking open.
• ACE inhibitors. They help relax blood vessels throughout the body.
• Ranolazine. It reduces the amount of oxygen the heart needs to do its work.

Moreover, when medical therapy does not relieve angina and if it suddenly progresses, more invasive treatments may be required.

An angioplasty is a surgical procedure wherein the doctor inserts a catheter into an artery in the groin or arm and then carefully maneuvers it into the blocked artery. Next, the doctor inflates a balloon at the artery’s tip, flattening the plaque that is blocking the artery.

• Sometimes, the balloon also expands a wire mesh stent to hold the artery open and leaves it in place.
• This process can take 30 minutes to several hours. A patient usually stays in the hospital at least overnight. The healthcare team tells them when they can return to their daily activities.
• Sometimes, the blockage returns after an angioplasty. Using a stent coated with medicine can help prevent this.

If unstable angina or stable angina affects some of the leading heart arteries and does not improve with stenting and other treatments, heart bypass surgery may be needed.

Coronary Artery Bypass Grafting is a surgical procedure wherein a surgeon uses a blood vessel from another part of the body to make a new channel. It diverts blood around the blocked coronary artery.

However, prevention is better than cure. Aside from medication and medical procedures, the best way to treat angina is to change one’s lifestyle ultimately. This includes but is not limited to:

• Stopping tobacco use and smoking. Smoking contributes to atherosclerosis, or the build- up of plaque in the arteries, which reduces blood and oxygen supply throughout the body. If a person needs help quitting, he/she should consult his/her healthcare team about therapies that can help.
• Losing weight if needed. Obesity accelerates early atherosclerotic changes, including the development of fatty streaks. It is associated with blood pressure, dyslipidemia, and hyperglycemia.
• Lowering blood sugar, blood pressure, and cholesterol levels. It concerns having a healthy diet, exercising regularly, managing emotional health, and quitting smoking.
• Adjusting daily activities. If a certain kind of activity can cause angina, try performing the activity more slowly. Also, since the heart is more stressed in the mornings and after meals, try reducing physical activities.
• Reducing stress and anger. Anger and stress activate the sympathetic nervous system and cause high blood pressure, as if in a “fight or flight” situation. If anger and stress regularly trigger angina, a stress-reduction program or meditation can help.
• Exercising regularly. A supervised exercise can safely strengthen the heart and gradually reduce angina.
• Having a healthy diet. A healthy diet can fight the cholesterol-filled plaque in atherosclerosis, which is responsible for angina. It can lower weight, blood sugar, and cholesterol levels. Eventually, it will reduce angina.

Is angina life-threatening?

Angina itself is not life-threatening. However, the underlying factors or diseases that it indicates can be life-threatening. Thus, it is crucial to address angina symptoms immediately and appropriately, such as going to the doctor, to avoid further complications.

References

Angina (Chest Pain). (2021). American Heart Organization. https://www.heart.org/en/health- topics/heart-attack/angina-chest-pain

Angina – Symptoms and causes. (n.d.). Mayo Clinic. https://www.mayoclinic.org/diseases- conditions/angina/symptoms-causes/syc-20369373

Angina treatment: Stents, drugs, lifestyle changes — What’s best? (2023, May 27). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/coronary-artery-disease/in-depth/angina- treatment/art-20046240

Cardiac Catheterization. (2023). American Heart Association. https://www.heart.org/en/health- topics/heart-attack/diagnosing-a-heart-attack/cardiac-catheterization

Harvard Health. (2021, September 21). Angina: Symptoms, diagnosis and treatments. https://www.health.harvard.edu/heart-health/angina-symptoms-diagnosis-and-treatments

Hermiz, C., & Sedhai, Y. R. (2023, June 6). Angina. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557672/

National Library of Medicine. (n.d.). Angina. Chest Pain | MedlinePlus. https://medlineplus.gov/angina.html

What      is      Angina?      |       NHLBI,       NIH.       (2023,      June      30).               NHLBI,                NIH.

https://www.nhlbi.nih.gov/health/angina