By Nicole Pajer

Chances are you’re aware of the classic signs of a heart attack: the crushing chest pain, the shortness of breath. But what about heart disease? This killer doesn’t always strike with a big bang; some indicators of ticker trouble are far less obvious than others. Here are 10 little-known signs that you may have heart problems.

1. You struggle to breathe when lying flat

If breathing is hard when you sleep on your back but often improves when you sit upright, you may have fluid buildup in the lungs, which can indicate heart failure. “When you lie flat, your blood volume gets redistributed,” says Jim Liu, M.D., a cardiologist at the Ohio State University Wexner Medical Center. “The heart can have problems pumping this extra blood volume, and this can lead to increased shortness of breath due to increased fluid in the lungs.” This condition, known as orthopnea, needs a doctor’s immediate attention.

Snoring can also be a red flag. Sleep-disordered breathing, such as sleep apnea, “is associated with metabolic syndrome, which is associated with heart disease,” says Eleanor Levin, M.D., clinical professor of cardiovascular medicine at the Stanford University School of Medicine.

2. You have leg or hip pain (or both) while walking

Lower-body pain can result from injuries, arthritis or being out of shape, but it may also signal circulation problems in the legs from peripheral artery disease. “Much like blockages in the heart arteries can cause heart attacks, blockages in the leg arteries can cause pain when walking,” says Deepak L. Bhatt, M.D., executive director of interventional cardiovascular programs at Brigham and Women’s Hospital in Boston, Massachusetts. If large leg arteries are clogged, smaller arteries in the heart probably are, too.

Circulation-related pain often occurs when you exercise and ends when you stop (the obstruction limits the amount of oxygen reaching the muscles). “When you stop walking, you don’t need that much oxygen and the pain goes away,” says Levin.

3. You experience erectile dysfunction …

Diabetes or chronic stress can cause erectile dysfunction (ED), but it may be a sign of budding heart disease, says Michael Blaha, M.D., director of clinical research at the Ciccarone Center for the Prevention of Cardiovascular Disease at Johns Hopkins Medicine in Baltimore, Maryland. ED is often a blood-flow problem, and risk factors — from smoking to hypertension — are similar for vascular ED and atherosclerotic cardiovascular disease (hardening of the arteries). The root cause of both issues is endothelial dysfunction, in which blood vessels have difficulty expanding and contracting properly, which reduces blood flow to the heart and the penis.

4. … or vaginal dryness

Blood-flow issues aren’t limited to men. In one study, 84 percent of men and 87 percent of women with heart failure reported some degree of sexual dysfunction. For women, the signs can include vaginal dryness and a lack of libido and clitoral sensation: Endothelial dysfunction leads to less elastic blood vessels, which impairs blood flow to the sexual organs.

“The first step of developing cardiovascular disease, or coronary artery disease, is the endothelial dysfunction,” says Ernst von Schwarz, M.D., a cardiologist, researcher and clinical professor at Cedars-Sinai Medical Center and the University of California Los Angeles. This leads to blood vessel issues as well as blood-flow abnormalities, plaque formation, artery calcification and blockage, and, eventually, a heart attack.

5. Your ankles are swollen

When the heart isn’t efficiently pumping blood, fluid can swell both legs. In a study of adults with no history of cardiovascular disease, fluid in the lower extremities was associated with future hospitalizations for heart failure. Swelling can also occur when veins in the legs can’t return fluid to the heart. In cases related to heart failure, swelling often occurs in both legs. Swelling in one leg could be due to a blood clot or an infection. Call your doctor if leg swelling is accompanied by heart failure symptoms such as shortness of breath.

6. You’re fatigued for no reason

If everyday activities make you tired — like needing to rest while making the bed — you may have an obstructed coronary artery.

Most women cite fatigue as their first symptom before having a cardiac event, says Jean McSweeney, professor emerita at the University of Arkansas for Medical Sciences College of Nursing. Fatigue can occur months before a heart attack and may result from lower blood flow to the heart. If you feel unusually tired from mundane activities, call your doctor.

7. You wake up to pee

Waking up to pee isn’t only due to chugging too much beer. A weak heart pumps less blood to the kidneys, which can result in fluid buildup and swollen ankles and legs. At bedtime, gravity drains fluid in the legs back to the heart. The kidneys have more fluid to filter, increasing the need to pee.

Nighttime urination may increase with age, especially in men with enlarged prostates and women with incontinence issues. But waking more than once a night to pee is concerning, says Bhatt, especially if paired with swollen ankles.

8. You have bad breath

Bad breath is caused by out-of-control bacteria, and it can damage more than your social life. Bacteria can enter your bloodstream through bleeding or diseased gums, which is linked to inflammation, clogged arteries and stroke. “There’s a correlation between people who have periodontal disease and people with cardiovascular disease,” says Florida periodontist David Genet.

9. You spot fatty growths

Known as xanthomas, these lesions feel like calcium deposits in the tendons, and they can indicate sky-high cholesterol. Tendon xanthomas typically occur near the ankles and elbows, and are especially prominent in people with a family history of high cholesterol. One study found that the risk of cardiovascular disease was three times higher among those with familial hypercholesterolemia — a genetic predisposition to high cholesterol.

10. You’re feeling nauseous

Unexplained queasiness could be a sign of heart failure, says Cleveland Clinic cardiologist Nicholas Ruthmann, M.D. When the heart struggles to pump blood, fluid and pressure can build up in the lungs, abdomen and lower extremities. Bloating and water retention may lead to nausea, feeling full quickly and decreased appetite.

There’s also a link between queasiness and heart attacks (women are more likely to report nausea as a heart attack symptom). Those with heart failure or a heart attack history should watch for persistent nausea that occurs with bloating, weight gain, swelling in the legs or ankles, and shortness of breath. If these symptoms occur alongside acute chest, jaw or shoulder pain, call 911.