Our heart tirelessly pumps blood through the body to nourish our tissues with oxygen and nutrients and to remove waste. The human heart has four chambers: the two upper chambers are the left and right atria and contract first. The two bottom chambers, called the left and right ventricles, contract second.

The right side of the heart receives oxygen-poor blood from veins and pumps it to the lungs to get oxygen and remove carbon dioxide. The oxygen-rich blood from the lungs fills the left side of the heart and then flows to the aorta, the largest artery in our body.

Even though oxygenated blood circulates through the heart all day long, the heart cannot obtain oxygen and nutrients directly from the blood it pumps. The heart has a designated “blood supplier,” called the coronary arteries, that deliver the freshest and best quality nutrient-rich blood. These arteries are the first branches stemming off from the aorta.

The coronary arteries have a relatively small diameter and can be clogged by a fatty buildup called atherosclerotic plaque, which interferes with the blood flow. As a plaque in coronary artery develops, the blood flow to the heart decreases, which can lead to chest pain and discomfort (angina).

This blockage of blood flow causes cells in the heart muscle (called the myocardium) to die. This is what we refer to as a heart attack, or myocardial infarction. The symptoms of heart attack vary from person to person and in males and females. In addition to chest pain, symptoms may include:

• tightening or burning sensation in the chest;
• shoulder pain, arm or jaw pain;
• indigestion or nausea;
• shortness of breath;
• fatigue; and
• dizziness or lightheadedness.

During a heart attack, irregular contractions of the myocardium prevent blood delivery to vital organs, which is why a defibrillator may be required to restart the heart and restore its normal beating. This is why it’s so important to call 911 immediately so that medical professionals can start treatment immediately.

After a heart attack the myocardium develops scar tissue, which can fill a hole in the heart, but it makes it harder to do the important job of the cardiac muscle, which is to pump blood. Medication, surgery or a combination of treatments can repair blockages and help the heart beat more efficiently after a heart attack.

Heart attacks can be fatal and life altering, but they are preventable. Cardiovascular health is something that we can all improve in our day-to-day lives. Adding an exercise, such as swimming, to our everyday routine is a great way to support our heart health by increasing the thickness of the heart muscle—the myocardium—and enhancing blood circulation. Other great ways to support a heart-healthy lifestyle include running or jogging, jumping rope or riding a bike for at least 30 minutes a day.