Coronary Heart Disease

Coronary heart disease or coronary artery disease is the most common type of heart disease in many industrialised countries.

What is Coronary Heart Disease?

Coronary heart disease arises from the narrowing of the coronary arteries, resulting in reduced blood flow and consequently, oxygen supply to the heart muscle. This process is known as atherosclerosis.

Why is Coronary Heart Disease Dangerous?

Over time, coronary heart disease might weaken the heart muscle, leading to heart failure and eventually death as the heart is unable to supply blood normally¹.

Common Causes of Coronary Heart Disease

The narrowing of coronary arteries is typically caused by atherosclerosis. Atherosclerosis is a progressive disease in which arteries harden and narrow; walls lose their elasticity due to the accumulation of fatty deposits, otherwise known as plaque buildup. Other contributory factors include spasms in the coronary vessels, diabetes, high blood cholesterol, high blood pressure, adverse physical reactions to mental stress, and heavy smoking.

Symptoms of coronary heart disease

• Angina or angina pectorisSqueezing chest pain and/or discomfort that may radiate to the neck, jaw, abdomen, and upper left part of the body. These are pain and/or discomfort signals that the heart is not receiving sufficient blood and oxygen.

  Angina may present itself in different ways. For instance, people with “silent” angina tend to feel no physical discomfort or pain.

  Angina may also be stable or unstable. Stable angina refers to chest pain and/or discomfort, which occurs in a regular or predictable pattern (for instance, whenever the patient walks up a flight of stairs). The patient usually becomes better with rest.

  In contrast, unstable angina is a discomfort that is more serious or occurs without warning. The patient may experience sudden sharp pain, even with little or no physical exertion. This may happen even when the patient has no symptoms of coronary heart disease previously.

• Palpitations or racing heartbeatsThe reason for palpitations is the sensation felt over the upper part of the chest, by fast heartbeats or abnormal heartbeats.

  Usually, normal rhythm would not be noticeable, and palpitations reflect the sudden cardiac rate or rhythm changes. It is the abnormal movement of the heart in the chest that is felt³.

• Oedema or swelling of soft tissuesThere are several causes, such as heart failure, deep vein thrombosis (clots forming in the deep veins), varicose veins, liver cirrhosis, lack of proteins in the blood, kidney failure, as a side effect of certain blood pressure medicines, etc. In relation to heart failure, as the heart is unable to pump out the blood adequately from the veins, congestion results in an increase in the venous blood pressure that pushes fluids in the veins out into the tissues resulting in oedema. The fluid is mostly water. The oedema also can occur with an infection when it is more localised to the site of infection with tenderness and redness of the overlying skin. The oedema fluid in this cause is protein-rich with inflammatory cells. Oedema may be generalised or localised in one’s body. It is also often associated with weight gain and obesity; the patient also has puffy eyes upon waking up and tight shoes by the end of the day⁴.
• SyncopeSyncope is a sudden, brief fainting followed by a spontaneous revival. The patient suffering from this is motionless and unresponsive; the patient has a weak pulse, shallow breathing and is usually cold to touch.

  Brief involuntary muscle jerks may occur occasionally, resembling a seizure.

  Most syncope cases occur due to insufficient blood flow to the brain causing fainting spells⁵.

Diagnosis of Coronary Heart Disease

The methods to diagnose coronary heart disease include:

1. Electrocardiogram (ECG)An electrocardiogram is a non-invasive test, which records the heart’s electrical activity.

   Small patches called electrodes are placed on the chest and limbs, connected by wires to the ECG machine.

   The heart’s electrical impulses are then translated into a wavy line on the paper, allowing experts to determine the pattern of electrical current flow in the heart to diagnose diseases or heart damage.

2. CT Calcium Score and CT Coronary AngiogramCholesterol deposits in the coronary arteries attract calcium. Determining the calcium score estimates the amount of cholesterol and the sites of the cholesterol plaques in the arteries. A dye injected through the vein in the arm during the scan allows estimation of degree of narrowing in the coronary arteries by the plaques.
3. Echocardiogram (ECHO)Echocardiogram is a non-invasive test, which translates the ultrasound waves reflected off the heart by the ultrasound emitting probe placed over the chest, into a structural image of the heart.

   It can determine how the heart is pumping, how the blood flows in the heart and blood vessels, how big the heart is, and whether the valves are functioning.

4. Stress echocardiogramA stress echocardiogram is a non-invasive test; stress tests are used to see how the heart responds to physical stress.

   The heart may be stressed with exercise such as running on a treadmill or stationary cycling. If physical activity cannot be conducted, medications can be used to increase the heart rate to simulate normal reactions of the heart to exercise. During these stress tests, the ECG electrodes and wires are worn so that the electrical signals of the heart can be recorded.

5. Stress Thallium TestStress thallium tests are minimally invasive. The test includes two segments: a treadmill stress test and then a heart scan after injection of a radionuclide material which allows doctors to quantify the blood flow reaching the heart muscles, the shape, and the function of the heart.

   The test has been used safely to demonstrate the blood volume that the heart receives under either stress or rest conditions.

   It has been used safely for many years to demonstrate the amount of blood the heart is getting under various conditions — rest and stress⁶.

6. Coronary angiographyCoronary angiography is an invasive study which is considered the gold standard for diagnosing coronary heart disease.

   It is performed under local anaesthesia, when X-ray dye or contrast medium is injected into the coronary arteries via tubes called catheters. An X-ray camera then captures the blood flow to show the site and severity of artery narrowing.

   This test can show if blood vessels in the heart have narrowed; it determines whether the heart is pumping normally, whether blood is flowing correctly. This test can identify any inborn heart defect or congenital abnormality.

Who is at higher risk?

People who suffer from the following conditions are more at risk of contracting coronary heart disease⁷.

• ObesityPeople with obesity require more blood and oxygen supplied to their bodies, leading to an increase in blood pressure and a higher risk of coronary heart disease.
• Diabetes mellitusHigh blood glucose may damage blood vessels as well as nerves that control the blood vessels and heart, leading to heart disease. It also increases cholesterol deposition and calcium in the arteries.
• High blood pressureHigh blood pressure increases the force on the arterial walls which may cause damage to blood vessels, leading to plaque buildup and narrower arteries, which in turn causes coronary heart disease.
• Sedentary lifestyleA sedentary lifestyle may lead to fatty deposits on the arterial wall, narrowing the arteries, and thereby causing a higher risk of heart attacks.
• SmokersSmoking increases the buildup of plaque on the arterial wall; this narrows the arteries and causes heart disease.
• High blood cholesterolHigh blood cholesterol causes more deposits on the arterial wall, leading to narrowed arteries and results in coronary heart disease.

Complications with other diseases⁸

1. Aortic aneurysm and dissectionAn aneurysm is the enlargement of part of the aorta that may rupture, while a dissection is a tear in the aorta. Both of these are capable of resulting in death.
2. ArrhythmiasArrhythmias are irregular or slow heartbeats which can be serious. An abnormal heart rhythm may lead to death.
3. CardiomyopathyCardiomyopathy happens when heart muscles become enlarged and stiff which may lead to insufficient blood being transported to parts of the body.
4. Heart failureHeart failure is caused by the buildup of fluid in the lungs, liver or feet. The heart is too weak to supply enough oxygen-rich blood to parts of the body, and this might eventually result in death. Heart failure is the end stage of other heart disease.
5. Pulmonary hypertensionPulmonary hypertension occurs when pressure is too high in the arteries leading from the heart to the lungs. The increase in pressure may damage the arteries, and heart failure might occur.
6. Valvular heart diseaseValvular heart disease refers to having deceased valves that do not fully open or close like normal valves. When there are deceased valves, the heart is unable to pump blood efficiently and must work harder. This may lead to enlargement of the heart and heart failure.
   

   Treatments

   Drugs could be used in the treatment of coronary heart disease.

   

1. StatinsThis drug can reduce cholesterol levels and plaque buildup in the arteries.
2. Beta-blockersThis drug slows the heart rate and reduces blood pressure and stress on the heart.
3. AspirinThis drug thins the blood and helps to prevent blood clots which may cause a blocked artery.
4. Calcium channel blockersThis drug helps to reduce the symptoms of chest pain and blood pressure.
5. NitratesThis drug helps to dilate arteries in the heart and increases the blood flow.

   Medical procedures and Surgery could also be used as a treatment for this disease10.

6. PacemakerThese are mini electrical computers implanted under the skin in the upper chest with electrical wires introduced through the large vein and attached internally to the heart chamber. There are different types of pacemakers according to the requirement of a patient, such as heart block with slow heart rhythm, to detect life threatening abnormal rhythm and electrically to rectify it, and to synchronise the right and left side of the heart in heart failure in selected patients. These pacemakers monitor the heart rhythm continuously and respond as appropriately programmed.
7. Coronary angioplasty
   Coronary angioplasty is a percutaneous coronary intervention (PCI). It may be a planned or unplanned procedure. Coronary angioplasty is used for someone with angina or urgent treatment, should the symptoms of coronary heart disease worsen.A coronary angiogram is required to determine the patient’s eligibility for any procedure.

   During the procedure, a small balloon is inserted to push the fatty tissue in the narrowed artery outwards to allow the blood to flow more easily; in addition, a metal stent is used to hold an artery open.

8. Coronary artery bypass grafting
   This surgery, also known as a heart bypass surgery, is carried out for people with multiple blocked arteries.A blood vessel is grafted between the main artery leaving the aorta of the heart and a part of the coronary artery beyond the narrowed or blocked area as a bridge. Often, an artery that supplies blood to the chest wall is used and diverted to one of the heart arteries. This allows the blood to bypass the narrowed or narrowing sections of coronary arteries and prevents heart attacks.
9. Heart transplant
   A heart transplant is needed when the heart is already severely damaged and the medications are no longer working or when the heart fails to pump blood properly to all parts of the body.A heart transplant requires a healthy donor heart from an irreversible brain-damaged donor with no chance to live, to replace the recipient’s damaged heart.
10. Mechanical Cardiac Support (LVAD)This is an electrical pump implanted in the heart to support the failed heart. It is used as a bridge to transplant until a suitable donor heart is available or as a long term therapy for those patients who are not suitable to receive a heart transplant.

Conclusion

The heart is a vital organ that works throughout a person’s lifespan. Finding a donor match for a heart transplant is difficult; hence, primary prevention is the best way to protect your heart from contracting coronary heart disease. Adopt a healthy lifestyle; eat healthily and move often to maintain a healthy weight, and go for regular health checks to keep tabs on the risk factors that could put you at an increased risk of coronary heart disease.

Citations

1. Centers for Disease Control and Prevention (2021, July 19). Coronary Artery Disease (CAD). CDC. Retrieved September 11, 2023, from https://www.cdc.gov/heartdisease/coronary_ad.htm#:~:text=Coronary%20artery%20disease%20is%20caused,arteries%20to%20narrow%20over%20time
2. National Heart, Lung, and Blood Institute (2022, Mar 24) Retrieved September 11, 2023, from https://www.nhlbi.nih.gov/health/coronary-heart-disease
3. Thompson, A. D., & Shea, M. J. (2022). Palpitations. MSDmanual. Retrieved September 11, 2023, from https://www.msdmanuals.com/en-sg/professional/cardiovascular-disorders/symptoms-of-cardiovascular-disorders/palpitations
4. National Center for Biotechnology Information (2017, July 27). Complications of coronary artery disease. NCBI. https://www.ncbi.nlm.nih.gov/books/NBK355309/
5. Thompson, A. D., & Shea, M. J. (2022). Syncope. MSDmanual. Retrieved September 11, 2023, from https://www.msdmanuals.com/en-sg/professional/cardiovascular-disorders/symptoms-of-cardiovascular-disorders/syncope
6. University of California, San Francisco (n.d.). Coronary Artery Disease. UCSFhealth. Retrieved September 11, 2023, from https://www.ucsfhealth.org/conditions/coronary-artery-disease/diagnosis#:~:text=Coronary%20Angiography%20Coronary%20angiography%2C%20also,for%20diagnosing%20coronary%20artery%20disease.
7. Singhealth (n.d.). Coronary Artery Disease. Retrieved September 11, 2023, from https://www.singhealth.com.sg/patient-care/conditions-treatments/coronary-artery-disease
8. Centers for Disease Control and Prevention (2023, March 21). Other Conditions Related to Heart Disease. CDC. Retrieved September 11, 2023, from https://www.cdc.gov/heartdisease/other_conditions.htm
9. Mayo Clinic (2022, May 25). Coronary Artery Disease. Mayoclinic. Retrieved September 11, 2023, from https://www.mayoclinic.org/diseases-conditions/coronary-artery-disease/diagnosis-treatment/drc-20350619
10. National Health Organization (2020, March 10). Treatment. NHS. Retrieved September 11, 2023, from https://www.nhs.uk/conditions/coronary-heart-disease/treatment/