The heart is a hollow muscular organ the size of a fist. It lies in the center of the chest, slightly to the left and under the sternum or breastbone.
The heart’s function is to pump blood containing oxygen and nutrients to all parts of the body. The heart is divided into four chambers (two atriums and two ventricles). The right side of the heart receives "used" blood from the body and pumps it to the lungs, where it picks up oxygen. The oxygen-rich blood then returns to the left side of the heart and is pumped through the aorta to all parts of the body.
There are four valves in the heart. These are located between the upper and lower chambers of the heart and in the major blood vessels of the heart. The valves keep blood pumping in one direction.
At rest, a heart beats an average of 60–100 times a minute. Each beat or contraction is caused by an electrical stimulus triggered by specialized cells called the SA node. The electrical impulse from the SA node travels through a series of fibers located throughout the heart chamber and causes a contraction of the heart muscle.
The heart, like the other organs in the body, needs oxygen to function effectively. The coronary arteries provide oxygen-rich blood to the heart muscle.
The coronary arteries branch off the aorta. They lie on the surface of the heart and have many branches to feed all of the heart muscle.
Coronary Artery Disease
The lining inside a healthy coronary artery is normally smooth. Damage to the inner lining of the artery contributes to gradual build up of material (fatty layers and other deposits - called atherosclerosis). This build-up blocks the flow of blood and may eventually lead to serious problems such as angina or heart attack.
The build up is much like what happens in an old rusty pipe. Only a trickle of blood can get through which creates an imbalance between the demand of the heart muscle for oxygen and the ability of the narrowed coronary artery to meet that demand.
What is angina?
When the heart does not receive enough oxygen-rich blood some discomfort called angina may be experienced. Angina is also caused by a spasm in the coronary artery. Angina is the heart's way of warning that it needs more oxygen.
Each person may experience any of the many different symptoms associated with angina.
- Pain, aching or discomfort
- Squeezing or cramping
- Numbness or tingling
- Shortness of breath Tightness
- Fullness or heaviness
- Sweating or dizziness
Symptoms may be felt in the chest, shoulders, upper back, arms, neck, throat or jaw. Angina can be triggered in times of stress, during vigorous physical activity, or after heavy meals. Never ignore angina. Rest and medication are both effective ways to relieve angina.
What is a Heart Attack or Myocardial Infarction?
A heart attack occurs as a result of a blocked coronary artery. Since the coronary arteries are like pipelines running through the heart, a clot, blockage or spasm will restrict blood flow. The area of the heart that does not receive oxygen may become permanently damaged. Damage to the heart muscle occurs when the cells of the heart are starved of oxygen. These cells die because of the blockage. Eventually scar tissue is formed in the damaged area.
How your heart muscle heals?
After a heart attack, the heart muscle is damaged. The damaged area will heal and scar tissue will form. Small blood vessels can enlarge to nourish the area that surrounds the scar or damaged site. A partial scar is formed in three to four weeks. A firm scar develops anywhere from six weeks to three months after the initial injury.
New circulation surrounding the damage area is called collateral circulation. Aerobic exercise helps to form this new circulation that nourishes the heart. Rest and gradual increase in activity is the key to success. Aerobic exercise will strengthen the heart muscle and help it become a more efficient pump.
Congestive Heart failure
Congestive heart failure (CHF) occurs when the heart is unable to pump forcefully enough to circulate blood to all parts of the body. If the heart is weakened or damaged, it may be a less effective pump. When this happens, blood begins to back up in the chambers of your heart, lungs or other parts of the body.
Symptoms of CHF include:
- Shortness of breath - may be all time, with exertion, or only at night
- Sudden weight gain from fluid not fat
- Swelling (edema) of hands, feet or abdomen
- Extreme fatigue
- Dry, hacking, frequent cough
- Difficulty sleeping
Most of the time these symptoms can be controlled with rest, diet and medications.
You can help control these symptoms by:
Contacting your doctor
when any of the above symptoms concern you. Take your medications as prescribed. They will help prevent water retention and increase effective heart contraction. Weigh yourself each day, recording your weight and call your doctor with any rapid weight gain. Follow a low sodium diet as recommended by your doctor. Rest when you feel tired. This will help to reduce the workload on your heart.
Damage to the heart can affect the electrical impulse in the heart and change the rhythm. Disturbance in the rhythm of the heartbeat is called an arrhythmia. It has various causes. Arrhythmias
can be too slow, too fast, irregular or all of these.
Some are serious. They can be treated by medications and sometimes surgery. Some arrhythmias may need a pacemaker. Life -threatening arrhythmias may need emergency shock treatment (defibrillation) to restore the heart's rhythm.
Find more information about arrhythmia treaments
What causes heart disease?
There are many unanswered questions when it comes to heart disease but there are certain risk factors that have been identified as contributing to its development and progression.
Coronary risk factors are habits or personality characteristics that may increase a person's risk of developing heart disease. Risk factors are divided into two groups: the controllable risk factors that can be altered, and the uncontrollable risk factors that cannot be altered.
It's important to note that while you can’t change your age, gender or family history, you can modify or delay their effects by working on controllable risk factors that can be changed. You can prevent future cardiac problems.
Uncontrollable risk factors
- Family history: Your chance of having a heart attack is greater if you have parents, grandparents or siblings with heart disease. Familiar lifestyles as well as genetic tendencies may contribute to this fact.
- Age 55 or over: Coronary artery disease is associated with the aging process. The older a person becomes the more likely he or she is to develop atherosclerosis.
- Gender: Current research shows that coronary artery disease is more prevalent in men than in women. This may be due to hormonal factors. Women after menopause have increased risk of cardiac events.
Controllable Risk Factors
- Cigarette smoking: Smoking contributes to lung cancer, bronchitis and emphysema. Smokers have more than twice the risk of heart attack and are two to four times more likely to die of sudden cardiac death than non-smokers. Smoking is also detrimental to family members. The nicotine in cigarettes causes the heart to work harder, increasing the heart rate and blood pressure. The carbon monoxide in cigarette smoke clings to the hemoglobin in your blood more readily than oxygen does, thus your heart may not get the oxygen it needs. These chemicals may also contribute to injury in the artery walls. Do not smoke!
- High Blood Pressure: High blood pressure can speed the process of atherosclerosis and put an added strain on your heart. The pumping force needed to supply blood for your body is greater with elevated blood pressure.
- Hypertension increases your risk of heart attack, heart failure or stroke. You can control hypertension by modifying your diet, exercising regularly, taking medications your doctor has prescribed as directed and learning relaxation and stress management techniques.
- High Cholesterol: Cholesterol is a fatty substance made by your body and found in some foods. Cholesterol is the main ingredient of the fatty deposits that are found in the coronary arteries when coronary artery disease develops. The higher the cholesterol levels in your blood, the greater the chance this disease will develop and progress quickly. To keep blood cholesterol at a healthy level, it is important to follow a low-fat, low cholesterol eating plan.
- Diabetes: Diabetes Mellitus is a disorder characterized by raised blood sugar levels. This is caused by the failure of the body to produce insulin (a hormone that helps to move sugar from the blood to the body’s cells), or the body resisting the insulin that is present. Prolonged high levels of blood sugar damage the inside lining of blood vessels and encourage plaque deposits to accumulate (atherosclerosis). Keeping your diabetes well controlled reduces the risk.
- Sedentary lifestyle: Inactivity has been shown to increase the risk of developing coronary artery disease. Regular exercise has numerous benefits. It can strengthen your heart muscle and help it work more efficiently. It can also help lower your cholesterol level, maintain an ideal body weight and aid your coping with stress. If you do not exercise regularly (at least three to five times per week) and your job does not involve regular physical activity, you have a sedentary lifestyle. Beginning a safe exercise program after a heart attack or bypass surgery can help you to recover more rapidly and help prevent further cardiac problems. It is important to start slowly, increase your level of exercise gradually and have fun. Most people find it helpful to participate in a cardiac rehabilitation program designed to help you begin a safe exercise program which is individualized to meet your needs.
Other factors to consider:
- Diet: A low fat and low cholesterol diet can help to prevent atherosclerosis (the deposit and build up of fatty substances in your arteries). Foods to avoid are foods that contain large amounts of saturated fats such as meats, fast foods, butter, and full fat dairy products.
- Stress: Negative stress has been linked to many physical ailments ranging from heart attacks to tension headache. Learning to recognize your stress response and anticipating situations that trigger it may help avoid some stressful situations.
- Obesity: If you are obese or overweight, your heart has to work harder to supply your tissues with blood, oxygen and nutrients. An overweight person's heart also works harder to do activities than a person at his or her ideal body weight. Reducing your weight with exercise and sensible diet can help you modify other controllable risk factors.
- Excessive use of alcohol: Prolonged use of excessive amounts of alcohol can contribute to elevated fat (triglyceride) levels in the blood. It may also damage your heart muscle, thus interfering with your heart's ability to pump blood to the rest of your body.
How do you know if you have heart disease?
There are often no signs that a person has heart disease. A doctor can use a number of tests to determine if there is a problem.
- History and physical examination
A complete physical examination can help determine if you have or may develop heart disease. Your medical history is also important. Questions about smoking history, alcohol intake and exercise habits, will be asked. Information about your health history as well as a history of your family's health will also be important.
- Electrocardiogram (EKG or ECG)
ECG is short for Electrocardiogram, which measures the heart's electrical beating pattern. Electrodes are placed on the chest wall to pick up the electrical impulses, which are then printed on a graphed paper. A similar pattern is seen in normal functioning hearts. A change in this pattern may indicate that an area of the heart is injured or damaged. This is a very simple procedure and can be easily performed in any doctor’s office.
A stress test is similar to a resting ECG test in that a series of leads are attached to your chest. However, the recording is made while exercising, such as walking on a treadmill or riding a stationary bicycle. This exercise intensifies the demands on your heart by increasing your heart rate and blood pressure. This test is used to evaluate the heart's response to physical stress, including: electrical abnormalities, the amount of blood flowing to the heart muscle, and the heart muscle's response to exercise.
Cardiac enzymes are substances normally stored in heart muscle cells. When the heart is damaged, enzymes are released into the bloodstream. These blood tests show an increase in the level of enzymes when you have had a heart attack.
An echocardiogram uses high frequency sound waves to take moving pictures of your heart. Your doctor studies the pictures to measure and determine the function and structure of your heart.
A radionuclide scan is a test in which a radio-active substance (Radionuclide) is injected into your blood stream and travels to your heart. A special camera projects a picture of your heart on screen, showing any malfunction of your heart.
- Heart Catheterization (angiogram)
A heart catheterization is an X-ray test performed by a doctor. A thin, flexible tube is passed through the blood vessel in your groin and follows the artery to your heart. A special dye is injected through the tube. The location of any narrowing or blockages can be seen on an X- Ray screen.
Treating Heart Problems
- The number of blockages
- The location of blockages
- Your medical history
- Your individual needs
There are many medications that can be used to treat heart disease, and they all work in different ways. Some decrease the stress on your heart and others may increase its ability to pump blood.
- Coronary Angioplasty and Stent Placement
Coronary angioplasty (PTCA) and stent insertion is a method used to open a blockage in a coronary artery from inside the artery. Like an angiogram, a long tube or catheter is threaded through to the heart from the artery in the groin or arm. The catheter used has a special balloon at the tip. The balloon catheter is threaded down the coronary artery containing the blockage. The balloon is inflated at the blockage and compresses the plaque of cholesterol, thereby opening a new channel for blood flow. Where possible, an expandable metal tube (stent) is implanted in the blockage, using the balloon catheter. The stent acts like a scaffold in the blockage and provides a better opening in the artery.
Open Heart Surgery is done when normal circulation is changed by coronary artery disease, heart valve disease, or other heart problems. Common heart surgeries are:
Coronary artery surgery is done to bypass each narrowed artery with a healthy vein or artery from your body. A leg vein (usually the saphenous vein) or an artery from your chest (internal mammary artery) and from your arm (radial artery) or Gastroepiploic artery can be used for the bypass graft. Your doctor will decide on what type of graft to use depending on the number and location of your blockages. The bypass increases blood flow to the heart muscle to relieve angina and improve heart function.
The valves can be abnormal or damaged by birth defects, infection (rheumatic fever or scarlet fever) and degeneration from aging. When scarring or thickening occurs, this makes the valves harder to open (stenosis) or unable to close completely (insufficiency). A damaged heart valve may be repaired but more often it must be replaced with a mechanical or tissue valve.
The atrial septum is the wall that divides the upper chambers (atria) of the heart. An atrial septal defect (ASD) is an opening in this wall "hole in the heart" that fails to close during fetal development. The surgery is designed to repair this hole so that blood will follow the normal pathway through the heart chambers.