Patient Education & Resources

Patient Education Module 1 - Introduction To The Heart

SECTION I: Introduction To The Heart

The heart is a strong muscular organ about the size of your fist. It is in the centre of your chest and is tilted slightly to the left. Its job is to pump blood though the blood vessels, which takes oxygen and nutrients to all parts of the body.

I: The Heart Function: Blood Flow Through the Heart

A thick band of muscle tissue (the septum) divides the heart into two pumps, the right heart and the left heart. Each side of the heart has a different function in the heart's pumping action.

The right side of the heart receives unoxygenated blood returning from the organs of the body and pumps it to the lungs. There the blood picks up a fresh supply of oxygen while carbon dioxide (a waste product) is breathed out.

The left side of the heart receives the oxygen-rich blood from the lungs and pumps it out through the aorta (main artery) to all parts of the body.

The right side and left side of the heart are each made up of two chambers:

1. the upper chamber, called the atrium, and
2. the lower chamber, called the ventricle.

The upper and lower chambers are connected by valves. Valves are like one-way doors that allow the blood to flow through the heart in only one direction. In both sides of the heart the blood is pumped from the atria to the ventricles.

II: Blood Supply to the Heart: Coronary Arteries

The heart muscle itself must also be supplied with oxygen and nutrients in order for it to keep working. These are delivered to the heart muscle through blood vessels called coronary arteries. There are two main coronary arteries:

1. the right coronary artery, and
2. the left coronary artery, which divides into two branches, the left anterior de­scen­ding branch and the circumflex branch.

These two coronary arteries are located on the outside of the heart, reaching into the heart muscle, supplying every portion of it with blood.

SECTION II: What Is Coronary Artery Disease?

Coronary Artery Disease is a process that gradually narrows the coronary arteries. This is called atherosclerosis. This narrowing of the coronary arteries is caused by fatty material (primarily cholesterol) in the blood, which forms sticky plaques that attach to the inside of the blood vessels. These plaques can get larger and larger, clogging the arteries and damaging the arterial wall, which in turn may also trigger clot (thrombus) formation.

If the coronary arteries become severely narrowed or blocked, the amount of blood flow through them decreases and interferes with the oxygen and nutrient supply to the heart muscle. The amount of nutrients and oxygen reaching the heart muscle may not be enough to meet the need, and portions of the heart muscle become deprived.

This is particularly true when you increase the workload on your body, for example:

• during exercise
• stressful situations
• exposure to cold or windy weather
• eating rich or large meals
• excitement

The heart must then beat faster, and needs more oxygen and nutrients to meet the demand. The clogged coronary arteries restrict the heart's ability to obtain the oxygen and nutrients it needs. This reduction of blood supply to the heart muscle causes the aching discomfort of angina.

SECTION III: What Is Angina?

The body may receive its earliest warning signal of inadequate blood supply in the form of a symptom called angina. It is a name used to describe a type of chest pain or discomfort. It is symptom of coronary artery disease (CAD).

Angina is often associated with an increased demand on the heart. Some people have stable angina, and can predict when they may experience chest discomfort. Others have unstable angina, and cannot predict when they may have chest discomfort. This type of discomfort may occur during any type of activity, or even at rest.

Symptoms of Angina

Patients have described the sensation in many ways, such as crushing, heavy-feeling, squeezing, tightness, aching, pressure, choking, and even burning and tingling.

The discomfort of angina usually occurs just under the breast-bone, located in the centre of your chest, often spreading to the left shoulder and down the arm to the back, or even up to the neck and jaw. Angina pain is often accompanied by:

• anxiety
• difficulty in breathing, or shortness of breath (SOB)
• sweating
• nausea
• dizziness

Shortness of breath, fatigue and weakness are common symptoms of angina in women.

Treatment of Angina

Angina usually lasts three to five minutes, and will usually go away with rest. If an angina attack occurs:

1. stop whatever you are doing
2. rest until it passes
3. place a nitroglycerin tablet under your tongue, or use the spray
4. if the pain is not promptly relieved, take another nitro every five minutes until a total of three pills or sprays have been taken
5. if you still have angina pain, go to the nearest emergency department
6. take the medications that have been prescribed for you on a regular basis, and exactly according to your doctor's instructions.

Angina may occur several times a day or infrequently, with weeks or months between. It is important to notify your doctor if your pattern of angina changes, for example if it is:

• more frequent
• longer lasting
• provoked by less exertion
• occurs during rest
• wakes you at night.

Note that chest pain can also be caused by many conditions besides angina, such as:

• indigestion
• anxiety
• muscle disorders
• infection
• injury, and so on.

Only your doctor can determine the cause of your symptom. Angina is not a heart attack.

SECTION IV: What Is a Heart Attack?

A heart attack in medical terms is a 'myocardial infarction' (MI) or 'coronary thrombosis' or 'coronary.' It is the result of severe narrowing or obstruction in the coronary arteries, which blocks the blood supply to a particular area of the heart and causes permanent damage to that area.

The amount of muscle damage determines the size of the heart attack.

The most common type of heart attack is caused by coronary thrombosis, which occurs when a clot (thrombus) blocks one or more of the coronary arteries. Coronary thrombosis is one of the manifestations of coronary artery disease.

Heart attacks sometimes occur in people with little or no coronary artery disease. Spasm, or sudden constriction of the coronary artery, may cause a heart attack.

Spasm may occur in a coronary artery that is totally free of atherosclerosis (as well as in one that is heavily affected by that condition), and this may explain why many people suffer angina and other cardiac problems without any evidence of underlying blockage of the arteries.

Symptoms of a Heart Attack

A heart attack can come on gradually, preceded by several attacks of angina over days, weeks, months, or even years. But a heart attack may also occur without any apparent warning and in people who have never previously experienced any chest pain.

Typically you may experience any or all of the following when having a heart attack:

• discomfort or band-like pressure, heaviness, tightness, burning or squeezing
• indigestion, fullness or choking sensation across the chest or anywhere in the upper body
• it may commonly spread to the back, jaw, arms (especially the left arm)
• it may vary in intensity from tightness to one of agonizing crushing or bursting
• it may be continuous, or it may last a few minutes, fade, and then recur
• it may be associated with:
  • sweating
  • nausea and/or vomiting
  • dizziness
  • palpitations
  • loss of consciousness
  • severe weakness
  • shortness of breath

Heart attack pain is usually stronger than angina pain and does not go away when you rest or take medication.

The majority of women who have a heart attack do NOT experience chest discomfort. Women most frequently complain of shortness of breath, weakness and fatigue.

SECTION V: Reducing the Risk of Having a Heart Attack

A variety of different approaches may be taken to deal with the underlying coronary artery disease and to reduce the possibility of a heart attack:

1. Increased awareness of risk factors and their correction play an important role in preventing or slowing down the progression of heart disease.

   Risk Factors Over Which You Have No Control

   • being male
   • your age
   • your family history

   Risk Factors That Can Be Altered

   • cigarette smoking
   • high blood pressure
   • high blood cholesterol (LDL, or 'bad' cholesterol)
   • low HDL ('good') cholesterol
   • obesity
   • diabetes
   • lack of exercise
   • stress

2. Drug Treatment. The use of drugs depends upon the nature of the heart attack and underlying coronary disease. Antihypertensive drugs may be prescribed to lower the blood pressure. Other drugs may be given to improve heart function, prevent angina, or lower the level of blood cholesterol.

3. Other Treatment. Other forms of treatment are also available. Two (invasive) ones are:
   • coronary artery bypass graft
   • coronary angioplasty

   Their use depends on individual needs.