Carrying groceries leaves you winded. At night, you gasp for breath. Your shoes are snug because your feet are swollen. You shrug off the discomfort as the result of recent weight gain and advancing age, but you may actually have heart failure.

Heart failure is not a heart attack but is a life-threatening condition that occurs when your heart is damaged or forced to work too hard. As a result, the heart can't pump enough blood to the other organs. According to the American Heart Association, nearly 5 million Americans are living with heart failure, and 550,000 new patients are diagnosed each year. The condition is especially common among African Americans, who tend to get heart failure at an earlier age and are more likely to be hospitalized or die prematurely. In recent years, the incidence of heart failure has gone up, causing more than a million hospitalizations a year.

While most forms of heart disease occur predominantly in men, heart failure is an equal-opportunity condition that's evenly split between the genders. Among women over the age of seventy, one in ten will wind up with heart failure.

Unlike heart attack, which occurs more suddenly, heart failure develops over several years and gets worse over time. Clogged arteries caused by high-fat diets and inactivity, high blood pressure, diabetes, cigarette smoking, and previous heart attacks stress the heart and gradually reduce its ability to pump blood. Other causes include abnormal heart valves, diseases of the heart muscle, heart defects, severe anemia, hypo- and hyperthyroidism, and abnormal heart rhythms.

The Thyroid Link

Hypothyroidism slows everything down, including your heartbeat. If you have heart failure and develop hypothyroidism, your heart condition will worsen. Without enough thyroid hormone, the heart can't speed up to compensate for the weakness caused by heart failure.

Treatment for hypothyroidism should be started immediately, but the effects may take several weeks to kick in. It may also take a while before you pin down the proper dosage. In the meantime, you can take measures to improve heart health by continuing to take other medications you take for heart conditions, such as high blood pressure medications, and make the necessary lifestyle changes. Tough as it may sound, that means getting some daily exercise, losing excess weight, controlling stress, and eating a healthy diet.

People who have hyperthyroidism may get an unusual type of heart failure called high output failure. In this condition, the heart is pumping so fast that it doesn't have time to fill up with blood, so it becomes incapable of pumping enough blood to the body. Unlike regular heart failure, the medication used for high output failure slows the heart's rapid pumping. Treating the underlying hyperthyroidism also improves high output failure.

Why It's Bad

At first, heart failure is largely an invisible condition. Your heart will compensate for its deficiencies by getting bigger and pumping faster. Over time, as your heart's pumping ability diminishes, the heart can no longer compensate. The result is typically shortness of breath, persistent fatigue, and swelling in your feet and legs as fluid builds up in your body. You may also develop a nagging cough, caused by a backup of fluid in the lungs. In some people, it may become difficult to lie flat on their back.

These days, medications and lifestyle changes — like losing weight, eating healthy, and quitting smoking — can often allow patients with heart failure to live for several years. But experts agree: the best way to treat heart failure is to prevent it in the first place.