Guest Author - Denise Howard, M.D., M.P.H.

Heart Disease is the number 1 cause of death in the U.S. and the world! What is Heart Disease? How does it occur? What can be done to prevent it?

In order to understand this disease you must first understand the heart. The heart is a muscle about the size of a fist. It is located in the thoracic cavity between the lungs. It contains 4 chambers which are separated by walls and contains structures like doors, called valves, which controls the flow of blood from one chamber to the next. The primary goal of the heart is to pump blood through the body. Blood comes to and exit the heart through large blood vessels called the Great Vessels.

The heart is divided into a right and left side. Each side contains 2 chambers called the atrium and the ventricle. They are referred to as the right atrium and right ventricle or the left atrium and left ventricle. The right side receives blood from the body that is depleted of oxygen and full of carbon dioxide. The blood is transported to the heart through the superior and inferior vena cava. The blood is then pumped to the lungs where the carbon dioxide is removed and oxygen added. This blood is then sent to the left side of the heart and the heart then pumps it through the Aorta to all parts of the body supplying the oxygen needed for our cells to function.

The blood is pumped to all organs through vessels called arteries. These arteries branch to smaller vessels like tree limbs divide into smaller and smaller parts and eventually become twigs. The blood returns to the heart through smaller vessels that merge to larger vessels called veins and eventually to the Vena Cava. The heart also needs oxygenation and the arteries that supply it are referred to as the coronary arteries. They too branch into much smaller vessels like the twigs on a tree.

The heart pumps in a rhythmic fashion. The heart has to relax to allow blood to fill its chambers and then it needs to squeeze to pump the blood the lungs and the rest of the body. This must be coordinated otherwise it wouldn’t be able to perform its function. This cadenced beating of the heart is controlled by an electrical circuit that is conducted through the heart. The tissue contracts in cycles like the falling of dominoes. If one tissue area beats out of cycle the whole rhythm is thrown off and the heart will malfunction.

Heart disease encompasses any injury to any structure of the heart. The most common is damage to the coronary arteries from the buildup of plaque in the lining of the vessels. The vessels can become constricted or the blockage can limit blood supply during times of increased demand. The result is tissue death. We know this as a Heart Attack.

The right or left side of the heart can become overworked. This results when a person has high blood pressure and the heart is pumping harder and harder to supply blood to the tissues. Over time the overworked heart can no longer function ideally. This is known as Heart Failure.

The conduction system can malfunction leading to an abnormal rhythm. The rhythm can be too fast or too slow. The pumping mechanism can be affected. This could lead to sudden death in some cases. This is called a Cardiac Arrhythmia.

The heart valves can be damaged resulting in malfunction. They can become too stiff or too floppy. This is called Valvular Disease. The consequence is that too little blood is pumped to the body or lungs or not enough blood is removed from the lungs. The damaged valves can also set up blood clot formation that may lead to sudden death in the form of an emboli or a stroke.

The heart has a clear-cut function but the processes that require implementation is quite complex. The consequences of heart damage are great. Subsequent articles will focus on specific heart problems and how to prevent these.