All of the body’s organs require blood in order to function properly. Blood is composed of a liquid portion known as plasma and several cell components. The cell components are known as red blood cells, white blood cells and platelets. The red blood cells are the cells that carry oxygen to the body’s organs. The blood vessels that carry the oxygen-rich blood to the organs are known as arteries. During the process of metabolism the organs develop carbon dioxide.

As the oxygen-rich blood passes through the organ, the oxygen in the red blood cells is exchanged for the carbon dioxide. Blood rich is oxygen is a bright red, whereas blood that has had the oxygen extracted is a dark red to purple color. The blood that has had its oxygen extracted is known as de-saturated blood. The blood vessels that carry the de-saturated blood away from the organ are known as veins.

Your heart is a muscle about the size of your fist. This muscle pumps nonstop to keep your body supplied with blood that is rich in oxygen. To do its job, your heart needs its own oxygen-rich blood supply. Blood gets oxygen from the lungs and travels to your heart through the coronary arteries.

Normal Coronary Arteries Carry Blood

A large vessel called the aorta carries blood from your heart to the rest of your body The coronary arteries branch off from the aorta. Smaller arteries branch off from the coronary arteries. These smaller arteries run over and through the heart muscle. They nourish every part of the heart with blood.

There are several coronary arteries which deliver oxygen and nutrients to the heart's own tissue. These coronary arteries can become blocked by a buildup of cholesterol fats, often referred to as "plaque". Plaque deposits can make the arteries stiff and irregular. This is called atherosclerosis, or "hardening of the arteries". There can be a single blockage or multiple blockages, and they can vary in severity and location.

Above: Atherosclerosis

Any narrowing, or blockage, of the coronary arteries reduces the blood supply to the heart tissue, therefore reducing the amount of oxygen and nutrients delivered. This inhibits the normal function of the heart muscle.

Above: Thrombosis

A person with one or more blocked arteries may feel pain and periodic discomfort in the chest, radiating to the neck and/or arms (usually on the left side). Symptoms can be triggered by physical exertion, eating, changes in temperature, extreme emotion or may be present even at rest. The symptoms may last 3 to 5 minutes until the cause is relieved; otherwise symptoms may last longer. If this continues, it can starve the heart muscle cells of oxygen and eventually lead to a heart attack.

What are the risk factors that contribute to CAD?

Several factors are known to contribute to the buildup of plaque in the coronary arteries. It is often the combination of several of these risk factors, rather than a single factor that contributes to the development of CAD. Some of the risk factors such as gender, age, and heredity can only be noted--they cannot be changed. Other factors, however, can be controlled, including:

• High blood pressure
• Smoking
• High cholesterol levels
• Lack of proper exercise
• Body weight
• Diabetes
• Stress
• Poor Diet

How prevalent is CAD?

Coronary artery disease is a huge health problem in the United States. According to the most recent figures from the American Heart Association, coronary heart disease is the single leading cause of death in America today.

More than 12 million people alive today have a history of heart attack, angina pectoris (chest pain) or both. An estimated 1.1 million Americans will have a new or recurrent coronary attack this year--one third of these patients will die.

CAD patients are usually men over age 65. Historically, coronary artery disease has been considered a man's disease, but it is also the leading cause of death among women in the U.S. According to the National Institute of Health, African-American women in particular are 24% more likely to die of coronary artery disease than their Caucasian-American counterparts.

Older women also have significantly higher rates of coronary artery disease than younger women. On average, women develop coronary artery disease fifteen years later than men and 39% of women die from the disease as compared to 31% of men.

The schematic diagram below illustrates the four valves of the heart and how they are oriented within the heart. The heart valves in reality are not in this simplified orientation, but the diagram serves to show the valves and their relationship to each other.

The heart is generally thought of as having a right and left side. In reality, the heart is one organ and not divided into two separate organs. The heart is made up of four chambers, two on the right and two on the left. The chambers are known as atria and ventricles. Each side of the heart is composed of one atrium and one ventricle. The atria are the receiving chambers of the heart, receiving blood flowing back to the heart. The ventricles are the chambers of the heart that pump the blood out of the heart.

The valves of the heart are located within the chambers of the heart and are critical to the proper flow of blood through the heart. All of the valves, when functioning normally, act as one-way valves, allowing blood to flow either from one chamber to another, or allowing blood to flow out of the heart, in only one direction. The valves control the flow of blood through the heart by opening and closing during the contractions of the heart. The opening and closing functions of the valves are controlled by pressure differences generated within the heart, as well as some muscles located within the heart.

The four valves are known as:

1. The tricuspid valve
2. The pulmonic or pulmonary valve
3. The mitral valve
4. The aortic valve

The easiest way to understand how the valves work with each other is to describe the flow or circulation of blood through the heart, which cannot be done without describing the location and function of the valves.

The veins of the body all eventually drain into the right atrium, which is the receiving chamber of the right side of the heart. Once the right atrium is full, the tricuspid valve opens, allowing the de-saturated blood to flow into the right ventricle.

The right ventricle then fills with the de-saturated blood. As the pressures begin to change in the right atrium and right ventricle, the tricuspid valve closes. The right ventricle then contracts and pumps the de-saturated blood through the pulmonary valve, and into the lungs.

As the de-saturated blood leaves the right ventricle, it passes through the pulmonary valve, which has been closed as the right ventricle was filling. The pulmonary valve opens, allowing the blood to leave the right ventricle and flow to the lungs via the pulmonary artery. Once the right ventricle has emptied, the pulmonary valve closes, thereby keeping the blood from re-entering the right ventricle.

As the de-saturated blood passes through the lungs, the carbon dioxide that was added to the red blood cells by the body’s organs is exchanged for a new supply of oxygen. The newly oxygenated blood then flows from the lungs to the left atrium, which is the receiving chamber on the left side of the heart. The valve located in the left atrium is the mitral valve. As the left atrium fills with the newly oxygenated blood, the mitral valve remains closed.

As the pressure changes within the left atrium and left ventricle, the mitral valve opens, allowing the oxygenated blood to flow into the left ventricle. As the left ventricle fills, the pressures in the left atrium and left ventricle begin to change. Once the left ventricle is filled, the mitral valve closes as the left ventricle begins to contract. By closing at this time, the mitral valve prevents the oxygenated blood in the left ventricle from flowing back to the lungs.

The left ventricle is the pumping chamber of the left side of the heart and is the most muscular portion of the heart. When you hear some say their blood pressure is 120 over 80, it is the left ventricle that is generating these pressures. As the left ventricle contracts, the oxygenated blood leaves the heart and crosses the aortic valve, which is the valve that helps to control the flow of blood out of the heart to the body. The oxygenated blood leaving the left ventricle and crossing the aortic valve enters the main artery of the body, known as the aorta. The aorta then travels to the body’s organs via branches that carry the blood to the individual organs. Once the left ventricle has emptied, the aortic valve closes to keep the blood that has just been pumped out from re-entering the heart.

The valves of the heart open and close in a sequential fashion and are critical to normal heart function. Various conditions can affect the function of the heart valves. In general, the two main categories of valve problems are: a) Stenosis and (b) insufficiency or regurgitation. Stenosis is a condition in which the valve narrows and does not open fully. Insufficiency or regurgitation is a condition that prevents the valve from fully closing. Both stenosis and insufficiency may over time cause problems and eventually require surgery to either repair the valve if possible, or replace the valve if a satisfactory repair cannot be performed.

Heart failure impairs both the heart muscle and the heart's electrical system. Disturbances of the heart's normal rhythm - known as arrhythmias - result from problems with the electrical system. Because of heart muscle damage, patients with heart failure commonly have arrhythmias, especially from the lower chambers of the heart (the ventricles) consisting of slow, fast, or irregular heart beats.

Management of arrhythmias in heart failure patients is a specialized field and requires the collaboration between arrhythmia and heart failure specialists. Some of the drugs made to suppress these rhythm disturbances can also decrease the heart's pumping ability, which could worsen heart failure and in turn cause more arrhythmias. The goal of therapy is to treat the arrhythmia and the heart failure together.

Extra or rapid heart beats, called palpitations, are sometimes felt as "fluttering sensations" in the chest. Some people faint or feel dizzy or short of breath. Still others may feel chest pain or nothing at all when they have an arrhythmia. Generally, but not always, the longer the arrhythmia lasts, the more severe the symptoms.

Arrhythmias are divided into two main types:

• Bradycardias (slow heart rates)
• Tachycardias (fast heart rates)

Both can be especially dangerous to someone with heart failure and a weakened heart muscle (cardiomyopathy). When the heart beats too slowly, too little blood is pumped out to the rest of the body. When the heart beats too quickly, it cannot fill completely so the body does not receive the blood volume it needs to function properly.

Arrhythmias are often diagnosed by cardiac exam, electrocardiogram (ECG), Holter monitor, event recorder, or an invasive examination of the heart called electrophysiology study. After thoroughly examining you and determining that you do have an arrhythmia or are at high risk to develop one, the doctor may order one or more tests to determine the type of arrhythmia present, what may have caused it, and how to treat it.

Heart failure is a chronic syndrome that may present with the following signs and symptoms:

• Shortness of breath, especially with activity (dyspnea)
• Nighttime shortness of breath (orthopnea, paroxysmal nocturnal dyspnea)
• Swelling of the feet, ankles, legs, hands, and abdomen from fluid buildup (edema)
• Weight gain
• Fatigue
• Lightheadedness or fainting
• Fluttering of the heart (palpitations)

Who has heart failure?

Approximately 4.9 million Americans, or 1-2% of the entire US population, have heart failure (HF). Each year, there are about 400,000-700,000 newly diagnosed cases of HF and nearly one million hospitalizations due to this illness.

It can affect the young, middle-aged, or elderly. Among the elderly, HF is the number one cause for hospital admissions.

What causes heart failure?

Among the many causes of heart failure, the more common ones are:

• Heart attack
• High blood pressure
• Disease of the heart muscle (cardiomyopathy) from a virus, alcohol, drugs, etc.
• Diabetes
• Diseases of the heart valves
• Diseases of the sack around the heart (the pericardium)
• Continuous fast heart rates

Are there different types of heart failure?

Two types of heart dysfunction can lead to heart failure: "systolic" and "diastolic". They may be present together or separately.

"Systolic" heart dysfunction occurs when the heart is weak and enlarged. It is unable to pump enough blood to supply the needed amounts of oxygen and nutrients to the rest of the body. The walls of the left heart chamber are thinned and the chamber is dilated.

"Diastolic" heart dysfunction occurs when the heart becomes stiff and unable to relax such that the pressure in the heart is elevated and transmitted to the lungs. The walls of the heart are thickened and the size of the left heart chamber is normal to reduced.

Systolic cardiac dysfunction is more common (present in 70% of heart failure cases) compared to diastolic dysfunction as a cause of heart failure.

What are the goals of therapy?

Fortunately, we live in an era in which significant advances have been made in the understanding of the progression of heart failure. Effective therapies continue to be developed to:

• Relieve symptoms and improve quality of life
• Slow disease progression
• Reduce the need for emergency room visits and hospitalization
• Help people live longer