Coronary heart disease overview

Heart muscles require uninterrupted and sufficient supply of blood to pump blood. The coronary arteries which run along the surface of the heart, pick up oxygen-rich blood from the aorta and furnish the heart. In coronary heart disease, a combination of calcium, fatty material, proteins and inflammatory cells deposit along the inner walls of the coronary arteries. This leads to the formation of plaques. They differ in size. They are soft and spongy on the inside and hard on the outside.

Formation of plaques within the coronary arteries makes them narrow. This hinders smooth flow of blood through them and the heart does not receive adequate oxygenated blood. As a result, the heart muscle cells starve for oxygen and soon they start dying. This damage is permanent and can’t be reversed. The slowing of blood flow may cause angina or chest pain. If the plaques totally block a coronary artery, it may lead to a heart attack or a fatal rhythm disturbance (sudden cardiac arrest). Coronary heart disease is a major cause of disability and death.

A human heart is four-chambered that is it consists of four separate compartments: an atrium/auricle and ventricle on the right and an atrium/auricle and a ventricle on the left side of the heart.

Veins collect de-oxygenated or carbon-dioxide-rich blood coming from all the body parts and pour it into the right atrium. This blood then flows into the right ventricle, from where it is pumped to the lungs for purification. After purification, the oxygen-rich blood enters the left atrium. From there it flows into the left ventricle and is pumped at high pressure into the arteries. The entire process makes one heartbeat.

The pumping action of heart requires great energy in order to pump blood to each and every cell of the body. The heart muscles need to contract with great energy to keep the blood flowing throughout the body and for that, they must receive plenty of oxygen and nutrient supply coming via the coronary arteries. These arteries are usually quite flexible, elastic and strong.

There are 3 major coronary arteries, each one of them supplying different regions of the heart. The right coronary artery provides oxygenated blood to the right ventricle of the heart and a lower portion of the left ventricle. The left coronary artery supplies the left side of the heart. It is divided into LAD and LCX. The left anterior descending (LAD) branch furnishes the front part of the heart and the left circumflex (LCX) branch furnishes the left lateral and back side of the heart.

In children, the inner lining of the coronary arteries is very smooth and allows easy flow of blood. As a person ages, the cholesterol and calcium contents form plaque deposits along the inner walls of these arteries, making them thicker and less elastic.

As blood hits the plaques during each heartbeat, they may crack open. This promotes blood clotting. Blood clots may further decrease the blood flow, causing severe chest pain (angina), or complete blockage of the artery.

Coronary heart disease causes and symptoms

Coronary heart disease causes

Coronary heart disease can occur due to any problem with the coronary arteries which prevents the heart from getting sufficient oxygen- and nutrient-rich blood. Several factors speed up the deposition of fat and calcium along the inner lining of coronary arteries. This makes them thicker and less elastic. This is known as atherosclerosis and is the most common cause of coronary heart disease.

Atherosclerosis or narrowing of the coronary arteries obstructs and slows down the flow of blood supplying the heart muscles. This makes the heart muscles deficient in oxygen and nutrients. Lack of adequate blood is called ischemia, so coronary heart disease is sometimes called as ischemic heart disease.

There are several risk factors which are related to the cause of coronary heart disease. The following are the most common:

• Inheritance or heredity: Coronary heart disease runs in the family.
• Use of tobacco: This includes chewing tobacco and smoking any form of tobacco such as, cigarettes, cigars, pipes, etc.
• High blood cholesterol: Variations in normal levels of cholesterol in the blood that is, high levels of low-density lipoprotein (LDL), the bad cholesterol, and low levels of high-density lipoprotein (HDL), the good cholesterol.
• High-fat diet
• Obesity
• Hypertension or high blood pressure
• Diabetes
• Lack of regular exercise
• Emotional stress
• Type A personality characterized by impatience, aggressiveness, competitiveness, etc.

Coronary heart disease symptoms

The common symptoms of coronary heart disease include:

• Angina pectoris which is a condition in which chest pain arises due to exertion. It may be relieved by rest.
• Shortness of breath on exertion
• Pain in jaw, back or arms, especially on left side of the body, either during exertion or rest.
• Palpitations which include irregular, rapid or strong heartbeats due to exertion, agitation or illness.
• Light-headedness, dizziness, or fainting
• Weakness on exertion or at rest
• Arrhythmia or irregular heartbeat

The most devastating symptom of coronary heart disease is sudden and unexpected cardiac arrest. Cardiac arrest takes place when the heart stops beating, suddenly and without any warning.

Cardiac arrest usually occurs in people who have had suffered from heart attacks, but it may occur as the first symptom of coronary heart disease.

Most people display some symptoms or discomfort.

Symptoms generally occur while doing some activity or exercise. This is because the coronary arteries are blocked and fail in meeting the increased demand for nutrients and oxygen by the heart muscles.

When to seek medical care?

Inform your healthcare provider if you notice any of the following symptoms, which suggest angina (chest pain):

• Chest pain, fullness, pressure or a feeling of indigestion after physical exertion, which may not be relieved by rest
• Pain in shoulder or arm involving left, right, or both sides during physical or mentally stressful activity
• Pain in jaw which is unexplained by another cause like, a sore tooth
• Shortness of breath after exertion or walking uphill
• Fainting spell which lasts for a few seconds to a few minutes. It happens when the brain doesn’t get sufficient oxygen.
• unexplained vomiting, nausea or, sweating
• Dizziness or light-headedness
• Palpitations

The most important factor is time. Each year thousands of people die because they ignore these symptoms and do not seek medical attention on quickly. This may prove to be the difference between life and death.

The most common symptoms of heart attack are as follows:

• Continuous or prolonged chest pain, chest pressure, or a feeling of heartburn
• Pain in shoulder or arm (left or right) or abdomen. It doesn’t go away on it’s own.
• Shortness of breath after minimal activity or while resting
• Blackout spells
• Unexplained, excessive sweating, nausea, or vomiting
• Recurrent chest pain or uneasiness at rest

Exams and tests

The symptoms of coronary heart disease are uncertain which means they can be caused due to many different conditions. During diagnosis, your healthcare provider will ask you questions about your symptoms, the medications you take, your general health and specific medical problems and, your medical and surgical history. He will also do a physical examination, blood test, an ECG or electrocardiogram, lab tests and imaging tests like X-ray or CT scan.

• Blood tests are done to check your blood cells, the chemical composition of your blood, etc. to predict a heart attack.
• ECG is a painless test which is done to determine the electrical activity of the heart. The test gives clues about the underlying cause of cardiac symptoms.
• Chest X-ray can show abnormal changes in the size or shape of the heart.

If you are diagnosed to have angina symptoms or your healthcare provider infer that you have a coronary heart disease, you may have an exercise (treadmill) stress test. In this test, ECG tracings are measured before, during and, after stressing the heart by exercise. The accuracy of this test is 60-70%.

If a blockage is found in the coronary arteries then, you may undergo a nuclear (radionuclide) stress test. This test uses a radioactive tracer to identify the quantity of blood flowing into different parts of the heart muscles. This test is expensive but it’s quite successful.

More exams and tests

Echocardiography

Echocardiography is based on SONAR (SOund Navigation And Ranging) technique. It uses sound waves to create an image of the heart as it beats. The movements of the ventricular walls are compared when at rest and stress. The heart can be stressed either by exercise on a treadmill or by administration of a drug. The motion of the walls drops during stress if the coronary artery supplying that part of the heart is severely blocked.

Electron beam CT scan

Electron beam CT scan is a non-invasive method and does not require introduction of instruments into the body. It measures the amount of calcium deposited in the plaques of coronary arteries. It can detect blockages of only 10-20% of an artery, which may not be visible in other tests.

Coronary angiography

Coronary angiography by cardiac catheterization is the best way to estimate coronary heart disease. It is an invasive test as it requires a long, thin plastic tube (catheter) to be threaded into the opening of your coronary arteries from a blood vessel in either your groin or your arm. It is the only test that helps a cardiologist know whether to treat you with a by-pass surgery, stent placement, a less-invasive technique like, angioplasty or just medications.

Medical Treatment: Medications

Treatment for coronary artery disease aims towards balancing blood supply to the heart with heart oxygen demand and preventing further damage. Following are the medications which are effective in the treatment of the disease and should only be taken on a doctor’s prescription:

• Aspirin: Aspirin is a blood thinner. It reduces the possibility of clot formation in the coronary artery and thereby, prevents a heart attack. The common side effects of aspirin are ulcers and bleeding problems.
• Beta-blockers: They help in reducing the heart’s demand for oxygen by decreasing the heart rate and blood pressure.
• Nitroglycerin: It reduces the heart’s oxygen demand and also increases the oxygen supply by dilating the coronary arteries. This is how it brings relief from chest pain.
• Calcium channel blockers: They improve blood flow in the coronary arteries by causing dilation in them. They also lower blood pressure and slow heart rate.
• ACE inhibitors: Angiotensin-converting enzyme or ACE inhibitors work by dilating blood vessels, increasing blood flow. They are very useful in people with diabetes and those with weakened heart muscles.
• Statins: These drugs work by reducing the amount of cholesterol and other fats in the blood. This lowers the chance of plaque formation in the lining of the blood vessels and thus, reduces the progression of coronary heart disease. They prevent repeat heart attacks.

Medical Treatment: Invasive Procedures

When medical treatment is not enough for the worsening symptoms of angina, you may need an invasive procedure to clear the blocked artery. These procedures are complicated and are performed by a cardiologist.

Percutaneous Transluminal Coronary Angioplasty (PTCA)

This procedure is similar to cardiac catheterization or coronary angiography but it can be used for both treating as well as diagnosing a disease.

• This time, a stronger tube (guide catheter) is inserted into an artery in the groin or arm and a hair-thin guide wire is threaded via it into the coronary artery.
• A much thinner catheter is threaded over the guide wire into the blocked artery. There is a tiny balloon at the end of this thinner wire.
• The balloon is carefully positioned at the blockage and is inflated to widen the artery and improve the blood flow. It is then withdrawn.

Stent

A stent comprises of a small, sieved, coil-like metallic tube mounted over a balloon.

• A stent is inserted and positioned at the blockage. The balloon is inflated, which expands the stent.
• The balloon is then withdrawn but the stent is kept at that site. It prevents the artery from narrowing again.

Like arteries treated with angioplasty alone, arteries treated with a stent can eventually get blocked again. However, the stent is a longer solution for many people.